Typical intensities of wIRA are 80-160 mW/cm^2 delivered in a large area with mostly Red and NIR wavelengths. [1]
This intensity range should be recognizable, as it is similar to the range we are currently seeing in many "highest intensity" LED red light therapy panels, that we affectionately call more appropriately as LED Heat Lamps.
The wIRA therapy attributes the benefits to both thermal and non-thermal mechanisms.[1] However, despite using NIR wavelengths that could be for Photobiomodulation, they know that wIRA wouldn't fit in the category of LLLT/PBM since it is a heating therapy.
wIRA states the minimum dose is 20 minutes to raise the skin surface temperature by about 6C up to about 39C.[1] Well below any safety concerning high temperature 43-45C while still maintaining therapeutic heating.
Even at the lowest dose of 80mW/cm^2 for 20 minutes, that is an Energy Density of 96 J/cm^2. Which would often be considered inappropriate for Photobiomodulation.
Luckily for us, heat therapy doesn't follow the Law of Reciprocity. That is the law of photochemistry that allows us to calculate "dosage" based on Energy (Joules or J/cm^2) by the multiplication of Intensity and Time.
One study on wIRA states this plainly:
"the Bunsen-Roscoe law of reciprocity (which states that a certain biological effect is directly proportional to the total energy dose irrespective of the administered regime) cannot be applied to the thermal effects of IR radiation in tissue"
[2]
Since most of the photons will be converted to heat, we can throw away the dosing calculations for J/cm^2 or Joules.
As one Photobiomodulation review article clearly states:
"Using higher intensity, the photon energy will be transformed to excessive heat in the target tissue"
[3]
High intensity photons being converted into heat is derogatory in the context of LLLT/PBM which are non-thermal, and those photons cannot be counted towards the energy dosing calculations.
"At low irradiances and/or energies, laser-tissue interactions are either purely optical or a combination of optical and photochemical or photobiostimulative. When laser power or pulse energy is increased, photothermal interactions start dominating."
[4]
As the quote above tells us, high irradiances (intensity) will cause heat mechanisms to dominate, not the photochemical and photobiostimulative mechanisms from true "cold" LLLT/PBM at lower intensities.
Essentially, "High Intensity Red Light Therapy" simply becomes Radiant Heat Therapy by converting photons to heat and triggering the thermal mechanisms to dominate. Or perhaps another name for this new science could be PhotoThermalBioModulation. Inserting the word Thermal into PBM to make it clear when heat is being utilized.
Our previous blog covered using LED Heat Lamps as an energy therapy. However, this blog will cover how they could be more appropriately used as what they are - a heat therapy.
As we can already see, wIRA is a much closer science to LED Heat Lamps than anything else. LED Heat Lamps have reverse-engineered wIRA, and pushed themselves out of the categories of non-thermal LLLT/PBM.
The most important dosing technique with LED Heat Lamp therapy is to monitor skin temperature during treatment. This makes sure you are in the proper therapeutic heating zone and monitor for excessive temperature to avoid damage. We use the Berrcom Non-Contact Infrared Thermometer from Amazon.
LED Heat Lamps could be dosed similarly to the research on wIRA and Passive Heat therapies that we can find on PubMed.
A safe heat therapy range is typically between 38 to 41 °C for therapeutic passive heat therapy, typically sustained for 15-90 minutes per treatment.
This is assuming a normal starting skin temperature around 34-36 °C. Meaning typically we look for a skin temperature increase of about 2-6 °C for therapeutic heating. Temperatures up to 42 °C may be acceptable for some contexts or treatments. However typically 41-43 °C are a precautionary range.
Temperatures above 43-45 °C will typically cause a burning sensation and heat pain - sustained or repeated exposure at this temperature could be deleterious unless under medical supervision.
Applications: The best known applications of heat therapy are for temporary pain relief, muscle relaxation, wound healing, inflammation reduction, workout recovery, skin tightening, fat loss, circulatory and cardiovascular health, and more.
Safety: Naturally heat therapy runs the risk of burns if using excessive temperatures for long periods of time or repetitively. Erthyma Ab Inge is a hyperpigmentation response that can occur from sustained or repeated heat therapy. Erthyma is the skin redness from heat or inflammation of the skin similar to sunburn. Blood pressure drops from Nitric Oxide release may be a precaution with people with hypotension (low blood pressure).
Heat therapy can be delivered by fire, sunlight, hot water bottles/bladders, hot water baths, heating suits, infrared heat lamps, saunas, electric heat pads, ultrasonic, radio frequency (RF), high powered lasers, incandescent bulbs, wIRA, and now high-powered LED panels.
Many brands and influencers have proposed using LED Panels as a form of heat therapy. But we need to apply real scientific parameters to this rhetoric. How much heat? What temperature? How long should we sustain the temperature dosage?
Like considering any drug or light therapy, we must look at the proper parameters of heat therapy. Typically the temperature and exposure time are the most important to heat therapy. Then how often/frequently it is used and how many treatments are required.
As one heat therapy explains about the considerations needed:
"To optimize heat therapy, future studies could use the principles of exercise prescription [frequency, intensity, time and type (mode)] in the context of passive heating (Cullen et al., 2020)."
[5]
Similarly, we need to establish some basic parameters and education how to optimize LED Heat Lamp therapy. Which likely follow similar parameters as wIRA and Passive Heat Therapy.
Radiant Heat Therapy must be dosed differently than Cold Light Therapy, and naturally has different protocols and safety considerations.
Dosing "cold" LLLT/PBM:
Dosing Heat Therapy:
Regardless of the type of heat therapy, the main objective is simply to elevate the tissue temperature for the proper amount of time.
While understanding the intensity of an LED Heat Lamp is important as a general indicator, every person will respond differently based on skin tone, skin thickness, and circulation. The skin temperature should be monitored with a thermometer for best results.
Passive Heat Therapy Treatment Protocols:
Similar to wIRA, an emerging therapeutic field is simply called Passive Heat Therapy. This is using various forms of heating to promote healing. Sometimes for spot treatments or whole-body heating.
"Passive heating methods have been used to increase core and/or muscle temperature via different temperature and exposure time, depending on their mechanistic target (e.g., part- or whole-body heating). Hyperthermia is achieved with low-temperature applications (e.g. < 41 °C applied for about 60 min) that increase blood flow and metabolic rates (Habash et al., 2006b), while interventions targeting cellular death (e.g., tumours) via heat-induced protein denaturation require hotter applications (Raaphorst, 1990)."
[6]
One passive heat therapy study utilized a hot bath of 40C (104F) for 20-30 minutes 3 times a week for osteoarthritis.[7]
It is important to keep in mind that therapeutic heating is usually capped at 41C. The consumer has a right to informed consent if they are getting an LED heat lamp, and be informed how to use it safely and effectively.
None will deny that Heat Therapy is very beneficial and effective, in fact, it may be one of the oldest known therapies to humankind.
The internal process of inflammation has its root word in latin meaning "flame". It was coined by Roman physician Cornelius Celsus when observing the redness, swelling, heat, and pain from an injury. [8] Which we now know inflammation triggers healing mechanisms.
More famously, is the body's usage of fever is to raise internal temperature to fight infection. Hippocraties is credited to saying that if given the power to induce fever then he could could cure any illness.
Yes, the power to use heat to heal has been inside us all along. It is an innate part of our biology.
However, humans quickly learned that externally applied heat can also stimulate a healing response. Thus, heat therapies have emerged even in ancient civilizations.
Another quote from Hippocrates is as follows:
"“those who cannot be cured by [medicine or] surgery can be cured by heat; and those who cannot be cured by heat are to be considered incurable”."
[9]
Many passive heat therapy studies introduce themselves by referencing Hippocrates:
"The use of thermal therapies involving passive heating has occurred since the time of Hippocrates (Papaioannou et al., 2016). Since then, passive heating has been therapeutically administered as part of various cardiovascular, metabolic, oncological, and other health treatments (Brunt et al., 2016; Habash et al., 2006a; Maley et al., 2019; Pallubinsky et al., 2017)."
[6]
Here is a quote saying Heat Therapy being credited as being centuries old, we would say heat therapy is actually many millennia old.
"Passive heat therapy is in fact not novel but centuries old, historically used as a form of healing to treat health conditions such as rheumatism and skin conditions (Fagan, 2006; Lehtmets, 1957; Nicholls & Harwood, 2017)."
[10]
This lack of novelty has led many companies selling LED Heat Lamps to promote themselves as Red Light Therapy instead.
Although Heat Therapy is tested by time and well-recognized as beneficial, it is more marketable to piggy-back claims on a newer type of therapy like Photobiomodulation, even though PBM is explicitly defined as non-thermal.
Amazingly, brands have accidentally re-invented heat therapy with new LED technology. It's like the old saying of re-inventing the wheel, except heat therapy is also older than the wheel.
Benefits of Heat Therapy:
Conventionally heat therapies are utilized for wound healing, muscle relaxation, and temporary pain relief.
Whole-body heat therapies like sauna and hot baths are known for supporting cardiovascular health, brain health, mental health, and detoxification.
Similar to Red Light Therapy, Passive Heat therapies are also getting a lot of attention in recent Pubmed studies and articles.
Articles like these are very positive torwards the many benefits of heat therapy.
2016: Passive heat therapy: the next hot thing for cardiovascular health!
2017: Heat: A New Approach to Treating Depression?
2021: Heat therapy: mechanistic underpinnings and applications to cardiovascular health
Even a low level laser therapy study acknowledges the benefits of heat:
"Use of applications that increase the temperature of muscle tissue in the physiotherapy clinic generates many therapeutic effects such as vasodilation (dilation of blood vessels), promoting blood flow, muscle cell activation that can encourage relaxation, tissue renewal that helps promote DNA synthesis and therefore cell proliferation [12]-[14]."
[11]
And another one notes that small temperature increases are used in skincare and dermatology:
"Indeed, it is recognised by the dermatology community that a small incremental rise in temperature of 1–2 °C can enhance the quality of healing processes [73,74]." [12]
We expect the clinical studies on Heat Therapy will rapidly expand similar to Red Light Therapy, especially with the many new technological methods available apply heat therapy.
Mechanisms of Heat Therapy:
One of the most exciting things about Photobiomodulation is the mechanisms of improving mitochondrial function and using fancy words like CytoChrome C Oxidase, Chromophores, and Electron Transport Chain.
Perhaps if we can uncover some equally exciting mechanisms for heat therapy, then brands will be brave enough to promote themselves properly as the LED Heat Lamps that they are.
"That said, there is much that we still do not know, and more studies on the mechanisms that underpin the benefits of passive heat therapy are warranted."
[13]
However, with a lot of recent research on the topic of heat therapies, here are many mechanisms we could find:
Many of these mechanisms and benefits should sound familiar to LLLT/PBM.
It would be the perfect crime to sell high-intensity LED Heat Lamps under an exciting new category of LLLT/PBM Red Light Therapy - and the consumer won't notice the difference that they actually got a Heat Lamp as long as they get similar results.
Safety of Heat Therapy
Brands registered at Medium-Risk Class II Heat Lamps under the ILY code have a medical obligation to provide informed consent to their customers and patients of possible risks of heat therapy.
"How safe is it? No side effects were reported in the studies, but in general, studies report that thermotherapy is safe when applied carefully."
[16]
Carefully applied heat therapy is indeed extremely safe. Keyword being "carefully".
Unfortunately, if the manufacturers aren't designing devices properly and not properly educating the consumer with informed consent, then improperly applied heat therapy is certainly problematic. As we know sustained temperatures of >45C causes deleterious effects.
One wIRA study describes how they monitor skin temperature during treatment with 185 mW/cm^2 of Red and NIR.
"During some of the treatments the skin surface temperature of the treated skin area was continually monitored by the infrared camera. On other occasions the skin temperature was periodically checked during the treatment using a Raytek Raynger MX4 high performance non-contact hand held infrared thermometer (Raytek, Berlin, Germany). Skin surface temperature was not allowed to increase above 41°C. "
[17]
Then they increase the distance (and thus decrease irradiance) to manage the temperature properly or if the patient felt unpleasantly warm.
"On the few occasions that the patient felt that the skin surface temperature was uncomfortably high, the irradiation distance was increased by approximately 5–10 cm. "
[17]
Assuming the temperatures are monitored (<41C) and intensities and exposure times are not excessive. Then generally heat lamp therapies can be safely administered with proper training and awareness.
One study with wIRA showed unsafe heating with 250mW/cm^2 in less than 10 minutes to reach 43C. [18]
Which is likely why they found 80-160 mW/cm^2 is the ideal range for the proper amount of heating. So even with heat therapies, there is a limit to the appropriate amount of intensity.
Most people are aware of the risks of burns with heat therapy. Which is why skin temperature monitoring is crucial. As studies do clearly recognize that prolonged and/or excessive heat exposure has safety hazards. [5]
In some extremely boring YouTube videos, we documented the first attempted usage of high intensity LED panels as a potential for theraputic heating.
We had custom-made high intensity LED panels made with single-wavelengths to test the effects of different wavelengths and intensities on the heating profile. We also tested on high-intensity LED Heat Lamp from AliExpress.
On the chart above, we see the individual wavelengths at high intensity 105-115 mW/cm^2. While we want to be in the optimal heat therapy zone 38-41 C, we see within only 4 minutes all of the wavelengths caused heating past the ideal theraputic zone. So ironically intensities >100mW/cm^2 are not only inappropriate for Photobiomodulation, but these intensities may also be too much for even a heat therapy usage.
Now at intensities between 54-61mW/cm^2 we see a much more gradual heating up period. So this range may be more ideal for a heat therapy, with proper monitoring and adjusting the distance if the temperature gets too high.
Notice how the 630nm and 660nm Red wavelengths deliver significantly more heating than the Near-Infrared wavelengths.
This has been well documented that Red is more heating than NIR. And as we recommended previously that NIR will be required for high-intensity devices to reduce superficial skin heating that is caused by Red. So if you have a high-intensity LED Heat Lamp already, it is better to turn off the Red to reduce heating.
With a 5-wavelength panel from AliExpress with 69mW/cm^2 shows a nice temperature profile that stays in the theraputic range. The plateau of temperature that we see in these graphs shows the thermoregulation mechanisms of my skin (i.e. increased blood flow) working to balance out the constant heat load from the panel.
So even with our initial rudimentary testing, a reasonable heat therapy intensity would be between 55 to 70 mW/cm^2 with LED Panels, and of course monitor the skin temperature and adjust the distance or intensity to stay within the theraputic range for the required exposure time (20+ minutes).
Influencers promoting high-intensity LED Panels have inadvertently declared that Radiant Heat Therapy is the best form of Red Light Therapy.
Many brands have already FDA-registered as the ILY code as heating lamps under the Class II medium-risk category. Conspicuously not registered as true Photobiomodulation devices that even the FDA defined as non-thermal.
https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfRL/rl.cfm?lid=712608&lpcd=ILY
A disclaimer on Joovv's website reads:
"*Joovv light therapy products are intended to provide topical heating for the purpose of elevating tissue temperature"
[Link]
https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfRL/rl.cfm?lid=735369&lpcd=ILY
A disclaimer on Mito Red Light's website reads:
"DISCLAIMER: Mito Red Light devices are Class II wellness devices aimed at affecting the body through topical heating"
This should be rather strange, as PBM and LLLT studies don't describe themselves as intentionally causing heating.
Literally the opposite, as the PBM and LLLT are strictly a non-thermal light therapy that is dosed by low intensities and delivering the proper amount of Energy (J) or Energy Density (J/cm^2).
Statements like "topical heating" and "elevating tissue temperature" are literally describing a Heat Therapy, not a Red Light Therapy.
They mostly instruct the consumer how to use them as a red light therapy device and dose based on Joules, but we think they don't provide adequate warnings and instructions to use them for what they are actually FDA-registered for - as a heat therapy.
Joovv actually provides some instructions on how to use their panels as a Topical Heating device:
"The topical heating treatment distance is ideal for treating symptomatic areas. 10-20 minute treatments at 1-2 inches from your device is optimal"
[Link]
As we accurately prophesied in our Distance blog, using high-intensity LED Panels too close turns them into a Heat Therapy. Joovv has finally accepted their FDA-registered status as a "true medical grade" heat lamp.
A similar instruction would be expected for all the other brands FDA-registered as heat lamps.
According to the world's leading fake reviewer, the Best Red Light Therapy devices aren't even red light therapy at all, they are Therapeutic Heating devices as registered with the FDA.
A cynical person would assume that these brands got registered this way as a convenient loophole to make meaningless marketing claims of being FDA-Registered for a different category of medical product than they are actually selling. But that would be incredibly misleading, and these brands have never given us any reason to doubt their integrity or authenticity.
As positive people, we have to assume these brands got FDA-Registered as Therapeutic Heating devices because they genuinely believe that their products are indeed Heat Lamps.
It is clear these brands and influencers have doubted the efficacy of true "cold" red light therapy. Perhaps as a silent admission that their non-contact Red Light Therapy devices were ineffective, many brands secretly started selling LED Heat Lamps instead. A LED Heat Lamp at least delivers a tangible feeling of warmth for instant gratification.
Regardless, if "experts" want to debate that LED Heat Lamp Therapy is better than true "cold" Red Light Therapy - then we are all for it. However, we at least think there should be more transparency and giving the consumer informed consent that they aren't getting a true "cold" LLLT/PBM device, they are getting a fancy heat lamp.
Benefits and Safety would actually be improved if LED Heat Lamps provided proper instructions on how to use them as a heat lamp as we detailed in this blog, and not being misled as a different medical category of LLLT/PBM that is non-thermal.
High Intensity LED Panels reside in a perfect grey area of being not exactly PBM, not exactly LLLT, not exactly HILT, not exactly wIRA, and not exactly Passive Heat Therapy.
They are the Schrodinger's Box of delivering all of these therapies simultaneously for massive benefits, none of these therapies for inhibitory actions, or worse could overheat the skin for detrimental effects.
In these recent 2 blogs, we dared to open the box and collapse the superimposed state. Giving these products a name of LED Heat Lamps perhaps under new sciences like High Intensity Light Therapy (HILT) and PhotoThermalbiomodulation. This way the naming is properly indicative of expecting heat, whereas LLLT and PBM are clearly for light therapies that do not deliver significant heating.
In the first blog, we likened LED Heat Lamps to High Intensity Laser Therapy (HILT), with dosing based on Energy (Joules or J/cm^2). This could prove to be an effective way to dose high intensity LEDs, but there are massive differences between a large LED panel and a laser delivering extremely high intensity at a small spot size.
In the current blog we considered allowing LED Heat Lamps to deliver heat therapy akin to the sciences of wIRA and Passive Heat Therapy. Heat therapies require longer treatment times of 20-60 minutes to saturate the tissue with a therapeutic amount of heating, contrary to brands claiming higher intensities shorten the treatment times.
This would deliver an inhibitory amount of Red Light Therapy, but promote the heat therapy mechanisms to dominate. Skin temperature should be monitored by thermometer to keep the temperature increase in the therapeutic range of 38-41C for the duration of the treatment, with adjusting the intensity or distance if the heat becomes uncomfortable or outside the safe range.
Ironically, intensity measurements are not as relevant for LED Heat Lamps, as we don't need to calculate J/cm^2 anymore, and just monitor the tissue temperature with a cheap thermometer. So after years of lying about intensity anyway, the LED Heat Lamp brands have made intensity entirely irrelevant to dosing for their products that they specifically claim to "elevate tissue temperature" and provide "topical heating".
Indeed, there are very few true Red Light Therapy devices left on the market. Most of them have become glorified LED Heat Lamps. When brands and fake experts stop false advertising their LED Heat Lamps as Photobiomodulation devices, then it would actually vastly improve safety, effectiveness, and informed consent to the consumer.
Perhaps one day LED Heat Lamps will become their own area of medical science, and we are simply witnessing the advent of a new health device.
[1]
Hoffmann G. Principles and working mechanisms of water-filtered infrared-A (wIRA) in relation to wound healing. GMS Krankenhhyg Interdiszip. 2007;2(2):Doc54. Published 2007 Dec 28.
[2]
Piazena, H.; Kelleher, D.K. Effects of Infrared-A Irradiation on Skin: Discrepancies in Published Data Highlight the Need for an Exact Consideration of Physical and Photobiological Laws and Appropriate Experimental Settings. Photochem. Photobiol. 2010, 86, 687–705.
[3]
Zein R, Selting W, Hamblin MR. Review of light parameters and photobiomodulation efficacy: dive into complexity. J Biomed Opt. 2018;23(12):1-17. doi:10.1117/1.JBO.23.12.120901
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De Moor RJ, Verheyen J, Diachuk A, et al. Insight in the chemistry of laser-activated dental bleaching. ScientificWorldJournal. 2015;2015:650492. doi:10.1155/2015/650492
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Pizzey, F. K., Smith, E. C., Ruediger, S. L., Keating, S. E., Askew, C. D., Coombes, J. S., & Bailey, T. G. (2021). The effect of heat therapy on blood pressure and peripheral vascular function: A systematic review and meta-analysis. Experimental Physiology, 106, 1317–1334.
[6]
Patrick Rodrigues, Gabriel S. Trajano, Lee Wharton, Geoffrey M. Minett,
Effects of passive heating intervention on muscle hypertrophy and neuromuscular function: A preliminary systematic review with meta-analysis,
Journal of Thermal Biology,
Volume 93,
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ISSN 0306-4565,
https://doi.org/10.1016/j.jtherbio.2020.102684.
(https://www.sciencedirect.com/science/article/pii/S0306456520304563)
[7]
Upper-Limb High-Intensity Interval Training or Passive Heat Therapy to Optimize Cardiorespiratory Fitness Prior to Total Hip or Knee Arthroplasty: A Randomized Controlled Trial
Brendon H. Roxburgh, Holly A. Campbell, James D. Cotter, Ulla Reymann, Michael J. A. Williams, David Gwynne-Jones, Kate N. Thomas
First published: 20 September 2023
https://doi.org/10.1002/acr.25238
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Rivas F. In this Issue: Inflammation. Cell. 2010 Mar 19;140(6):755,757. PMID: 20361418.
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Roxburgh BH, Campbell HA, Cotter JD, et al. Acute and adaptive cardiovascular and metabolic effects of passive heat therapy or high-intensity interval training in patients with severe lower-limb osteoarthritis. Physiol Rep. 2023;11(11):e15699. doi:10.14814/phy2.15699
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Durmuş, Hüseyin & Gün, Neslişah & Karaböce, Baki & Seyidov, Mirhasan. (2021). Investigation of temperature effects of a low-level laser source within the muscle phantom. International Journal of Advances in Applied Sciences. 10. 373. 10.11591/ijaas.v10.i4.pp373-377.
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Cronshaw M, Parker S, Grootveld M, Lynch E. Photothermal Effects of High-Energy Photobiomodulation Therapies: An In Vitro Investigation. Biomedicines. 2023;11(6):1634. Published 2023 Jun 4. doi:10.3390/biomedicines11061634
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[15]
Passive heat therapy in sedentary humans increases skeletal muscle capillarization and eNOS content but not mitochondrial density or GLUT4 content
… See all authors
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[19]
These are no longer true Red Light Therapy as that follows the non-thermal light therapy sciences of Low Level Light Therapy and Photobiomodulation. As we discuss in great detail in a previous blog.
As is the basic definition described in most studies:
"Instead of utilizing heat, PBM harnesses the photochemical conversion potential of low-intensity near-infrared (FR/NIR) light within the range of 630–1000 nm.15–18"
[1]
The quote above, like many others we find, emphasizes that heat is not utilized for PBM.
With the essential detail of being low intensity that does not cause significant heating as Dr. Hamblin describes in this article below:
"The reason why the technique is termed LOW-level is that the optimum levels of energy density delivered are low when compared to other forms of laser therapy as practiced for ablation, cutting, and thermally coagulating tissue. In general, the power densities used for LLLT are lower than those needed to produce heating of tissue, i.e., less than 100 mW/cm2, depending on wavelength and tissue type."
[2]
The optimum intensities for LLLT and PBM must fit the criteria to be low enough to not cause heating. For a small laser beam this is usually <100mW/cm^2, for large treatment area devices we find this is generally <50mW/cm^2.
We are at a pivotal moment in light therapy history with this discovery. LLLT was also accidentally discovered by Endre Mester in the 1960's when he used a low power laser on rats. He had meant to use a higher-powered laser, but was surprised at the result that the low power laser caused a biostimulatory responses like improved hair growth and wound healing.
Now in 2024, many brands have accidentally discovered LED Heat Lamp Therapy by making unprecedentedly high powered panels, measuring them with solar power meters, hiring influencers to promote them, and then experimenting on humans with them without informed consent.
Thus, we find many devices are now in an entirely new category of of light therapy, since high-intensity LED panels will cause significant heating on the skin and will no longer be categorized as LLLT or PBM. These blogs will be the first to document and explore the scientific concepts for LED Heat Lamp Therapy.
*Medical Disclaimer* This blog is for educational purposes and is not to be used as medical advice. We recommend consulting with a doctor before proceeding with any therapies or treatments, especially experimental ones like high intensity light therapy that haven't been fully studied.
You could use standard LLLT/PBM dosing (2-10 J/cm^2) and calculate your exposure time to be very limited with high-intensity panels. Our dosing calculator on another blog can help make sure high intensities are not being overdosed.
Since high-intensity devices promise to deliver significantly better penetration, then it is even more important to start with proper low doses 2-10 J/cm^2, even for deep tissue treatments. Where for true LLLT/PBM the higher doses up to 50 J/cm^2 are used for deeper tissue due to having less penetration.
Preferred wavelengths for High-Intensity light therapy are NIR larger than 800nm. This is important for the goal of deeper penetration, but to also avoid the superficial heating caused by Red light or shorter wavelengths that could cause burning or damage.
Pulsing and Scanning modes will also be more important for LED Heat Lamp Therapy to reduce the risk of overheating and burns, similar to high intensity Lasers.
Applications: The best known applications of high-intensity red light therapy are for temporary pain relief, muscle relaxation, wound healing, inflammation reduction, and various musculoskeletal pain conditions.
Safety: High intensity light therapy runs the risk of burns if using excessive temperatures for long periods of time or repetitively. Erthyma Ab Inge is a hyperpigmentation response that can occur from sustained or repeated heat therapy. Erthyma is the skin redness similar to sunburn. Blood pressure drops from Nitric Oxide release may be a precaution with people with hypotension (low blood pressure).
Large LED Arrays (panels) delivering high power density (>50mW/cm^2) will often deliver a heating effect on the tissue. Thus no longer meeting the basic definitions of Low Level Light Therapy (LLLT) or Photobiomodulation (PBM) which we cover in a previous blog is well-known as being a non-thermal "cold" light therapy.
These new high-intensity LED devices must be studied under a different therapeutic category: especially for proper dosing, safety, mechanisms, and benefits.
Studies have identified a new category called High-Intensity Laser Therapy (HILT), a separate therapy from LLLT or PBM. These HILT lasers use higher powers than typical LLLT cold lasers.
"Unlike LLLT, HILT produces a thermic effect on the treated tissues."
[4]
Again emphasizing the lack of thermic (heat) effect from true LLLT.
Since high-intensity LED Panels also produce a thermic (heat) effect, then a new category of therapy could be High Intensity Light Therapy (HILT) that also uses LEDs. Similar to how LEDs initially piggy-backed into LLLT. Or a more common term will be LED Heat Lamps, similar to how we refer to Incandescent NIR Heat Lamps.
In this blog, we will be examining the potential dosing in the Laser therapy called HILT, and implications on high-intensity LED devices, however it may be irrelevant due to natural differences in LED and Laser.
We like to assume that Red Light Therapy and Heat are complimentary to do together.
However, as PBM and LLLT are typically a "cold" light therapy, it is usually optimized by using techniques that minimize heating like non-thermal wavelengths, low intensity, pulsing that allows tissue cooling between pulses, scanning methods, and external cooling like cold packs and cold air.
Heating has been documented to decrease the penetration of light by increasing blood vessel volume and blood flow.[4] Heat has been also attributed to a rise in ROS when combined with Red/NIR light, which would play a role in the inhibitory responses (biphasic dosing).[5]
Like combining any medicines or therapies - the best thing to do is to truly test your theories. Salespeople using rhetorical arguments that "sunlight is warm" and that the "heating feels good and anecdotally is beneficial" only confirms an apparent lack of science to back up this combination of Light and Heat therapies.
Studies on HILT are indeed very positive on their speculations that you get the best of both worlds when you combine light therapy and heating.
"low-level laser therapy (LLLT) and high-intensity laser therapy (HILT) while both shared similar photo-biomodulation and anti-inflammatory effects, LLLT (energy output ≤500 mW) reaches superficial tissues only, while HILT (energy output >500 mW) can reach deeper tissues. In addition, HILT can produce photothermal effects [7, 8]."
[6]
With the quote above emphasizing the difference that HILT adds the photothermal effects whereas LLLT does not have thermal effects.
One study states:
"HILT offers distinct advantages over LLLT as it enables the delivery of higher energy over time. HILT allows for more energy deposition in deep tissues, resulting in both the biological effects of LLLT and thermal effects [13, 14, 18]."
[7]
The contrast is important that if you are having thermal effects then you simply aren't doing LLLT/PBMT. Adding heat to PBM simply becomes a different type of therapy like HILT.
And another study states:
"HILT is hypothesized to have similar properties to LLLT, but with augmented effects due to its higher power. A commonly mentioned advantage of HILT is that, with increased power, the depth of penetration may also increase (ref)."
[8]
Although many studies mention HILT is implied to have better penetration than LLLT, I have not seen any comparative data to confirm. Ironically the quote above has a placeholder for a reference (ref), but the author likely forgot to add the citation.
One article notes that LLLT average penetration is 2-4 cm, and HILT average penetration is 10-20 cm. But they do emphasize the use of NIR for HILT for deeper penetration. [7]
Another article says:
"These advantages include (i) a higher energy output than low-level laser therapy [11]; (ii) an anti-inflammatory effect with pain modulation and impact on nerve endings for pain relief [8,11]; and (iii) a scattering mode of laser radiation with therapeutic photo-thermal effects that induce localized muscle relaxation, reducing muscle spasms [13]."
[10]
The researchers conducting HILT trials are assuming it combines the benefits of LLLT with heating as well as potentially better penetration due to the nature of high intensity. Some studies mention a Photomechanical and Photothermal effect only gotten by HILT, and not from LLLT which is only a Photochemical effect.
Even if we can make hypothetical arguments that Light and Heat combined are beneficial, then we once again have made "red light therapy" much more complicated by adding a new variable of heat.
As always, the devil is in the details. How do you properly dose high intensity heating devices? How do you make sure it is safe? That it is effective and optimal?
In HILT, doses are ranging from typical PBM doses (2-10 J/cm^2) up to hundreds or even thousands of J/cm^2. [11] There aren't as solid dosing guidelines like we have for cold LLLT/PBM.
"One group preferred to use a fluence (energy density) range of 9 to 225 J/cm2 while another group reduced fluence to 1.2 to 6 J/ cm2."
[11]
Even if we had consistent HILT dosing, a small laser dose will be very different than a large high-powered LED panel.
HILT studies may not be relevant at this time for commercial LED panels until they actually start doing HILT studies with larger devices.
In various musculoskeletal conditions and pain, there have been a few trials comparing LLLT and HILT.
One study found that HILT performed better than LLLT on 98 humans with carpel tunnel. Both used the same dose of 8 J/cm^2 or 20 J/cm^2 and found the High Intensity Laser Treatment was most effective at 8 J/cm^2. [11]
Confirming a biphasic dose response as the 20 J/cm^2 was not effective, even in a human study. The LLLT was 50mW and HILT was 1,600 mW, but the intensity was not specified (the size of the laser spot was not specified so I can't calculate it either). [11]
Both LLLT and HILT showed improvement, the HILT had better results overall. And even with HILT the biphasic dose response must be observed.
One study compared LLLT and HILT on plantar fasciitis in 102 humans and found that both groups improved, but no significant difference was found between HILT vs LLLT. The parameters of both lasers were very different, both treatments were around 7 minutes with a dose of 4 J/cm^2 for LLLT and a dose of 120 J/cm^2 for HILT. [12]
Another study used LLLT of 400mW and HILT of 5,000mW again with unspecified intensity. The LLLT was 830nm at 10 to 12 J/cm^2 and the HILT was 1064nm at 19 to 150 J/cm^2. Both groups saw improvement for Knee Osteoarthritis, but the HILT group saw statistically significantly more benefit. [13]
They acknowledge the differences in wavelengths and dose also could have an impact. They note the LLLT could be more effective used in the stationary mode (holding it still), and there is a preference to use HILT to be used in the scanning mode (slowly moving it back and fourth across the treatment area).
Another review article discusses comparisons of LLLT to HILT used for musculoskeletal and found a lack of consistency to determine which would be better. They suggest more studies on this topic.
"A well-designed RCT should be conducted to compare the effects of LLLT versus HILT for musculoskeletal pain disorders in order to confirm or infirm the superiority of HILT over LLLT."
[14]
Since LLLT did indeed provide benefits in all of these cases, we emphasize our point to start with the safest, low intensity, low dose treatments. In most cases this produces a beneficial healing response, and only carefully implement higher intensities as needed.
For safety and to manage the heating produced by high intensities, then pulsing and scanning techniques become almost essential for effective usage of HILT.
"Furthermore, it has been suggested that pulsed mode could yield better outcomes than continuous laser mode because the photothermal effects can be controlled and limited for patient safety by modulating pulse intensity and frequency"
[14]
Pulsing essentially allows for higher peak intensities while reducing the average intensity. During the "off" time of the pulses it gives the tissue a small amount of time to cool off and thermoregulate.
Another article comments on how scanning high intensity lasers (waving them slowly back and forth over the treatment area) is a more effective way to deliver HILT.
"Moreover, with specific consideration of HILT (as it delivers a higher dose of laser energy), scanning mode is preferable as it theoretically allows for deeper penetration, greater stimulation of cellular processes, and better heat dissemination (to avoid skin burn) [18]."
[10]
If high intensities were to be properly implemented into LED panels, it would require more complex electronics like pulsing modes to reduce the heat on the skin. As that is the primary reason studies use pulsing anyway is to allow the skin to cool between pulses, not for any magical mechanisms related to the pulse frequency itself.
It would require more from the consumer/patient/user to understand the scanning method and wave their device of body around to avoid the heat. Or perhaps use a cooling fan aimed at the patient to also reduce the heating on the skin.
LED Heat Lamps would need to use more of the ratio of wavelengths in the Near-Infrared to deliver on the promise of deeper penetration and avoid problematic heating caused by superficial Red wavelength absorption. For example the typical 50/50 split of Red/NIR would be inappropriate for high intensity LED panels, and should favor a much higher % in the NIR, or perhaps no Red at all.
In other words, simply standing in front of a low intensity true PBM panel for 10-20 minutes will become much more complicated with high intensities. We find many people are just now grasping the proper distance to use a panel, but now manufacturers will require them to dance around in circles as a type of scanning method.
One study on 114 people with Plantar Fasciitis used either a 10W or 25W laser for a dose of 10 J/cm^2. Both groups got similar results in reduction of pain, showing that a dramatically higher intensity does not inherently get better results.
[15]
This is another example where seemingly "low" doses of 10 J/cm^2 are used for deep tissue, because the high intensity lasers penetrate deeper.
Heat is an inevitable consequence of any energy therapy, although in LLLT and PBM it is managed and minimized as much as possible.
One study notes that monitoring tissue temperature will be important to understand the thermal effects of PBM. This will be important for Part 2 of this series.
"We demonstrate in this study that simply monitoring surface temperature is a very potent real-time clinical biomarker to ensure treatment safety."
"We strongly advocate reporting treatment surface irradiance and surface temperature, when available, in future PBM studies to aid in robust future reproducibility of specific treatment protocols."
[16]
One PBM article investigated the possible influence of heating on the therapy titled "Photothermal Effects of High-Energy Photobiomodulation Therapies: An In Vitro Investigation".
It notes that a small temperature increase of 1-2 C is potentially advantageous, but excessive or sustained temperature increase is detrimental. Even up to 6 C increase is acceptable as long as the temperature stays below 45C.
"It is accepted that beyond this extra 6 °C level, there is the potential for permanent deformation of structural tissue proteins to occur, as well as perhaps other biomolecules, when subjected to protracted exposure to temperatures above 45 °C"
[17]
Another PBM article reinforces this position of excessive temperatures from high intensities that could cause damage.
"But rising tissue temperature above 45° C causes irreversible damage [15]."
[18]
Luckily, the skin should detect significant heating at 41°C to pull away, and heat pain should be triggered at 43-45°C. However, this also means that high intensity light therapies are contraindicated for people that might not have normal heat sensations.
Regardless, the most prudent advice for safely using high intensity devices would be to monitor skin temperature for the safe temperature range, especially since skin tone, skin thickness, and circulation will all affect individual's heating response. We cannot use intensity alone to understand the expected amount of heating.
One 2022 PBM study used a 780nm LED at 3,800 mW/cm^2 for 3 minutes (pulsed) to treat neck and shoulder pain in humans. The dose was reported as 570 J/cm^2. [19]
They monitored skin temperature was risen on average of 6.8C up to about 41C. [19]
Skin redness was observed in 9 out of 10 patients due to the heating. This will likely be a common side effect for high-intensity Red Light Therapies in the future, although it is rarely reported since most PBM studies avoid causing significant heating like this. As well we already know one study found these side effects at 480 J/cm^2.
It is important to note that high intensities and/or doses of Red Light Therapy do well for temporary pain relief by leveraging the inhibitory side of the biphasic dose response. Specifically inhibiting the pain signals by nerve cells. This we show in our dosing blog as the analgesia region of the dosing graph. So for temporary pain relief high intensities and doses may be prefered, at the detriment of slower healing.
Which may explain the preference for HILT to be used in mostly areas of musculoscheletal pain management.
As the authors correctly point out, they cannot discern if the benefits were entirely from the PBM effects, the heat, or the combination. Especially since both PBM and Heat Therapy could certainly be used to treat areas of pain.
"One possible mechanism for the effectiveness of our device may be the physiological changes caused by the increase in skin temperature."
[19]
In most other PBM/LLLT studies they are clear that the benefits and gotten are from non-thermal interactions and mechanisms. The reason why heating is separated from PBM is illustrated by this study, that heat therapy mechanisms could end up influencing or dominating the effects.
More information on the differences between LLLT and HILT can be found in the article below.
It contains many practical tips for the application of HILT like pulsing, longer wavelengths, and that HILT is almost always non-contact to prevent overheating of the skin.
A fun fact according to the article; While we know LLLT was discovered in the 1960's and had it's first FDA approval for treating pain in 2001 - HILT was first published in 2009.
This is why LLLT/PBM has such a larger pool of studies and benefits. The article shows the contrast that LLLT has many more clinically studied treatments than HILT at this point.
It is important to remember the major differences between High Intensity Lasers and high intensity LEDs.
We can find a parallel that high-intensity LED Heat Lamps cause heat similar to HILT. LED Heat Lamps cannot fit in the PBM or LLLT categories due to heating.
In terms of the promise of higher penetration with high intensities, the (peak) intensities used in HILT are on the scale of thousands of mW/cm^2. [16]
So a "high intensity" LED panel only emitting 50-500 mW/cm^2 are still nowhere near the intensities needed for the penetration promised by HILT delivered by lasers. Despite many salespeople promising that their overpowered non-contact LED panels magically deliver deep penetration.
Truly high-intensity LED Panels would need similar modes as HILT like pulsing and scanning to properly manage the heat. Perhaps even abandoning Red wavelengths entirely and only using NIR to reduce heating and focus on deeper penetration.
We can see even for HILT that proper Energy Density (J/cm^2) will be even more important.
Since high intensities supposedly deliver deeper penetration, then proper dosages are often less than or equal to 10 J/cm^2. For LLLT sometimes the dosage is higher 10-50 J/cm^2 for deeper tissue, but since HILT penetrates deeper by virtue of high intensity, then the dosage usually needs to be lower.
High Intensity Laser Therapy appears to be chosen for various areas of musculoskeletal issues and pain. It is a new area of research compared to LLLT/PBM so proper dosing and applications have not been fully studied.
There is clearly a lot of hype and competition for LED Panels to deliver high intensity based on speculative superiority of benefits and penetration. Often encouraged by fake experts that don't understand the basic definition of LLLT/PBM as being non-thermal. This has easily crossed the line into an entirely new category of therapy that has not yet been studied.
High-Intensity LED Heat Lamps could indeed be implemented for the benefit of humanity, but only when it receives proper scientific research and it is mindfully implemented. In part 2 we will explore using them as a true heat therapy.
Until then, the promise of speculative benefits and lack of dosing guidance don't outweigh the massive amount of safety and effectiveness already proven by non-thermal LLLT/PBM.
[1]
Siqueira RC. Photobiomodulation Using Light-Emitting Diode (LED) for Treatment of Retinal Diseases. Clin Ophthalmol. 2024;18:215-225. Published 2024 Jan 22. doi:10.2147/OPTH.S441962
[2]
Hamblin, MR. MECHANISMS OF LOW LEVEL LIGHT THERAPY
http://photobiology.info/Hamblin.html
[3]
Chaki C, De Taboada L, Tse KM. Three-dimensional irradiance and temperature distributions resulting from transdermal application of laser light to human knee-A numerical approach. J Biophotonics. 2023 Sep;16(9):e202200283. doi: 10.1002/jbio.202200283. Epub 2023 Jun 14. PMID: 37261434.
https://pubmed.ncbi.nlm.nih.gov/37261434/
[4]
Tanaka Y, Tsunemi Y, Kawashima M, Tatewaki N, Nishida H. Objective assessment of skin tightening in Asians using a water-filtered near-infrared (1,000-1,800 nm) device with contact-cooling and freezer-stored gel. Clin Cosmet Investig Dermatol. 2013;6:167-176. Published 2013 Jun 26. doi:10.2147/CCID.S47299
[5]
The effects of infrared radiation on the human skin
Luke Horton, Joshua Brady, Colin M. Kincaid, Angeli Eloise Torres, Henry W. Lim
First published: 11 July 2023
https://doi.org/10.1111/phpp.12899
https://onlinelibrary.wiley.com/doi/10.1111/phpp.12899
[6]
Xie YH, Liao MX, Lam FMH, Gu YM, Hewith A Fernando WC, Liao LR, Pang MYC. The effectiveness of high-intensity laser therapy in individuals with neck pain: a systematic review and meta-analysis. Physiotherapy. 2023 Jul 20;121:23-36. doi: 10.1016/j.physio.2023.07.003. Epub ahead of print. PMID: 37812850.
https://www.physiotherapyjournal.com/article/S0031-9406(23)00037-8/fulltext
[7]
de la Barra Ortiz, H.A., Avila, M.A., Miranda, L.G. et al. Effect of high-intensity laser therapy in patients with non-specific chronic neck pain: study protocol for a randomized controlled trial. Trials 24, 563 (2023). https://doi.org/10.1186/s13063-023-07599-0
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10472636/
[8]
Starzec-Proserpio M, Grigol Bardin M, Fradette J, et al. High-Intensity Laser Therapy (HILT) as an Emerging Treatment for Vulvodynia and Chronic Musculoskeletal Pain Disorders: A Systematic Review of Treatment Efficacy. J Clin Med. 2022;11(13):3701. Published 2022 Jun 27. doi:10.3390/jcm11133701
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9267539/
[9]
de la Barra Ortiz HA, Avila MA, Miranda LG, Liebano RE. Effect of high-intensity laser therapy in patients with non-specific chronic neck pain: study protocol for a randomized controlled trial. Trials. 2023;24(1):563. Published 2023 Aug 31. doi:10.1186/s13063-023-07599-0
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10472636/
[10]
Ahmad MA, Moganan M, A Hamid MS, Sulaiman N, Moorthy U, Hasnan N, Yusof A. Comparison between Low-Level and High-Intensity Laser Therapy as an Adjunctive Treatment for Knee Osteoarthritis: A Randomized, Double-Blind Clinical Trial. Life. 2023; 13(7):1519. https://doi.org/10.3390/life13071519
https://www.mdpi.com/2075-1729/13/7/1519
[11]
Ezzati K, Laakso EL, Saberi A, Yousefzadeh Chabok S, Nasiri E, Bakhshayesh Eghbali B. A comparative study of the dose-dependent effects of low level and high intensity photobiomodulation (laser) therapy on pain and electrophysiological parameters in patients with carpal tunnel syndrome. Eur J Phys Rehabil Med. 2020 Dec;56(6):733-740. doi: 10.23736/S1973-9087.19.05835-0. Epub 2019 Nov 18. PMID: 31742366.
https://pubmed.ncbi.nlm.nih.gov/31742366/
[12]
Naruseviciute D, Kubilius R. The effect of high-intensity versus low-level laser therapy in the management of plantar fasciitis: randomized participant blind controlled trial. Clinical Rehabilitation. 2020;34(8):1072-1082. doi:10.1177/0269215520929073
https://journals.sagepub.com/doi/10.1177/0269215520929073
[13]
Ahmad MA, Moganan M, A Hamid MS, Sulaiman N, Moorthy U, Hasnan N, Yusof A. Comparison between Low-Level and High-Intensity Laser Therapy as an Adjunctive Treatment for Knee Osteoarthritis: A Randomized, Double-Blind Clinical Trial. Life (Basel). 2023 Jul 6;13(7):1519. doi: 10.3390/life13071519. PMID: 37511894; PMCID: PMC10381799.
https://pubmed.ncbi.nlm.nih.gov/37511894/
[14]
Starzec-Proserpio M, Grigol Bardin M, Fradette J, et al. High-Intensity Laser Therapy (HILT) as an Emerging Treatment for Vulvodynia and Chronic Musculoskeletal Pain Disorders: A Systematic Review of Treatment Efficacy. J Clin Med. 2022;11(13):3701. Published 2022 Jun 27. doi:10.3390/jcm11133701
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9267539/
[15]
Ketz AK, Anders J, Orina J, et al. Photobiomodulation Therapy Plus Usual Care Is Better than Usual Care Alone for Plantar Fasciitis: A Randomized Controlled Trial. Int J Sports Phys Ther. 2024;19(1):1438-1453. Published 2024 Jan 2. doi:10.26603/001c.90589
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10761604/
[16]
KHAN, I., ARANY, P.. Dosimetry for photobiomodulation therapy: response to Sommers et al. Annals of Translational Medicine, North America, 4, may. 2016. Available at: <https://atm.amegroups.org/article/view/10516>. Date accessed: 01 Mar. 2024.
https://atm.amegroups.org/article/view/10516/11143
[17]
Cronshaw M, Parker S, Grootveld M, Lynch E. Photothermal Effects of High-Energy Photobiomodulation Therapies: An In Vitro Investigation. Biomedicines. 2023;11(6):1634. Published 2023 Jun 4. doi:10.3390/biomedicines11061634
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10295700/
[18]
Durmuş, Hüseyin & Gün, Neslişah & Karaböce, Baki & Seyidov, Mirhasan. (2021). Investigation of temperature effects of a low-level laser source within the muscle phantom. International Journal of Advances in Applied Sciences. 10. 373. 10.11591/ijaas.v10.i4.pp373-377.
[19]
Odagiri K, Yamauchi K, Toda M, et al. Feasibility study of a LED light irradiation device for the treatment of chronic neck with shoulder muscle pain/stiffness. PLoS One. 2022;17(10):e0276320. Published 2022 Oct 17. doi:10.1371/journal.pone.0276320
]]>The published dosing guidelines by the World Association for Laser Therapy (WALT) are noted to be for Caucasian skin types:
"Recommended doses are for white/caucasian skin types based on results from clinical trials or extrapolation of study results with similar pathology and ultrasonographic tissue measurements."
https://waltpbm.org/documentation-links/recommendations/
While many studies acknowledge the potential impact of skin color on Photobiomodulation dosing and effects, it has not been thoroughly investigated yet.
One review article attempted to investigate the effects of using PBM to treat diabetic foot ulcers based on skin color, but of the 15 studies they reviewed; only one reported the skin color demographics and adjusted the dose based on skin type.[1]
"Most studies conducted thus far on PBM do not mention the skin color nor race of patients, which should be considered due to varying photon absorbencies by melanin. Only one of the studies evaluated in this review took skin color into consideration and adjusted the dose accordingly. " [1]
It is recommended that studies record the skin color of the participants in order to make analysis of results based on skin type. Even if no adjustment to the parameters is made yet, this will be valuable data to use in the future to improve treatments.
"Complete reporting should also include the distance of the light device from the tissue surface, spot size (cm2), skin color, and use of the current terms" [2]
In this blog we review the PBM articles that discuss how skin color impacts red light therapy, and the recommended dosing adjustments that can be made to improve results based on skin phototype.
Melanin is a pigment in the skin that primarily protects from excess sunlight exposure. Inevitably, this has a significant impact on light therapies.
Having a darker skin type means there is a higher concentration of melanin in the skin. Lighter skin types means there is relatively less melanin in the skin.
With higher melanin concentrations, wavelengths of light will be more superficially absorbed by this pigment. This leads to a reduction of light penetration, less dosage reaching target tissue, and superficial heat effects.
"Skin color and skin thickness affect transmittance and reflectance of laser light and must be accounted for when selecting energy dose to ensure therapeutic effectiveness at the target tissue. " [3]
For optimal red light therapy - adjustments to the wavelengths, intensity, application modes, and/or dose may be required to produce better results depending on Skin PhotoType (SPT).
There are two main theories for how to dose based on Skin PhotoType for Photobiomodulation (PBM).
1. As long as the device parameters and dosage are considered safe and non-thermal for all skin types, most studies make no adjustments based on Skin PhotoType for patients.
2. Adjustments for darker skin types may include:
These adjustments may be more important for treating deeper tissue. Reducing the intensity by even 25% and increasing the dose by 25% also means the exposure time will be increased by around 1.6 times!
For skincare and superficial treatments, it is likely fine to use the same parameters for all skin types - again assuming it is mostly non-thermal intensity and a reasonable dosage.
The Fitzpatrick scale from I to VI (one to six) is used to describe the general range of skin color in humans as determined by the melanin concentration in the skin.This is also shortened to Skin Phototype (SPT). [4]
A higher melanin concentration is important for UV protection from the sun.
A standard metric called the Mean Erythyma Dose (MED) is when the skin reddens from UltraViolet (UV) dosage (i.e. what we call Sunburn). The MED is 2-6 times larger for dark skin types compared to light skin types due to higher protection factor provided by the melanin. [5]
Which is overall a good thing in terms of protection from skin cancers, as is one of the functions of the Fitzpatrick PhotoType scale is to determine relative risk of skin cancer. With lighter skin types being 20-32 times more prevalent to skin cancers due to a lack of natural UV protection from melanin. [5]
However, some studies have found that people with darker skin types produce 1.3 to 6 times less Vitamin D than the same UV dose delivered to the lighter skin types.[6] These experiments confirm the reason why surveys find a correlation between people with darker skin types and Vitamin D deficiency. [7]
Another study mentions:
"Individuals with lighter skin can generate >50 nmol/L of 25(OH)D from 30 minutes of sun exposure daily, but darker skin requires upwards of two hours of exposure to reach the same amount produced "[7]
Requiring 4 times more sunlight exposure time than lighter skin types to produce the same amount of Vitamin D.
We introduce this background section to remind people how sunlight is essential to optimal health, and the parallel that longer exposure times may also be required for red light therapy for people with darker skin types.
Interestingly, it was noted in one study that the Fitzpatrick skin phototype scale was originally developed to help clinicians adjust the dose for UV-A treatment for psoriasis. The same concepts may apply to Red Light Therapy. [8]
Several studies have been conducted with Fitzpatrick Skin types ranging from II to VI with Red and Blue LED phototherapy to manage acne.[9][10][11]
A review article titled "Acne Vulgaris in Skin of Color: A Systematic Review of the Effectiveness and Tolerability of Current Treatments" concludes:
"Overall, LED appears to be tolerable and effective therapy for acne vulgaris in skin of color patients." [12]
One study used the Ominlux 633nm and 830nm clinical grade system for an improvement in melasma with 60 females Fitzpatrick IV-V. They used the same dosing protocol that is also used for skin rejuvenation trials for other skin phototypes. [13]
A study using the Omnilux for Men LED mask notes that people with darker skin types are more susceptible to postinflammatory hyperpigmentation, erthemya, and blistering particularly at higher intensities or doses. [14]
However, they reassure the reader that LED face masks have a large margin of safety for skincare even for darker skin types:
"The commercially available face mask doses used for treatment are far below this threshold associated with adverse events in skin of color patients. Larger randomized controlled trials (RCTs) with more racial and ethnic representation are needed to further evaluate safety, efficacy, and overall experience using PBM in darker skin types." [14]
As is often noted, there is a call to action that more studies are needed with better diversity in order to truly optimize the safety and effectiveness.[14]
So for superficial applications like skincare, it is likely fine to use the same dosing parameters for all skin types.
The general sentiment for dosing is summarized by the following quote. The parameters of PBM do not need to be adjusted based on skin type as long as it is non-thermal for all skin types.
"As the PBMT device used in the study causes no harmful thermal effects,[23] volunteers of different skin colors will be recruited." [15]
However, a recent 2024 study using PBM for plantar fasciitis found that the patients with darker skin types had poorer outcomes than people with lighter skin types. Although some benefits were gotten using the same dose for all skin types, it likely could have improved with some adjustments.
"The study had a significant finding that higher Fitzpatrick category was predictive for poorer outcomes in the FAAM ADL and sports subscale, but had no significant impact on pain. Though these results should be interpreted cautiously due to the small number of participants in higher Fitzpatrick categories, it is important to remember when designing treatment protocols to consider using a longer wavelength option (e.g., 980 nm) for those individuals" [16]
So although many benefits are gotten by treating all skin types with the same parameters, it is becoming clear that adjustments should be made to account for bioindividuality.
Here are a few studies and documents that advise adjusting the intensity, dose, wavelengths, and/or application mode (pulsed vs continuous) based on skin phototype.
One study recommends generally higher doses to reach deeper tissue targets:
"The clinical implication is that higher doses may be needed to deliver the same quantity of photons to the target tissue below the skin of persons with dark skin compared to those with light skin. Additionally, longer wavelengths may be more effective in treating deep lesion in individuals with darker skins.9,11" [17]
Another study notes that they increased the dose by 50% for people with dark skin in the trial:
"For dark residents with dark skin, the dose around the periphery was increased by 50%, as melanin absorbs photons and less is delivered to underlying tissue." [18]
In the Handbook of Low-Level Laser Therapy, authors Hamblin, de Sousa, and Agrawal comment that practitioners have observed less effectiveness treating wounds for darker skinned patients. They recommend increasing the dose by 25% and using pulsed modes to reduce heating. [19]
One study notes that the intensity was reduced by 50%, presumably to reduce superficial heating. However, it did not seem to increase the dose other than increasing the exposure time to deliver the same dose at the lower intensity (i.e. the exposure time would need to be doubled if the intensity was cut in half to reach the same dose).
"For patients with dark skin color, there is a pigment adjustment selection button on the laser console. When the pigment selection is activated, laser intensity is reduced by 50% and the software automatically recalculates the required dose." [20]
One study notes that for the lightest skin types the dose was decreased by 25% and for the darkest skin types the dose was increased by 25%:
"To address the possible effect of skin pigmentation on photon absorption, the Fitzpatrick Skin Type Scale (95) was used to determine skin type (pigmentation level), ranging from 1 (very fair skin) to 6 (darkest skin). The dose was adjusted when treating participants who had the lightest pigmentation, 1; or the darkest pigmentation, 6. Four participants had levels 1 or 6, and all others, in between. For those with the lightest skin, the treatment time/dose was reduced by 25%, and for those with the darkest, increased by 25%." [21]
One study comments that the recommendation is typically to increase the dose by up to 50% for darker skin types and decrease the dose by up to 50% for lighter skin types. However, they caution that this advice is "arbitrary", meaning it lacks evidence or substantiation. [8]
So we do have some clear guidelines that doses could be increased by 25-50% for the darkest skin types and even reduced by 25-50% for the lightest skin types. Reducing the intensity or using pulsing will also be helpful to reduce heat effects. However, many of these adjustments have not been well studied and standardized.
With superficial absorption and melanin's excellent ability to convert photons into heat, then safety becomes an important factor for dark skin.
"Melanin takes in excessive light energy and converts it to heat in a process called absorption; heat is then dissipated into the environment as infrared radiation, thereby protecting the underlying skin." [22]
One laser study monitored the skin temperature response in patients with a range of skin phototypes. They found that typical powers and doses did not cause significant heating in the light and medium skin tones, however with the higher powered laser the people with darker skin types felt a pain response from too much heat.
"The significant heating of dark skin by the 200 mW, 810nm laser has implications for irradiation safety and clinical practice. There was three to sixfold increase in skin temperature in dark skin, reaching 42-43C, when compared with light and medium skin. This temperature corresponds to the thershold for painful thermal stimuli and was achieved even at small irradiation doses." [23]
Another study investigated the dosing limits based on skin types, and found that darker skin types had adverse events at lower doses than lighter skin types.
"Adverse events (AEs) included treatment-site erythema, hyperpigmentation, and blistering, all of which were mild and resolved without permanent sequelae.38 We concluded that LED-RL is safe up to 480 J/cm2 and may exert differential cutaneous effects depending on race and ethnicity, with darker skin being more photosensitive.38" [24]
Another study notes on the maximum intensity tolerated will be lower for people with darker skin types.
"Depending on the wavelength used, the upfront heat generated from absorption by melanin may be a dominant factor limiting the upper maximal limit of tolerable power intensity, particularly in darker pigmented individuals. " [25]
High intensities will cause more rapid heating which could lead to more adverse effects. Prolonged exposures and high doses are also correlated with more adverse effects.
This is why some clinicians are recommending reducing the intensity or using pulsed modes to reduce the heat. Near-Infrared wavelengths that will cause less heating compared to Red light will be more superficially absorbed by melanin.
Melanin is a strong pigment for visible light, but does continue absorption into Near-Infrared range.
We often refer to this chart of the primary chromophores that cause superficial absorption in the skin.
The brown line in the chart above is the Melanin absorption coefficient spectrum. You can see it steadily decreases with longer wavelengths. However, it is clearly a strong absorber in the Red range and even into the NIR.
What this chart doesn't tell you is the concentration of melanin in the skin, only the coefficient of absorption.
A relevant study titled "Melanin Density Affects Photobiomodulation Outcomes in Cell Culture" tells us that the melanin concentration of the skin ranges from 0.008% (light skin) to 0.023% (dark brown). [26]
This is a 3 times difference in melanin concentration depending on Skin Phototype. The study concludes that the dosage for people with darker skin types will likely need to be higher especially for deeper tissue targets. [26]
Another study notes:
"Dark skin typically contains four‐ to sixfold more melanin" [5]
Another study describes the percentage of melanin found in the epidermis.
"Melanin can be found in the epidermis by approx. 3% for Caucasians, up to 16% for Mediterraneans and 43% for highly pigmented Africans [27]. " [27]
With such a significant range of melanin concentrations of the skin, we cannot ignore the role it could play in the efficacy of light therapies.
One study notes that for what they call "fair skin" the optical window of wavelengths is from 600nm to 1300nm. Which is consistent with the range typically referenced in PBM literature. [28]
However, the same study says for what they call "black skin" the optical window is restricted to 750nm to 1300nm. Meaning that the Red wavelengths are no longer part of the ideal optical window for darker skin phototypes. [28]
https://link.springer.com/chapter/10.1007/978-3-030-92880-3_3
The above study has a good graph on this phenomenon.
We can also make a graph from the human skin reflection data collected by the NIST.
Many will remember this graph is the reason why skin contact is preferred to reduce the reflection losses from Red and NIR light, which is substantial at about 60% for Caucasian skin.
However, for the darker skin group we see much less reflection in the Red (660nm) range, around only 40%. The difference of 20% is likely being absorbed superficially by melanin. Again confirming the superficial absorption of Red that will cause more of a heat effect.
It shows much more reflection in the 800's and 1050's where all phototypes become more similar. High reflection is a good thing, as it means there is a lack of superficial absorption and better penetration.
Another study concludes:
"the status of pigmentation should be taken into account for PBM using visible light (635 nm)." [2]
By now it should be clear that red wavelengths are not preferred to be used for people with dark skin types, as the "optical window" of wavelengths is clearly shifted.
The penetration of wavelengths is substantially different depending on skin phototype.
One study finds up to 2 times less penetration in the darkest skin types compared to lighter skin types, even for 851nm light:
"Using the diffusion equation, Phan et al., determined the penetration of 851 nm light into varying skin-types and showed that light travelled the furthest through subjects with the palest skin pigmentation (ranging from approximately 1.8 mm – 4.75 mm amongst the 10 subjects) [65]. Light penetration was least for subjects with the darkest skin pigmentation, ranging from approximately 1.85 mm to 2.5 mm amongst 5 subjects." [29]
Another study noted a 24% decrease in penetration based on skin type with a 904nm laser.
"Over the range of Fitzpatrick scale values employed, from 2 to 6, there was a 24% decrease in energy transmission at this site. We calculated that for each Fitzpatrick scale point of skin pigmentation after a value of 2, there was a 6% decrease in energy transmission due to absorption by progressively darker skin colours." [8]
One study notes a drastically diminished light penetration (transmittance) with higher melanin concentrations with 635nm and 808nm laser. [3] With the 635nm having 60% less penetration and the 808nm having 30% less penetration.[2]
"As dark skin contains epidermic keratinocytes enriched with the melanin pigment, there was also less light transmittance of almost 60% and 30% after irradiation of 3.0 mm-thickness tissue with red and NIR light, respectively [77]." [2]
With a lack of penetration, this may be the reason why larger doses or exposure times will be needed to get adequate photons to the deeper layers of the body.
High intensity lasers are often used in dermatology clinics for skin resurfacing such as treating wrinkles, scars, acne, pigmentation, and tattoo removal.
These lasers are heating and ablative, essentially vaporizing surface layers of the skin or specific cells to promote regrowth. Often with downtime like skin redness for about 2 weeks after treatment. [30]
Since this is a high-intensity heat therapy with lasers, there has been a lot of work to distinguish optimal parameters based on Skin PhotoType, particularly to avoid adverse responses to people with darker skin types.
In contrast, Photobiomodulation is by-definition non-thermal and low intensity. This perhaps explains the lack of studies based on skin type for PBM. There hasn't been any urgency to adjust the dose for PBM because it does not pose an immediate safety risk.
However, we can certainly learn from these high-intensity laser studies to help inform us about optimizing PBM safety and dosing based on skin type.
One study titled "Laser photorejuvenation of Asian and ethnic skin" gives a good description of factors used to compensate for different skin phototypes.
They note:
"Since melanin absorption decreases exponentially with increasing wavelengths, lasers with longer and more deeply penetrating wavelengths generally produce safer and more reliable clinical results in dark skin (5)." [31]
Another study notes:
"Whereas early-generation lasers for hair removal and resurfacing were generally contraindicated for individuals with Fitzpatrick skin phototypes (SPT) IV–VI, advances in the past decade have given rise to a range of devices that can be safely used in ethnic skin. Longer wavelength lasers such as the 810 and 1064 nm Nd:YAG;" [32]
And another study tells us:
"We believe two wavelengths are generally appropriate for use in dark Latino skin, which include the Diode laser 810nm at low fluence and high repetition rate “in motion” (up to phototypes V) and Nd:YAG 1064nm (up to phototypes VI)" [33]
So this helps confirm why wavelengths like 810nm and 1064nm will be preferred to get adequate penetration and improve safety and effectiveness.
Water absorption was once considered an inactive chromophore and merely a hinderance to penetration. However, thanks to relatively new research by Gerald Pollack on the understanding ot EZ (Exclusion Zone) Water, it is now recognized as not only an active chromophore for photobiomodulation mechanisms - but water absorption may be a dominant mechanism for PBM effects.
Even blood absorption is now appreciated to have a more active role in Photobiomodulation by virtue of the recent discovery of cell-free mitochondria in the blood.[34] So again, once considered a hinderance to penetration, blood absorption is credited to play a role in systemic mechanisms of photobiomodulation.
Similarly, we have yet to discover if Melanin can play any active roles in photochemical responses by light absorption. The heat generated by the melanin absorption may confer some benefits as long as it is not burning.
Many organisms utilize melanin, and it seems to perform many more functions than merely protection from light.
"No other natural polymer is characterized by so many intriguing properties and is able to fulfill such a wide variety of different functions as eumelanin (called henceforth EU), which is the dark-brown/black component of the melanin family. " [35]
Neuromelanin is a type of melanin found in the brain. It seemingly has no business being there. However, neuromelanin clearly serves important brain functions since we know that the loss of this brain pigment is correlated with the progression of Parkinson's disease. [36]
A 2014 article titled "The role of human photosynthesis in predictive, preventive and personalized medicine" discusses the possibility that melanin can create energy as a kind of photosynthesis in humans and animals. [37]
A 2008 article titled "Melanin directly converts light for vertebrate metabolic use: Heuristic thoughts on birds, Icarus and dark human skin" references the paradox of migratory birds making long flights despite an apparent lack of energy sources. They also believe melanin to be providing energy from light to sustain the patterns of these birds. [38]
However, other articles have dubbed this theory of melanin producing energy as a kind of photosynthesis in animals and humans as pseudoscience. [39]
A real scientific phenomenon is the ability of melanated "melanopic" mushrooms to grow in highly radioactive environments like Chernobyl, as one paper titled "Melanin, Radiation, and Energy Transduction in Fungi" describes. This paper does confirm the mushroom's melanin is able to convert the radiation into a useful energy for their metabolism.[40]
With melanin being a unique light absorber with many enigmatic functions in living organisms, it will not be surprising if we do find an active role it plays in PBM in the future.
Red and Near-Infrared light therapy has the ability to help the health of all people. As always, to optimize the benefits of red light therapy for the individual is to appreciate the many aspects of bioindividuality.
The concentration of melanin in human skin is widely varied. As it is naturally a strong pigment for absorbing light, it plays an important role in how we implement light therapies.
Responsible usage of Red Light Therapy is safe and effective for all skin types. But, it is clear that the parameters should be adjusted to optimize the outcomes.
For darker skin types it may be ideal to increase the dose by 25-50%, prefer NIR wavelengths over Red, and reduce the intensity or use pulsing to reduce heating.
And vise-versa, people with the lightest skin types can tolerate higher intensities, both Red&NIR light, however may do well with lower doses due to higher penetration of the light.
There is still much to understand about the intracies of how Red and NIR light interacts with the body.
However, we do have a lot of evidence right now to help improve outcomes for more people.
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Water Absorption Coefficient Spectrum:
https://omlc.org/spectra/water/data/hale73.txt
https://omlc.org/spectra/water/abs/
[42]
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https://omlc.org/news/jan98/skinoptics.html
https://omlc.org/spectra/hemoglobin/summary.html
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Melanin Absorption Coefficient Spectrum:
]]>The question seems to answer itself. You need to cover 100% of your body for full body red light therapy.
What happens if you only cover 90% of your body? Is that no longer Full-Body Red Light Therapy? Have you suddenly forsaken all of the potential benefits that can only be gotten with 100% coverage?
What about only 80%, 60%, or 50% of body coverage? Is that too low for "full body" benefits? Do you get more benefits from larger devices? How big is the optimal size of a red light therapy device?
If you buy 2 modular devices, do you double your benefits compared to only 1? If you buy 4 and make a whole wall of light, have you quadrupled your benefits? How do we quantify the additional benefits of larger devices?
Or, as the marketing slogan often goes... since it is falsely presumed you need 100% of every crevasse of your skin to be engulfed in light - larger devices will save valuable time in treatments.
Full Body Red Light therapy isn't merely covering 100% of the skin with light, as that ignores all concepts of dosing in favor of optimizing profits by selling oversized devices.
The typical "dose" is referred to as J/cm^2 (Joules per Centimeter Squared).
However, many studies and scientists will prefer to use Total Joules for proper dosing.
The J/cm^2 multiplied by the treatment area (cm^2) of your device gives you the Total Joules dosage.
Full Body Red Light therapy typically delivers tens of thousands (10,000's) or even hundreds of thousands (100,000's) of Total Joules.
Smaller targeted areas do well with several hundred (100's) to several thousand (1,000's) Total Joules.
Using J/cm^2 only gives a small piece of the puzzle for dosing, where Total Joules will play a bigger role in the future for proper dosing of large devices.
Non-contact full-body light therapy is a systemic treatment and not a deep penetrating direct treatment. With that, we can appreciate the proper way of dosing is with the systemic mechanisms based on Total Joules.
As long as we get sufficient Total Joules from a reasonably sized "body-light" device, we should expect to get full-body benefits. Too much Total Joules could lead to a biphasic dose response.
Full-body systemic benefits are often gotten in studies by half-body sized devices covering one side of the torso, with minimum dosing ranging from a few thousand joules to tens of thousands of joules.
The original commercial "full body" LED panels were only about 3 feet tall (36 inches, 91cm) by 9 inches wide (23cm). This only covers the torso of an average sized adult male.
According to Bionumbers Harvard, the average adult skin surface area is 18,000cm^2 for males and 16,000cm^2 for females. The LED Panel described above is 91cm x 23cm - so about 2,093 cm^2.
https://bionumbers.hms.harvard.edu/bionumber.aspx?s=y&id=100578&ver=1
That coverage percentage is only 11% of the body for males and 13% for females! If they double their time and rotate to the back, that is only 22-26% coverage.
How could those original panels even produce any full-body effects? Why were they so effective and popular?
Did they inadvertently prove that full-body light therapy can be achieved by only covering a relatively small percentage of the skin? Yes.
In context, remember that a laser spot size typically used in Low Level Laser Therapy (LLLT) is 0.2 cm^2.[7] Yes, two tenths of a centimeter squared. So 0.2 divided by the male human surface area of 18,000 is 0.001% coverage of the body. How could Cold Laser Therapy be so amazingly effective with such a small coverage area?
We can appreciate that even 11% of body coverage with a 3 foot LED panel is already tremendously bigger than 0.001% body coverage with a laser. Which becomes problematic when some brands want to use the intensity of a small laser on a whole body. Where the opposite it generally true, the larger the device, the more prudent it is to reduce the intensity.
What are Total Joules?
The Energy Density (J/cm^2) is the amount of energy delivered to a unit of area. But for most situations, it is more important to know the total energy (Joules) delivered to a system.
It takes about 165,000 Joules of Energy to boil a 500ml mug of water from room temperature. We wouldn't use J/cm^2 to understand the thermodynamics of this situation, we need to know the total energy delivered to the system.
https://seesustainability.co.uk/blog/f/boiling-water---how-much-energy
The Density of an object is the Mass divided by its Volume. Rarely do we describe to objects by their Density as that is irrelevant for most situations, we refer to them by their actual Mass or Weight.
Similarly, only talking about Energy Density (J/cm^2) will mask the true dosing of Total Joules. In many ways the Total Energy is more relevant than just the Energy Density (J/cm^2).
If you know the Energy Density (J/cm^2) and the Size (cm^2) of your treatment, you can calculate the Total Joules through simple multiplication.
When asked about dosing of full-body devices, Dr. Hamblin will often bring up the Total Joules.
In an interview with Dr. Hamblin, this is what he says about dosing:
"Dr. Michael Hamblin: It’s a big area. Yeah, I think a few thousand joules is what you want from a photobiomodulation treatment. If it’s only a few hundred joules, it’s probably not enough to do anything unless it’s very carefully targeted to specific areas of the body. For a typical photobiomodulation session on the brain, three thousand joules is about right."
https://theenergyblueprint.com/red-light-therapy-benefits/
So according to Dr. Hamblin, a typical treatment should be at least a few thousand Total Joules. For targeted treatments the Total Joules could be a few hundred.
As well he notes that 10-20 mW/cm^2 is "high" for full-body light therapy, since that can easily deliver a high amount of Total Joules to the whole body. Which is why it is prudent to use lower intensities for full-body coverage devices.
In another interview between Dr. Hamblin and Joovv, he also reiterates the importance of considering Total Joules for dosing full-body devices, and that Thousands of Joules (1,000's) is a good dose.
This is reinforced by yet another interview with Dr. Hamblin on the CytoLED website. In it, he now says that a typical full-body dose is on the scale of 10,000's (tens of thousands) of Total Joules, and even around 100,000's (one hundred thousand) Total Joules.
https://cytoled.com/pages/at-home-versus-research-dosing
So notice that according to Dr. Hamblin, the dose of "full body" red light therapy doesn't seem to matter if it is actually covering 100% of the body. He seemingly changes the topic to talk about Total Joules when asked about dosing large devices.
Since full-body light therapy is a systemic (indirect) treatment anyway, it is more important to consider the Total Joules delivered to the skin, and not actually engulfing all the skin in light.
All we need to do is define what benefits to expect from "full body" red light therapy treatments, and then see what is the "minimum effective size" of device can achieve those benefits.
According to many brands and salespeople, full-body red light therapy can deliver every possible benefit studied in the thousands of articles on PBM and LLLT.
However, we know that most of these medical claims are extrapolated from targeted treatments using small devices, lasers, clusters of LEDs/Lasers held in contact with the skin.
When in reality we can only find 11 studies using whole-body Red Light Therapy, so we only know of limited applications like for athletic recovery, fibromyalgia, and long-COVID.
These applications actually require whole-body treatment, it would be reckless to treat the whole body and a lot of healthy cells with a therapy when only a targeted region needed treatment. Since healthy cells will only run into the biphasic dose response sooner, and red light therapy is more effective when targeting malfunctioning cells.
Studies have shown more consistently successful results with targeted skin-contact therapies and that full-body treatments get less consistent results. [2]
Full body light therapy is often speculated to simultaneously underdose the target tissue by lacking penetration with non-contact treatment, and also paradoxically overdose on the Total Joules to the body.
One review article on the use of Red Light Therapy for Sports Performance found that the whole-body PBM studies performed worse than targeted treatments.
"Therefore, we consider that whole-body PBMT has as its main limitation the lack of contact with the target tissue, and the optical profile (or focus on different deep tissue) affects substantially the power density in the muscles and the modulation of the mitochondrial activity, and so the effects of the whole clinical trial are corrupted." [1]
One of the failed whole-body LED studies notes that their delivered dose was 473,400 Total Joules. They comment that successful studies have used 60-300 Joules for large muscle groups and 20-60 Joules for small muscle groups. [2]
The researchers cannot ignore the possibility that the whole-body treatment delivered over a thousand times more total energy than the typical dose - leading to cause a biphasic dose response that explains the lack of benefits. [2]
It is rather impressive that Full-Body light therapy can exist in this limbo of being both inherently underdosed and overdosed at the same time.
This is where we need to appreciate the systemic effects of getting a reasonable amount of Total Joules per treatment.
One study on systemic blood sugar response exposed patients backs to 670nm LED light therapy.
The area was 800cm^2, intensity was 40mW/cm^2, and they quantified the dose as 28,800 Joules.
So again notice that many studies are using Total Joules rather than J/cm^2 for these large devices:
"participants exposed a 800 cm2 region of upper back to 670 nm light for 15 min at an intensity of 40mW cm− 2 (28,800 J)." [3]
The study specifically notes that they can achieve systemic results with a relatively localized treatment, and not needing 100% full body light therapy.
"Significant reduction in blood glucose was observed following local red light illumination of the body, rather than requiring whole body exposure." [3]
This shows us that we get a whole-body effect by just targeting the torso. This could be achieved similarly with a "half-body" or other smaller panel for a systemic effect on the whole body.
One research group has used a 940nm LED Vest for several human studies on the systemic effects on the body. [4][5]
They have treated the systemic effects and inflammation from viral respiratory illnesses.
"The LED system parameters over the vest area were total optical power of 6 W and an average power density of 2.9 mW/cm2, corresponding to 5.4 kJ total optical energy during the 900 s of irradiation time. "
So even with a relatively low intensity of 2.9mW/cm^2, because they are treating a large area the Total Joules is 5,400 (5.4 kJ = 5,400 J).
And of course they were successful in achieving a systemic "whole body" effect for an important virus that causes systemic inflammation - again by treating a large area of the torso with Low Intensity but Thousands of Total Joules.
One study compared the results of a LED Whole Body device to an LED Helmet for treating Long-Covid symptoms for 14 patients. [6]
They used the same intensity of 24mW/cm^2 for 14 minutes leading to a dose of 20.2 J/cm^2. [6]
However, the full-body device covered 18,000 cm^2 and the helmet only covers 650 cm^2. Leading to a total dose of 363,000 Total Joules for whole-body and 13,130 Total Joules for the helmet. [6]
This is a perfect example where the "dose" of 20 J/cm^2 appears to be the same for both devices. This is why J/cm^2 is so deceptive. The differentiating factor is the coverage area and Total Joules when comparing the doses of different devices.
Despite the big difference in coverage area and Total Joules, both modalities delivered the same benefits based on statistical significance. [6]
Since Long-Covid symptoms like brain fog are often a product of lingering systemic inflammation, it makes sense that both devices could offer a reduction in symptoms through systemic mechanisms.
This shows that even a relatively small device helmet device delivers comparable results to a whole-body device.
How big of a device do you need for full body red light therapy? What is the best size of red light therapy device in inches or centimeters?
A half-body sized panel covering one side of the torso or head has been shown to deliver full-body systemic results in these 4 human studies. This can be delivered with anywhere from 2.9 mW/cm^2 to 40mW/cm^2 of intensity, since even at relatively low intensities covering a large area delivers a large amount of Total Joules.
Studies have confirmed that half-body LED devices deliver systemic full-body benefits for several applications. A relatively small helmet delivered similar benefits to a full-body pod. The worlds leading researcher often discusses proper dosing of full-body light therapy in terms of Total Joules, and doesn't mention needing 100% skin coverage.
A systemic benefit can be gotten from as little as a few thousand (1,000's) Joules up to tens of thousands (10,000's) of Joules. So simply multiplying your typical J/cm^2 dose by the area of your device (cm^2), you can get a rough idea for your Total Joules dose.
Despite the overbearing salespeople insisting you need 100% coverage for any benefits at all, larger devices have not shown to significantly improve results than a reasonably sized half-body panel. The dosing and effects of Whole Body Red Light Therapy have been inconsistent so far with full body devices in the research.
Large whole-body light therapy devices can deliver hundreds of thousands of Joules even at relatively low intensity (24-28 mW/cm^2), which have been shown to be effective in cases requiring full-body treatments like intense athletic recovery, fibromayalgia, and long-Covid.
However, the larger devices must be used with caution to not overdose on the extremely high Total Joules, often taking advice from Dr.Hamblin that the intensity should be lowered to around 10-20mW/cm^2 to avoid overdosing on Total Joules.
Certainly, a large Whole Body Red Light Therapy device is luxurious and relaxing to engulf the entire body in light. However, it may not be necessary for the benefits of red light therapy.
If we believe the sensational marketing of needing huge devices and excessive intensities, then perhaps those brands and salespeople are more focused on placebo effects and profits than evidence-based effective doses.
Red Light Therapy can help a lot more people if we appreciate the usage of simple devices delivering reasonable intensities at manageable sizes. This can make it not only more affordable and accessible, but in many cases will prevent overdosing on Total Joules anyway.
Since non-contact whole-body devices lack the penetration and deliver unprecedented Total Joules compared to typical clinical grade devices - we will need more studies in the future to understand how to properly dose them.
[1]
How do we make sure we are doing true clinical grade red light therapy according to medical definitions, NASA, the FDA, and leading researchers?
You may want to know what to expect to feel during red light therapy treatments, especially if you are new to this topic. Or more likely, many people already using red light therapy should be checking the literature to make sure what they feel is in alignment with true clinical grade Photobiomodulation as described in the studies.
Summary: The patient typically doesn't feel anything at all with properly designed clinical studies and devices. Since the definitions of LLLT and PBM are clearly non-thermal according to every authority in the field, then typically barely any warmth should be expected. Feeling rapid heating is a sign the device is too powerful and hasn't been clinically studied for LLLT/PBM.
As always, you don't need to take our opinion on the matter. This blog we dig into the research to find direct quotes and descriptions of what is felt during true LLLT/PBM clinical treatments.
Red Light Therapy is the common name used to describe products and protocols that follow the science of Low Level Light Therapy (LLLT) and Photobiomodulation (PBM). The most popular wavelengths studied in these sciences are in the Red to Near-Infrared range of wavelengths 600nm-1100nm.
When brands and experts claim there are 7,000+ studies to back up their products, they are referring to the databases of LLLT and PBM articles. When brands and experts reference specific studies to make medical claims - they are usually referring to the studies in the LLLT/PBM literature.
While we love to get caught up in the parameters and dosing of Joules, Watts, Hertz, Nanometers, and more - often we don't hear about what should be felt during red light therapy treatments.
The medically-approved definitions for LLLT and PBM must be met in order for a study to be placed in the appropriate category on PubMed and other databases.
One article tells us the official medical definitions for LLLT and PBM:
"Low-level light therapy (LLLT) is defined as “Treatment using irradiation with light of low power intensity so that the effects are a response to the light and not due to heat. A variety of light sources, especially low-power lasers are used.” in the Medical Subject Headings (MeSH) Descriptor Data 2017.
Photobiomodulation (PBM) therapy is “A form of light therapy that utilizes non-ionizing forms of light sources, including lasers, LEDs, and broadband light, in the visible and infrared spectrum. It is a nonthermal process involving endogenous chromophores eliciting photophysical (i.e., linear and nonlinear) and photochemical events at various biological scales. This process results in beneficial therapeutic outcomes including but not limited to the alleviation of pain or inflammation, immunomodulation, and pro-motion of wound healing and tissue regeneration.” as a defined in Anders et al. [10].
It is now agreed that “PBM therapy” is a more accurate and specific term for the therapeutic application of low-level light compared with “LLLT”."
[1]
And we can appreciate clearly that the definition of LLLT is that the effects are "not due to heat" and the definition of PBM is that "it is a nonthermal process".
You can also read more in Dr. Anders' peer-reviewed paper discussing the definition of LLLT/PBM. It notes that the definitions were intentional to exclude any form of heating devices such as high powered lasers or heat lamps. [2]
Based on these broad definitions, you can use a wide range of wavelengths and light sources to do LLLT/PBM. It is very easy to meet this criteria, the only thing you can't do - is heating. Many high intensity devices causing radiant heat are no longer considered true LLLT/PBM.
You will literally never find any LLLT/PBM study that intentionally uses light for radiant heating - as it would be excluded and put into a different category.
The definitions of LLLT and PBM both include that they are the non-thermal (no heat) application of light to cause biological effects.
Hence, the popular term like Cold Laser that describes low-powered lasers intended for LLLT/PBM that don't cause significant heating like industrial lasers do.
A term like Cold LED was never defined, as it was assumed that LEDs would never be powerful enough to emit intensities high enough for radiant heating.
[3]
[4]
However, thanks to many brands that don't understand the science and influencers promoting high-powered "value" over optimal intensities, the LED Heat Lamp has indeed been invented in recent years. Which is a technological marvel that even the researchers didn't predict.
This innovation of LED Heat Lamps shouldn't be celebrated until it is fully proven, as heating technology is often contraindicated by the LLLT/PBM science:
"Heat is a compounding limitation in achieving optimal phototherapeutic effects. As surface heating of the skin increases, the biological effect begins to decrease."
[35] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9980499/
Heat Therapy is obviously different than Light Therapy. It has different mechanisms, dosing protocols, and safety considerations to do properly. If Red Light Therapy was meant to be a heat therapy, it would simply be called Red Heat Therapy or Radiant Heat Therapy. Like the NIR Heat Lamps that some people use for therapy, they aren't called NIR Light Lamps because their main mechanism is heating.
The definition of LLLT/PBM is often reiterated in the Introduction or Background sections of most studies.
Dr. Hamblin wrote this definition in a future-dated 2024 article on photobiomodulation of the brain.
[5]
This definition shows the crux of the problem with many modern LED panels on the market. The intensity must be low enough to not cause tissue heating to meet the LLLT/PBM criteria according leading researcher Dr. Hamblin.
As Dr. Hamblin and many other publications have noted - using low intensities that don't cause tissue heating is a main point of doing proper LLLT/PBM.
In an article by Dr. Barolet, Dr.
[6]
Naturally, the heating effects are often subjective and depend on bioindividuality like skin phototype, skin thickness, heat sensitivity, and blood circulation for thermoregulation. So this means everyone will "feel" heat at different intensities depending on many factors. As well, the size of the treatment area also matters when it comes to heating like a small laser vs a big panel.
[7]
The quote above tells us that high intensity will lead to the photons being converted into heat. Thus, not contributing to the Joules/cm^2 for proper dosing of red light therapy. The energy (Joules) calculation only works for Photochemical reactions and not for Photothermal reactions.
[7]
Now this quote makes more sense, since at >100mW/cm^2 a significant amount of photons will be converted to heat. So you cannot use the standard dosing calculations for high intensity (>100mW/cm^2) light therapy - especially because we know heat therapy has no reciprocity (no linear dosing calculation) like PBM has.
Generally, large LED devices with intensities > (greater than) 50mW/cm^2 would lead to not meeting the definitions of LLLT/PBM, and thus not being able to dose it properly, not being backed by 7,000+ studies, and not expect the same safety and efficacy of devices that follow the science that are < (less than) 50mW/cm^2.
In a marketing gimmick as worn-out as my Tempur-Pedic Foam Mattress, many LED panel manufacturers will claim their technology was originally developed by NASA.
However, lets take a look at a couple of quotes describing the NASA LED therapy in published peer-reviewed literature.
[8]
The NASA LED therapy is described as producing no heat. As well we can see that non-heating LEDs are non-significant risk by the FDA.
Here is another desription of the NASA LED, in a study actually using a device that came from the NASA research mady by Quantum Devices, Inc.
[9]
So we can appreciate the nuance here that inevitably the application of low Intensity or Joules of any wavelength will make fractional temperature increases on the tissue - however this is rarely felt by the patient and does not affect the therapy.
As this quote confirms and thousands of studies also confirm - the benefits of LLLT/PBM are from light therapy, not activating heat therapy mechanisms.
So if you are using high intensity LED panels as a heat therapy, you are no longer doing the NASA-developed LED light therapy - which is described clearly as being non-thermal.
The FDA recently issued guidelines for their definition of LLLT/PBM and criteria for device applications and approvals:
In both the Introduction and Background section the FDA notes that LLLT/PBM is non-thermal.
Introduction:
"The device is designed to deliver a non-heating dose of light energy into the body to provide clinical benefit to the patient."
(pg 5, FDA draft guidance for PBM, Jan 12, 2023)
Background:
"For the purpose of this guidance, the term “photobiomodulation” is defined as the application of light at an irradiance that does not induce heating with the goal of altering biological activity."
(pg 6, FDA draft guidance for PBM, Jan 12, 2023)
So if you want to do the FDA Recognized version of true medical grade Photobiomodulation - then you need to make sure it is "non-heating" and "does not induce heating" as they clearly state. It is so important to be non-thermal that they say it twice in the same document.
And this explains why many LED Heat Lamp manufacturers are registered as medium-risk Class II heat lamps under the ILY code - not as non-thermal PBM devices. The FDA still maintains an exclusion that low-risk non-thermal LEDs for general wellness do not require registration.
And again, we could make a drinking game out of how many times the emphasis is on having low power, low intensity, or low irradiance (aka low power density, mW/cm^2) as the primary factor to make sure there is no heating for true LLLT/PBM.
High intensities are the enemy of true medical grade LLLT/PBM, despite the paradoxical marketing that everyone needs the "highest intensity" device to be effective.
Endre Mester is often credited as the grandfather of LLLT/PBM for his discovery and research starting in the 1960's.
[10]
So even dating back to Dr. Mester, we know that this therapy has always been a non-thermal usage of light. Amazingly, many brands and experts are trying to re-write a 60+ year old definition so that Red Light Therapy matches their marketing narrative of selling overpowered LED Heat Lamps.
Lets see what the research tells us you should feel during red light therapy.
A 2018 Textbook on LLLT/PBM published by SPIE with co-authors including Dr. Hamblin, Dr. Ferraresi, Dr. Huang, Dr. Freitas, and James Carroll had this to say about the user experience:
[11]
They describe the experience that there are no visible or tangible changes during treatment. The usage of the word "tangible" would imply there is nothing felt like heat on the skin.
The user naturally doubts the effectiveness of true "cold" light therapy because they cannot feel anything during the treatment. We can understand why many people want to use light therapy as a heat therapy because they seek that instant gratification of feeling something during treatment.
The textbook reassures the reader that there are Photochemical effects that leads to all the benefits of LLLT/PBM, despite the lack of Photothermal (heat) effects.
One study used 633nm and 870nm LED clusters on the forehead to treat the brain emitting 22.2 mW/cm^2 for 13.3 J/cm^2 per area to treat TBI and improve cognition.
This is what they had to say they felt during treatment:
"No sensation of heat or pain was reported during the LED application to the skin or scalp." [12]
Another study using cold lasers for acupuncture had this to say:
"There is usually no sensation to help determine whether or not a point has been stimulated with laser as it is with needle acupuncture." [13]
And another study with cold laser for acupuncture also said this:
"Typically, patients do not feel any sensations when a low-light laser is used,23 although some patients have reported a tingling or “light touch” sensation.24" [14]
One Low Level Laser Therapy had this description for what is felt during treatment:
"The powers used in laser therapy are by definition too low to cause tissue damage by either heating or acoustic effects. Nonetheless, it seems possible that the same effects that are claimed to promote beneficial processes could also be detrimental. However, neither experience nor literature searches reveal substantive risk. Patients do comment at times about transient warmth or “tingling” during or shortly after treatment. However, in our experience this has occurred in both active and placebo subjects." [15]
This quote is interesting as both the treated and control groups feel warmth or "tingling" - perhaps because the placebo effect encourages the people to produce some internal response despite not feeling anything. As well they directly note the therapy must use power that is low enough to not cause any heating.
Two published articles refer to an LED panel emitting 50mW/cm^2 of 830nm wavelength. This is how they described the sensation:
"The majority of student-athletes receiving 830 nm LED-LLLT indicated having achieved an excellent result, namely a reduction in pain and inflammation, while also noting pleasantly mild surface heating of the skin." [16]
And in another publication:
"Within 5–10 min, a gentle warming of the face is also felt as the microvasculature brings more blood to the superficial dermis through vasodilation." [17]
So this is likely the maximal intensity that is appropriate. Only a mild heating is felt after 5+ minutes of exposure. This may not even be from direct radiant heat at all, but a warming sensation through Nitric Oxide release causing vasodilation (local blood flow increase).
If you are feeling immediate or rapid skin heating with a high intensity LED panel, it is likely it is too powerful to be considered true clinical grade LLLT/PBM.
Remember that this uses the least heating 830nm wavelength and using Red would actually cause more heating at this intensity.
The standard for clinical trials is to have a placebo group, and have both the treated group and placebo group "blinded" (i.e. unaware) if they are getting the placebo or true treatment.
One study describes the importance of blinding in studies this way:
"Blinding is critical to clinical trials because it allows for separation of specific intervention effects from bias, by equalising all factors between groups except for the proposed mechanism of action." [18]
Placebo groups are very easy to do with traditional drugs, as you can simply give the patient a sugar pill or some other inert substance in the same size and shape of the drug.
However, proper blinding with devices is very challenging, as you need to replicate the device and simulate the sensation of the treatment without actually doing the treatment.
For example, one review article on Cupping therapy for obesity notes that a blinded placebo was impossible - as you cannot replicate a false sense of cupping without actually doing cupping. [19]
Similarly, it is difficult to have "blinding" from heat therapies. Since obviously a person should feel if they are experiencing heat or not and would know if they are in the placebo or treatment group.
With LLLT/PBM - due to the nature of being non-thermal - you can do blinded studies. With invisible Near-Infrared wavelengths this is even easier as there is nothing to see either, and with Red wavelengths you can simply blindfold the patients in both groups.
One study using PBMT LED/Laser cluster for muscle performance had this to say:
"During PBMT and placebo applications, subjects used opaque glasses that blocked their view. In addition, PBMT did not cause any sensitive stimuli (heat, cold, skin irritation, and pain) that could provide participants with information about the dose or treatment being administered." [20]
One study used a combination Laser and LED cluster for fibromyalgia had this to say about the blinding procedure for placebo:
"The assessors, therapists, and patients were blinded. The assessors of the study were unaware of a patient’s allocation and the PB MT-sMF device was preprogrammed to active or placebo mode. The sounds emitted from, and information displayed on, the device’s screen were identical, regardless of the programmed mode. In addition, the device used had no thermal effects,26 enabling the blinding of the therapists and patients to be maintained throughout the treatment." [21]
Studies with the Vielight device are able to be double-blinded because there is no heat or sensation to be felt during treatment. They simply strap on another Vielight device and don't turn it on for the allotted amount of time. [22][23]
A recent study covered by the MedCram YouTube channel describes using 670nm light at 40mW/cm^2 on the backs of patients:
"The LED array was positioned 400 mm from the participants back, surrounded by a shield that rested on the participant’s skin, to prevent light leakage, and to blind the participant to which group they were randomised into. The placebo group underwent the same procedure, except the LED array was not switched on during their intervention OGTT." [24]
Since there is no heat expected from 40mW/cm^2 and non-contact LED treatment, they were able to have a successful blinded placebo control group by simply not turning on the LED panel for the placebo group. And yes, 15 minutes of non-contact non-thermal LED exposure at 40mW/cm^2 was indeed effective. [24]
Having properly blinded placebo-controlled trials for LLLT/PBM has led to the strength of the science proving that it is effective. If it were a heat therapy, this would be very challenging to do properly blinded trials.
Clinical grade red light therapy is defined to be non-thermal, with most studies reporting no sensation of heat (or anything at all) ( ideally <50mW/cm^2). High intensities (~50mW/cm^2) will naturally produce a mild warming sensation after several minutes. Excessive intensities (>100mW/cm^2) will lead to rapid heating and no longer meet the definition of true LLLT or PBM.
"The thermal effect of radiation does not appear when the irradiance is below 100 mW/cm2 (in our study, the irradiance of 53 mW/cm2 was used and the absolute increase of 1.5°C was observed in blood temperature, which recovered to the baseline values within 3 minutes). Considering the fact that the temperature during the analysis in the multiplate aggregometer reaches 37°C, we assume that the mentioned above increase of 1.5°C has a negligible effect on the observed results." [26]
Many studies even monitor skin and tissue temperature changes to make sure it is minimal. With many only reporting less than 1-3 degrees C change, which would be hardly even felt as warmth by most people especially as the heating is slow and gradual. [28][29][30][31][32][33][34]
Dr. Hamblin writes in one article:
"By now everybody will accept that PBMT using red or NIR radiation (or indeed blue and green wavelengths) can produce biological effects by a photochemical mechanism as opposed to a photothermal mechanism." [27]
Ironically, the people selling and promoting high-intensity LED heat lamps have clearly not accepted this fact. Perhaps people doubt the efficacy of non-thermal LLLT/PBM as detailed in 7,000+ articles. Perhaps the salespeople think they are smarter than the doctors and researchers using non-thermal light therapy in clinical studies.
However, these high powered devices are far beyond what has actually been studied in full-body red light therapy trials and higher than natural sunlight intensity for these wavelength ranges. We don't know the long term effects of chronic usage of intensities higher than nature intended, even if they feel good in the short term.
It is a bait-and-switch deception when high-intensity (>100mW/cm^2) brands make medical claims based on LLLT/PBM research, and then sell you a glorified LED heat lamp that doesn't fit the clinical definitions or dosing to achieve those benefits. If they are proudly selling a LED Heat Lamp, then they need to advertise it accordingly and stop refercing non-thermal LLLT/PBM studies for their safety and benefits.
At GembaRed we will stick to the established science that has confirmed effectiveness and non-significant risk for low-intensity non-thermal LED light therapy.
Our definition of "value" is that products are safe and effective in accordance with the science, not some sales gimmick of getting the most Watts per Dollar.
A high-intensity LED Heat Lamp holds no value to me, not only because it lacks the science, safety, and efficacy of true LLLT/PBM - but because I can get NIR Incandescent Heat Lamps for $10, or get a Beurer heat lamp for $80, I already enjoy my Presto Radiant Heater in the winters, and radiant heat therapy is redundant to my routine usage of my infrared sauna and infrared heating pads. If I want a true "light" therapy then I want it non-thermally in accordance with the science to activate the photochemical mechanisms, not photothermal mechanisms.
So while influencers will sell you on gimmicks of high intensity and tell you how much they enjoy LED heat therapy for their affiliate payments - they suddenly have diminished their therapeutic "value" and brought them into a mundane low-cost category of competing with generic heat lamps and infrared heating pads.
Which actually makes LED Heat Lamps an overpriced (and inefficient) form heat therapy, rather than a valuable nuanced therapeutic of cold LLLT/PBM. Impressively, they manage to help you improperly dose two types of therapy now, as you aren't doing Photobiomodulation Therapy or Heat Therapy correctly with these LED Heat Lamps.
Consider that the converse of this blog is also true. If we had found dozens of studies and definitions explaining how LLLT/PBM was indeed a heat therapy - then we would have designed our products and education accordingly. We have found that the mere definition itself has restricted the 7,000+ articles to support a "cold" light therapy, not a "hot" light therapy.
Here are a few more quotes I had collected for this blog clearly stating that LLLT/PBM is non-thermal (no heating).
It is rather difficult to ignore these definitions if you have read enough studies. One starts to feel it is rather important to be non-thermal if only for the sheer repetition of seeing it so often in studies. And obviously being non-thermal is actually important to activate the correct mechanisms, be absolutely safe with minimal side effects, increases penetration, allows you to use skin contact, and reduces the risk of excess ROS and biphasic dose response.
We have to wonder if any experts promoting high intensities have ever read a single LLLT/PBM study to have missed these clear definitions, or more likely they conveniently ignore information that doesn't match thier sales narratives.
Quotes:
https://www.sciencedirect.com/science/article/pii/S1836955320300643?via%3Dihub
The above quote is from a systematic review of many articles on PBMT. Notice how high-intensity lasers are excluded, as high intensity devices do not fit the definition of PBMT.
"LLLT is an athermic photochemical modality, where red or near-infrared light is used to stimulate tissue healing and reduce pain and inflammation.22–24"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9528593/
With "athermic" being a fancy way of saying non-thermal.
https://pubmed.ncbi.nlm.nih.gov/30614743/
https://www.jkslms.or.kr/journal/view.html?doi=10.25289/ML.2020.9.2.89
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD002046.pub2/abstract
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2830167/
https://www.mdpi.com/2304-6732/10/1/90
https://onlinelibrary.wiley.com/doi/10.1111/odi.14618
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7118506/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3065857/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8887026/
https://www.sciencedirect.com/science/article/abs/pii/S1572100023004817?via%3Dihub
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4833286/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8537491/
https://trialsjournal.biomedcentral.com/articles/10.1186/s13063-023-07599-0
https://www.ncbi.nlm.nih.gov/books/NBK593483/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4256027/
https://pubmed.ncbi.nlm.nih.gov/19913903/
https://pubmed.ncbi.nlm.nih.gov/19913903/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7154450/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8122620/
https://www.nature.com/articles/s41598-022-14812-8
"The reason why the technique is termed LOW-level is that the
optimum levels of energy density delivered are low when compared to other forms of laser therapy as practiced for ablation, cutting, and thermally coagulating tissue. In general, the power densities used for LLLT are lower than those needed to produce heating of tissue, i.e., less than 100 mW/cm2, depending on wavelength and tissue type (Huang YY et al., 2009)."
https://www.researchgate.net/publication/221920419_Laser_in_Orthodontics
"The typical power output for a low level laser device used for this therapy is of the order of 10-50 mW, and total irradiances at any point are of the order of several Joules. Thermal effects of LLLT on dental tissues are not significant, and do not contribute to the therapeutic effects seen."
https://www.researchgate.net/publication/221920419_Laser_in_Orthodontics
Thank you for reading all the way to the end of this bonus section. Because you understand the basic definitions of LLLT and PBM, you are now a better expert of light therapy than most brands selling high intensity LED panels and the influencers promoting them.
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Low Level Laser Therapy (LLLT) for Neck Pain: A Systematic Review and Meta-Regression
Anita R Gross*, 1, Stephanie Dziengo3, Olga Boers3, Charlie H Goldsmith2, Nadine Graham1, Lothar Lilge4, Stephen Burnie3, Roger White5
1 McMaster University, Hamilton, Canada
2 Simon Fraser University, British Columbia, Canada
3 School of Rehabilitation Sciences, Physiotherapy Program, McMaster University, Hamilton, Canada
4 Department of Medical Biophysics, University of Toronto, Toronto, Canada and Senior Scientist at the Ontario Cancer Institute, Princess Margaret Cancer Centre, UHN, Canada
5 Theralase Inc., 1945 Queen Street, East Toronto, Ontario M4L 1H7, Canada
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The "optical window" of wavelengths preferred for Red Light Therapy are the Red to Near-Infrared (NIR) range from 600nm to 1100nm.[1]
But which one is the absolute best?
In this blog we will propose that 830nm Near-Infrared is the best wavelength for Red Light Therapy.
It will likely take decades more of research to truly find the best wavelengths for Red Light Therapy, and even then it will be nuanced and based on context.
So, this will be a "thought experiment" and discussion around what we would look for in the best wavelength. Using 830nm as the model that currently seems to have the best evidence supporting it.
What defines the best wavelength? The deepest penetration? The best benefits? The safest? The best systemic effects? The most successful studies? Or that it activates important biological mechanisms? Yes.
Even a rudimentary analysis of the database of studies shows that 850nm is not the most popular Near Infrared wavelength for red light therapy.
We should expect to find overwhelming scientific studies and doctors and researchers clearly stating that 850nm is the best. Which is conspicuously absent when you start reading the research.
Lets look at some quotes from peer-reviewed published articles by real researchers and experts.
"It is believed that optimal wavelengths are near 810 – 840 nm, since in these regions the surface chromophores have weak absorption, and therefore there is maximum penetration of light into the skin, generating an optimal window of penetration and absorption by organic molecules [38]." [2]
This quote establishes that the range between 810nm to 840nm contains the best wavelengths especially for penetration and absorption mechanisms. Unfortunately, 850nm is excluded from this range and is implied to be less optimal than the wavelengths within this range.
"Red to near-infrared light photons with long wavelengths can directly transfer energy to cytochrome C oxidase, leading to an increase in enzyme activity and energy metabolism, which may play a key role in further inducing PBM. Based on the literature summary above, light wavelengths at 635–680 nm and 810–830 nm are more suitable for inducing PBM to treat retinal diseases." [3]
Again, conspicuously excluding 850nm while highlighting the optimal range of 810-830nm for eye health.
"Both scattering and absorption of light by tissue are highly wavelength-dependent and NIR light around 810–830 nm have been found to have the deepest penetration and homogeneous illumination of the full dermis and part of the hypodermis [12,15]." [4]
"Based on the data presented above, using wavelengths in the range of 808–835nm, laser devices, higher power densities, and pulsed parameters will likely increase efficacy." [5]
"The most extensively studied spectrum for PB includes light
in the spectrum of 630–830 nm." [6]
It is disturbing that so many of these quotes don't include 850nm within their range of the most studied wavelengths and/or optimal wavelengths for PBM.
Bjordal et al find that wavelengths of 632 to 660 nm, or infrared lasers with wavelengths of 810 to 830 nm, show anti-inflammatory effects" [7]
They don't directly mention 850nm in the article quoted above, but they note the average wavelength of 846nm was associated with negative outcomes compared to wavelengths closer to 810nm were associated with positive outcomes.
"For clinical pain relief, the usual wavelengths are in the red range (λ=632.8 and 670 nm) and in the NIR (λ=780; 810 to 830; 904 nm)." [8]
Now this quote purposely skips over 850nm in their list of wavelengths to include 810-830nm and then jumps to 904nm. At this point it is rather laughable that these ranges are specifically excluding 850nm.
This list of quotes above would lead us to question if these researchers even consider 850nm as a viable wavelength at all, not even bothering to debate if 850nm is the best.
What would cause these researchers to forget about 850nm, the supposedly "best" wavelength acclaimed by many brands?
Did these researchers miss the memo about how great 850nm is? Or are they just following the actual evidence?
All of the quotes in the previous section always include 810nm and 830nm wavelengths in their optimal ranges.
So in reality, the debate should be between 810nm and 830nm for the crown of best NIR wavelength, especially now that we know 850nm has been dethroned.
One excellent review article on Photobiomodulation Mechanisms published in 2020 by a long list of 14 researchers had this to say:
"The optimum wavelength in treatment is usually considered to be 810 nm [11]." [9]
In very clear terms, this group of researchers seem to be in agreement that 810nm is typically considered to be the best wavelength.
An interesting 2022 PBM article had this to say:
"The 810nm LED is the most commonly used light sources in the field of PBM" [10]
A 2023 review of wavelengths used for Aspects of Muscle Function (they abbreviate to AoMF) had this to say as a conclusion:
"However, regarding the wavelength of the low power laser, it is hypothesized that wavelengths of 808 – 810nm promote more satisfactory results for AoMF, as approximately 37.5% of favourable studies used this wavelength." [2]
These quotes would lead us to believe that 810nm is not only the optimal wavelength, but has a high number of successful studies to support it.
However, a free article from a 2017 textbook on Photomedicine had this to say about the optimal wavelength:
We finally believe that 830 nm offers very interesting properties compared with other wavelengths, making it the wavelength of choice because of its superior depth of penetration, and larger number of cells and targets it has been shown to photoactivate." [11]
Indeed, we find many articles by Dr. Calderhead and many prominent researchers expressing a favoritism for 830nm. We will explain why in the mechanisms section.
We could not find any peer-reviewed published literature clearly stating that 850nm should be considered the optimum wavelength. If you do find any, please email us a link.
With 810nm and 830nm being very close to each other on the wavelength spectrum with only a 20nm difference between them - it would be very challenging to discern a difference in overall benefits without large-scale trials. So far we have not found any studies directly comparing the effects of both 810nm and 830nm under the same conditions.
In one interview, Dr. Hamblin states that all the low-800's and all the mid-600's have the same benefits. Even the Red and NIR wavelengths have the same benefits. Thus, perhaps making this entire blog a moot point.
One study may have confirmed this observation by showing that an 800nm Laser and 850nm Laser had non-significant differences (i.e. they were the same results).
"Moreover, 800 nm and 850 nm lasers produced identical, non-significant (p > 0.05) PBM effects on the human forearm in vivo in all three (or four) physiological metrics. This observation is expected since the light absorption and scattering properties of blood and CCO are very similar in the wavelength range between 800 and 850 nm. " [10]
You can see the above quote discussing how wavelengths in the 800-850nm range are generally expected to produce the same benefits because they have similar optical properties and absorption mechanisms.
Update: One study compared 800nm vs 850nm laser on transcranial application (through the forehead) on human subjects. They found a much more significant response from 800nm compared to 850nm. [30]
However, in this one case we will temporarily ignore Dr. Hamblin's guidance and continue our analysis.
The deepest penetration wavelength is often considered to be 810nm. This is the lowest intersection of all of the primary absorbing molecules of the skin (blood, melanin, water). Shorter wavelengths will have less penetration by superficial absorption from melanin and blood. Longer wavelengths will have less penetration by superficial absorption from water.
An article by Dr. Jan Tuner states this concept plainly:
"And, actually, it is the other way around, or, rather with red having low penetration, *810 nm is the best and then penetration is lowered as the wavelength is further increased." [12]
Which would be a detriment to our case for 830nm, as it is implied that 830nm would have slightly less penetration due to more water absorption - and even worse for 850nm. However, this is balanced out by the fact that melanin absorption continues to decrease with longer wavelengths.
Another review article on PBM for a recent viral respiratory illness noted this about the optical windows for best penetration being around 810nm and 1064nm.
"More current investigations have identified distinct optical windows within the near infrared spectrum (810nm and 1064nm) with marked differences in production of oxygenated hemoglobin and cytochrome c oxidase [59]. " [13]
However, once again there are other researchers believing that 830nm has the best penetration.
"Deepest penetration is achieved around 830 nm in the near infrared. " [11]
The above article shows a diagram that measured penetration of wavelengths through a human hand, with clearly the deepest point of penetration was 830nm.
One review article on brain health did observe a similar penetration between 810nm and 830nm through the skull.
"On the other hand, no significant difference has been shown between light penetration through the human skull for LED (830 nm) and laser (810 nm) light [95]." [14]
This is made even more impressive that the 830nm was LED and 810nm was Laser, which typically we assume LED has less penetration than laser due to the divergent beam angle of LED and non-coherence.
We have pointed out in previous blogs that targeting deeper tissue and optimizing penetration requires using the skin contact technique. Many "experts" have wrongfully emphasized the importance of wavelengths, intensity, and pulsing for deep penetration; while conveniently ignoring the skin contact method while selling their affiliated non-contact panels.
We covered in previous blogs that non-contact (at a distance) treatment is inherently superficial penetration regardless of wavelength. Using skin contact not only improves absorption with less reflection losses, but changes the skin optics by providing optical coupling, compressing the skin, and blanching out superficial blood.
As such, even if we concede that 810nm has the best penetration by a small margin - the promise of deep penetration is only delivered with skin-contact devices.
Studies on brain health with 808nm/810nm lasers tend to use skin contact to ensure you are getting the full penetration possible. [14]
The popular clinically-studied Vielight headset devices use 810nm LEDs pressed onto the head and encourage users to part the hair so it can make direct contact to the scalp. [15]
In other words, 810nm is only considered the superior wavelength in the context of achieving deep penetration with skin contact. The aspect that makes 810nm optimal is squandered when used in non-contact LED panels.
When used in non-contact therapy like LED panels, we need to re-evaluate the effectiveness based on more superficial systemic mechanisms. Which opens the door for 830nm to be the most viable candidate especially in LED systems and non-contact delivery.
The mechanism department is where 830nm truly shines. The most widely accepted mechanism for red light therapy has been the absorption into Cytochrome C Oxidase (CCO).
In the seminal research by leading researcher Dr. Tiina Karu, she notes the absorption peaks at the following wavelengths:
"with well-pronounced maxima at 620, 680, 760 and 825 nm."
http://photobiology.info/Karu.html
More importantly, each peak corresponds to a specific oxidized or reduced state of the iron (heme) or copper (Cu) molecules in CCO.
For example 760nm corresponds to the reduced state of CuB. So even though 760nm does have an absorption peak, this particular wavelength range in the 700's is often found to be not particularly effective. Perhaps due to this particular Cu state not utilizing the absorbed energy in a beneficial way.
"Low biochemical activity occurs in wavelengths in the range of 700–770 nm." [9]
Light doesn't just need to be simply absorbed by CCO, but it needs a mechanism of action from that absorption. Absorption into the 760nm chromophore is not very effective. So we need to find the absorption peak that corresponds to the best biological response.
Graph adapted from http://photobiology.info/Karu.html
Another study describes the configuration of the molecules as follows corresponding to their absorption peaks:
"CCO has absorption peaks in the red (Heme a, 605 nm; CuA reduced, 620 nm; heme a3/CuB, 655 nm; CuB oxidized, 680 nm) and the NIR spectral regions (CuB reduced, 760 nm; CuA oxidized, 825 nm) [36,37]. When light is shone on CCO, photon energy is absorbed by the various metal centers of CCO and their electrons are excited from the ground state to upper excited states [38]." [14]
Essentially, researchers have found that targeting the CuA in the Oxidized state leads to tremendous response and benefits - which is at the 825nm peak.
It should go without saying that 830nm is closer to the peak of 825nm than 810nm for the purposes of this debate.
"The oxidized form of cytochrome c oxidase has a broad absorption band above 800 nm that is centered at 830 nm (62)."
http://photobiology.info/Karu.html
In fairness to 810nm and 850nm; the peak for CCO is around 830nm has a "broad absorption band" meaning that by proximity then 810nm and 850nm will also activate the same chromophore to a lesser extent. Confirming why these wavelengths ultimately all have similar benefits.
Now we can see why many subsequent studies have specifically chosen 830nm for it's superior absorption peak in CCO and mechanism of action.
The Near Infrared wavelengths are often preferred for deeper tissue treatments like targeting the brain.
Most prominently is that 810nm is the preferred wavelength for transcranial Photobiomodulation (targeting the brain through the head) due to it's promise of having the deepest penetration, as one review article for tPBM had this to say:
"When we investigated the wavelength selection for transcranial LLLT in SCI-indexed articles and other published reports, we found that the most frequently used and concerned wavelength was 810 nm (Fig. 1)." [16]
Another 2023 review article on transcranial photobiomodulation had this to say about a common successful dosing protocol for the brain.
"One of the most common protocols for clinical populations employed devices delivering near-infrared light (810 nm), the irradiance of 20-25 mW/cm2, and fluence of 1-10 J/cm2." [17]
Clearly, 810nm is one of the most-used wavelengths for brain health.
However, 830nm often has it's fair share of studies on the brain. Most notably several studies have used 830nm LED devices on the brain for depression and anxiety disorder in humans. [18][19]
They often state something like this about the choice of wavelength:
"The benefits of t-PBM are wavelength specific: a mitochondrial enzyme, cytochrome c oxidase, is the primary chromophore for the t-PBM with peak absorption close to 830 nm.7" [19]
These quotes confirm a tradeoff that while 810nm promises the best penetration making it preffered for transcranial targets, 830nm is often selected for it's superior mechanisms of targeting the CCO absorption peak. Both of which are very important for brain benefits.
Some actual clinical-grade and clinically studied LED devices have used 830nm in a non-contact delivery system.
These devices are the Healite II and the Omnilux LED system (not the masks, the clinical grade panels they sell). [20]
These have been studied for a range of benefits particularly for wound healing and dermatology. [20]
An important paper titled "Is light-emitting diode phototherapy (LED-LLLT) really effective?" in 2011 lays the groundwork for the scientific backing for the LED panel craze we know today. If it weren't for the success of these early LED panels using 830nm, then LEDs would likely not be considered a viable theraputic option.
"The LED system being used must have first of all, and most importantly, the correct wavelength for the target cells or chromophores. At present, the published literature strongly suggests 830 nm for all aspects of wound healing, pain, anti-inflammatory treatment and skin rejuvenation" [21]
With this quote really establishing that 830nm is preferred for a wide range of benefits from wound healing, pain, inflammation, and even skin rejuvenation - particularly for LED systems. As well it offers the ideal wavelength for the target chromophores and mechanisms regardless of penetration.
This is where the versatility of 830nm NIR shines for superficial wounds and skincare - not only for deep tissue treatments. Where typically NIR is not considered for skincare.
In fact, one study compared a 633nm and 830nm LED panel for skincare and found that the 830nm wavelength gave more satisfactory results than the 633nm. Which debunks the myth that many people falsely prefer Red for skincare. And they found the combination of 633nm and 830nm gave the best overall results for skincare. [22]
An excellent 2016 study covers the use of the Healite 830nm LED panel on treating 395 injuries in student athletes over a 15 month period, with resounding success in most treatments. The discussion section shows much favorability for 830nm LED treatments especially for the systemic response. [23]
One study compared different wavelengths for hair growth in animals, and found that 830nm performed better than 632, 670, and 785nm. [24]
One study on supporting eye health used 830nm on rodent retinas and found very good mitochondrial support and protection. So while there is a lot of hype around 670nm for eye health, it is clear there is some preliminary research that 830nm NIR will be very helpful for the eyes as well. [25]
So we can see many studies identify a possibility unexplored potential for 830nm to support everything from brain health to skincare to hair and eye health. As well the Near-Infrared 830nm is changing some misconceptions that people are incorrectly avoiding NIR for eye health and skin health.
While 810nm may have the best penetration, the real benefits of red light therapy rely on absorption and activation of specific chromophores and biological mechanisms. This is where 830nm has been shown to be superior.
For targeting deeper tissue, then a skin-contact device with 810nm would be ideal to make sure enough photons reach the target tissue. Which is why we have our skin-contact Vector model with a 810nm option.
For a wider range of versatility from deep tissue to skincare based on peak absorption mechanisms - the optimal choice of wavelength is 830nm. Non-contact devices like commercial LED panels need to focus more on wavelengths with systemic benefits due to the lack of penetration. For example, our full-body Overclocked panel puts more proportion into 830nm than the other NIR wavelengths.
As always, we can get too far down a rabbit hole and lose perspective. It may be redundant to debate the benefits of 810nm, 830nm, and 850nm due to their close proximity on the spectrum and similar penetration and mechanisms.
Remember that wavelengths alone do nothing. It is extremely reductive when brands and "experts" make a list of medical claims based on a wavelength alone and then sell devices that are completely different than the studies used. It is the proper implementation of dosing, the device parameters, how it is used, and the bio-individuality of the patient that truly determines the benefits. Understanding context is how we can identify that certain wavelengths are more suitable for skin-contact technique vs non-contact method as a major factor.
Based on this blog's findings - why include 850nm at all in devices? Even GembaRed includes a lot of 850nm in many of our products. While the Red 600-700nm and NIR 800-840nm focus on CCO absorption mechanisms - longer wavelengths like 840nm+ will start to focus more on the other two important PBM mechanisms of developing EZ water in the cells and modulating light-gated ion channels. So by including 850nm we can access more synergistic mechanisms than if we only used 810 or 830nm. We cover this more in a previous blog.
1064nm was also overlooked as a potential wavelenght for red light therapy based on the lack of CCO absorption. So even though 1064nm has great penetration (perhaps better than 810nm), it was thought that 1064nm wouldn't activate any beneficial mechanisms. Until now that the mechanisms of EZ Water and Light Gated Ion channels has been accepted, as well as more studies and devices confirming benefits in clinical trials with 1064nm. [29]
Most of the full-body red light therapy studies have indeed used 660nm+850nm LEDs in the NovoThor pod. Unfortunately in this industry if we say something is not optimal, it is mistaken for us saying it is not effective. 850nm is certainly effective, just not optimal.
So what do you think is the best wavelength? Is this blog biased and cherry picked? If this blog was cherry picked, then someone should be able to easily provide dozens of direct quotes from published literature plainly stating that 850nm is optimal, has ideal penetration, and activates beneficial mechanisms specific to this wavelength - as we have done in this blog for 810nm and 830nm.
[1]
Hamblin MR. Photobiomodulation for traumatic brain injury and stroke. J Neurosci Res. 2018 Apr;96(4):731-743. doi: 10.1002/jnr.24190. Epub 2017 Nov 13. Erratum in: J Neurosci Res. 2019 Mar;97(3):373. PMID: 29131369; PMCID: PMC5803455.
[2]
Cubas IH, Eckert JA, Canalli LV, Carvalho AR D, Bertolini GR F. Photobiomodulation in aspects of muscle function – a scoping review. J Pre Clin Clin Res. 2023;17(1):32-36. doi:10.26444/jpccr/161689.
[3]
Zhang, Chun-Xia et al. “Considerations for the Use of Photobiomodulation in the Treatment of Retinal Diseases.” Biomolecules vol. 12,12 1811. 3 Dec. 2022, doi:10.3390/biom12121811
[4]
Keshri, Gaurav K et al. “Photobiomodulation with Pulsed and Continuous Wave Near-Infrared Laser (810 nm, Al-Ga-As) Augments Dermal Wound Healing in Immunosuppressed Rats.” PloS one vol. 11,11 e0166705. 18 Nov. 2016, doi:10.1371/journal.pone.0166705
[5]
Askalsky, Paula, and Dan V Iosifescu. “Transcranial Photobiomodulation For The Management Of Depression: Current Perspectives.” Neuropsychiatric disease and treatment vol. 15 3255-3272. 22 Nov. 2019, doi:10.2147/NDT.S188906
[6]
Bath, A.S., Gupta, V. Cardio-light: nitric oxide uncaged. Lasers Med Sci 34, 405–409 (2019). https://doi.org/10.1007/s10103-018-2671-x
[7]
Taylor, David N et al. “Low-Level Laser Light Therapy Dosage Variables vs Treatment Efficacy of Neuromusculoskeletal Conditions: A Scoping Review.” Journal of chiropractic medicine vol. 19,2 (2020): 119-127. doi:10.1016/j.jcm.2020.06.002
[8]
Pires de Sousa, Marcelo Victor et al. “Transcranial low-level laser therapy (810 nm) temporarily inhibits peripheral nociception: photoneuromodulation of glutamate receptors, prostatic acid phophatase, and adenosine triphosphate.” Neurophotonics vol. 3,1 (2016): 015003. doi:10.1117/1.NPh.3.1.015003
[9]
Dompe, Claudia et al. “Photobiomodulation-Underlying Mechanism and Clinical Applications.” Journal of clinical medicine vol. 9,6 1724. 3 Jun. 2020, doi:10.3390/jcm9061724
[10]
Pruitt, T.; Carter, C.; Wang, X.; Wu, A.; Liu, H. Photobiomodulation at Different Wavelengths Boosts Mitochondrial Redox Metabolism and Hemoglobin Oxygenation: Lasers vs. Light-Emitting Diodes In Vivo. Metabolites 2022, 12, 103. https://doi.org/10.3390/metabo12020103
[11]
Calderhead, Robert Glen, and Yohei Tanaka. ‘Photobiological Basics and Clinical Indications of Phototherapy for Skin Rejuvenation’. Photomedicine - Advances in Clinical Practice, InTech, 17 May 2017. Crossref, doi:10.5772/intechopen.68723.
[12]
Tunér J. The Laser Wound Healing Contradiction. Photomed Laser Surg. 2015 Jun;33(6):343-4. doi: 10.1089/pho.2015.3905. PMID: 26067944.
[13]
Kitchen, Lydia C et al. “Rationale for 1068 nm Photobiomodulation Therapy (PBMT) as a Novel, Non-Invasive Treatment for COVID-19 and Other Coronaviruses: Roles of NO and Hsp70.” International journal of molecular sciences vol. 23,9 5221. 7 May. 2022, doi:10.3390/ijms23095221
[14]
Salehpour, Farzad et al. “Brain Photobiomodulation Therapy: a Narrative Review.” Molecular neurobiology vol. 55,8 (2018): 6601-6636. doi:10.1007/s12035-017-0852-4
[15]
Zomorrodi, Reza et al. “Pulsed Near Infrared Transcranial and Intranasal Photobiomodulation Significantly Modulates Neural Oscillations: a pilot exploratory study.” Scientific reports vol. 9,1 6309. 19 Apr. 2019, doi:10.1038/s41598-019-42693-x
[16]
Wang P, Li T. Which wavelength is optimal for transcranial low-level laser stimulation? J Biophotonics. 2019 Feb;12(2):e201800173. doi: 10.1002/jbio.201800173. Epub 2018 Oct 1. PMID: 30043500.
[17]
Lee TL, Ding Z, Chan AS. Can transcranial photobiomodulation improve cognitive function? A systematic review of human studies. Ageing Res Rev. 2023 Jan;83:101786. doi: 10.1016/j.arr.2022.101786. Epub 2022 Nov 9. PMID: 36371017.
[18]
Cassano, Paolo et al. “Transcranial Photobiomodulation for the Treatment of Major Depressive Disorder. The ELATED-2 Pilot Trial.” Photomedicine and laser surgery vol. 36,12 (2018): 634-646. doi:10.1089/pho.2018.4490
[19]
Maiello, Marco et al. “Transcranial Photobiomodulation with Near-Infrared Light for Generalized Anxiety Disorder: A Pilot Study.” Photobiomodulation, photomedicine, and laser surgery vol. 37,10 (2019): 644-650. doi:10.1089/photob.2019.4677
[20]
Ablon, Glynis. “Phototherapy with Light Emitting Diodes: Treating a Broad Range of Medical and Aesthetic Conditions in Dermatology.” The Journal of clinical and aesthetic dermatology vol. 11,2 (2018): 21-27.
[21]
Kim, Won-Serk, and R Glen Calderhead. “Is light-emitting diode phototherapy (LED-LLLT) really effective?.” Laser therapy vol. 20,3 (2011): 205-15. doi:10.5978/islsm.20.205
[22]
Lee SY, Park KH, Choi JW, Kwon JK, Lee DR, Shin MS, Lee JS, You CE, Park MY. A prospective, randomized, placebo-controlled, double-blinded, and split-face clinical study on LED phototherapy for skin rejuvenation: clinical, profilometric, histologic, ultrastructural, and biochemical evaluations and comparison of three different treatment settings. J Photochem Photobiol B. 2007 Jul 27;88(1):51-67. doi: 10.1016/j.jphotobiol.2007.04.008. Epub 2007 May 1. PMID: 17566756.
[23]
Foley, John et al. “830 nm light-emitting diode (led) phototherapy significantly reduced return-to-play in injured university athletes: a pilot study.” Laser therapy vol. 25,1 (2016): 35-42. doi:10.5978/islsm.16-OR-03
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4846838/
[24]
Kim TH, Kim NJ, Youn JI. Evaluation of wavelength-dependent hair growth effects on low-level laser therapy: an experimental animal study. Lasers Med Sci. 2015 Aug;30(6):1703-9. doi: 10.1007/s10103-015-1775-9. Epub 2015 Jun 6. PMID: 26048721.
[25]
Gopalakrishnan, S., Mehrvar, S., Maleki, S. et al. Photobiomodulation preserves mitochondrial redox state and is retinoprotective in a rodent model of retinitis pigmentosa. Sci Rep 10, 20382 (2020). https://doi.org/10.1038/s41598-020-77290-w
[26]
Water Absorption Coefficient Spectrum:
https://omlc.org/spectra/water/data/hale73.txt
https://omlc.org/spectra/water/abs/
[27] Hemoglobin Absorption Coefficient Spectrum:
https://omlc.org/news/jan98/skinoptics.html
https://omlc.org/spectra/hemoglobin/summary.html
[28] Melanin Absorption Coefficient Spectrum:
https://omlc.org/spectra/melanin/mua.html
[29]
Kitchen, Lydia C et al. “Rationale for 1068 nm Photobiomodulation Therapy (PBMT) as a Novel, Non-Invasive Treatment for COVID-19 and Other Coronaviruses: Roles of NO and Hsp70.” International journal of molecular sciences vol. 23,9 5221. 7 May. 2022, doi:10.3390/ijms23095221
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9105035/
[30]
Red Light Therapy is a great way to support a wide variety of health and wellness goals.
However, Light only provides cellular energy and signalling, but our cells still need the basic building blocks from proper diet and hydration to function optimally.
Like most holistic alternative treatments, red light therapy is optimized by combining it with proper macro-nutrients, micro-nutrients, vitamins, minerals, antioxidants, and healthy lifestyle choices like sleep and exercise.
In this blog we seek to identify some synergistic supplements and topicals that have been used in the Red Light Therapy clinical literature. In this way it helps us learn about the mechanisms and methods of these interactions to help improve red light therapy.
We categorized several types of supplements and topicals that have been used in red light therapy studies.
Complimentary/Holistic Combinations:
Mitochondria Support - Electron Donors:
Nitric Oxide Donors:
Antioxidants:
Metals:
Blue Light and UV Photoprotection:
Herbal Extracts:
Practical Recommendations:
We should be mindful of precautions when combining Red Light Therapy and other interventions. Always consult a doctor when considering adding red light therapy or supplements for your particular condition.
There are two major potential drawbacks to "enhancing" red light therapy effects with additional supplements or topicals.
1. Hindering ROS
Chugging antioxidants and slathering them on the skin can inhibit the benefits of red light therapy when used recklessly. A major benefit of Red Light Therapy has been the production of signalling ROS. Taking away that mechanism must be carefully considered depending on the context.
Bodybuilders have already learned a long time ago that even though taking antioxidants seems to reduce muscle soreness, it actually hinders the the gains by blunting the ROS and RNS produced by exercise that would promote growth. [1]
Another study mentions the usage of antioxidants on healthy individuals have no apparent benefit, but only speculative benefits on reducing excess ROS that could lead to age-related illness. [2]
"chronic supplementation with mitochondrial-targeted antioxidants may not be immediately beneficial to healthy individuals but may offer some protection against future development of mitochondrial-ROS related pathologies, particularly in those individuals with antioxidant deficiencies (Margaritelis et al.2 018; Paschalis et al. 2018)." [2]
2. Photosensitization
Anything that claims to "increase absorption" or "increase effectiveness" can act as a photosenitizer too. Essentially, we still need to consider biphasic dose response and possibly reduce the therapeutic dose required.
In that way these supplements don't inherently "enhance" red light therapy at all, but now you need to titrate the dose of red light therapy and juggle titrating the dose of additional supplements to see how they interact. Adding more variables like supplementation doesn't automatically improve red light therapy, it just makes it more complicated.
In most sections as we review different supplements and topicals, we will also note where the same exact combination can decrease the effectiveness of photobiomodulation.
A different form of light therapy is called Photodynamic Therapy (PDT). PDT is intentionally meant to damage or inhibit unwanted cells like bacteria or cancer cells. They use a photosensitizer chemical that enhances light absorption, then the appropriate wavelength to cause damage. Examples of photosensitizers are Methylene Blue, Curcurmin, Arginine, and Ascorbic Acid - which are the exact same we will also note can be synergistically beneficial to red light therapy in lower doses. [3][4][5][6]
So we should take pause when supplements or topicals claim to enhance light absorption, since that would imply it could have a PDT effect and not a PBM effect.
The examples in this section illustrate the need to combine red light therapy with other holistic interventions to maximize results. In other words, these examples are not specifically synergistic to red light therapy, but simply help fulfill the goals and benefits by using multiple modalities.
Kitchen Sink Approach
The best clinical example of a holistic approach was a case study recently published in September 2023 in the Journal of Avian Medicine and Surgery.
In it, a parrot had suffered a spinal cord injury and was struggling with it's health. The treatment was to administer fluids, Vitamin A, D, E, anti-inflammatory drugs and painkillers. It also underwent Photobiomodulation, acupuncture, Tui-na massage, and rehabilitation exercises. After 20 days it was released with significant improvement. [7]
So it is valuable to consider a near-future that photobiomodulation is not only a standard of care, but will be used as a combination therapy with other modalities that help achieve the health goals of the patient.
Weight and Health Markers:
One study combined Low Level Laser Therapy (LLLT) with the Mediterranean Diet to help manage fatty liver disease and help weight loss. [8]
Another study combined LLLT with exercise and found an improvement over exercise alone to improve lipid markers and manage weight. This study was performed on rats being fed a high-fat diet, and interestingly they tended to gain more weight with LLLT alone without exercise. [9]
Exercise and PBM for Pain Management:
One study treated osteoarthritis by combining LLLT and exercise - and found the combination worked best. [10]
Another study on chronic low back pain combined LLLT, spinal manipulations (chiropractic adjustments), and exercise. They found the combination of all 3 treatments performed best. [11]
This is essentially what I did to solve my own personal chronic low back pain several years ago. It likely would not have been resolved with light therapy alone, it was in combination with working with a chiropractor and exercises.
B Vitamins and PBM
One study combined B Vitamins and PBM to manage neuropathic pain in rats. They found the combination worked faster than the individual interventions.[12]
For reference, here are the B Vitamins used for this trial on combination with PBM:
"vitamins B complex, thiamine, pyridoxine and cyanocobalamin (B1, B6 and B12, respectively)". [12]
Another study also used B Vitamins and PBM to treat pain in rats. While all groups showed an improvement, the combination did not show a significant advantage over the individual interventions. [13]
Weight Loss and Body Circumference:
A review of LLLT on fat reduction makes this statement about the recommended supplements to combine with the LLLT treatments.
"In addition, manufacturers encourage consumers to use some supplements such as vitamin B5 and L-carnitine, Ginkgo biloba or green tea to reinforce circulatory and lymphatic systems (56)." [14]
Another study made this comment that the results were confounded by the combination of supplements and LLLT. Even though the patients lost significant inches during the trial, they can't say for sure if it was from the LLLT, the supplements, or the combination.[15]
"However, the study had several limitations such as lack of control group as well as administration of dietary supplements (niacin, niacinamide, l-carnitine, omega-3 fish oil, ginko biloba, and decaffeinated green tea) in the study subjects [68]." [15]
So despite confounding the variables, it may be complimentary to take some of these supplements if the goal is weight loss or reduced body circumference.
Now lets look at some supplements that offer synergistic mechanisms to red light therapy.
The following supplements not only have obvious antioxidant and anti-inflammatory actions, but specifically support mitochondrial function that have been studied to be synergistic with Red Light therapy.
On the mitochondrial membrane is the Electron Transport Chain, which we know Photobiomodulation up-regulates primarily through Complex IV called Cytochrome C Oxidase (CCO). CCO is the "rate limiting" step on the chain to produce ATP, which is why Photobiomodulation is extremely effective entirely on it's own.
Other studies confirm PBM up-regulates Complex III also.[16] And we know that from the EZ Water mechanism that PBM improves Complex V aka ATP Synthase.
As the name implies, the Electron Transport Chain facilitates the transfer of electrons through various exchanges that we know as Oxidation and Reduction. These chemical reactions are two sides of the same coin, often shortened to Redox Reactions.
Thus, while red light therapy will mostly upregulate CCO and ATP Synthase (Complex IV and V), it is often helpful to the mitochondria to have supplements that support Redox and the other steps of the Electron Transport Chain.
Methylene Blue, Ubiquinol (CoQ10), Quercetin, and Curcumin are all related to each other via the Quinone family of chemicals. Either in their original state like MB and CoQ10, or in their oxidized states like Quercetin and Curcumin. [17]
Essentially these supplements can cycle between their Oxidized and Reduced forms while exchanging electrons at various points in the Electron Transport Chain.
The three supplements (CoQ10, Quercetin, and Curcumin) have been shown to boost NAD+ levels or at least play a role in supporting NAD+/NADH exchange through the Redox Reactions. Which plays another important role in supporting mitochondrial function. [18]
Unsurprisingly, all four of these supplements have been studied in combination with red light therapy.
Methylene Blue (MB):
Methylene Blue is a synthetic blue dye that has been used as a medication in malaria treatment, methemoglobinemia, and cyanide poisoning. Methylene Blue has been shown to seek out high-metabolic cells and cross the blood-brain-barrier and act as an electron donor to the mitochondrial respriation process. [19]
A review article covers the mechanisms and synergies with combining methylene blue and photobiomodulation for neuroprotection like in Alzheimer's, Stroke, and Parkinson's disease. [19]
Another review article also describes the methods of neuroprotection with MB and PBM. [20]
One study combined oral MB with PBM to manage COVID-19 symptoms on 8 human case studies. 6 of them reported no long-covid symptoms after follow-up, and they all showed to hold lasting immunity. [21]
A study found the combination of MB and PBM improved brain metabolism in rats suffering from cognative decline. [22]
Note that Methylene Blue has high absorption in the Red wavelengths, which as we mentioned earlier can be used as a destructive therapy called Photodynamic Therapy (PDT). There are many studies using MB and Red light for PDT, but that is outside the scope of this blog other than mentioning it as a precaution.
CoQ10 / Ubiquinone
If taking an artificial dye is too daunting, then the dietary supplement CoQ10 may be a preferred alternative for supporting the mitochondria.
One review article notes that while CoQ10 is found in all cells, it is concentrated in the cells that have the highest metabolic activity like the heart - which confirms it's role it is playing in supporting the mitochondria. The human body synthesizes and recycles most of it's CoQ10 levels naturally, but there have been studies where theraputic supplementation has been effective. It notes the average daily intake from the diet is about 5mg/day, but clinical trials with CoQ10 supplementaiton is about 300mg/day for 2-4 weeks to reach theraputic levels.[88]
In the diet, CoQ10 is predictably found in mitochondria-rich organ meats like liver and heart. It is also found in fatty fish and whole grains. One article dubbed CoQ10 as an essential nutrient. [74]
One PBM article describes CoQ10 as:
"Coenzyme Q10 (CoQ10) also known as ubiquinone, is an essential cofactor for the activity of complexes I-III of the mitochondrial electron transfer chain acting either as a donor or acceptor of electrons(Dallner and Sindelar, 2000)." [23]
So we can see it's synergistic value that CoQ10 supports Complex 1-3, while we know PBM upregulates Complex 4 and 5.
So there could be merits to supplementing CoQ10 entirely on its own for heart health and brain health to support the mitochondria, and here we find some preliminary studies on rats that show the potential to combine CoQ10 supplementation with red light therapy for additional synergy.
Quercetin:
Quercetin is a flavanoid that also holds similar mitochondrial mechanisms as CoQ10.[27] Its action is often on the Complex 1 of the electron transport chain. [27]
So again we have some preliminary data and one small human study showing the potential to combine Quercetin with light therapy for additional effectiveness.
Curcumin:
Curcumin is the active compound found in Tumeric root, giving the distinctive yellow color to many curry dishes. Curcumin alone has been studied for a wide range of health benefits particularly as a powerful antioxidant. [32]
Three studies have found positive results when combining Curcumin and PBM for wound healing in rats. [33][34][35]
Nitric Oxide is an important metabolite in the body that is often correlated with blood flow, heart health, and vasodilation.
Red Light Therapy famously increases Nitric Oxide levels as one of it's primary mechanisms.
Interestingly, PBM does not directly affect the usual Nitric Oxide (NO) production cycle. In fact one study excluded participants taking any drugs or supplements that would affect Nitric Oxide synthesis so they could monitor the NO pathways. [36]
Instead, PBM releases intracellular stores of Nitric Oxide often assumed to be in the blood or bound to CCO.
"Nitric oxide (NO) may be photo-released from extra intracellular storage, such as nitrosylated hemoglobin and nitrosylated myoglobin, in addition to being photo-dissociated from Cox [11]. Furchgott first identified light-mediated vasodilation in 1968 while working on the nitric oxide project that would earn him the 1998 Nobel Prize [12, 13]." [37]
However, there could be cases where NO stores are depleted, or additional NO could be beneficial.
One study combined LLLT and a Nitric Oxide producing drug and found improved wound healing. [38]
Arginine is an amino acid that is a precurser to Nitric Oxide. Topical Arginine has been used in 3 studies in conjunction with PBM to enhance wound healing in rats. [39][40][41]
Arginine and its relative Citrulline are both popular Nitric Oxide booster supplements on their own. Although it hasn't been studied in conjunction with PBM, L-Citrulline and Citrulline Malate seem to be preferred for their better oral absorption and they metabolize into Arginine in the body to act as a NO donor. [89]
As a precaution - one study combined LLLT with NO donor drugs and found the LLLT effectiveness reduced. [42] Likely because excess NO is a primary reason for the biphasic dose response (overdose of red light therapy). Which is also why Arginine has been used in Photodynamic Therapy as well.
Antioxidants famously counteract inflammation and Reactive Oxygen Species (ROS).
The speculation is that antioxidants can mitigate the excess ROS produced by Red Light Therapy. While this may be true, we cannot be sure if this is always a good thing, as the signalling aspects of ROS also provide many benefits.
Paradoxically, Red Light Therapy often acts as an antioxidant itself, and the net effect of red light therapy is that it promotes better antioxidant balance with less oxidative stress. [43][44]
So, potentially intervening with the Red Light Therapy by applying exogenous antioxidants could produce different or unexpected results until these combinations are fully studied.
N-Acetyl-Cysteine (NAC):
NAC is sulfur-containing compound that is a precursor to glutathione (a master antioxidant) and a powerful antioxidant/anti-inflammatory even on its own.
NAC has a wide range of applications including heart health, lung health, neurological health, liver health, and much more. [45]
Low Level Laser Therapy and NAC have been confirmed to have synergistic benefits in a study on inflammation markers. [46]
Another study combined LLLT and NAC to reduce hearing loss in rats. [47]
One study notes the mechanism that NAC protected against inhibitory ROS from Blue and Green light, but it did not affect the activity of Red light. Again potentially confirming a synergistic action with Red light while offering protection from Blue light damage. [48]
Another article found that Photobiomodulation combined with NAC or Vitamin C were able to reduce the ROS-induced inflammatory marker NF-kB, but the cells still showed increased ATP production. [49] So that is overall a good thing if we want to increase ATP production but use the antioxidants to mitigate the ROS.
"The fact that antioxidants do not abrogate the ATP increase suggests that the action of light increases electron transport, which in the absence of antioxidants can cause increased electron leakage producing superoxide." [49]
However, one study showed that NAC hindered the benefits of laser therapy, and directly mentioning that ROS plays an important role in the benefits of red light therapy. So blunting the ROS is not always a good thing for red light therapy.
"On the contrary, in the presence of NAC, laser irradiation was not able to induce any cell proliferation, suggesting a crucial role of ROS in this laser-induced cell effect." [50]
An another study showed that using NAC hindered the beneficial Nitric Oxide typically generated from laser therapy.
"Interestingly, upon treating cells with NAC, NO generation with 1064 nm laser exposure was significantly inhibited" [51]
However, most of these studies used NAC directly on isolated tissues. We assume that oral ingestion by a human would help disperse the antioxidant and reduce the risk of hindering too much of the ROS capacity of red light therapy.
Molecular Hydrogen:
Molecular Hydrogen is the therapeutic usage of H2 (hydrogen gas). It can be ingested when dissolved in water or inhaled as hydrogen gas. Molecular Hydrogen has been shown to be a powerful selective antioxidant.
One pilot study recruted 18 individuals with Parkinson's disease for a trial with a 940nm LED panel emitting 6 mW/cm^2, combined with oral ingestion of 2.5ppm hydrogen water. [52]
The pilot study concluded that this combination of Molecular Hydrogen and Red Light Therapy was safe and offered relief from the severity and symptoms of the disease.
Vitamin C:
Vitamin C (ascorbic acid) is a famous antioxidant found in citrus fruits and many other fruits and vegetables.
Vitamin C has long been known to play a role in dermatology and photoprotection of the skin from sunlight. And may even play an important role in regulating pigmentation and melasma. [53]
One study on isolated tissue showed a synergistic benefit of Vitamin C and PBM on cell proliferation. [54]
A human study with 20 people in the active group used Vitamin C and glycolic peels combined with non-thermal Blue and Near-Infrared light therapy for an improved result over the topicals alone. The 5% Vitamin C cream called Active C by La Roche was applied after the irradiation at night. [55]
However, one study did note that ascorbic acid prevented the effects of Photobiomodulation.
"Additionally, the effect of ascorbic acid on preventing PBM effects in PDT shows that ROS play an important role in the early mechanisms of PBM-PDT." [57]
So again confirming the importance of ROS from Red Light Therapy, that it is not something that we need to inhibit since it could reduce the overall effectiveness of red light therapy itself.
Resveratrol and Vitamin C Protects from High Dose Red Light Therapy:
One application of red light therapy is to purposefully do high doses that specifically causes high ROS and cell death. Which is why we always promote low doses for true Photobiomodulation therapy. For example one study used 120 J/cm^2 from 633nm laser to induce apoptosis (cell death). [57]
"High fluence low-power laser irradiation (HF-LPLI) is a newly discovered stimulus through generating reactive oxygen species (ROS) to trigger cell apoptosis." [57]
These studies will often use antioxidants to see if it can inhibit the ROS mechanism of cell death. Indeed, one study used Vitamin C and others have used Resveratrol to reduce the ROS from high dose red light therapy. [58][59][57]
It seems to be an excellent business model to sell overpowered devices that generate high ROS and then sell a recurring cost of a supplement or topical that protects you from the excess ROS. When a more effective and cost-saving solution would be to just sell appropriate low-intensity devices and promote low doses that are proven clinically effective on their own without supplementation.
Chia Seeds
Chia Seeds are the seeds of the Salvia hispanica L. plant. Chia Seeds are a popular dietary supplement for for it's nutritional profile. [60]
Two separate articles investigate the combination of chia seeds and 670nm photobiomodulation on rats with diabetic retinopathy with positive results for the combination. [61][62] So this combination could play in important role in supporting eye health.
The mitochondria are dependent on proper Iron and Copper levels, as well as being modulators of Iron and Copper functions.
"Iron is the dominant metal in mitochondrial metabolism, but copper has important roles (Figure 1). Fe-protoporphyrin (heme), Fe-S clusters and Cu are essential components of the mitochondrial inner membrane complexes constituting the electron transport chain." [91]
We know that the primary light-absorbing molecules in the mitochondria are the Iron and Copper based molecules within the Cytochrome C Oxidase.
Iron status and anemia are well known to affect wound healing on their own. [63]
One study looked at wound healing in rats in two separate groups that were iron-deficient (anemic) or had healthy iron levels. While Photobiomodulation showed an improvement in both groups, the group with the normal levels of iron responded better to Laser treatment, and the anemic group responded better only to LED treatment. [64]
So this one small study does indicate an interaction between iron deficiency and photobiomodulation. However, there has been no direct follow-up studies to this one performed in 2013.
Another study makes this connection between Ferritin (stored iron in the blood) and Near-Infrared Light therapy:
"Two chemical components, NO and ferritin, are probably involved in the cell reactions induced by the exposure to the near-IR (850- to 900-nm) light." [55]
One human study with a Near-Infrared helmet even pre-screened their participants for ferritin, which may imply they understand the implications that iron status may have on Photobiomodulation effectiveness, or at least on the particular condition they were treating. [65]
Copper deficiency has been shown to reduce activity of Complex 4 (CCO) in the mitochondria. [66] Which of course is the important target of PBM. If the CCO is dysfunctional due to inadequate copper, we could assume a reduced response from red light therapy.
A PBM study makes this note about the role of copper in CCO for light absorption.
"Copper broadly absorbs NIR in the range of 700–1000 nm, and the copper centers in COX have been suggested to function as the primary photoacceptors for NIR14,15,16." [67]
The late Dr. Ray Peat (1936–2022) makes the following connection to Red light and copper/iron in CCO in one of his articles:
"Cytochrome oxidase is one of the enzymes damaged by stress and by blue light, and activated or restored by red light, thyroid, and progesterone. It's a copper enzyme, so it's likely to be damaged by excess iron. It is most active when it is associated with a mitochondrial lipid, cardiolipin, that contains saturated palmitic acid; the substitution of polyunsaturated fats lowers its activity. Mitochonrial function in general is poisoned by the unsaturated fats, especially arachidonic acid and DHA." - Ray Peat
Iron or Copper supplementation is a case where we would not recommend haphazard supplementation, as too much copper or iron can also lead to toxicity.
Monitoring the status of these important metals and working with a professional to keep them balanced may play an important role in overall health, mitochondrial function, and photobiomodulation effectiveness.
Blue light causes large amounts of ROS and oxidative damage at relatively much lower intensity and doses than Red/NIR light. So if you are considering blue light therapy exposure then some of these supplements may help mitigate the potential damage. As well, these mechanisms may also help us understand synergistic effects with Red/NIR light since they also produce ROS but at much lower levels.
Supplemental Eye Protection from Blue Light Exposure
One study on retinal (eye) cells confirmed that Blue Light directly produces ROS by inhibiting the Electron Transport Chain in the mitochondria (typically the opposite effect we want from red light therapy).[68]
The same study confirmed this effect by using MitoQ to reduce the ROS production by supporting the mitochondria as an antioxidant. MitoQ is a synthetically oxidized form of ubiquinone, sharing similarities to CoQ10. [68]
Another article reviewed several antioxidants that have been shown to be protective of the eyes from blue light hazard.
"Oxidative stress plays an important role in blue light hazard. Studies have confirmed that antioxidants, such as lutein, curcumin, vitamin E, and Prunella vulgaris, can suppress the accumulation of oxidative stressors." [69]
In addition to the protective supplements listed above like lutein, curcurmin, and Vitamin E, another study showed Astaxanthin as protective of the eyes to blue light. [70] Which generally most of the dietary carotenoid family can be protective of eye health.
Of course, supplements are not a substitute for using eye protection or simply avoiding direct blue light exposure to the eyes. Remember that Neutrogena recalled their LED mask due to the close proximity of blue LEDs to the eyes. Another peer reviewed published case study describes eye damage caused by another LED Mask emitting blue light between 460nm-470nm. [71]
Supplemental Skin Protection from Blue Light:
The high amounts of ROS from blue light can also be detrimental to the skin. One study mentions the following antioxidants for mitigating the ROS from blue light.
"ROS detoxification in skin is achieved by low molecular weight antioxidants, such as Vitamins C and E, and carotenoids like β‐carotene, as well as by enzymes and antioxidant proteins" [72]
In our previous blog it was established that blue light causes hyperpigmentation either through the ROS pathway or through Opsin 3 activation. One study found niacinamide and a microalgae extract were effective in reducing the hyperpigmentation response from blue light. [73] So this may not only be important for blue light exposure, but it may be worthwhile for people to try niacinamide with Red/NIR exposure if they are struggling with a hyperpigmentation response even with the non-blue wavelengths.
Another study investigated the role of niacinamide (also known as nicotinamide, a form of Vitamin B3) and controlling skin aging and pigmentation. [75] They point out another well-known role of niacinamide is to promote NAD+ levels, which we could speculate it could also be synergistic with Red Light Therapy in that way like the earlier sections about supporting the ETC, although we could not find any direct studies with niacinamide and Red/NIR Photobiomodulation.
One review article details the important photoprotective effects and mechanisms of niacinamide. It says up to 80mg per Kg of body weight is well tolerated, or it can be used as a 3-5% topical solution. Both ingested or topical application of niacinamide has been shown to be photoprotective from UV. [76]
Another study mentions this about the role of Niacinamide/Nicotinamide in the mitochondria for neurodegeneration:
"Nicotinamide (Vitamin B3) and its derivates are also being explored as strategies to restore ATP production. In this line of investigation, Nicotinamide has been observed to normalize redox levels, with initial studies reporting that it may also affect metabolism-regulating sirtuins (Prasuhn et al., 2021). Nicotinamide metabolism is highly relevant for mitochondrial complex I and could be used to rescue ETC disturbances (Lehmann et al., 2017)." [77]
We also speculate Niacinamide/Nicotinamide would be synergistic to supporting the mitochondria, NAD levels, and ATP production. As shown by it's Blue/UV photoprotective effects already, this would be an interesting supplement to see it combined with red light therapy in the future.
Many herbal extracts have been used in combination with red light therapy.
Famously, an article with a single patient claims a vast improvement by using a Green Tea preparation on the skin before red light therapy treatment. [78] However, we have not seen any follow-up studies from that 2009 article to confirm the results in a larger population.
One 2011 article on 60 females does confirm the use of Green Tea and other polyphenols as photoprotective from UV light. This study had the participants consume a green tea as a beverage, not as a topical.[79]
Indeed, one excellent review article covers a wide range of plant extracts and their ability to offer photoprotection. They included Green Tea, Rooibos Tea (Aspalathus linearis), Coffee, Bergamot Tea, Orange, Grapefruit, Fennel, Ginsing, and more. [80] Most of these have been tested topically or orally to protect from UV-B light, but we do not see any direct studies on Red/NIR light therapy. But they do note the potential to incorporate these compounds in cosmetics to mitigate photoaging.[80]
One study by Silva et al. investigated various herbal extracts and it's combination with PBM on isolated cells.[81] They make a valuable observation that even herbal extracts have a dose-response curve, so more is not better even for herbals and antioxidants.
"However, the administration of polyphenols should respect the dose-response concept, since adverse effects may be observed when larger amounts of polyphenols are used. The literature reports that excessive doses of polyphenols may promote adverse effects, such as toxicity [34]."[81]
They found their preparations of green tea, rosemary, and pomegranite all presented toxicity so they chose not to combine with PBM. The combination of PBM and Fig extract yielded no significant improvement. The combination of PBM and Nutwood extract resulted in a negative response of cell death, the authors note it is from the photosensitization of the cells to red light caused by the nutwood.[81]
Another study combined a 5% Lycium barbarum fruit (goji berry) extract combined with 660nm PBM to test its effects on photoprotection from UV.[82]
They found that applying the Goji Berry extract before PBM had worse results than using PBM first then applying the Goji Berry extract second.[82]
"However, in our study, the application of LBPF followed by PBM promoted a decrease in birefringent collagen fibers. Therefore, an inhibitory effect may have occurred due to PBM-associated fraction composition (LBPF) in this order of application." [82]
This study even references the previous study in saying:
"Silva et al. [17] have shown that combining PBM with natural extracts may be a useful strategy, but choosing a natural extract is very challenging due to work concentration and other properties, such as photosensitivity, which may bring
unwanted results." [82]
Another study used Porophyllum ruderale leaf extract combined with 670nm PBM for wound healing.[83] Once again, they found that the extract applied before PBM led to worse results than either component separately:
"A probable explanation for this fact may be related to the permanence of the green pigment of leaves in P. ruderale extract"[83]
Essentially, various plant pigments and phytochemicals from plants can act as photosensitizers, light absorbing/blocking mediums, or add to their own oxidation or toxicity especially under direct light exposure.[84] So even if the "active ingredient" is shown to be safe, the extraction process may include other unwanted phytochemicals.
One study combined Calendula officinalis (marigold) oil and 658nm LLLT to heal diabetic ulcers in humans.[85] They applied the LLLT first, then the oil which was successful in reducing pain and wound size. The order is particularly important as many essential oils have been shown to be photosensitizers (to UV, not tested with Red/NIR). [86]
Another study made this comment about how antioxidants can have a pro-oxidant effect when light is applied to them.
"Other extracts with antioxidants properties have also showed to be oxidative when exposed to light in a specific wavelength [19]." [87]
Interestingly that study was using a plant extract and blue light as a Photodynamic Therapy for it's antimicrobial action on halitosis. [87]
So there is a vague line between using topicals for destructive Photodynamic Therapy (PDT) versus stimulatory Photobiomodulation (PBM) Therapy. We cannot assume benefits until these have been tested, since we could falsely assume that something is an antioxidant but it could have pro-oxidant effects when it is irradiated with light.
Bottom Line: Topical Extracts and Antioxidants should be applied after red light therapy, not before. They have a higher probability of causing a detrimental response according to the current research. In our previous blogs, we know the peak of metabolic activity occurs 3-6 hours after the red light therapy session has ended. This gives a huge window to apply the topicals shortly after red light therapy to still mitigate the ROS and give supportive cosmetic phytochemicals, while avoiding directly irradiating the topicals which would cause unwanted effects.
Photobiomodulation is extremely effective entirely on its own. It upregulates the electron transport chain on the mitochondria, promotes NO liberation, and improves antioxidant balance on its own accord. In that way, photobiomodulation is the most effective "supplement" you can use.
In that way, many of these supplements and topicals may be redundant to PBM effects in the same ways they are potentially synergistic. Using combination therapy should be considered only after individual therapies are attempted.
The challenge with red light therapy is threading the needle of balancing stimulatory and inhibitory mechanisms - and additional supplements don't universally enhance red light therapy but need to be considered as part of the overall dosing protocol.
Based on the current research, is it likely safer (and more effective) to use topicals after red light therapy. Red light therapy should be applied to bare, clean, dry skin. In some cases with dry skin - exfoliating the skin, applying a no-active-ingredient moisturiser, and then cleaning it off before red light therapy treatment can be helpful.[90]
Unless the doctor or formulator of the topical has clear data showing safety of their specific formula with the specific wavelengths, intensity, and dosage of light that you will be using - you don't want to become a guinea pig based on speculative benefits.
Oral ingestion of mitochondrial supplements and antioxidants is likely fine, as there will be limited absorption and the supplement being metabolized and dispersed around the body - to the point that the amount actually reaching the cells being irradiated with PBM will only have minimal amounts of the supplement. This is a good thing as the body will be limiting the potential downsides of the supplements interfering directly with PBM effects.
In most cases, this blog is not meant to "sell" you on supplements or topicals. Red Light Therapy works best with adequate diet, exercise, sleep, and lifestyle habits that support good health. Addressing basic nutrient and mineral deficiencies may play an important role in overall health and red light therapy responsiveness. We speculate that Red Light Therapy will be synergistic with a wide variety of supplements, and only a limited number have been clinically tested so far.
The risk is that brands are selling overpowered devices and encouraging overdosing where the benefits will be limited by the biphasic dose response - then they sell you a supplement and topical that counteracts the inhibitory ROS. When the real solution is to just use lower intensity and doses, such that way you don't need supplements to protect you from the low levels of beneficial ROS.
This preliminary research only gives some small guidance about how to use combination therapies properly. And more interestingly it highlights the importance of the ROS mechanisms and that we cannot make assumptions about whether a supplement will act as an "enhancer" or "photosensitizer" until there are clear studies for each interaction.
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]]>
The basic premise and definition for Photobiomodulation (PBM) and Low Level Laser/Light Therapy (LLLT) has been that it is the science of the non-thermal interaction of light on biology. [1]
The Red to Near-Infrared wavelength range from 600nm to 1100nm are typically considered to be the "optical window" of the skin that not only penetrate deepest into the skin compared to the rest of the spectrum, but also deliver the least heating to the tissue.
"LLLT consists of non-thermal red or near infrared light (600–1000 nm) which might affect many cellular processes" [2]
"The use of low level light (laser) therapy (LLLT) consisting of non-thermal red and/or near infrared light (600–1000 nm) delivered from a laser or from a non-coherent light source has been shown to have beneficial effects on a wide range of pathologies." [3]
Notice the above quotes referring to the wavelengths of PBM/LLLT as non-thermal.
However, any wavelength can cause heating at high intensities. As it often denoted by the common term "cold laser" to separate low intensity lasers from the high intensity ones that cause heating.
PBM studies are careful to use low intensities to ensure it is a non-thermal tissue response. Or they may use other methods such as pulsing or external cooling to reduce the deleterious heat from high intensities.
As this quote reminds us, it is important to use intensities that are low enough to not cause significant heating of the tissue.
However, if we can find which wavelengths have the least heating effect, then we could potentially maximize the intensity that can be used safely. For example if 810nm is less heating than 650nm (it is), then we could use relatively higher intensity of 810nm than 650nm without causing heat.
The wavelengths that generate the least heat on the skin also correspond to being the ones that penetrate the deepest. So this is a simple way to confirm which wavelengths have the best penetration.
And we will finally put to rest another myth that Near-Infrared is more heating than Red. When it is the opposite, Near-Infrared wavelengths produce less heat on the skin compared to Red.
Spoiler: Near-Infrared wavelengths around 800nm-850nm produce the least heat on the skin. Where the Red wavelengths are significantly more superficial absorption leading to more skin heating. For people with darker skin types it may be important to use longer wavelengths around 1064nm due to the higher melanin absorption with the shorter Red and NIR wavelengths.
Finding the least heating wavelengths is particularly important for people with sensitivity to heat, people predisposed to hyperpigmentation and melasma, or people wanting an evidence-based treatment for true "cold" light therapy called photobiomodulation.
As we have noted in previous blogs, heating will drastically increase the ROS production leading to a faster biphasic dose response - and increase circulation which actually hinders penetration. So for optimal PBM benefits, most studies are carefully designed to minimize heating. The first step to minimizing heating is selecting the proper wavelength.
Many people falsely assume that all Infrared wavelengths are intrinsically heating.
In his book Zapped, author Bob Berman reminds us of the obvious:
"Infrared radiation is not heat. Rather, infrared radiation creates heat. " (pg. 39) [5]
Bob Berman explains to the reader that Visible light wavelengths can also generate heat. The real difference is how the different wavelengths are absorbed.
Lets say we have:
Which one is the most heating?
We know the first law of thermodynamics is that energy is normally never created nor destroyed - it only changes form. [6]
"As a representative phenomenon of light–matter interaction, the photothermal effect is generally characterized with the temperature increase in a material through the absorption of light." [2]
So 10 Joules of any light wavelength is the exact same amount of potential heat energy.
This is the same kind of riddle to say "if you have 10 kilograms of steel and 10 kilograms of feathers, which one is heavier?" In the same way we know 10 Joules of Red light is the same potential heat energy as 10 Joules of Far-Infrared.
So what is the real difference when we think about how wavelengths get transformed into heat? Absorption.
When an electromagnetic wave (i.e. light) encounters matter (anything from solid objects, air molecules, water, etc), then it has 3 fundamental choices:
Many semi-transparent objects will exhibit a combination of all 3 of these features. Even a glass window may reflect some light as glare, absorb some light as heat, and let most of the visible light transmit though.
Obviously Reflection and Transmission would not contribute to any heating effect, and only absorption can have a heating effect.
This phenomenon is rather intuitive, but it is so crucial that it is called the First Law of Photochemistry/Photobiology; that only absorbed radiation will have an effect on the molecules. It is also called the Grotthuss-Draper Law after the researchers who cemented this concept in the early 1800's. [7]
When a photon is absorbed by a molecule, the photon is annihilated and the molecule enters a higher energy state. Since energy is conserved via the 1st law of thermodynamics, the molecule must resolve this higher energy state to maintain some equilibrium and stability.
There are 3 fundamental options for the molecule to do after absorbing a photon:
(pg 36) [8]
In laymen's terms, the result is:
The goal of Photobiomodulation is to focus on the chemical reactions that are facilitated by by photon absorption whilst minimizing heating. As we can see in the below quotes.
"PBM is devoid of thermal and ablative mechanisms and exploits the absorption of light to affect a chemical change [9]. " [10]
For example the energy provided can break the bond between Nitric Oxide and CytoChrome C Oxidase to up-regulate the Electron Transport Chain, or to impart it's energy to form EZ Water in the cell, or modulate proton gradients and ion channels.
A more common chemical or molecular change is a phase change. When water transforms into steam it consumes energy without increasing temperature. The name of this is "latent heat" which is a stored potential energy now in the higher-energy state of steam. The same way many chemical reactions will consume energy without neccesarily changing temperature.
This is indicative of the 2nd Law of Photochemistry/Photobiology. Also called the Stark-Einstein law of photoequivalence, it tells us every absorbed photon will cause a single elementary reaction to a molecule. As we have already listed the elementary changes that can undergo are heat, luminescence, or chemical changes.
Ultimately the end result promotes the production of the chemical energy currency of the cell, ATP. These are all photochemical events, and with minimal influence of photothermal effects.
It is generally agreed upon that Red has more superficial absorption and Near-Infrared is deeper penetrating. Yet this is contradictory to the myth that Near Infrared is more heating than Red.
One study explains this concept well:
Only a comparable small fraction of the higher red wavelength’s energy is being absorbed, as most of it is reflected and the absorption is spread out over a larger volume due to the long wavelength’s increased penetration depth." [11]
Now this example discusses how Blue and Green light is more heating than Red light. But the concept remains the same.
The wavelengths with the deepest penetration can spread it's energy out in a wider volume. Wavelengths that are superficially absorbed will cause more superficial heating.
For example, consider heating a pot of water that is half-full compared to a pot that is completely full. Obviously the half-full pot heats up faster because it has less volume. Similarly if Near-Infrared penetrates twice as much as Red, it has twice as much volume to disperse it's energy into. Therefore, less skin heating from NIR.
As discussed in earlier blogs, the "optical window" of the skin is where there are the lowest absorption of primary chromophores like Melanin, Hemoglobin, and Water.
[12][13][14]
Here we see the least absorption ranges are around 800-850nm and then another low absorption range 1040nm to 1100nm. We often see these ranges are popular in clinical trials due to their deep penetration.
Incidentally, the "optical window" wavelengths also correspond to the wavelengths that have the highest reflection from the skin.
[NIST Skin Reflection Spectrum]
Here we see the highest reflection from 630nm to 900nm, and another reflection peak around 1050nm to 1120nm. Interestingly the reflection spectrum is nearly the inverse of the absorption spectrums, which makes sense because they affect each other.
Having the lowest absorption and highest reflection is why these wavelengths have the least thermal impact on the skin. Which also corresponds to wavelengths that are expected to penetrate the deepest.
While many will dispair at the high reflection losses when using non-contact red light therapy (i.e. at 6 inches away), this is a good thing. The reflection properties will cause forward scattering once the photons are in the body - especially aided by using skin contact technique to overcome the initial reflection losses.
Now lets look at some examples. An article compared the heating effects from a standard incandescent halogen lamp versus a Water Filtered IRA (wIRA) lamp.
In the wIRA lamp, the heating wavelengths are filtered by water so only non-thermal wavelengths are passed through.
"The threshold temperature for heat pain—defined according to DIN 33403-2 as being approximately 43C (see ref. [24])—was observed at an incident irradiance of approximately 1000 W m)2 for the unfiltered IR halogen lamp and of about 2500 W m)2 for the wIRA radiator (see Fig. 10a)." [15]
With a standard halogen bulb the tolerated intensity is only up to 100mW/cm^2. However with the filtered wIRA lamp the tolerated intensity limit is 250mW/cm^2.
Confirming the premise that we could use higher intensities if we focus on the least heating wavelengths.
Lets look at another example that used lasers.
"The irradiance values, that produce unacceptable heating of the tissue, are governed by the wavelength and are
We see that the 400-500nm range (blue light) has much higher heating effects leading to "unacceptable heating" at only 100mW/cm^2. Blue, green, and even yellow light is highly heating due to superficial absorption from melanin - similar to how far-infrared causes heating from water absorption.
And the crux of this blog is already illucidated in this quote. That you can tolerate more than twice as much NIR (800-900nm) intensity than Red (600-700nm) before unacceptable heating occurs.
We could say Near-Infrared is 2.5 times less heating than Red according to the differences in intensity here. And we can see the parallel with penetration that some studies confirm Near-Infrared has nearly twice as much penetration as Red.
So if we want to use higher intensities with less heating on the skin, then we would choose Near-Infrared (800-900nm).
Now these laser intensity numbers are much higher than the recommended non-thermal intensity numbers we usually recommend from large LED panels to be less than 50 mW/cm^2 to avoid heating.
Which firstly we want to stay far away from the pain or damage threshold of high temperatures as a so-called maximum tolerated dose, but maintain practically no temperature change with low intensities for true Photobiomodulation.
In the previous example with the wIRA lamp, the authors explain the impact of surface area on heating. [15]
A wide surface area from an LED panel or Incandescent bulb using 100mW/cm^2 will be a lot more total energy and total watts than a small spot of a laser delivering the same intensity.
"thermal effects in tissue will depend on the size of the area exposed. Thus, with any given irradiance, the maximum temperature reached at the exposed area increases with area size" [15]
So the larger area being irradiated, the higher the heat. With relatively lower intensities, a large area treatment will have more heat effects.
The laser may have high intensity but has low overall power, and there is more area for the laser heat to diffuse. A large LED panel will saturate a large area of the skin with intensity, leading to more energy the skin needs to manage with less volume that is unaffected.
Lets look at a diagram to explain.
So we can note that 250mW/cm^2 with non-thermal wavelengths covering a wide area will lead to deleterious heating, whereas the laser example can use 300-750mW/cm^2 of non-thermal wavelengths before causing heat damage due to the small spot size.
So this is why we often see much higher intensities used with lasers, and it is recommended to use much lower intensities with wide-area treatments like LED panels.
One study used mathematical modelling based on the properties of of human skin optics to look at penetration and temperature increases based on wavelength.
They found in the following order the least heating to the most heating:
1064nm < 980nm < 905nm < 905 < 850 < 808 < 1200 < 660 < 632
[17]
Surprisingly 1064nm had the least heating, while this study confirms that the Red wavelengths are significantly more heating than Near-Infrared.
However, the big drawback to this study is that it was done with mathematical modeling, which may not be able to fully calculate the complexities of human skin optics and thermoregulation processes.
A study that compared several wavelengths was conducted on isolated tissue with real lasers.
They found the following relationship with the wavelengths they tested:
810nm <<< 650nm ≈ 1064nm < 980nm
[18]
In laymens terms this says that 810nm is much less heating than 650nm. The heating from 650nm and 1064nm are roughly equal. And the 980nm had the highest heating.
This is in better alignment with the penetration models that 810nm is expected to have the least heating. Both 1064nm (NIR) and 650nm (Red) are about the same heating, as there is a tradeoff between higher melanin absorption from Red and higher water absorption with the longer wavelength NIR. There is a peak of water absorption in the 900's, which makes sense that 980nm was actually the hottest wavelength tested.
But again there is a minor drawback that the authors mention that this was on an isolated tissue sample that doesn't fully represent all the layers of the skin or the thermoregulation as part of a body.
By now it should be clear based on the theory and research examples that Near-Infrared is certainly less heating than Red wavelengths, despite the constant myths otherwise. This means we need to consider Melanin absorption as just as important for causing heating with shorter wavelengths as Water absorption is for longer wavelengths.
Here are some possible explanations as to why Near-Infrared is falsely associated with heating:
"Another disadvantage of NIR laser neuromodulation is the accidental overheating of brain tissue, which may cause inherent injury and inhibit neural activity, producing side effects in addition to normal regulation" [21]
In this way we may still choose Red light in cases that we want to avoid accidental heating of deeper sensitive organs. Or simply use properly low intensities to avoid any problems at all.
If we want to avoid heating superficial tissues for example to avoid hyperpigmentation, then we would choose deeper penetrating Near-Infrared.
We often think of selecting wavelengths in terms of the benefits it can deliver, sometimes preferring a specific penetration depth, specific mechanisms, or specific chromophore targets.
In this blog we think of selecting wavelengths in a different way, in choosing ones that cause the least heat.
"As an increased wound temperature can correlate with decreased wound healing and wound bed score [37], the choice of the wavelength used has to be carefully considered." [11]
For some therapeutic contexts, choosing the least heating wavelength will be more important for effectiveness and safety.
The deeper penetrating 810nm wavelength is expected to produce the least heating for most skin types, and in darker skin types the 1064nm wavelength will be more important for avoiding superficial melanin absorption.[22]
Near-Infrared wavelengths could still deliver unwanted heat into deeper tissues like organs that are highly sensitive to heat. In this way we must consider if we are trying to control the heating to superficial tissues or deep tissues. Choosing Red wavelengths may avoid overheating sensitive organs, even though it will have more heating to the skin.
Ultimately, utilizing low intensities will ensure there is minimal heating as is the basic definition of photobiomodulation. This helps the cells focus on the beneficial photochemical effects and minimizes risks and complications often caused by heating.
The foundation of Red Light Therapy is with deep penetrating "non-thermal" wavelengths in the Red to Near-Infrared range. Selecting the optimal wavelength is often based on many factors including bioindividuality.
We may be able to avoid many myths from being generated if we are strong in the basics of optical physics, photochemistry, photobiology, and skin optical properties. So this blog was hopefully able to convey some of these important concepts in relatable ways.
[1]
Anders, Juanita J et al. “Low-level light/laser therapy versus photobiomodulation therapy.” Photomedicine and laser surgery vol. 33,4 (2015): 183-4. doi:10.1089/pho.2015.9848
[2]
Hossein-Khannazer, Nikoo et al. “The Role of Low-Level Laser Therapy in the Treatment of Multiple Sclerosis: A Review Study.” Journal of lasers in medical sciences vol. 12 e88. 28 Dec. 2021, doi:10.34172/jlms.2021.88
[3]
Huang, Ying-Ying et al. “Low-level laser therapy (LLLT) reduces oxidative stress in primary cortical neurons in vitro.” Journal of biophotonics vol. 6,10 (2013): 829-38. doi:10.1002/jbio.201200157
[4]
Ahmed, S., Bewsh, G., Bhat, S., & Babu, R. (2013). LOW LEVEL LASER THERAPY: HEALING AT THE SPEED OF LIGHT. Journal of Evolution of medical and Dental Sciences, 2, 7441-7463.
[5]
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[6]
Photothermal Nanomaterials: A Powerful Light-to-Heat Converter
Ximin Cui, Qifeng Ruan, Xiaolu Zhuo, Xinyue Xia, Jingtian Hu, Runfang Fu, Yang Li, Jianfang Wang, and Hongxing Xu
Chemical Reviews 2023 123 (11), 6891-6952
DOI: 10.1021/acs.chemrev.3c00159
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Albini, A. Some remarks on the first law of photochemistry. Photochem Photobiol Sci 15, 319–324 (2016). https://doi.org/10.1039/c5pp00445d
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E.J. Land (1983) The Science of Photomedicine, International Journal of Radiation Biology and Related Studies in Physics, Chemistry and Medicine, 43:4, 471-472, DOI: 10.1080/09553008314550531
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[10]
Leyane, Thobekile S et al. “Cellular Signalling and Photobiomodulation in Chronic Wound Repair.” International journal of molecular sciences vol. 22,20 11223. 18 Oct. 2021, doi:10.3390/ijms222011223
[11]
Dungel, Peter et al. “Wavelength-Dependent Effects of Photobiomodulation for Wound Care in Diabetic Wounds.” International journal of molecular sciences vol. 24,6 5895. 20 Mar. 2023, doi:10.3390/ijms24065895
[12] Water Absorption Coefficient Spectrum:
https://omlc.org/spectra/water/data/hale73.txt
https://omlc.org/spectra/water/abs/
[13] Hemoglobin Absorption Coefficient Spectrum:
https://omlc.org/news/jan98/skinoptics.html
https://omlc.org/spectra/hemoglobin/summary.html
[14] Melanin Absorption Coefficient Spectrum:
https://omlc.org/spectra/melanin/mua.html
[15]
Piazena H, Kelleher DK. Effects of infrared-A irradiation on skin: discrepancies in published data highlight the need for an exact consideration of physical and photobiological laws and appropriate experimental settings. Photochem Photobiol. 2010 May-Jun;86(3):687-705. doi: 10.1111/j.1751-1097.2010.00729.x. Epub 2010 Apr 16. PMID: 20408985.
[16]
Zein, Randa et al. “Review of light parameters and photobiomodulation efficacy: dive into complexity.” Journal of biomedical optics vol. 23,12 (2018): 1-17. doi:10.1117/1.JBO.23.12.120901
[17]
Chaki C, De Taboada L, Tse KM. Three-dimensional irradiance and temperature distributions resulting from transdermal application of laser light to human knee-A numerical approach. J Biophotonics. 2023 Jun 1:e202200283. doi: 10.1002/jbio.202200283. Epub ahead of print. PMID: 37261434.
[18]
Cronshaw M, Parker S, Grootveld M, Lynch E. Photothermal Effects of High-Energy Photobiomodulation Therapies: An In Vitro Investigation. Biomedicines. 2023 Jun 4;11(6):1634. doi: 10.3390/biomedicines11061634. PMID: 37371729; PMCID: PMC10295700.
[19]
Park, Bomi, and Seong Jin Kim. “Cooling the Skin: Understanding a Specific Cutaneous Thermosensation.” Journal of lifestyle medicine vol. 3,2 (2013): 91-7.
[20]
Ahn, J.-C & Kim, Y.-H & Rhee, C.-K. (2013). The effects of low level laser therapy (LLLT) on the testis in elevating serum testosterone level in rats. Biomedical Research (India). 24. 28-32.
[21]
Pan, Wei-Tong et al. “Advances in photobiomodulation for cognitive improvement by near-infrared derived multiple strategies.” Journal of translational medicine vol. 21,1 135. 22 Feb. 2023, doi:10.1186/s12967-023-03988-w
[22]
This blog reviews some of the basics for why red light therapy dosing is confined to certain ranges of J/cm^2 (Joules Per Centimeter Squared) for optimal benefits.
Like most drugs or therapy: too little has no effect, but too much will have negative effects. We are always seeking an optimal "Goldilocks dose" for red light therapy. This is well summarized by the following quote from a PBM review article by Dr. Hamblin et al.
"Dosages that are either substantially less or substantially more than those “sweet spot” values, can have either less benefit or no benefit at all. In some cases very high dosages can even have a negative effect, which is sometimes said to be on the inhibitory side of the Arndt-Schulz curve for the biphasic dose response [20]." [1]
Like learning any science, we start with the most basic concepts - which is the biphasic dosing model. Then we realize that human biology is much more complicated than a simple 2D model and a linear dosing calculation.
"It is suggested that the PBM dose response as a simple binary model of PBM effects as represented by the Arndt-Schulz law is clinically less useful than a multiphasic biological response." [2]
Studies find complex and paradoxical dosing models like:
In this blog we review several human studies that exhibit biphasic dose response (where lower doses perform better than higher doses). There have been myths that humans don't have a biphasic response due to the lack of studies confirming it. However, we find studies that indeed show that lower doses perform equally or better in humans.
We find an excellent new dosing model that promotes biostimulation at 2-10 J/cm^2. At higher doses 10-30 J/cm^2 will have an inhibitory response. At >30J/cm^2 the risk of damage occurs. However, the inhibitory dose can be properly used for analgesia (pain) at the detriment of slower healing. [2] [3]
Red Light Therapy follows the same dosing concept for medicine and pharmacology called the Arndt-Schultz Law, where it is stated:
"For every substance, small doses stimulate, moderate doses inhibit, large doses kill." [4]
In Red Light Therapy and other modalities, this theory is often simply called the Biphasic Dose response. It is often represented as this simple chart.
Most clinical researchers are aware of this theory, and are careful to design the studies with intensity and dosages that are safe and effective. It is only the clever salespeople whom encourage excessively high intensity panels and doses.
Assuming you are using reasonable non-thermal intensity and doses - the line between "stimulatory dose" and "inhibitory dose" is extremely vague. In some cases, we don't know if healing from red light therapy is slow due to non-optimal doses, or due to the persons bio-individual response.
There are many studies documenting the Biphasic Dose response in isolated cells, tissues, and small animals. This is rather easy and predictable. Laboratory rodents can be nearly genetically identical and raised in the exact same environments, diets, and conditions. So they exhibit the biphasic dose response in a predictable manner. Humans, not so much.
This is well documented in these two entire review articles about biphasic dose response. Both are free to read and very informative with co-authors YY Huang, SK Sharma, James Carroll, and Michael R Hamblin.
Biphasic dose response has been confirmed in many more recent studies.
For example a 2023 study on healing diabetic ulcers in rats used 4, 6, 8, 10, 12 and 15 J/cm^2. They found the 4, 6, and 8 had the best wound healing response, and the higher doses were not as effective. [5]
Another 2023 study on treating Erectile Dysfunction in rats inflicted with diabetes used 0 J/cm^2, 4 J/cm^2, 8 J/cm^2, or 16 J/cm^2 with 808 nm Near-Infrared light therapy. They found the optimal dose was at 4 J/cm^2. [17]
So we can find many studies on isolated cells and small animals confirming the biphasic dose response, however it has been challenging to find similar studies on humans.
This lack of data has allowed many salespeople to promote "the highest intensity" and high doses as an easy marketing gimmick. Even though they don't have evidence behind their claims, they also know there hasn't been any direct evidence refuting their claims either. Until now.
Recently we have found several human studies confirming a biphasic dose response. Meaning the higher doses were less effective than the lower doses.
1. Dose Response for Blood Sugar control in human diabetics.
A recent study using an LED flexible pad with 830nm LEDs on 10 patients with type 2 diabetes. [6]
They used a dose of either 5.71 J/cm^2 or 13.72 J/cm^2 and found that the lower dose promoted better response in blood sugar control. The higher dose was not at effective. [6]
They also note a possible Triphasic dose response and that exposure time is important.
2. Human Biphasic Dose for brain treatments.
A study that was reviewed on the excellent brain-PBM YouTube channel covers a clinical trials for blood flow and depression with transcranial light therapy treatments.
It seems to report on the results for this study:
https://www.mdpi.com/2304-6732/10/1/90
They used 3 different sets of dosing with an 808nm wavelength.
A high dose of 166.7 J/cm^2, a medium dose of 97 J/cm^2, and low dose of 50 J/cm^2.
The medium and low doses had the most positive response, and the high dose was not as effective.
Interestingly, the high dose was delivered with 40Hz pulse to reduce the potential heat damage, and the other two doses were delivered as continuous wave.
In addition to being a biphasic dose response where blasting the brain with high doses isn't superior, this is also an example of a brain treatment where continuous modes performed better than the pulse mode. As we have noted in previous blogs; pulsing doesn't magically improve results - having proper dosing is more important.
3. Osteoarthritis
A systematic review article of LLLT for Osteoarthritis made this statement.
"Lower dosage of LLLT was found as effective than higher dosage for reducing pain and improving knee range of motion." [7]
Where typically in medicine if a lower dose can deliver the same result as a higher dose, it is prudent to choose the lower dose.
4. Eye Health
You may recall some papers on supporting eye health with 670nm flashlights became viral on many mainstream news outlets.
The first wave of hype was based on this 2020 article using 40 mW/cm^2 for 3 minutes in the mornings. [8]
However, the same group did a follow-up study in 2021 with only 8 mW/cm^2 for 3 minutes in the mornings.[9]
In the second article the researchers specifically comment that they used drastically lower intensities and thus lower doses for this study, and still found good results. For example the first study would be 7.2 J/cm^2 and the second study was only 1.44 J/cm^2.
However, note that since the intensity was dropped and the exposure time stayed the same, this is another point that the exposure time may be more important than either intensity or dose alone.
So particularly for eye health where the eye is most sentitive to light and there are concerns of cataracts from heating effects of high intensity red light therapy - if we can get equal benefits from a high dose or low dose - it is prudent to choose the lower intensity and dose.
5. Musculoskeletal Pain
A review article of high-intensity laser therapy for Musculoskeletal therapy categorized 3 groups of dosing for analysis. They consistently found a trend where the lower doses and medium doses were better than high doses in the various categories. Even for pain.
"No differences were observed in terms of dosage when 10–50 J/cm2, 50–100 J/cm2, 100–300 J/cm2) but the effect tended to decrease with higher dosages" [10]
6. LLLT for Neck Pain
A review article that analyzed the doses used for neck pain found this range of effective treatment.
"Investigators who used doses outside the minimum (0·075 J and 0·06 J)40,49 and maximum (54 J)44 limits of these ranges did not show any effect of LLLT, lending further support to a dose-dependent response for LLLT in neck pain." [18]
Again showing a clear limitation that exceeding 54 J did not show any effect, which is just as bad as being too low.
The authors make this important comment in the discussion.
"Additionally, a very high dose (54 J) of 830 nm LLLT used in one trial did not cause beneficial nor harmful effects.44 This finding suggests not only that doses of this magnitude are higher than the therapeutic window, but also that LLLT is safe even if such an overdose is delivered." [18]
Similar to what we stated earlier, we may not be able to detect if an "overdose" was delivered since there are practically no side effects to red light therapy. There is only a lack of benefits or slowed benefits when you overdose. They are clearly mentioning a "therapeutic window" of proper dosing that refers to the biphasic dose response in humans.
7. Biphasic Dose in Athletic Performance
Many studies have been conducted on using Photobiomodulation/LLLT for improving athletic performance and recovery.
Some recent review articles discuss the biphasic dose response in human athlete studies.
One study with 40 male volunteers used 10 J, 30 J, 50 J, or placebo in 6 points on the thighs. They found better performance and less DOMS with the optimal dose at 30 J.
"They administered 10, 30, and 50 J, or placebo, in six points on the front of the thighs ... concluding that the 30 J dose was the best." [11]
Another review article summarized several articles and noticed that studies using doses higher than 80 J led to a negative response.
"We could identify a therapeutic window, or PBM window, suggesting a biphasic dose-response [73,74] for total energy applied on the biceps brachii (20–80 J), regardless whether PBM was applied as a muscular pre-conditioning protocol or after exercise." [12]
This quote is clearly attributing the effect to the biphasic dose response in these human studies.
8. Human Biphasic Dose for Oral Mucositus
For treatment of oral mucositis there are also clear examples and recommendations to use proper low doses for healing.
Where one group proposes a range of 2 - 10 J/cm^2 for healing and biostimulation, and higher doses of 10-30 J/cm^2 will have an inhibitory response.
Here is their commentary about one human trial with too high of a dose.
"This was clearly appreciated by Simoes et al. who applied 10 J/cm2 at a delivery power of 1.0 W as a pain relief PBM dose, which was recorded as beneficial, although the healing associated with the OM was subsequently found to be slower than that found at a lower applied dose [67]." [3]
So the higher dose still delivered some healing benefits, it is just slower and less optimal. However, this "overdosing" leads to enhanced temporary pain relief, which obviously can be advantageous in many contexts.
The research group led by Dr. Mark Cronshaw introduces their dosing model we stated in the introduction. That 2 to 10 J/cm^2 is the optimal red light therapy dose range for a stimulatory response, and 10 to 30 J/cm^2 is the inhibitory range.[2][3]
This is their new multiphasic dose model, which has some subtle but important differences than the original one we presented.
Dosing Model Reminiscent to those seen in the following studies. [2][3]
https://www.mdpi.com/2304-6767/8/3/87
https://pubmed.ncbi.nlm.nih.gov/31329512/
This dosing model is for direct treatment on the tissues. For example for deeper penetration you may use higher dose at the skin surface because you want to have a sufficient dose reach the deeper tissues like the brain.
So lets take the example of the brain treatments that used 166.7 J/cm^2, a medium dose of 97 J/cm^2, and low dose of 50 J/cm^2.
Even though we are clearly overdosing at the skin level on the medium and high doses, lets look at the estimated dose that would reach the brain.
Since we know only 1-3% of the light will reach the brain, then that brings the actual dose that reaches the brain down to:
So the 0.5 to 3 J/cm^2 could be an adequate dose for the brain, since we certainly don't want to overdose the brain to an inibitory response as it is highly sensitive to light.
The typical dosing range for deep tissue treatments ranges up to 10 to 60 J/cm in red light therapy.
According to the following quote, superficial targets follow the range we established above, however deeper tissues need higher doses at the skin surface:
"Another respected source suggests that doses used for superficial targets tend to be in the region of with a range of 1 to .16–18 Doses for deeper-seated targets should be in the 10 to range.19–21" [4]
A clear limitation would be to not damage the skin with excessively high doses because you are targeting deeper tissue.
"It is noteworthy that LLLT irradiation can induce both proliferation (low energy density—0.8 J/cm2) and apoptosis (higher energy density—60 J/cm2)" [13]
Since naturally damaging the skin would be counterproductive to induce ROS and inflammation, and would likely be overdosing the more sensitive deeper tissues anyway.
So that is why we still see an upper limit to deeper tissue treatments at up to 50-60 J/cm^2 as skin level maximum per session.
Then we can appreciate that the brain cells have the highest mitochondria compared to normal cells, so it will be more responsive to lower doses.
Further, the brain will be more sensitive to biphasic dose response at relatively lower doses than what the model established.
This theory of adjusting the dose based on the mitochondrial density of the cells is reviewed in an excellent article titled "Review of light parameters and photobiomodulation efficacy: dive into complexity" [4]
For example, a conclusion they draw is:
"Ineffective studies on cells with higher numbers of mitochondria are as likely to be due to over-dosing as they are to under-dosing." [4]
Essentially they summarize that it is much easier to overdose high-mitochondria density cells like the eyes and brain. It is less likely to overdose cells that have less mitochondria like skin cells.
People using high intensity and doses are likely still enjoying some benefits like temporary pain relief. However, long term cellular healing will be slowed and less optimal than lower doses as demonstrated by these human studies confirming the biphasic dose response.
Brands have an incentive to make ineffective panels by making them as powerful as possible. The slow healing will encourage consumers to purchase more "modular" units, which may even make the healing even slower. Thus making repeat customers where a properly designed low intensity unit could have sufficed.
Our sentiment is confirmed in the following quote written in a paper by Dr. Hamblin et al.
High Intensity Class IV (4) lasers are using irrelevant Class 3B studies to justify their devices - then falsely imply having more power would be superior. When the studies show the opposite is true and over-dosing is more likely to cause poor results.
"There are manufacturers of class IV laser devices that refer to clinical trials performed with a class 3B laser. These same class IV device manufacturers then claim that because 3B laser results are sometimes negative, the extra power of a class IV laser will be more effective (systematic reviews show that the opposite is true, that over-treatment is more often the problem)." [1]
The same way the "highest intensity" LED panels are basing their claims on much lower power and lower doses studies, but then falsely imply their devices will be superior than the studies. When in reality high intensity LED panels will suffer the same problem and could produce worse results.
Another quote states the following:
"A common misconception is that energy (in J) or energy density (J/cm2) is all that is necessary to replicate a successful treatment, irrespective of the original power, power density, and duration parameters (14, 15)." [14]
As this quote implies, the intensity and exposure time are often more important than just the "dose" in J/cm^2. So even though this blog focuses on reviewing the Energy Density (J/cm^2), the true "dose" is considering all of the parameters together.
Brands that use very high intensity that market as a time-savings could be encouraging the users to get less results by getting inadequate exposure time or causing less effects due to the biphasic dose response.
Like most medicine, the goal is to obtain consistent results with the Minimum Effective Dose (MED).
A so-called "Maximum Effective Dose" is not really a thing in medicine, except perhaps now as a sales fallacy for selling red light devices.
The Maximum Tolerated Dose (MTD) is the highest dose with toxicity below a certain level. Naturally as you increase the intensity and dose, you are increasing the potential for risks and side effects, without much promise of actually getting better benefits. [15]
This article titled "Why maximum tolerated dose?" by Dr. Stampfer et al. is an excellent free review of the basic principals of pharmacology dosing. [15]
The ED50 (Effective Dose 50) is the center of the dose response curve which achieves half of the maximum drug effect in the average population.
The article recommends starting at an ED50 for most drugs, then titrating up as needed and monitoring for progress or possible adverse effects.
Dr. Stampfer recommends an old maxim of "start low and go slow" when implementing medicine and incrementing the dose.
Starting at the Maximum Tolerated Dose is unwise with little promise of performing better and can only result in higher risks of adverse events.
"In most illness, there is merit in maintaining patients on the lowest effective dose, with close clinical monitoring for efficacy, tolerability and adverse events." [15]
The goal is to maintain a minimum effective dose. However, notice there is no "one-size-fits-all" for drugs or red light therapy. Monitoring your results and adjusting the dose will be the only way to optimize.
If Red Light Therapy wants to be taken seriously as a "clinical grade" therapy, then the influencers and brands should understand basic pharmacology principals.
It is prudent to understand the Arnlt-Shulz Law for biphasic dose response, follow the Minimum Effective Dose, avoid the Maximum Tolerated Dose, learn to titrate the dose, and not fall prey to fallacies that "more is better".
These examples helped prove the old adage that "less is more" is literally true for red light therapy even in humans.
In addition to the extremely large body of research confirming biphasic dose response in tissues and small animals, which informs the rationale that nearly all clinical researchers design their dose around.
Put another way, Dr. Hamblin states it as follows in one article:
"It is often said in this context that “more does not mean more”."[16]
This blog explored the complexities of dose in red light therapy, where the optimal dose range for normal tissues is between 2-10 J/cm^2. Higher doses from 10-30 J/cm^2 will have a slower response but may be advantageous in certain contexts like analgesia.
When targeting deeper tissues we may need higher doses at the skin surface to get a sufficient dose to the deeper tissues. However, even that seems to be limited at a maximum of 60 J/cm^2 at the skin surface for deep tissue targets.
Dosing red light therapy becomes increasingly complex when we adjust for large complex mammals (humans), different skin thicknesses, skin phototype, mitochondrial density of the target cells, genders, age, medical conditions, and long term cumulative dosing.
Starting with reasonable doses and low intensities at a routine interval is always the best way to get started with Red Light Therapy.
Being informed of these dosing models, you can titrate your dose up or down to find what works best for your bioindividuality and lifestyle and specific conditions.
"Titrating adequate doses and defining the essential PBM parameters as per evidence gathered in a systematic way for each indication is a prerequisite for the successful use of this treatment modality." [14]
However, the challenge is the consumer needs to be educated and empowered to control their own dosing - and not rely on false medical authorities to tell them backdoor generic prescriptions with red light therapy devices.
Applying some mindfullness, being aware of reasonable doses, and adjusting your personal dose is always going to be the best way to optimize your red light therapy.
[1]
Michael R. Hamblin, Marcelo Victor Pires de Sousa, Praveen R. Arany, James D. Carroll, Donald Patthoff D.D.S., "Low level laser (light) therapy and photobiomodulation: the path forward," Proc. SPIE 9309, Mechanisms for Low-Light Therapy X, 930902 (5 March 2015); https://doi.org/10.1117/12.2084049
[2]
Cronshaw M, Parker S, Arany P. Feeling the Heat: Evolutionary and Microbial Basis for the Analgesic Mechanisms of Photobiomodulation Therapy. Photobiomodul Photomed Laser Surg. 2019 Sep;37(9):517-526. doi: 10.1089/photob.2019.4684. Epub 2019 Jul 19. PMID: 31329512.
https://pubmed.ncbi.nlm.nih.gov/31329512/
[3]
Cronshaw M, Parker S, Anagnostaki E, Mylona V, Lynch E, Grootveld M. Photobiomodulation and Oral Mucositis: A Systematic Review. Dentistry Journal. 2020; 8(3):87. https://doi.org/10.3390/dj8030087
https://www.mdpi.com/2304-6767/8/3/87
[4]
Randa Zein, Wayne Selting, Michael R. Hamblin, "Review of light parameters and photobiomodulation efficacy: dive into complexity," J. Biomed. Opt. 23(12) 120901 (11 December 2018) https://doi.org/10.1117/1.JBO.23.12.120901
[5]
Karkada G, Maiya GA, Arany P, Rao Kg M, Adiga S, Kamath SU. Dose-Response Relationship of Photobiomodulation Therapy on Matrix Metalloproteinase in Healing Dynamics of Diabetic Neuropathic Ulcers-An in vivo Study. Photochem Photobiol. 2023 Jul-Aug;99(4):1172-1180. doi: 10.1111/php.13754. Epub 2023 Jan 15. PMID: 36477863.
https://pubmed.ncbi.nlm.nih.gov/36477863/
[6]
Clara Maria Cobra Branco Scontri, Flávio de Castro Magalhães, Ana Paula Moraes Damiani, Michael R. Hamblin, Antonio Roberto Zamunér, Cleber Ferraresi Dose and time–response effect of photobiomodulation therapy on glycemic control in type 2 diabetic patients combined or not with hypoglycemic medicine: A randomized, crossover, double-blind, sham-controlled trial
First published: 12 May 2023
https://doi.org/10.1002/jbio.202300083
https://onlinelibrary.wiley.com/doi/10.1002/jbio.202300083#pane-pcw-references
[7]
Brosseau L, Welch V, Wells G, DeBie R, Gam A, Harman K, Morin M, Shea B, Tugwell P. Low level laser therapy (Classes I, II and III) for treating osteoarthritis. Cochrane Database Syst Rev. 2004;(3):CD002046. doi: 10.1002/14651858.CD002046.pub2. Update in: Cochrane Database Syst Rev. 2007;(1):CD002046. PMID: 15266461.
https://pubmed.ncbi.nlm.nih.gov/15266461/
[8]
Harpreet Shinhmar, MSc and others, Optically Improved Mitochondrial Function Redeems Aged Human Visual Decline, The Journals of Gerontology: Series A, Volume 75, Issue 9, September 2020, Pages e49–e52, https://doi.org/10.1093/gerona/glaa155
https://academic.oup.com/biomedgerontology/article/75/9/e49/5863431
[9]
Shinhmar, Harpreet et al. “Weeklong improved colour contrasts sensitivity after single 670 nm exposures associated with enhanced mitochondrial function.” Scientific reports vol. 11,1 22872. 24 Nov. 2021, doi:10.1038/s41598-021-02311-1
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8613193/
[10]
Arroyo-Fernández R, Aceituno-Gómez J, Serrano-Muñoz D, Avendaño-Coy J. High-Intensity Laser Therapy for Musculoskeletal Disorders: A Systematic Review and Meta-Analysis of Randomized Clinical Trials. Journal of Clinical Medicine. 2023; 12(4):1479. https://doi.org/10.3390/jcm12041479
https://www.mdpi.com/2077-0383/12/4/1479
[11]
Ailioaie LM, Litscher G. Photobiomodulation and Sports: Results of a Narrative Review. Life. 2021; 11(12):1339. https://doi.org/10.3390/life11121339
[12]
Ferraresi, Cleber et al. “Photobiomodulation in human muscle tissue: an advantage in sports performance?.” Journal of biophotonics vol. 9,11-12 (2016): 1273-1299. doi:10.1002/jbio.201600176
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5167494/
[13]
Rola P, Włodarczak S, Lesiak M, Doroszko A, Włodarczak A. Changes in Cell Biology under the Influence of Low-Level Laser Therapy. Photonics. 2022; 9(7):502. https://doi.org/10.3390/photonics9070502
https://www.mdpi.com/2304-6732/9/7/502
[14]
Robijns, Jolien et al. “Photobiomodulation therapy in management of cancer therapy-induced side effects: WALT position paper 2022.” Frontiers in oncology vol. 12 927685. 30 Aug. 2022, doi:10.3389/fonc.2022.927685
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9468822/
[15]
Stampfer, Hans G et al. “Why maximum tolerated dose?.” British journal of clinical pharmacology vol. 85,10 (2019): 2213-2217. doi:10.1111/bcp.14032
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6783596/
[16]
Hamblin MR. Shining light on the head: Photobiomodulation for brain disorders. BBA Clin. 2016 Oct 1;6:113-124. doi: 10.1016/j.bbacli.2016.09.002. PMID: 27752476; PMCID: PMC5066074.
[17]
Where are all of the studies for 100mW/cm^2 with full body LED red light therapy?
Medical Devices and Drugs often carry the phrase "safe and effective" when being described. These are two separate aspects that must be examined. A product could be safe, but not very effective. A product could be effective for treating a specific problem, but not very safe in terms of side effects.
Many brands and experts have claimed that 100 mW/cm^2 (milliWatts per centimeter squared) is the best intensity for LED Red Light Therapy. Even more have implied that 100mW/cm^2 is the bare minimum intensity. The best intensities should be even higher like 150mW/cm^2, 170mW/cm^2, 180mW/cm^2 or even over >200mW/cm^2!
However, in accordance with basic advertising law - explicit or implied claims must be supported with evidence.
Given the repetition of many brands and experts, we would expect an abundance of data in the 7,000+ studies on Low Level Light Therapy (LLLT) and Photobiomodulation (PBM) that confirm >100mW/cm^2 is the best for large LED panels.
The added layer of deception is the false claims to be FDA Approved, Medical Grade, or Clinical Grade that also would imply the devices delivering >100mW/cm^2 are indeed safe and effective according to medical authorities.
According to Ari Whitten's book published in 2018, Ari Whitten recommends large LED panels with the ideal intensity of 100mW/cm^2 at 6 inches away. [1] He also implies that intensities less than 30mW/cm^2 are insufficient. [1] Just check page 181 in his book if you have it.
Ari Whitten does not actually cite any relevant scientific references as to why exactly 100mW/cm^2 is so effective with full-body non-contact LED light therapy. At best there are some rhetorical arguments about getting short dosing time and getting enough penetration.
Previous sections of the book were well referenced, yet this section on intensity and dosing is conspicuously lacking in relevant credible references. It seemed these intensity recommendations conveniently matched the advertised intensity from his affiliated brands.
In a YouTube interview after the book was published; Dr. Hamblin tells Ari Whitten that between 10-20 mW/cm^2 of intensity is "high" for full-body red light therapy.
This should have been fairly shocking that Dr. Hamblin debunked Ari Whitten's own book recommendations. It completely contradicts Ari's claim that you need "at least 30mW/cm^2" and is literally 5 to 10 times less intensity than the 100mW/cm^2 that Ari recommends as ideal.[1]
On Page 208, Ari Whitten even discusses the NovoThor pod that has been actually clinically studied (unlike the brands he was recommending) and notes the intensity at that time was publicly thought to be 17mW/cm^2.[1] As is the case for most of the book, Ari Whitten does some rhetorical word salad to explain why this number doesn't match his narrative. Finally settling on the excuse that this lower intensity is more for skincare or systemic benefits.[1] When in reality the NovoThor pod is highly popular for athletic recovery and even has a study for Fibromayalgia and another study on Brain Fog.
So somehow Ari Whitten's book ignores the recommendations from experts like Dr. Hamblin and James Carroll (from NovoThor) by a wide margin which seem to correlate in the 10-20mW/cm^2 range, in favor of intensity numbers that conveniently align with his affiliated brands. Even going so far to falsely disparage the NovoThor intensity to help Ari's sales narrative.
All of the studies on full-body red light therapy use less than 50mW/cm^2 as we have collected all of them in a previous blog.
Where the most prominent intensities used for full-body red light therapy is between 24-28 mW/cm^2 in half of the clinical trials using the NovoThor LED bed. [4][5][6][7][8][9]
Much higher intensities (>50mW/cm^2) have not been clinically tested on humans to be safe and effective in the context of full-body LED red light therapy. Despite all the companies lying that their >100mW/cm^2 device is medical grade or clinical grade or FDA Approved.
Extrapolations of the science to assume "more power is better", "higher doses are better", and "higher intensity means less exposure time" are inherently pseudoscience. In fact, it is often specifically advised against in the published literature.
"if the power doubled and the time is halved then the same energy is delivered but a different biological response is often observed." [2]
I enjoy this quote, because of the marketing meme that many brands claimed to be twice the intensity as Joovv. Even if they did deliver twice the intensity as Joovv (they didn't), they have never actually proven it was more effective. These quotes would imply it is not proven to be more effective with higher intensity.
In a 2017 handbook of phototherapy, the chapter on Dosing Parameters (page 42) written by James Carroll of NovoThor notes the following:
"It is argued (by sales and marketing people) that more power means the required "dose" is achieved in less time, and mathematically that is true; however, it has been shown many times that there is a "dose-rate effect" and if the dose is delivered too quickly the beneficial effects are diminished. This is because the intensity (irradiance/power density) is too high." [3]
The people promoting "higher power is better" are only telling you one thing; they are not an expert. They are a sales and marketing person. This is a common theme in Ari Whitten's book and with most "reviewers" of red light therapy devices.
Essentially, higher intensities could have a negative effect. Either they encourage people to overdose on energy and potential heat effects, or they encourage people to reduce the exposure time which is inherently important for the optimal benefits. As is mentioned in the above quote with the dose-rate effects.
Ironically the number 100mW/cm^2 is often mentioned directly in the literature, but more as the upper limit of intensity or a heating risk.
In the excellent free-to-read article by Dr. Barolet, Dr.
"Lower irradiance (<50mW/cm2) is less likely to induce skin hyperthermia leading to potential deleterious effects." [10]
This seems to correspond well with why we normally see intensities less than 50mW/cm^2 in full-body LED light therapy studies as mentioned above.
They go on:
"Moreover, photoinhibitory deleterious effects may occur at higher irradiances. Such a biphasic pattern may explain the reported increase in MMP-1 when the artificial IR-A irradiances are too high (> 100 mW/cm2), inducing skin hyperthermia." [10]
They clearly state that above 100mW/cm^2 will initiate significant risks to overheating the skin, biphasic dose response, and skin degradation.
In another article by Dr. Barolet, he notes the optimal intensity should mimic sunlight which he estimates as 30-35mW/cm^2 in the Red/NIR range.[11] He specifically calls out that >100mW/cm^2 is associated with photoaging - which obviously would be very concerning for anyone using red light therapy for skincare and potentially overheating their face.[11] Let alone people damaging their skin for the false promise of deeper penetration.
As we already mentioned, the intensity and exposure time is more important than just calculating the dose as J/cm^2. This below quote literally tells us that if you have a device of >100mW/cm^2 then to throw the dosing equations out the window.
"Within a certain range of parameters, perhaps between 1 and
A review of Photobiomodulation for skin health notes the following:
"Phototherapy employs light with wavelengths 390-1,100 nm and can be continous wave or pulsed. In normal circumstances, it uses relatively low fluences (0.04-50J/cm^2) and power densities (<100 mW/cm^2)" [13]
Again seeming to confirm that it is extremely undesireable for the skin to expose it to >100mW/cm^2.
Another review of Photobiomodulation on the gut-brain benefits has this to summarize the range of intensities typically preferred in the literature. Again confirming the 100mW/cm^2 is the upper limit, and not the ideal.
"Power densities are usually in the region of 10–100 mW/cm^2" [17]
Another review including LLLT for Orthodontics states the following:
"In general, the power densities used for LLLT are lower than those needed to produce heating of tissue, i.e., less than 100 mW/cm2, depending on wavelength and tissue type (Huang YY et al., 2009)." [16]
A study on treating diabetic rats showed this concern about using high power densities on humans.
"Although a biphasic dose response in external PBM with low energy density and multiple sessions may be beneficial [10,14], external PBM may be required for multiple sessions with a relatively large power density (75–100 mW/cm2) and may be unsuitable for large animal studies or human trials with large body surfaces compared to rat or mice models [18,19,20]." [14]
Just appreciate the wording here. That intensities of 75-100mW/cm^2 are called "relatively large power density". Which is to say these are not the "normal" or "typical" power density for benefits, but they are the upper limit relative to the intensities usually desired for studies.
Even a review article about transcranial brain treatment states the following:
"10–70 mW/cm2 is the typical LED irradiance used in the studies [123,203]." [15]
But most people seem to presume they need tons of intensity to blast their brain cells. But they specifically separate that LED devices (which tend to be larger in coverage area and total energy delivered) have lower intensities than Laser. Which we will address later.
So for both deep treatments like organs and brains, as well as certainly to avoid skin problems - intensities less than 100mW/cm^2 are often recommended when using large LED devices. With ideal intensities we saw in the previous section are usually less than 50mW/cm^2.
It should start to become clear that 100mW/cm^2 is not the best intensity. The evidence points to 100mW/cm^2 being the upper limit of the range for PBM, and carries acute risks for skin damage and risks the biphasic dose response. It certainly has not been promoted as the best intensity in the literature.
You likely already know the plot twist. The original brands were false advertising 100mW/cm^2 at 6 inches away all along.
Ari Whitten himself takes measurements with a solar power meter which is an embarrasment not only to himself, but the entire red light therapy industry. He even posts the pictures of the solar power meter measurements on page 157 of the book.[1]
From the picture, we can tell it is a Tenmars TM-206. So we can just use these numbers in our Solar Power Meter Conversion Calculator blog and get the following numbers.
So what were the intensities of these brands in 2018?
Joovv Mini at 6 inches: 36.6 mW/cm^2
PlatinumLED Bio 300 at 6 inches: 42.8 mW/cm^2
Red Rush 360 at 6 inches: 45.3 mW/cm^2
These are likely more realistic estimations of the intensity these products actually delivered back in 2018.
Lets try to ignore the blatant false advertising here. We have already covered that enough.
But try to appreciate the reality of the situation.
Essentially, despite being incompetent companies that measured their medical devices incorrectly, they might have accidentally delivered reasonable intensities to the consumer back in 2018.
It is rumored that Ari Whitten may be publishing an update to his 2018 red light therapy book in the near future.
In it, hopefully there is more accurate intensity measurements for devices.
However, the more interesting narrative to watch is to find what the new "best" intensity will be?
We speculate there would be 3 options for the book's new narrative:
The 2nd option is going to be the most likely scenario. Of course a clever wordsmith would make any of their recommendations sound like they are based in science. As we can see from the first book effectively brainwashing the industry for 5 years.
Often brands have resorted to cherry-picking Laser studies to support thier LED Panels. Not only are they very different technologes that should be studied separately, but a laser will have very high intensity despite being very low in power. Smaller devices tend to have higher intensities to compensate for the low power. Which is why we are very clear in this blog we are talking about large LED devices like half-body and full-body panels.
There has been two big lies that have pervaded the Red Light Therapy industry.
The first lie has been easy to grasp, that companies and "experts" have false advertised their intensity by a wide margin. They often used solar power meters which measure falsely high in the Red/NIR wavelength range.
The second lie is that "100mW/cm^2 is the best intensity" and that "more intensity is better". Which is much more challenging to understand. But hopefully this blog at least plants a seed of doubt to these narratives.
Notice how Joovv still claims a meaningless Optical Irradiance of >100mW/cm^2 on their product pages under the "Tech Specs" dropdown, not even referencing any distance or what exactly this number is anymore.
Notice that Mito Red Light has an asterisk on their misleading intensity claims stating it is based on solar power meter measurements. And their intensity claims range from 105mW/cm^2 to 170mW/cm^2 on the MitoPro series.
Again, the first problem is apparent that these are extremely misleading intensity claims right on the product pages for these brands. The FTC is rather clear that using asterisks, fine print, or supplemental details on other pages are not sufficient especially if the clarification blatantly contradicts a claim that was made. Especially when the average consumer should not be expected to understand the intricacies for optical measurements with solar power meters. These are not valid legal loopholes. Even if they were, we certainly should trust medical device salespeople that are constantly looking for loopholes to manipulate the consumer.
Joovv doesn't even bother to use an asterisk anymore like they used to claim something about "depending on the distance" or "at device surface" in their 2nd generation website. The >100mW/cm^2 is literally just a random number floating there on the product page, not relevant to anything at all. Apparently they think that is some sort of loophole too.
The second problem is more insidious. These companies seem to imply that 100-170mW/cm^2 is safe and effective for large LED panels. Why else would they be advertising it still? Often implying they are affiliated with the FDA to make it seem like these are safe and effecive numbers reviewed by an authority.
They know the consumer has been brainwashed into expecting to see a number bigger than 100 to assure them of the efficacy of their products. Even if it is irrelevant to the devices they deliver or the actual science.
We have laid out an argument in this blog that 100mW/cm^2 is the absolute upper limit where heating effects would potentially start to cause damage. Numbers like 170mW/cm^2 would even be strongly cautioned against to avoid.
At some point it is reckless and irresponsible for "experts" and brands to promote numbers like >100mW/cm^2 that have never been tested on humans in full-body red light therapy clinical trials to determine safety and efficacy.
Rather than re-educate the consumer about appropriate intensity ranges, and admit they accidentally measured their devices wrong initially - most brands are continuing to follow the same profitable narrative. A narrative that was reinforced by "independant experts" blogs and books for lucrative affiliate kickbacks.
Of course if brands admit they were ignorant enough to use solar power meters in the first place, and they were malicious enough to manipulate the science to make it seem like these are appropriate numbers, and for years after getting 3rd party data they are still promoting misleading intensity numbers - maybe a few consumers would get the impression that they should never trust these fake experts and brands ever again.
So brands are stongly incentivised to keep increasing the intensity from their LED panels simply to follow the false marketing narratives that "more power is better". They are also strongly incentivised to keep lying about intensity - because fake experts will conveinently ignore the problems and endorse these brands anyway for their affiliate commissions.
Despite knowing that reasonable intensities like 10 to 50 mW/cm^2 being safe and effective for red light therapy - that is not a catchy sales narrative. Listening to the actual researchers and following the evidence of published clinical studies doesn't correspond to increasing sales.
Even if we get more honest, accurate intensity numbers - will the consumer be properly eductated about appropriate intensity ranges for photobiomodulation? Will the consumer be made into guinea pigs with unpredicented high intensity levels from brands that falsely imply they are FDA Approved? Can salespeople ever encourage moderation and scientific evidence over flashy marketing fallacies? Can affiliates pretend to hold integrity when they are knowingly endorsing brands that false advertise?
[1]
Whitten, Ari. The Ultimate Guide to Red Light Therapy. 2018 Archangel Ink
[2]
Ghigiarelli JJ, Fulop AM, Burke AA, Ferrara AJ, Sell KM, Gonzalez AM, Pelton LM, Zimmerman JA, Coke SG, Marshall DG. The Effects of Whole-Body Photobiomodulation Light-Bed Therapy on Creatine Kinase and Salivary Interleukin-6 in a Sample of Trained Males: A Randomized, Crossover Study. Front Sports Act Living. 2020 Apr 29;2:48. doi: 10.3389/fspor.2020.00048. PMID: 33345040; PMCID: PMC7739664.
https://pubmed.ncbi.nlm.nih.gov/33345040/
[5]
Navarro-Ledesma S, Carroll J, González-Muñoz A, Pruimboom L, Burton P. Changes in Circadian Variations in Blood Pressure, Pain Pressure Threshold and the Elasticity of Tissue after a Whole-Body Photobiomodulation Treatment in Patients with Fibromyalgia: A Tripled-Blinded Randomized Clinical Trial. Biomedicines. 2022 Oct 23;10(11):2678. doi: 10.3390/biomedicines10112678. PMID: 36359198.
https://pubmed.ncbi.nlm.nih.gov/36359198/
https://journals.sagepub.com/doi/full/10.1177/20406223221078095
[6]
Navarro-Ledesma S, Carroll J, Burton P, Ana GM. Short-Term Effects of Whole-Body Photobiomodulation on Pain, Quality of Life and Psychological Factors in a Population Suffering from Fibromyalgia: A Triple-Blinded Randomised Clinical Trial. Pain Ther. 2023 Feb;12(1):225-239. doi: 10.1007/s40122-022-00450-5. Epub 2022 Nov 11. PMID: 36369323; PMCID: PMC9845459.
[7]
Rentz LE, Bryner RW, Ramadan J, Rezai A, Galster SM. Full-Body Photobiomodulation Therapy Is Associated with Reduced Sleep Durations and Augmented Cardiorespiratory Indicators of Recovery. Sports (Basel). 2022 Jul 31;10(8):119. doi: 10.3390/sports10080119. PMID: 36006085; PMCID: PMC9414854.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9414854/
[8]
Bowen R, Arany PR. Use of either Transcranial or Whole-Body Photobiomodulation Treatments improves COVID-19 Brain Fog. J Biophotonics. 2023 Apr 5:e202200391. doi: 10.1002/jbio.202200391. Epub ahead of print. PMID: 37018063.
[9]
Forsey JD, Merrigan JJ, Stone JD, Stephenson MD, Ramadan J, Galster SM, Bryner RW, Hagen JA. Whole-body photobiomodulation improves post-exercise recovery but does not affect performance or physiological response during maximal anaerobic cycling. Lasers Med Sci. 2023 Apr 26;38(1):111. doi: 10.1007/s10103-023-03759-5. PMID: 37099210.
[10]
While Sunlight and UltraViolet (UV) light are known to affect skin pigment through tanning, recent studies have looked into the influence of other wavelengths of light on skin pigmentation response.
The popularity of Red and Near-Infrared LED panels and many other types of light therapies at home has led to questions if it would affect or worsen hyperpigmentation conditions and melasma, with several anecdotal reports seem to confirm this possibility.
More importantly, light therapies could be used to manage hyperpigmentation and melasma when used properly.
So this blog sets out to investigate the possible interactions of how light therapies and heat affect the human skin pigmentation response.
Disclaimer: This blog is for informational and educational purposes only. It does not offer medical advice for the prevention, treatment, cure, or diagnosis of any medical conditions. Always consult your doctor for any medical recommendations.
Only a few small studies have reduced skin pigmentation or treated Melasma with true LED light therapy photobiomodulation. There is still much to be learned about what wavelengths and doses that can be used to reduce or avoid hyperpigmentation.
There are several co-factors of people who are at higher risk of pigmentation response from light therapy treatments, for example Females with Fitzpatrick Skin Type III and higher. So it is even more important to be aware of risk factors and use light therapies appropriately.
The most likely risk of exacerbating hyperpigmentation conditions is the heating effect of high intensity LED devices, regardless of wavelength used of Red or Near-Infrared (NIR). Proper Photobiomodulation is non-thermal by definition, which is what makes it so safe and effective with minimal reported side effects.
Too high of a dose of Red/NIR light therapy produces excessive ROS and NO that can trigger pigmentation responses in the skin. Face masks used on the skin could transfer heat to the user, or have "hot spots" where the LEDs are positioned.
Intensities less than 50mW/cm^2 are often recommended to minimize the risk of skin heating which would lead to deleterious responses like increased inflammatory ROS. Intensities >100mW/cm^2 are often specifically recommended to be avoided to reduce the risk of skin hyperthermia (overheating) and side effects. [1]
Near-Infrared (NIR) is often wrongfully accused of causing heating and hyperpigmentation, yet many studies we find show that proper usage of Near-Infrared can be used to treat melasma or reduce pigmentation and has very low thermal impact.
Red light often causes more skin heating by superficial melanin absorption particularly in Fitzpatrick Skin Phototypes III-VI. This would mean that if someone has to choose between turning off Red or NIR in a panel to reduce heating, it would be turning off the Red.
Avoiding triggers from unprotected Sunlight, UV light, and Blue light on the same days as the Red/NIR LED light therapy treatments can also help prevent a hyperpigmentation response.
Blue light should be cautiously used if trying to prevent hyperpigmentation response, as there are many recent studies showing a direct causal effect of blue light on increasing melanin production. Hyperpigmentation is a common side effect even with properly used blue light therapy clinical trials.
Wavelengths like Green (532nm), Yellow (585/590nm), Red (633nm, 660nm), and Near-Infrared (810nm, 830nm, 850nm, 940nm, 1064nm) all could potentially decrease melanin and treat hyperpigmentation conditions. Contrary to popular opinion, Near-Infrared is often a preferred wavelength to prevent or reduce hyperpigmentation response in light therapy treatments.
Like most photobiomodulation; the intensity, exposure time, dosing, usage interval, and other treatment parameters are more important than just the wavelength. The bioindividuality of the patient and their specific condition may also need adjustments to find the ideal treatment parameters.
Ultimately, we find that properly used non-thermal (and low-thermal) Red and NIR LED Light Therapy will have little effect on skin pigment. It is very rarely (perhaps never) reported as an unintended side effect of dermatology photobiomodulation.[2] It generally offers protective effects from UV and inflammation, as well improves overall cosmetic satisfaction.
The purposes of this blog is to examine this complex issue and appreciate the possible dosing and mechanisms that red light therapy could have on pigmentation.
Perhaps in the future, more studies will show how we can use photobiomodulation to control the skin pigmentation response.
A recent Nov 28th 2023 systemic review on the effects of PBM on Melasma covers a lot of the exact same science and reaches similar practical conclusions as we did when we originally published this blog in July 2023.
This is a free to read article titled "Photobiomodulation for melasma treatment: Integrative review and state of the art" by Thais Rodrigues Galache et al.
https://onlinelibrary.wiley.com/doi/10.1111/phpp.12935
Their summary in the Abstract reads:
"Specific wavelengths (red: 630 nm; amber: 585 and 590 nm; infrared: 830 and 850 nm) at radiant exposures between 1 and 20 J/cm2 exert modulatory effects on tyrosinase activity, gene expression, and protein synthesis of melanocytic pathway components, and thus significantly reduce the melanin content." [77]
Which confirms with these evidence-based wavelengths and reasonable doses could be used to help manage melanin in melasma.
And they also note many studies showing a possible contraindication with Blue Light on melasma:
"On the other hand, blue light mostly seems to increase hyperpigmentation in melasma rather than treat it" [77]
It is nice that our own blog is validated by this new literature review by published researchers that is in alignment with our own research and conclusions.
A recent May 2023 editorial from Dr. Michael Hamblin titled "Photobiomodulation for Skin Pigmentation Disorders: A Dual-Function Treatment" discusses this paradoxical outcome that sometimes red light therapy can increase skin pigmentation or decrease it. [3]
Red Laser 633nm has been used to increase pigment in Vitiligo treatment trials. Conversely LED Photobiomodulation has been used in several small studies to decrease pigment in Melasma. [3]
The fear is that the reverse can be true. We could cause unwanted pigmentation responses with improper dosing with at-home devices.
This dual-nature of red light therapy is what makes it so interesting and challenging. It falls along the lines of what we know about the biphasic dose response, hormetic response, and trying to find a "goldilocks dose" for particular conditions.
Essentially, we are trying to find which wavelengths and doses will inhibit melanin production in the skin. This can be through direct or indirect mechanisms. We also need to know which parameters will stimulate melanin production so we can avoid those as potential triggers of hyperpigmentation.
Dr. Hamblin's editorial refers to a study by Dr. Daniel Barolet in treating Melasma with a Photobiomodulation protocol published in 2018 titled "Dual Effect of Photobiomodulation on Melasma". [4]
This pilot study was conducted on seven female patients with melasma that were unresponsive to standard treatment. The study prepared the skin with Microdermabrasion before LED treatment.
The LED device was 940nm Near-Infrared with pulsed light at 50% duty cycle with peak intensity of 90mW/cm^2 and average intensity of 45mW/cm^2. The device was used 2.5 cm away from the skin for 5 minutes per treatment for a total dose of 13.5 J/cm^2.
The results showed a statistically significant improvement in the treated side of the face. Treatment was performed once a week for 8 weeks, but Dr. Barolet comments that three treatments per week would have been preferred for potentially better results.
Dr. Barolet mentions the reason for using 940nm Near-Infrared wavelength was due to a previous in vitro study on isolated melanocyte cell cultures found that NIR wavelengths of 830nm, 850nm, and 940nm initiated systemic mechanisms to reduce melanin production.
"As for wavelength, 830nm and 850nm have been shown to downregulate pigmentation equally well in vitro,23 so future studies using these wavelengths should to be considered." [4]
So Dr. Barolet is recommending future studies to use Near-Infrared wavelengths to downregulate pigmentation response in melasma or hyperpigmentation disorders.
The second study Hamblin references is a recent December 2022 study. They recruited 10 patients with mild to severe melasma for treatment with LED light therapy. [5]
The device was 585nm (yellow/amber) LED at 20mW/cm^2 continuous wave (not pulsed) and 20 J/cm (16.6 minutes exposure), once a week for 8 weeks. The device appears to be designed for non-contact method but the distance was not specified.
Again with a positive result:
"Collectively, these results tentatively verify the efficacy and safety of 590 nm LED phototherapy to ameliorate the hyperpigmentation and facial erythema in melasma patients." [5]
One study titled: "The Management of Melasma on Skin Types V and VI Using Light Emitting Diode Treatment" recruited 60 females aged between 25-60 years with Fitzpatrick Types V and VI who had melasma. [78]
The used Red Light 633nm treatment at 105 mW/cm^2 for 20 minutes once a week and NIR Light 830nm treatment at 55mW/cm^2 for 20 minutes once a week.[78]
After 36 treatments over 9 months there was a statistically significant improvement in melasma analysis. [78]
One 2006 study used Blue (415nm) and Red (633nm) LED light therapy to treat acne vulgaris, but observed pigmentation changes during treatment. [6]
This was also a non-contact device used 3-5 cm from the face. Treatments with 40mW/cm^2 of blue light for 20 minutes led to an increase in pigment, and treatments with 80mW/cm^2 of red light for 20 minutes led to a decrease in pigment.
Treatments with blue light were conducted once a week, then the red light was 3-4 days later - for a total of 2 treatments per week for 4 weeks. There was an overall decrease in pigmentation over the course of the study.
All 24 patients had Fitzpatrick Skin PhotoType IV, and 14 of them spontaneously reported an increase in skin brightness as a positive side effect of the treatment. [6]
One study determined that Yellow/Amber (590nm) combined with Near-Infrared (850nm) performed better together for treating pigmentation than separately in vitro. [7]
They conducted a small study on 5 female patients between 30 to 40 years old, Fitzpatrick Skin PhotoType III-IV, and having pigmentation spots.
Treatment was with 25 J/cm^2 of 590nm Amber LED with simultaneous 5 J/cm^2 850nm NIR Laser. For a ratio of 16.6% NIR and 83.3% Amber.
Treatments were conducted once a week for 4 weeks. Which they observe a successful reduction in pigmentation.
The authors also make this important note that is often seen in these types of studies.
"It is important to mention that the patients were informed about the importance of sun protection after procedure to avoiding the hyperpigmentation post inflammatory." [7]
Which seems to be very good advice for people with a predisposition to hyperpigmentation while using light therapy treatments.
The GentleWaves LED device has been used in several studies with reported improvement in pigmentation.[38]
The device uses 590nm Yellow and 872nm Near-Infrared LEDs as a full-face non-contact panel. The intensity is 2.15 mW/cm^2 (Yellow) and 0.5 mW/cm^2 (NIR).
The studies used dosing of 0.1 J/cm^2 (~8 minutes of exposure) twice a week for 4 weeks. This is surprisingly low intensity and dose that got very good results. [38]
A well-designed study that was randomized, placebo-controlled, double-blind, and split face used Red (633nm) and NIR (830nm) LED arrays for skincare. [8]
The study had 112 patients (2 males and 110 females) and split them into 4 groups. Red-Only treatment, NIR-Only treatment, Red+NIR treatment, and control group.
Red light treatments were 105mW/cm^2 and NIR treatments were 55mW/cm^2, both were non-contact at 3-5 cm away and treatments were 20 minutes. Treatments were twice a week for 4 weeks. The Red+NIR group got the NIR treatment first and then the Red treatment second each week.
All treatment groups showed a slight decrease in melanin measurements, with only the Red-Only 633nm group having a statistically significant decrease.
The study concludes the Red+NIR treatment had the best wrinkle reduction, the Red-only had the best melanin reduction, and the highest overall cosmetic satisfaction was in both the groups that used NIR.
"Considering that skin rejuvenation aims at both wrinkle reduction and improvement of skin tone, we consider that the combination of 830 and 633 nm LED treatment would offer the best clinical effectiveness by combining the different bioadvantages produced by these two wavelengths of light." [8]
A recent July 2023 study on 7 males using an Omnilux for Men LED Mask looks at several metrics for cosmetic improvements. [9]
The mask uses 633nm, 830nm, 1072nm - presumably with more emphasis on deeper-penetrating Near-Infrared for thicker male skin. The mask was instructed to use 3-5 times per week, 10 minutes per treatment, for a duration of 6 weeks. [9]
The study does not specify the intensity or dose. The Omnilux website says the device uses 66 double-chip LEDs and according to the GoalsToGetGlowing blog the intensity is 35mW/cm^2. Which we calcuate a dose of 21 J/cm^2 for each 10 min treatment.
Benefits included improvements in fine lines, wrinkles, skin texture, UV spots, and brown spots.[9]
One recent July 29th 2023 study used an LED Mask with 630nm, for 12 minutes, intensity of 21.7 mW/cm^2, and a dose of 15.6 J/cm^2. There were 20 participants (15 female and 5 male) that used this treatment twice a week with recommendation to space each dose by 72 hours to avoid a cumulative overdose. [76]
The authors note the low intensity and wavelength was specifically chosen to avoid exaserbating skin pigmentation problems and heating issues, which can happen more frequently with darker skin types. [76]
The study showed an improvement in many skincare metrics, including some skin lightening effect which they attributed to overall improved skin tone consistency. [76]
One study used a Red and NIR LED face mask on a single female patient. Treatments were daily for 20 minutes for 3 weeks. [10]
The device was reported to use 72 LEDs, but they do not report any other parameters like the actual wavelengths used, intensity, joules/cm^2, or even the brand or model of the device.
The study reports a positive effect for skin lightening. Although overall this study is not very helpful for reproducibility since it fails to report many parameters and only had a single patient.
One study with 100 patients investigated the maximum safe doses with 87.5mW/cm^2 Red 633nm wavelength. [11]
In Fitzpatrick type I-III the maximum was 480 J/cm^2 and Fitzpatrick type IV-VI the maximum was 320 J/cm^2. We calculate that would be 91 minutes and 61 minutes of exposure, respectively. [11]
The dose was administered 3 times weekly for 3 weeks. Over 30% of participants in both skin type groups developed hyperpigmentation, which resolved itself within 3 months after all the treatments had ended. [11]
It comes as no surprise that excessively high intensity and/or high doses of Red LED light can certainly cause a transient hyperpigmentation response as a side-effect.
And we can appreciate the paradoxical nature that several of the studies above used 633nm to reduce pigmentation, but this study with excessive dosing caused hyperpigmentation. So it is never the wavelength alone that causes an effect, it is the dosing that makes either beneficial or detrimental.
Now lets roll back to cover some background and basics.
The coloration of human and mammalian skin and hair is mostly determined by the concentration of melanin pigment in the forms of eumelanin and phenomelanin.
Melanin is produced by cells called melanocytes which are stored in the basal layer of the epidermis. Melanin is also stored and transported in melanosomes.[12][13]
Interestingly the concentration of melanocytes are the same in all skin types, but the human skin phototype variations comes from having different concentrations of melanin and melanosomes. [13]
Melanin is known as photoprotective by absorbing UV light, but also has antioxidant and free radical scavenging properties. [14]
Increased melanin production is a natural defense mechanism against light exposure and ROS in the skin. In many climates people experience seasonal variation of the pigment during summer versus winter by nature of tanning from sunlight. [15]
Ultraviolet (UV) light is the short wavelength invisible "light" on the sunlight spectrum. It is divided into UVA (320nm-400nm), UVB (280nm-320nm) and UVC (100nm-280nm).
Ultraviolet light exposure is the most commonly accepted wavelengths that induces tanning of the skin by stimulation of melanocytes and keratinocytes. Depending on the wavelength and exposure, there can be immediate tanning during exposure or delayed tanning effects over a few days or weeks afterwards. [16]
The most dominant scientific definition for pigmentation levels of the skin are rated on the Fitzpatric Scale of I, II, III, IV, V, and VI (Roman numerals 1 thru 6).
One study describes it as the following:
It is important to remember this scale for this blog as we will see the interaction of light with various skin types will be different. Wavelengths and doses may need to be tailored appropriately for different skin photoypes.
We will use the shortened term for human Skin PhotoType which is SPT I - VI to not have to repeat the term Fitzpatrick Skin Scale numerous times in this blog.
Pigmentation disorders (sometimes called dischromia) generally arise from irregularities in the skin's natural defense mechanism to produce more melanin in response to light exposure or inflammation in the skin. The melanin response is generally healthy and beneficial, and these conditions are not life-threatening or directly harmful to the individual.
However, many studies will report that pigmentation disorders resulting in cosmetic abnormality will affect the individual's self-esteem and quality of life, often resulting in depressive and anxiety symptoms. [17][4]
In Melasma, the melanin concentration is often asymmetrical, blotchy, and darker than the bulk the the skin. It typically occurs in areas of the skin commonly exposed to sunlight like the face. [4]
Postinflammatory Hyperpigmentation (PIH) is when inflammation or damage to the skin results in hyperpigmented areas. This can be caused by a wide variety of sources like acne, scars, insect bites, skin irritants, burns, cosmetic procedures and of course UV exposure and excessive light exposure.[18]
Erthyma ab inge is a hyperpigmentation resulting from overheating, commonly associated with being too close to heaters, heat pads, heat from laptops on the legs, and occupational infrared exposure.
"Erythema ab igne is a reticular, hyperpigmented rash that is acquired from moderate heat and infrared exposure, with temperature often ranging from 43 to 47°C [2]. " [20]
One PBM review article addressing the risks of Infrared potentially causing hyperpigmentation notes the following:
"The thermal nature of erythema ab igne means that the irradiance of exposure was elevated and that the cumulative dose (fluence) was very high." [1]
So the reasearchers already know the possible connection between high intensities, high dose, and overheating the skin as a likely cause of hyperpigmentation from red light therapy photobiomodulation treatments.
One study confirms on heat:
"According to the literature, it is evident that melasma worsens after exposure to heat conditions." [78]
In a study mentioned earlier, it produced 30% hyperpigmentation for all skin types with Red 633nm LEDs at high intensity and excessive doses.[11] Perhaps a combination of ROS from the high dose and heating.
Several other types of pigmentary responses are associated with photoaging particularly in people that spend a lot of time in the sun. This can be seen as freckles, age spots, brown spots, liver spots, solar lentigines, and mottled hyperpigmentation. [13]
Several studies have outlined the co-factors and risk groups for melasma and hyperpigmentation.
Males account for 10-20% of reports of melasma. In males they find similar cofactors of SPT III+, age ranges, occupational sun or heat exposure, hormonal influences, hypothyroid, and usage of unspecified cosmetics. [24] [25]
People whom are in one or more of these categories would want to take extra precautions with light therapies. As we will see these same co-factors are likely more responsive to light therapy in nearly all examples we will discuss later in this blog, particularly SPT III and above.
People not meeting any of these criteria would be reassured they would be at a low risk for an unwanted pigmentation response with responsible usage of light therapies.
Recent studies have shown that Visible Light (400nm-700nm) also induces an increase in pigmentation.
One review article summarizes the following:
"Visible light (VL) is nonionizing radiation that penetrates the deep dermis and subcutis. Pigmentation is found only in darker phototypes (III–VI) after high doses of VL exposure, and only shorter wavelengths (420–470 nm, blue and violet) can induce pigmentation through the activation of opsin 3 (OPN3) receptors in melanocytes [31]." [26]
One study compared the effects of UVA versus Visible light on skin types IV-VI. They found the Visible Light would also show an increase in pigment using 200mW/cm^2 and a minimum dose of 40 J/cm^2 to initiate a response. A dose of Visible Light at 8 J/cm^2 made no effect on pigmentation. [27]
The authors note that despite filtering the Infrared wavelengths, the increased pigmentation doses coincided with an erythema (redness) response likely due to the absorbed light being converted into heat.
They also conducted the same treatments to SPT II, which they found minimal pigmentation response for all doses. Which a common pattern will be that SPT I and II are less likely to have hyperpigmentation responses from light therapy treatments. [27]
A subsequent review article noted the following about this visible light study.
"Greater awareness about the importance of photoprotection against these wavelengths, particularly for patients with melasma and PIH is increasingly needed." [28]
While the lamp used for this study was a broad-spectrum filtered Halogen incandescent lamp with a large amount of the spectrum in the Red wavelengths, more work needs to be conducted to isolate the effects of individual wavelengths on hyperpigmentation.
Many recent articles have confirmed the strong influence of Blue light on increasing pigmentation. The Opsin-3 (OPN3) in the melanocyte has a peak absorption in the blue light which triggers more melanin production. [29]
"Today, it is well established that irradiation with blue light causes hyperpigmentation in skin [15]. A consequence of this can be mottled hyperpigmentation, which is a visible sign of photoageing [16, 17], or age spots [18]." [30]
One study used 450nm Blue LED panel at 5 cm away for a dose of 60 J/cm^2. They treated Fitzpatrick Skin types III and IV for consecutive days and produced a hyperpigmentation response. [30]
A review article on the benefits of blue light therapy titled "Blue Light in Dermatology" references 5 articles that resulted in a high percentage of patients with hyperpigmentation side effects, particularly when treating psoriasis. [31]
So while we can appreciate the potential benefits of Blue Light, hyperpigmentation is not a surprising side effect. If Blue Light is used selectively to manage acne, that could be one way to reduce hyperpigmentation from acne scars.
Practical Note: The key aspect in many studies seems to be treatment on "consecutive days" for a sustained hyperpigmentation response. This is also true for many cases of erthyma ab inge that the heat exposure is "repeated" to cause the pigmentation response. Those concerned about hyperpigmentation response may want to reduce the frequency of light therapy treatments. As we can see the contrast of the studies that reduced pigment only did treatments once or twice per week.
While melasma and pigmentation treatments is a very large topic, it is worth here mentioning the high-intensity laser treatments for melasma.
Unlike PBM which is non-thermal, high intensity light and laser treatments are Intense Pulsed Light (IPL), Pulsed Dye Laser (PDL), Q-Switched Laser, Fractionated Laser, and other laser treatments.
These treatments are used for a wide range of cosmetic treatments like skin resurfacing, hair removal, and pigmentation reduction.
For melasma and hyperpigmentation, they generally will use high intensity pulses targeted to damage or inhibit the melanocytes, melanosomes, and break apart the melanin granules. [33]
However, many of the review articles for these high-power light treatments also point out the inconsistent and paradoxical results that may even cause more hyperpigmentation as a side effect. Which could be due to the heat, ROS, or general regression of the issue as it doesn't seem to treat the root cause. [33][34][35]
Dermotological lasers were originally studied in SPT I-III. However, different wavelengths and dosing parameters were needed to improve outcomes for SPT IV-VI, and to reduce side effects like hypo- and hyper- pigmentation. [35][36]
"The safest wavelengths for SPT IV–VI are those in the near infrared range: the 800–810-nm diode and the 1064-nm neodymium-doped yttrium aluminium garnet (Nd:YAG) lasers." [37]
Popular laser wavelengths for treating SPT IV-VI are Near-Infrared 810nm and 1064nm, which seems to be the ideal lasers for bypassing melanin absorption and reducing heat in the upper layers of the skin.
"Currently, low-fluence Q-switched lasers are mainly used in the treatment of melasma [182,194]. Low-intensity treatments mainly use the 1064 nm wavelength, which penetrates deeper into the dermis and leaves the epidermis relatively intact." [39]
Interestingly the dose of the 1064nm laser is rather low at only 4-5 J/cm^2. [40] Which might seem like a low dose in Photobiomodulation, but in this case it is delivered as a high intensity pulse and causes a thermal effect.
"QS Nd:YAG [1064nm] is the most widely used laser for the treatment of melasma. The fluence used is less than 5 J/cm2, spot size 6 mm, and frequency of 10 Hz. " [40]
High intensity delivered in a short amount of time causes an inhibitory/destructive action in the cells. Which is an important lesson we commonly point out that it is the intensity and exposure time are most important for light therapy dosing, and just looking at J/cm^2 can hide the true "dose" parameters.
Practical Notes: Although seemingly irrelevant to this discussion of non-thermal LED light therapy, there are some interesting recommendations that should be kept in mind as the science matures.
1. A clear preference for Near-Infrared wavelengths like 810nm and 1064nm for SPT IV-VI because it avoids superficial heating and penetrates deeper than any other wavelengths. This is likely good advice for ideal Photobiomodulation wavelengths for SPT IV-VI as well, since red light is more likely to be superficially absorbed by the melanin as heat (contrary to popular opinion).
2. Cooling the skin during high-intensity treatment can improve comfort and reduce overheating the epidermis, but too much cryo air cooling during and after laser treatment has shown to give a worsened hyperpigmentation response. [41]
3. These laser treatments will often recommend avoiding UV or Sunlight for days (or weeks) before and after treatment. Which again might be prudent for anyone trying to reduce hyperpigmentation and prevent rebound hyperpigmentation during the course of Photobiomodulation treatments too.
4. While we advocate for low intensity non-thermal LED Panel treatments to avoid pigmentation response, we can appreciate the paradox that high intensity pulsed light when used appropriately has been used to reduce pigmentation.
5. An unsurprising side-effect of high-intensity laser treatments has been hyperpigmentation, so again confirmation that heat and destructive treatments could cause a pigmentation response.
A common myth and anecdotal reports have told of Green light therapy for usage on hyperpigmentation and melasma.
We find no direct sources that Green LED or Green Photobiomodulation has been used in peer-reviewed published journals for hyperpigmentation.
However, there are many clinical studies of Green Laser 532nm used in the context of high intensity pulsed treatments for hyperpigmentation.
For example, here is one such study that many people selling green lights will reference.
https://pubmed.ncbi.nlm.nih.gov/14568830/
As explained in the previous section, high intensity green laser/IPL treatment is a very different context to green LED photobiomodulation and brands should not use completely irrelevant studies and technologies to promote their products.
We visited this article using high intensity Green and NIR lasers for pigmentation, and here is what they actually used when you read the article:
"Patients with Fitzpatrick skin types I through IV were enrolled in this evaluation for the first and third groups involving the 532-nm laser, and those with skin types I through V for the 1064-nm laser group. This skin type restriction was neccessary because the KTP [532nm] laser is well absorbed by melanin and can be problematic in treating darker skin types. The longer-wavelength Nd:YAG [1064nm] laser alone can safely be applied to skin types V and VI." [42]
Telling people to use Green light based on this irrelevant study would be double-bad advice again since longer NIR wavelengths (810nm & 1064nm) are prefered for SPT IV-VI and Green 532nm would cause superficial absorption and heating with more side effects (including possibly causing more hyperpigmentation as a side effect).
Here are two more high-intensity green laser studies being falsely used to sell green PBM for hyperpigmentation.
https://pubmed.ncbi.nlm.nih.gov/12623553/
https://pubmed.ncbi.nlm.nih.gov/26551773/
This is not a "soothing" green light therapy treatment, this is high intensity pulses to inhibit the cells or destroy melanin/melanosomes. One of the studies showed that 660nm (red) laser did better than the 532nm (green) laser to reduce pigmentation, but it doesn't matter because it is irrelevant to LED Photobiomodulation.
Lets try to find some actual PBM studies to see what they say about Green light on the skin.
One review article titled "Role of Photo-Biomodulation Therapy in Facial Rejuvenation and Facial Plastic Surgery" the author speculates the following even though the reference they provide doesn't have any real data to support it.
"530 nm (green): it might have some benefit for pigmented epidermal conditions and superficial skin conditions like stretch marks but its use for these conditions has not been proven yet." [43]
In that same article on the actual section reviewing pigmentation treatments, the author concludes that Near-Infrared LED wavelengths would theoretically give the best benefit to treating hyperpigmentation:
"Therefore, these LED wavelengths, particularly 830nm, might be helpful therapeutic tools for treating patients with hyperpigmentation." [43]
One review article on isolated melanocytes found that Green (530nm) light had increased melanin synthesis and tanning in SPT II and III (higher SPT were not tested). They noted that Green light activated OPN3 similar to blue light. [44]
A recent review article titled "The Emerging Role of Visible Light in Melanocyte Biology and Skin Pigmentary Disorders: Friend or Foe?" makes very clear that both Blue and Green light can contribute to photoaging and hyperpigmentation. [78]
A very relevant May 2021 review titled "Role of Visible Light on Skin Melanocytes: A Systematic Review" covers the different roles of blue, green, yellow, and red light on the melanocytes. They say the only documented benefits of green light (490nm-570nm) are for cellulite and wound healing, they don't say direcly how it affects pigmentation. They say green light can increase ROS and photoaging, which would seem to be contraindicated for the goal of reducing hyperpigmentation. Only Yellow light (570nm-595nm) had a direct effect on melanin inhibition according to this article. [45]
A June 2019 review article titled "Under the spotlight: mechanisms of photobiomodulation concentrating on blue and green light." would hopefully give us some insight.[46] They summarize the PBM benefits of Green light merely as:
"Published reports have indicated PBM effects for green light ranging from improved cellulite appearance (32) to reduced tissue swelling (33)." [46]
With no mention of Green light PBM for treating hyperpigmentation.
Another review article covering Photobiomodulation of the skin with Blue, Green, Red, and Infrared also makes no mention of clinical studies using Green to treat hyperpigmentation. [47]
At this point we can safely assume there are no direct studies using Green PBM to treat hyperpigmentation, not even from a mechanistic standpoint. Recommending Green LED is reckless as the mechanisms indicate it could increase hyperpigmentation via OPN3, induce ROS and photoaging, and be superficially absorbed as heat.
The famous brand Celluma similarly could not find any actual published studies on using green LED PBM for hyperpigmentation in their blog on the topic.
Another adjacent "energy medicine" is the Radio Frequency (RF) cosmetic treatments. RF wavelengths delivers heat therapy deeper into the skin is commonly used for skin resurfacing and tightening treatments. The common temperature for treatment is 38C - 44C. [48]
However, there are some reported side effects of hyperpigmentation from this therapy. Similar to the high-intensity pulsed laser treatments, it is unsurprising that a heat therapy has the possibility of causing hyperpigmentation side-effects. [48]
Excessive heat from high intensity Infrared exposure is often associated with increased pigmentation.
"Moreover, although intense heat leads to melanogenesis, there is no systematic study on solar heat (infrared radiation [IR]) in melasma, nor are validated methods to assess IR protection available. Thus, workers submitted to intense heat as cooks, bakers, metallurgists, glassmakers, and drivers should be advised of the role of intense heat in the chronicity of melasma." [33]
Another review article mentions the following:
To date, no systematic investigation has examined the role of solar IR radiation in melasma." [26]
It is clear that infrared and/or heat can initiate hyperpigmentation, worsen melasma, or cause erthyma ab igne.
The problem the review articles keep saying is the lack of studies on the actual infrared wavelengths, intensity, or doses that cause a pigmentation response.
Infrared is a wide range of wavelengths including Near-Infrared, Mid-Infrared, and Far-Infrared (780nm to 1,000,000 nm - yes a million nanometers).
We have already seen several examples where Near-Infrared has a very low thermal effect and is used to reduce pigmentation.
Here is one direct quote from an article:
"It has been reported that IR-A can penetrate epidermal and dermal layers and reach subcutaneous tissues without increasing the skin temperature significantly, whereas IR-B and IR-C are absorbed mostly in the epidermal layers and increase skin temperature significantly (Schieke et al., 2003)." [49]
It is clear the "heating" wavelengths are Mid-Infrared (IR-B) and Far-Infrared (IR-C), which are commonly associated with the exposures that produce hyperpigmentation or erthyma ab inge.
Near-Infrared (IR-A) gets wrongfully assumed to be a heating wavelength due to it's shared name with the longer-wavelength Infrareds. But Near-Infrared is most commonly agreed to being the least-heating wavelengths of the entire optical spectrum, despite the common myths circulating online.
One 2006 study titled "Effects of Infrared Radiation on Skin Photo-Aging and Pigmentation" used Far-Infrared therapy on 20 females Fitzpatrick Type III-IV with pigmented lesions. [50]
The study used wavelengths 900,000 to 1,000,000 nm with 35 mW/cm^2 intensity for 15-20 minutes daily (5 days a week) and showed no effect on pigmentation on the patients. [50]
The authors also note the skin temperature was increased to a "pleasant" 32℃ -35℃ , which would mean this treatment could be categorized as low-thermal photobiomodulation despite the long wavelength.[50]
There were improvements collagen and wrinkle reduction, there was no significant effect on pigmentation. [50]
Practical Note: This is a very important example where Far-Infrared exposure that doesn't significantly heat the skin is not associated with directly affecting pigmentation. For example Infrared Sauna usage would not cause pigmentation effects as long as the body is not too close to the heaters to overheat the skin.
With minimal studies confirming and only a few anecdotes, there is only one published article that mentions that sauna usage is accociated with erthyma ab inge hyperpigmentation in athletes.
"erythematous patches often with telangiectasias and hypo- or hyperpigmentation in areas exposed to excess external heat sources.51,52 In athletes, these sources may commonly be heating pads, hot water bottles, hot showers, hot baths or whirlpools, hot stone massages, sauna and steam rooms, and heated recliners, especially in those treated for muscle or joint aches or pains" [51]
While sauna is meant to increase core body temperature in a controlled way, the skin temperature should not be excessively high which could be due to sitting too close to the stove or heaters.
An important emerging new light therapy is called Water Filtered IR-A (wIRA) that uses incandescent light sources with a water filter in front of it. This water filter absorbs the "heating" wavelengths and allows to pass the most of the deeper penetrating Near-Infrared wavelengths.
Here is one descripion:
"wIRA irradiation can effectively heat the skin and subcutis up to a depth of approx. 2.5 cm with a low thermal load on the skin surface while delivering an effective energy level to deeper tissue layers (see Chap. 3, Fig. 3.5)." [52]
They report the goal is to induce mild skin hyperthermia with deep penetrating heat at 39℃-42℃. This is often achieved with intensities 110mW/cm^2 and higher. [53]
"Although applying local hyperthermia (44 °C/30 min) has been successfully used for treating common and facial warts, side effects include burning sensations, blister formation, and subsequent hyperpigmentation [10]. No such side effects have been reported using a wIRA radiator (type 501; Hydrosun®, Müllhein, Germany) [4], most probably because IR-A components, which would typically cause unwanted thermal stress and a stinging and burning sensation in the skin by interactions with water molecules, are reduced by a water filter [11]." [54]
Despite the purposeful heating with near-infrared wavelengths (which the heating isn't caused by the wavelengths used, but from the high intensity), the researchers report there has been no such side effects like hyperpigmentation from wIRA therapy so far.
Practical note: High intensity LED Panel treatments are becoming heat therapy more similar to wIRA rather than non-thermal photobiomodulation. Skin temperatures should be monitored when using an LED Heat Lamp with >50mW/cm^2 particularly with SPT III-VI. We see that Near-Infrared treatments with controlled skin temperature (<42C) does not have a direct impact on pigmentation on normal patients.
One article reported an additive effect of heating plus UVB increasing melanin production. [55]
Another article mentions the combination of Infrared and HEVL (high energy visible light, Violet/Blue wavelengths) also increases melanogenesis. [17]
One article pre-conditioned the skin with various wavelengths before UV exposure. The Near-Infrared wavelengths like 850nm, 870nm, and 970nm appeared to protect the skin better than Red wavelengths like 630nm and 660nm. However, looking closely at the picture, it is clear the Near-Infrared provided protection by facilitating more transient melanin production. [1]
Practical Note: As noted several times earlier, it would appear that avoiding the combination of Heat/Infrared plus UV/Blue during the treatment period would help prevent the melanogenic activity of hyperpigmentation response. Although in normal skin this is a highly protective effect.
Often Red and NIR light therapy is considered to be protective of the skin from "sunburn" from sunlight or UV exposure. One study used 660nm to precondition the skin.
"The results of the study showed a reduction in the UVB-induced erythema reaction in a significant number of the pre-treated subjects. Also a SPF-15-like sun protection factor effect and a reduction in post-inflammatory hyperpigmentation were observed." [1]
There is a protective effect when using Red/NIR before or after UV exposure by attenuating the inflammatory effects. Which could decrease hyperpigmentation responses from UV inflammation, although perhaps with a minor transient protective pigmentary increase.
The common fallacy is that NIR is more of a heating wavelength than Red. However, we have already seen many examples where NIR is preffered as the least heating wavelength on the skin.
One recent June 2023 article used mathematical modelling of skin optics to determine skin temperature profiles with different wavelengths.
"Because of the higher absorption coefficients, higher temperatures (approximately 45°C) were observed at the skin surface at the wavelengths of 632 and 660 nm, as compared to the longer wavelength of 1064 nm, which produced the smallest temperature increase (approximately 3°C)" [57]
The Red wavelengths have higher skin heating than NIR due to higher absorption coefficient into Melanin and Hemoglobin (blood).
The simple way to understand it is that the deeper the penetration, the less heating occurs at the surface of the skin.
The Near Infrared wavelength is dispersing into a larger volume of tissue due to it's deeper penetration. Which means it's potential heat energy is also spread over a wider volume, leading less superficial heating that would lead to a pigmentation response.
Several studies have confirmed that darker skin types can experience 3 to 6 times more heating from photobiomodulation treatments when using higher intensities and doses. [58][59]
In the study earlier, with 633nm red light at 87.2 mW/cm^2; the safe maximum dose for SPT IV-VI was 1.5 times less than the SPT I-III group, likely due to the higher heating effect reducing the safe limit.[11]
While the commonly accepted "optical window of the skin" for Red/NIR penetration is between 600nm-1300nm, one study notes for Fitzpatrick Type III-VI the optical window is between 750nm-1300nm.
Clearly showing that Red light (600-700nm) is superficially absorbed as heat in the melanin and not part of the ideal penetration window for SPT IV-VI.
"Presuming values for relative spectral absorbance ≤0.5, the optical window ranges from about 600 nm in fair skin and about 750 nm in black skin to about 1300 nm." [60]
Practical Note 1: This information is important for SPT III-VI since they are already predisposed to a hyperpigmentation response, but now we learn there is significantly more heat produced due to superficial absorption from the higher melanin content.
Practical Note 2: If you have made it this far, it is increasingly clear that deeper penetrating Near-Infrared like 810nm, 830nm, 850nm, and 1064nm are the preferred wavelengths to reduce minimize skin heat effects particularly in SPT III-VI skin. Red wavelengths are expected to have a higher heat response due to superficial melanin absorption and being outside the optical window for SPT III-VI. So again, people are getting double-bad advice to avoid NIR in favor of Red, when the science indicates the opposite preference.
Practical Note 3: Skin types III-VI may need to use lower intensities, lower doses, prefer non-thermal NIR wavelengths. It may be prudent to monitor skin temperature (<40C) with high powered LED devices to avoid significant skin heating.
Aside from directly impacting the melanocyte, there are a few interesting mechanisms that are related to Red/NIR light therapy.
Melatonin is famously known as the nighttime hormone excreted by the pituitary gland to induce sleep.
Recently, it has been discovered that 95% of melatonin is produced in the cells aided by Near-Infrared light exposure, and only 5% is produced in the pituitary gland. [61]
This is a profound discovery. Previously it has been known that Red and NIR light therapy can be used to help sleep and circadian rhythms in general. Now we know it also aids the intracellular production of melatonin as well.
Melatonin had been discovered in experiments that caused frogs' skin to modulate melanin. Researchers found that frogs consuming or exposed to exogenous melatonin caused their skin to lighten. [62]
Since that discovery, it has often been hypothesized that melatonin would play a role in human skin and hair pigmentation. [63]
One survey article found that patients with melasma had lower concentrations of melatonin than people without the condition. Which also was associated with an overall increase in oxidative stress. [64]
One excellent review article published February 2023 titled “Melatonin in Dermatologic Allergic Diseases and Other Skin Conditions: Current Trends and Reports” summarizes the effect of melatonin for skin conditions. They discuss one article that successfully used topical melatonin to treat melasma. [65]
This success is often attributed to the powerful antioxidant effect of melatonin, thus reducing inflammation of the skin and providing a competing antioxidant instead of the skin needing to produce excess melanin. Similar to how many other antioxidants are also employed for treating hyperpigmentation and melasma as well.
We would postulate that Near-Infrared would be a powerful contributor towards anti-inflammatory melatonin production in the cells, thereby being an additional mechanism to appreciate how it can help calm melanin production.
Heat Shock Proteins have often been made famous recently as a beneficial effect of sauna therapy.
One study found that using Radio Frequency (RF) treatment to bring skin temperature to 43C for 20 minutes successfully treated 10 female (SPT III and IV) patients with melasma. They hypothesized the increase in Heat Shock Proteins was one of the mechanisms for the results. [66]
One study found higher HSP70 concentrations in depigmented regions of Vitiligo patients. Which could confirm a correlation between higher HSP70 and lower pigmentation.[67]
Several Photobiomodulation studies have confirmed increased activity of HSP70, particularly with Near-Infrared lasers. [68][69]
A review article by
"HSP70 is part of the normal wound healing process, alongside IL-6 and TGF-β1. Visible (532 nm) and NIR (815 nm) light have been demonstrated to induce HSP70 expression in treated skin cells, and this is important for skin rejuvenation interventions, since there is a consequent effect consisting on the assistance of the correct folding and transport of newly synthesized collagen [93]." [75]
So this is the only mechanistic glimmer of hope that 532nm green light can induce HSP70 as a possible mechansim for controlling pigmentation, but we also see NIR is often favored for this effect as well.
So once again we could speculate the increased HSP70 activity with controlled low-thermal Photobiomodulation could be a mechanism for reducing pigmentation.
Nitric Oxide (NO) produced by Ultraviolet light exposure had long been known as one of the mechanisms for producing melanogenesis and associated with the risks of melasma and hyperpigmentation disease. [70][71]
Once again, it has been found that SPT IV-VI respond more greatly to NO than lighter skin types.[72]
In Red and NIR Photobiomodulation, one of the main mechanisms has been the release of Nitric Oxide from Cytochrome C Oxidase to remove the limiting factor from the Electron Transport Chain and produce more ATP. [73]
While Nitric Oxide is beneficial in homeostasis, for example to promote healthy circulation, excessive Nitric Oxide production is one of the assumed mechanisms for the biphasic dose response in Photobiomodulation. [74]
As well it is already known that high PBM doses produces ROS as part of the biphasic dose response, which already holds some risk of Post Inflammatory Hyperpigmentation. [74]
In addition to the potential thermal effects, excessive ROS or NO produced from overdosing Red and NIR light therapy could also be a mechanism for increased pigmentation response from treatments.
The effects of wavelengths light on hyperpigmentation and melasma is only recently being studied and understood.
Based on the current research, successful melasma treatments on humans have used 940nm NIR and 585nm Yellow light LED photobiomodulaiton. Skin lightening or brightening has been observed in 2 large studies using 633nm Red LED light, and to a lesser degree 830nm LED. Blue light is often confirmed to increase pigmentation.
There are many in vitro (tissue experiments, not on whole humans) studies that show various wavelengths of Yellow, Red, or NIR can also be used to treat pigmentation conditions. So far there is no scientific indication that Green LED Photobiomodulation would be used for treating hyperpigmentation, despite the constant claims otherwise.
Like all of photobiomodulation, the dosing is just as important as picking the correct wavelength. Improper dosing of any wavelength could lead to an unwanted pigmentation response.
When using high-intensity (>50mW/cm^2) LED panels that cause a heating effect, the skin temperature should be closely monitored to not reach excessive levels. It is possible that minor skin warming by a few degrees C with deeper penetration wavelengths could stimulate several processes to reduce pigmentation.
However, using any kind of heating in conjunction with the NO and ROS from Red/NIR could be a trigger for some forms of melasma or hyperpigmentation. So it may be prudent to always start with low intensities to see how the skin responds.
Contrary to popular opinion, Near-Infrared wavelengths are often regarded as the least heating wavelengths by nature of having less superficial absorption. This is particularly more important for SPT III-VI where melanin absorption of Red light would lead to more rapid superficial heating especially in the epidermis where the melanocytes reside.
We have a wide range of studies that help us use Red/NIR light therapy responsibly and minimize unwanted pigmentation side effects. In the future we expect to see many more studies that will help us control pigmentation effects to our desired outcomes more consistently.
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]]>However, can they reach important target tissues like muscles, bones, internal organs, and the brain? If they don't, can it have any effect on them?
Such questions would cast doubt on the efficacy of red light therapy. Often LED application can't reach very deep, Red wavelengths lack penetration, and not implementing skin contact method will severely limit penetration.
If the photons can't reach the target cells, many assume there would be no effect or benefit.
We noted in a previous blog that Red and Near-Infrared (NIR) can reach anywhere from 1 to 50 mm into the skin, which depends not only on wavelength but also on intensity and how treatment is administered (skin contact or non-contact). Even if we say it "reaches" 50mm deep, the final intensity at that depth is greatly attenuated (diminished) to only trace amounts.
So, there are many cases where photon penetration would be insufficient to deliver enough dose to the deeper target tissues.
However, photobiomodulation studies often note Red and Near-Infrared (NIR) light benefits deeper than the actual photon penetration depth, or benefits completely different parts of the body than the area treated.
Such benefits and applications are identified in the literature as a variety of names including Systemic Effects, Indirect Effects, Abscopal Effects, Remote treatment, Global effects, or Bystander effects.
Leading researchers are now utilizing systemic targets and methods to improve red light therapy treatments, benefits, and our understanding of how red light therapy is really working.
In a recent interview on the ProNeuroLIGHT LLC YouTube channel, Dr. Hamblin says this:
"I think this is one of the key issues in photobiomodulation today, to what extent is the organ and the tissue you are shining the light the important thing, and to what extent is the systemic effect involving stem cells and blood irradiation."
So we should be paying attention to these systemic mechanisms we will cover in this blog as Dr. Hamblin recently notes as a key issue for modern photobiomodulation.
By understanding the systemic targets ourselves then we can utilize it properly to benefit tissues deeper into the body despite limited direct photon penetration.
We know the primary photo-chemical mechanisms of how photons are absorbed by intercellular structures like the mitochondria will up-regulate ATP production, NO release, Ca+ flux, increase Oxygen consumption, produce signalling ROS, form EZ water, and much more.
But what happens after that? Do these effects only occur inside the cell that the photon was absorbed?
Even a 1998 paper by Tuner and Hode discusses how the systemic effects of red light therapy can affect study designs.
"The effect of a laser beam is not limited to the site of optical diffusion. Through metabolic mediators, the effect can reach very distant parts of the body." [23]
How Systemic Effects Occur:
Activated metabolites in the cells will initiate signalling mechanisms and growth factor release as a cascade of benefits that often take place long after treatment has ended. As well stimulation to stem cells, immune cells, improved circulation, improved lymph movement, and stimulated mitochondria in the blood will carry benefits to other parts of the body.
One randomized, double-blind, placebo controlled, split-face study used non-contact LED therapy for wrinkle treatment. They observed skin improvements in layers of the skin deeper than the theoretical penetration depth of 633nm.[3] This led them to comment on what they called the bystander effects of red light therapy.
"healing had been observed in regions other than the directly irradiated sites,
suggesting that the bystander effect may also occur in beneficial biological events. The current understanding of the bystander effect is that irradiated cells may secret intercellular signaling molecules or that the gap junctional communication between irradiated cells and non-irradiated cells may play an important role in causing this phenomenon." [3]
Similarly, split-face trials for red light therapy can be challenging. A split-face trial is often used in facial care trials where the treatment is only applied to one half of the face. That way the untreated half of the face can remain as it's own control.
However, for red light therapy the systemic effects and bystander effects can cause improvements on the untreated side of the face. Which is why the previous study used both a true placebo group and a split-face treatment.
Here is what another LED skincare study discussed about the lack of placebo control in their split-face trial.
it is entirely possible that even the unirradiated side on the LED-irradiated subjects healed faster than a true unirradiated subject."[4]
It is a remarkable challenge that red light therapy is so effective; researchers have to take extra precautions to monitor if the systemic and bystander effects will interfere with their study design.
Light irradiation of the blood is a common therapy with PBM. One article notes that it has been used for decades in Russia, with the article focusing on how blood irradiation can improve Asthma.[20]
Blood irradiation is often shown to improve oxygenation of red blood cells. [13] In an early 2020 article, the cell-free mitochondria has discovered in the blood as another possible explanation of activation of the blood by photon absorption. [19] The article on Asthma discusses the improved antioxidant and immune response. [20]
Blood irradiation can be administered intravenously by a syringe with fiber optic tip to deliver the light directly onto the blood, or it can be done transdermally particularly targeting large veins near the surface of the skin (inner wrists, aorta artery behind the belly button, and jugular vein).
Intranasal Red Light Therapy (putting LEDs and lasers up the nose) is often considered to be a systemic treatment of the blood, although it is often marketed for targeting the base of the brain. The inner nostril is rich with blood flow (ever get a "nose bleed"?) so it is a valuable site for blood irradiation.
"Systemic effects of nostril-based intranasal irradiation via the blood cells and components could likely contribute to the observed neurotherapeutic effects (Hennessy and Hamblin, 2016). The tissue around the nasal cavity has abundant blood capillaries with relatively slow blood flow." [18]
One article recommends about 20 minutes of exposure for proper blood irradiation, much longer than the recommended exposure time for direct treatments.[14] This will be important later.
Another study recently published online in 2023 treated the left radial artery in the wrist for 20 female nurses with low back pain. They treated the wrist for 30 minutes with at 100mW laser resulting in 33 J/cm^2 total dose. [15] Imagine signing up for a trial to treat your chronic low back pain and then you get treatment to your wrist?
We can appreciate that using red light therapy anywhere on the skin will have some blood irradiation, so there is always some expected systemic effects regardless of treatment area and type as we already noted in the skincare trials.
Dr. Hamblin said this in the same interview: "wherever you shine the light in the body, you will be irradiating the blood, by definition"
A remarkable 2004 human study inflicted two identical 1.27cm^2 wounds on forearms of 22 participants (both male and female). Half were given multiple-wavelength LED/Laser therapy on only one wound, and the other half only had placebo treatment. The intensity was 75mW/cm^2, dose 8 J/cm^2, and treatment area of 19.2 cm^2. [17]
The study found that both wounds of the treatment group healed faster than the untreated group, even for the 2nd wound that wasn't irradiated.
The authors made this profound statement:
"They suggested that LLLT may have caused release of tissue growth factors into circulation, which may have affected surrounding tissues or entire systems. Indirect healing could be a very beneficial effect of this modality in treating tissue damage of large size or at multiple locations. It might also suggest that deeper tissues could be affected by light therapy."[17]
Another study found excellent systemic effects from 830nm for burn injuries.
"An extra bonus associated with LED-LLLT is the systemic effect whereby tissues distant to the irradiated site also benefit from the LLLT effect. A recent study clearly demonstrated the powerful systemic effect of 830 nm LED-LLLT, whereby indirectly treated burn injuries distant to the actual irradiated area healed significantly faster than unirradiated controls. 17)" [24]
It is commonly observed that treatment on bones near the surface of the skin like the tibia (shin bone) can stimulate stem cell production. These stem cells can enter the circulatory system and often confer whole-body systemic benefits as well the stem cells are often directed towards areas of pathology in the body.
One 2011 study showed that targeting rat tibia improved healing of their infarcted hearts, initiating the investigations into stem cell responses from targeting bones with PBM.[16]
A recent 2023 article targeted the legs and abdomen of rats inflicted with Parkinson's disease, and no treatment to the brain.[5] They made this statement about the results.
"the degree of neuroprotection provided by remote PBM was at least as, if not more, effective than transcranial PBM." [5]
They noted that the benefits from targeting the abdomen are also that adipose tissue contains a rich source of mesenchymal stem cells, so this is also a target mechanism for stem cell stimulation by PBM. [5]
Which we know that many people undergo stem cell therapies that extract their own stem cells from adipose tissue and re-inject it to heal injured areas. Perhaps PBM can be a low cost indirect method of stem cell treatment for the body.
Leading researchers on red light therapy to the brain like Michael Hamblin and John Mitrofanis
will often write about the systemic effects.In one article, Dr. Hamblin writes: "It is in fact very likely that the beneficial effects of PBM on the brain cannot be entirely explained by penetration of photons through the scalp and skull into the brain itself. "[11] Referring to to the systemic effects and the lack of penetration to the brain.
They recognize that only 1-3% of the Red/NIR light can penetrate the scalp and scull, with minimal light reaching the midbrain regions.[10] Yet, treatment certainly benefits the brain. So they have to understand the systemic mechanisms to explain the effects, as well they can utilize knowledge of systemic targets to improve brain treatments.
A recent 2021 review article titled "Exploring the Use of Intracranial and Extracranial (Remote) Photobiomodulation Devices in Parkinson's Disease: A Comparison of Direct and Indirect Systemic Stimulations" is a very important article for understanding the systemic mechanisms for brain health. [10]
The article concluded the following:
"The direct stimulation may form the primary mechanism of neuroprotection, while the indirect systemic stimulation forms a secondary and complementary mechanism. We propose that for a maximal neuroprotective impact both types of stimulation should be activated, and both be working together."[10]
So, directly targeting the head is still the most important aspect of treatment for the brain. However, there could be systemic mechanisms at play with blood absoption in the scalp and stem cell activation in the skull bone. Since that is where 97-99% of the photons would be absorbed with only 1-3% reaching the brain itself.
Dr. Hamblin states: "when you put the light on the head, first of all it has to go through the scalp and there is a lot of blood flowing in the scalp. Then it has to go through the skull and theres a lot of bone marrow in the skull. So by definition before the photons get into the brain they have to go through the blood and the bone marrow."
So essentially targeting the head and the scalp can have simultaneous systemic effects and direct effects for the small amount that reaches the brain.
Cells with high mitochondria counts will be more responsive to red light therapy. This means they can benefit from low doses, but also will be more sensitive to biphasic dose response, overdose, or overheating. So indirect treatments could be safer in the long run.
We can see that brain disease treatments can be enhanced by targeting the gut, adipose tissue, tibia, and bloodstream as "remote" and systemic targets.
One 2022 review article on the prospects of PBM to improve Kidney health summarizes the importance of considering systemic and remote treatment methods.[12]
They recognize to target the kidney would have skin, muscle, bone, and fat in the way hindering direct photons reaching the kidney itself. Yet directly treating over the kidneys and absorption into nearby fat and muscles can reduce inflammation and still confer healing. [12]
"PBM can also provide protective effect through indirect systemic effects such as immune/inflammatory response or activation of secondary messenger pathways and transcription factors." [12]
They give a quick list of 13 articles showing systemic indirect responses for cardiovascular disease, diabetic retinopathy, Alziemer's, Parkinson's, lung injury, and depression.[12]
And they remind us that combining direct and systemic treatment methods can improve benefits and outcomes.
Another recent January 2023 study used only 2.9 mW/cm^2 intensity 940nm LED vest covering the chest and abdomen for 15 minutes to treat a recent novel coronavirus of unknown origin.[21]
Many would assume this treatment would lack penetration due to the low intensity, usage of LEDs, and longer wavelength used that has higher water absorption. However, the study was successful in reducing systemic inflammation and cardiopulmonary issues typically associated with the virus.[21]
The authors don't speculate on the mechanisms, but they note many other studies that also confirm their findings of a systemic reduction of inflammation particularly with this type of virus. The results of this study were also reviewed on this popular MedCram YouTube Channel. We give our perspective on our own YouTube channel.
Another recent study published April 2023 used either a transcranial 1070nm helmet or a 660/850nm full-body bed to treat brain fog from long covid (post covid) symptoms. [22] Although they assumed the direct helmet treatment would perform better, both treatments performed nearly equally. Both devices delivered 24mW/cm^2 intensity for 14 minute treatments 3 times a week for 4 consecutive weeks. Although both had the same dose in J/cm^2, the bed delivered about 27 times more total energy because it covers much more body area. The full-body bed showed slightly better improvement over the helmet, but it was not statistically significant. [22] But it could be said the systemic effect of full-body irradiation was why it was able to be as good or even slightly better than the direct treatment.
Here are a few tips to enhance red light therapy treatments with systemic treatments.
1. Always target as close as possible to the injured area or area you are trying to improve. For example, even if the photons don't directly reach the brain or gut or muscle or other deep organs, still treat directly over those areas because that gives you the best bystander effects. If there are bandages or clothes or hair or other barriers, then treat the bare skin as close as possible to the injured site.
2. Target "remote" areas for systemic benefits as a compliment to direct treatments. For example it is becoming commonplace for chronic brain diseases to not only treat the head directly, but also treat the gut and tibia for systemic support. Check out our other article on other areas to target for systemic full-body benefits.
3. Even though non-contact red light therapy (treatments at a distance and not with skin-contact) is inherently superficial absorption, they can still benefit deeper into the body via these systemic mechanisms. Use reasonable dosages and intensities and have patience with the systemic and cumulative dose responses over time.
4. The wavelengths and penetration depths may be of secondary importance, as long as you are treating in the therapeutic window of 600nm-1100nm. Deeper penetration depth does not always mean better benefits, we need to understand the activation of more superficial systemic pathways to understand the true benefits of red light therapy.
5. Using multiple-wavelengths particularly combinging Red and Near-Infrared often shows improved results over single-wavelength irradiation for a wide variety of applications. This could be explained now by the activation of multiple systemic mechanisms, and not just from direct penetration. Read more about multiple-wavelength treatments in this blog.
Utilizing non-contact red light therapy (like full-body panels) can certainly have deeper effects despite its apparent lack of penetration. However, users must be clearminded of the real target is the blood and systemic effects.
"As time goes on, the systemic effects of photobiomodulation are becoming more well accepted. You know one of these reasons for this is that the whole field is moving away from what used to be laser therapy when people had a focused laser beam and they shone it as a point on a joint or a wound or something... into large area LED arrays and large area LED arrays is certainly deliver a lot more systemic photobiomodulation than a focused laser beam."
Dr. Hamblin reminds us we have to consider large non-contact LED panels and LED beds as more of a systemic treatment, since we know the direct penetration can be limited due to a lack of skin contact application and not being a focused laser beam.
For proper dosing, activating systemic mechanisms seems to have a minumum amount of exposure time, perhaps to get enough exposure into the circulating bloodstream and to initiate the signalling mechanisms. It is an interesting coincidence that the 20 minutes recommended for blood irradiation is also a common effective dosing time for non-contact full-body LED red light therapy.
Which may help confirm that non-contact LED full-body light therapy is indeed a systemic therapy that needs adequate exposure time to impact the circulating blood and activate systemic mechanisms.
Ironically, we could say "full body light therapy" doesn't directly treat anything at all, it is mostly targeting superficial and systemic mechanisms.
A good compliment to a large red light therapy panel which delivers systemic therapy would be a torch (flashlight) or handheld cluster for direct skin contact. This way we can combine the indirect benefits of full-body panels plus the direct treatment pathways as recommended to benefit deeper organs and tissues.
Rather than people endlessly wasting money on oversized modular panel setups, getting a moderate-sized body-light panel plus a smaller direct contact device is much more efficient and cost effective to optimize treatments to combine both direct and indirect therapies at home.
In a previous blog we uncovered the myth that Far-Infrared is often falsely claimed to reach 3-4 inches into the body. We know the actual photon penetration is very shallow from water absorption, but the benefits observed are 3-4 inches into the body. Far-infrared sauna also clearly offers full body benefits like for cardiovascular health and brain health despite limited photon penetration.
And none can deny that UV-B absorption, which is very superficial, helps synthesis of Vitamin D which is crucial for whole body health and function. Our skin certainly does not play a passive role in how it blocks and filters light, it plays an active role in bringing the benefits of light deeper into the body.
Observations of systemic and remote benefits of Red & NIR Light Therapy have been commonplace for decades. But many mechanisms are still being recently discovered or speculated about. Which often makes it hard to believe until we fully understand the mechanisms.
Yet now it seems more logical that many of the benefits of Red and NIR are conveyed by indirect and systemic mechanisms, rather than direct penetration.
As mentioned in our previous blog on penetration depths, it is not advised to use excessively high power or intensity for the sake of deep penetration at the risk of damaging the skin. We can utilize a combination of direct targeting and systemic targets as a safer and more balanced approach.
By using direct targeting and systemic targets combined then we can find safe and effective ways to treat the deepest regions of the body, even if there is often an apparent lack of photon penetration.
[1]
[2]
Zimmerman, S. and Reiter, R. 2019. Melatonin and the Optics of the Human Body. Melatonin Research. 2, 1 (Feb. 2019), 138-160. DOI:https://doi.org/https://doi.org/10.32794/mr11250016.
[3]
[4]
[19]
https://www.liebertpub.com/doi/10.1089/clm.1998.16.245
[24]
In his latest reviews, Alex Fergus exposes many of the top red light therapy brands for their table top models.
Let's take a look at Alex's intensity measurements and how they compare to their advertised intensity.
So no surprise that again there is nearly a 100% difference across all these major brands. The advertised intensity claims may be inflated by about 2x of what the reality they are actually delivering at 6 inches away.
The top panels like Joovv, PlatinumLED, and Mito Red Light are all FDA Registered (not FDA Approved) as Class II medical devices.
The Class II category is not for effectiveness, but a safety category for devices that have "moderate to high risk to the patient and/or user" compared to low risk Class I or general wellness devices. So the Class II registration is for products of higher risk ranking, not a badge of honor implying more benefits.
https://bmpmedical.com/whats-
As well, most panels are FDA Registered under a loophole known as the ILY code, which is a code for heat lamps and other heating devices. The only indications they are legally allowed to market for are things like "temporary relief of minor aches and pains". Any advertised or implied benefits beyond minor pain relief or what they are registered for could be a form of medical malpractice.
And we know these companies may "accidentally" use the FDA logo on their website or marketing materials, which is generally forbidden for private companies to use the FDA logo which would falsely imply a direct affiliation with the federal agency.
Coupled with their high intensity output, the panels made by Joovv, Mito Red Light, and PlatinumLED should be considered as heating devices both in medical classification and function.
So, if you want to know the best moderate-risk Class II LED Heat Lamps with extra gimmicky features to buy, make sure to check out those companies.
Otherwise you can always visit GembaRed products for simple, low intensity, low risk, true photobiomodulation to support general wellness.
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The ideal distance from a device is where the user will receive the proper amount of intensity. There was never anything special about being 6 inches away to begin with.
After all, we are approximately 93 million miles away from the ultimate red light therapy emitter, the sun. So the distance has always been arbitrary, finding the correct intensity is key.
The latest generation of "highest intensity" red light therapy panels deliver way too much power for the user to be only 6 inches away, compared to the original panels that came to market in 2016.
Yet most companies have not updated their advertised distances because they are trapped by their own marketing narratives.
Intensities >50mW/cm^2 are well documented to risk overheating the skin, cause deleterious tissue response, or quickly reach the unwanted biphasic dose response. [2]
Many users can subjectively confirm they are feeling radiant heating from their "highest intensity" LED panels. Which they falsely assume is a good thing and a sign that they got "good value" from a LED panel.
With traditional "Low-Level" non-thermal light therapy, we need to consider it as a "cold" light therapy, rather than as seeking to use LED panels as glorified heat lamps.
The optimal intensity range for full-body non-contact LED panels is likely between 10 - 50 mW/cm^2, as that is the range seen in most full-body red light therapy studies and recommended by experts.
So if we want to use true medical grade photobiomodulation properly, which by definition is non-thermal, we need be at the correct distance to get the right benefits and not overdose the skin.
Lets take an example of two panels.
Our GembaRed OverClocked panels versus the SGROW VIGPRO 1500.
Try to imagine the SGROW VIGPRO 1500 as any of your favorite "highest intensity" brands.
The goal is to find the proper distance to be in the 10-50mW/cm^2 range. However, every panel will be different in terms of the power output, number of LEDs, beam angle optics, etc.
So when we measure the intensity at several different distances away, we get the following diagram.
We defined several different "zones" to define the meaning of different distances.
EMF Zone: Most manufacturers recommend being 4-6+ inches away from panels to avoid EMF exposure. This zone usually has many intensity hotspots, poor light uniformity, and poor blending of wavelengths. So even if you aren't concerned with EMFs, it is still ill-advised to use this type of full body red light therapy panels closer than 6 inches away.
Heat Zone: This is a new zone in the advent of the "highest intensity" panel trend. Intensities >50mW/cm^2 can lead to unwanted tissue heating, biphasic dose response, and deleterious effects. So unless you want to use a red light therapy panel as a glorified heat lamp, then you want to increase the distance away until you don't feel any heat.
Ideal PBM Zone: In the range of intensities roughly between 10-50mW/cm^2 is the ideal zone for non-contact non-thermal photobiomodulation (red light therapy) with large LED panels.
Ambient Lighting Zone: At some distance away when intensity is much lower than 10mW/cm^2, or usually even less than 1mW/cm^2 - we don't expect any true photobiomodulation effects. So at great distances away, there is no red light therapy effects, but leaving the light on might be pleasant as a general room light for ambiance.
Both panels certainly deliver sufficient intensities as long as the user is the proper distance away. For the GembaRed Overclocked, which represents first-generation reasonably powered panels, this ideal range is between 6 inches to 48 inches.
For the SGROW VIG1500 and many other "highest intensity" panels on the market, the minimum distance is now 18-24 inches away to avoid the heating zone. So we just shift the effective PBM zone further away to 18 to 60 inches.
No longer is it advisable to be only 6 inches away for such high powered devices.
Red Light Therapy is often considered to be extremely safe. Experts like Dr. Hamblin will often note a fun-fact that 1 hour of full-body exposure to sunlight (at the equator) is nearly 1 Million Joules of energy.
He says the Red & NIR compenent would not cause harm, but is much more than is needed. He generally uses thise example to explain the extreme safety of the much lower doses used in clinical trials that are effective. Not to actually endorse such high doses.
In another interview he states 10-20mW/cm^2 is "high" for full-body irradiation, and even at 10mW/cm^2 for 10 minutes is about 120,000 Joules of energy. Which is an effective dose, about one tenth of laying in sunlight for an hour at the equator.
However, there is a theory that red light therapy is indeed difficult to overdose, since as the light penetrates the layers of the skin at least one layer is getting the perfect dose.
Although we don't know of any true published literature confirming this theory, it may help explain the wide ranges of effective intensities from 10-50mW/cm^2 and doses from 4 - 60J/cm^2 for a variety of ailements.
However, it is not to imply that extremely excessive intensities or doses are a good idea. Since damaging the skin would create new inflammatory responses that would counteract the benefits we are seeking.
Similarly it is often difficult to "overdose" on drinking water. However, occasionally people can override their logic and die from consuming too much water. We don't want people to override their logic to think that an infinite amount of intensity from red light therapy is fine.
If you are feeling heat from a non-contact LED red light therapy panel, then you are using it as a glorified heat lamp. Since the literal definition of photobiomodulation is clearly defined as a non-thermal interaction of light and biology.
A peer-reviewed article talks about the importance of the definition of PBM:
"The use of this term is key, as it distinguishes photobiomodulation therapy, which is nonthermal, from the popular use of light-based devices for simple heating of tissues as can be accomplished using near-infrared (NIR) lamps, or other applications of light energy that rely on thermal effects for all or part of their mechanism of action. This fact will likely also have significant impact on safety and regulation of commercial products specifically marketed for this use." [1]
Notice the end of the quote is the "significant impact on safety and regulation of commercial products" - which means even LED Panels must abide by this definition of being non-thermal, otherwise they are no longer qualified to call themselves photobiomodulation.
Many studies go through great lengths to monitor skin temperature that it does not increase in clinical trials. As they know it can alter the benefits or lead to detrimental responses.
"LLLT, phototherapy or photobiomodulation refers to the use of photons at a non-thermal irradiance to alter biological activity."[11]
Notice this quote specifically says the irradiance (intensity) needs to be non-thermal. Intensity is the rate of energy delivery and if it is too high then our skin cannot regulate the temperature properly.
Here are a few quotes and peer-reviewed examples to emphasize the importance of not using LED Panels as heat lamps.
"The photon intensity i.e., irradiance (W/m^2 or spectral irradiance), must be adequate. Using higher intensity, the photon energy will be transformed to excessive heat in the target tissue" [3]
This quote is particularly important because we learn that "higher intensity" does not contribute to PBM benefits, it just gets transformed into heat.
According to this quote, the intensity must be "adequate". Which is a very neutral way of presenting the facts that we don't need too much or too little.
"Lower irradiance (<50mW/cm2) is less likely to induce skin hyperthermia leading to potential deleterious effects." [2]
"Some studies have shown that there is an increase in collagen degradation and ROS generation with a relatively small increase in temperature." [2]
The excessive ROS which would lead to the unwanted biphasic dose response much quicker, and even "relatively small" temperature increases from high intensity heating can cause this problem.
"Papillary dermis temperature was thus monitored in our clinical study throughout LED exposure to ensure that skin temperature was kept normal in order not to hinder photobiochemical reactions associated with collagen metabolism." [5]
This is key to consider especially for skincare trials to not elevate skin temperature significantly to not alter collagen mechanisms.
Several studies have indicated that keeping the skin cool will lead to better tissue optics and penetration.[2][6][7]
So if we want to optimize penetration, then we paradoxically don't want too much intensity that would cause dramatic heating.
One study that used cryotherapy before treatment found a 27.5% increase in penetration. [2][7]
Another study clearly modeled this effect:
"the calculated light penetration depth (d) increased as temperature was lowered, indicating cooling-induced transparency of human skin."[8]
So if people want to optimize photon penetration, then we need to consider intensities and methods that keep the skin cool during treatment.
It is counterintuitive that some "experts" have stated you need very high intensity to optimize penetration, yet too much intensity that causes heating will hinder penetration.
Many falsely assume that skin optics stay constant with temperature. It does not, and several studies have investigated this fact.
One study found an increase of absorption coefficient of 10.1% per degree Celcius raise in tissue temperature.[9] This would directly correlate to a loss of penetration, as well as create a snowball effect of even more superficial heating.
The same study states the following:
"On the other hand, tissue temperature during LLLT should be maintained below 40 °C, for thermal damage of tissue can occur as the temperature rises above 40 °C" [9]
So for "true" photobiomodulation therapy, the skin temperature should remain below 40°C (104°F) during treatment. If normal skin temperature is between 33-37°C (92-99°F), then it is allowable for a small temperature increase of 3-7°C (5-12°F).
However, for every degree increase there could be a loss of penetration due to increase absorption coefficent. As well as increased ROS as noted in the previous studies. [2]
From a textbook on LLLT, the authors tell us this:
"If heat is used in combination with laser therapy, the laser treatment should come first. Heat will increase blood flow in the tissue, thus increasing the absorption of the light in blood. The opposite then applies to cryogenic therapy."[13]
So the authors are summarizing what we already learned, that heating increases absorption which decreases penetration to the target tissue. So to do light therapy before heat therapies (and not combine them like a full-spectrum sauna).
One study comparing the differences between LLLT (Low-Level-Laser-Therapy) and HILT (High-Intensity-Laser-Therapy) noted that LLLT is almost always a temperature change of less than 1°C. They also show that LLLT lasers are less than 500mW and HILT lasers are greater than 500mW. [12]
In that regard perhaps we should draw a line for large LED light therapy that any panels above >100mW/cm^2 at treatment distance should certainly be considered more of "High Intensity LED Therapy" and no longer true "Low-Level-Light-Therapy".
"if the power doubled and the time is halved then the same energy is delivered but a different biological response is often observed." [4]
We get a different biological effect if we double the intensity but decrease the exposure time in half. This mathematically works for Joules (energy), but the studies often discourage this concept as it does not work as predicted. The human body is not a linear math equation.
So companies that claimed to be "twice the intensity of Joovv" never actually proved that was more effective or superior for therapy. They just were using a false "value" proposition that was never based in science.
You may be familiar with the term "cold laser" in the LLLT/PBM clinics.
Technically these lasers are not truly "cold", but they mean to imply that these lasers are low enough power not to produce heat. The name is an important reminder that Photobiomodulation uses low-level non-thermal lasers.
Here is one direct quote:
"This process is referred to as ‘low-level’ because the energy or power densities employed are low compared to other forms of laser therapy such as ablation, cutting, and thermally coagulating tissue." [11]
So we know lasers can be heating devices which is why the high-powered ones are excluded from LLLT/PBM. And again, the energy and power density (another term for intensity) is the key criteria to define a heating response.
It was assumed that LEDs could not get powerful enough to cause too much of a heating response. But as most technologies develop on an exponential curve, we have already witnessed the "heating" LED panels on the market.
Perhaps now we should coin a term for "Cold LED therapy" to distinguish true medical grade photobiomodulation panels. The "highest-intensity" heating LED panels will now be excluded from photobiomodulation, the same way high-powered lasers are excluded from this therapy category.
Few will remember the Heliotherapy clinics and Open-Air Hospitals that were opened in the early 1900's that preferentially were located in "cool" mountain air. [10]
One direct quote from "the Sun Doctor" Auguste Rollier who opened one of the first clinics in Leysin, Switzerland in 1903:
"The intense heat of the sun is tempered and rendered wonderfully bracing by the action of the dry, cold air on the whole surface of the body."[10]
So even before Endre Mester discovered LLLT with his cold lasers in the 1960's, the Heliotherapy doctors in the 1900's already knew the importance of "cold" light therapy.
Having the "highest intensity" LED Red Light Therapy panels didn't add more value or effectiveness. They only increased the distance the user needs to be to be in the appropriate PBM Intensity range.
Yet, without updating their advertised distances away from 6 inches, higher intensity panels may indeed be less effective if used improperly.
If users are seeking heat devices, they could save a lot of money and just buy an incandescent heat lamp, rather than an expensive overpowered LED Panel.
Otherwise we should keep in mind that we want "cold" light therapy to be true medical-grade photobiomodulation.
The "first generation" red light therapy panels and reasonably powered red light therapy panels can indeed be used properly at 6 inches away up to about 48 inches away to stay in the correct intensity range.
The "latest generation" high powered LED panels may require to be much further away, with a minimum distance of 18 or 24 inches away (2 feet!), and perhaps the effective distance is also extended to 60+ inches away and still get benefits.
While "being further away" may seem attractive, there are certainly scenarios where there is limited space for a user to be able to stand 2+ feet away from a panel. Especially for clinics that want to position panels on both sides of the users, it would take up a lot more space as shown below.
Having to be "far away" from a panel can take up a large footprint in a small apartment, clinic, or closet - especially trying to position multiple panels for each side of the body.
Yet the marketing narrative has not been updated by most major brands, and many consumers are enjoying the instant gratification of using LED panels as glorified heat lamps. Occasionally with detrimental effects of skin pigmentation or eye complaints.
Children and Pets may not be able to comprehend that they need to be 2 feet away from red light panels for safety, even if brands start updating their recommended distances.
The technology is rapidly evolving and growing more powerful, yet the marketing strategies also need to evolve to abandon the "6 inches" standard in favor of advertising distances that deliver the right intensity for safety and effectiveness based on the actual clinical science.
In the absence of honest intensity advertising or updated recommendations to increase the distance, our original recommendation from the first part of this series stands as prophetic and timeless.
Just keep increasing your distance away from the panel until you don't feel any heat anymore. That's the best "science" you can get while using the "top" brands that don't share accurate intensity data.
End
Read Part 1 of this series to learn about how being 6 inches away was not supported by the science, and was a byproduct of faulty product design and clever marketing.
Read Part 2 of this series to learn the optimal ways to use non-contact red light therapy, assuming one is aware of the differences between the two main methods of red light therapy treatments.
[1]
Kim, S., Jeong, S. Effects of temperature-dependent optical properties on the fluence rate and temperature of biological tissue during low-level laser therapy. Lasers Med Sci 29, 637–644 (2014). https://doi.org/10.1007/s10103-013-1376-4
https://link.springer.com/article/10.1007/s10103-013-1376-4
[7]
Many people have recently learned there are two main methods of applying red light therapy, with skin contact method or non-contact method (at a distance).
The skin contact method is typically preferred in clinical studies as delivering superior absorption and penetration.
However, in many cases the non-contact method is more convenient and sufficient to deliver benefits despite its shallow penetration and high reflection losses.
As with any medicine, the goal is to find the "minimum effective dose". And non-contact treatment can certainly deliver minimal doses even though it is more superficial and delivers less photon absorption.
Yet, we need to dig deeper into the published literature to see what the real advantages of non-contact treatment could be, the types of treatments and benefits it delivers, and how we can dose it properly with at-home panels.
We found a handful of non-contact red light therapy studies, such that we can actually learn the proper contexts to use it. Here are a few of the advantages.
One non-contact treatment study mentions using a skin moisturizer to improve light absorption. They note that dry skin can have higher reflection losses.
"To maximize LED photoinduction, a topical moisturizer without active ingredients was applied daily, as dry skin is known to enhance skin surface reflectivity (Friedman et al., 2002)." [13]
This may explain other studies that used a green tea application before treatment. [14] Perhaps the moisturizing effect was the reason for the better effectiveness, in addition to the antioxidant effect.
Unfortunately the study does not specify the "topical moisturizer" used, only that it did not have any "active ingredients".
Looking up the Friedman et al study and we found they were using EMLA cream, which was cleaned off immediately before treatment. But EMLA cream is an anesthetic cream, containing lidocaine and prilocaine. So perhaps we need to find something similar without those active ingredients.
It would seem that any moisturizing cream without additives could be helpful in this endeavour, and that the consumer can resist the marketing of special creams from clever salespeople looking to make a couple extra bucks to "enhance" red light therapy absorption.
There is nothing magical about distances like 4 inches, 6 inches, 12 inches, or even 10cm, 15cm, or 20cm. These are convenient distances that the general population will recognize. It has nothing to do with clinical relevance.
The key is to find the correct distance in accordance with the intensity that you want the skin to be exposed to. As every brand and LED panel will be different in terms of the power consumption, number of LEDs, beam angle, LED layout and spacing, etc – then we shouldn’t always use arbitrary distances like “6 inches” for all devices on the market.
For example, if a full-body light therapy pod uses 28mW/cm^2 for 20 minutes to treat fibromyalgia.[2] Then to reproduce those results with a panel you need to find the correct distance that corresponds to that exact intensity.
For example our OverClocked panel would deliver this ideal intensity at about 18 inches away. For super high intensity panels from our competitors, the distance could be much further away, assuming they give honest and accurate intensity measurements for their product in the first place.
Exposing the skin to higher intensities than the studies does not necessarily deliver "better" or "faster" results, as the therapy must abide by a dose-rate response with adequate exposure time. And excessively high intensities >50mW/cm^2 run the risk of overheating the skin and causing deleterious effects.[15]
Finding the correct distance for red light therapy means looking up the accurate intensity data provided by the manufacturer and choosing the correct distance in accordance with the relevant science.
Humans can be frustratingly fidgety, which makes maintaining the proper distance from the device challenging. Here is one quote that seems to stress the problem and importance of maintaining a consistent distance to proper dosing in a wound healing study:
"During this study, a lot of care was taken to maintain a working distance of 2.5cm (±1mm) away from the target surface during LED therapy, as power density/light intensity—a key variable for optimal photoinduction—is greatly influenced by the distance between the light source and the surface of the skin (Hart and Cameron, 2005). " [13]
This seems to be another deterrent from using non-contact red light therapy in clinical studies. Where the preference is just to hold a device on the skin to maintain a consistent dose. The logistical issues of keeping the distance exactly the same for the duration of the treatment will lead to inconsistent dosing, and make it difficult to design clinical trials.
We were able to find a handful of actual studies that used non-contact LED Red & NIR light therapy to help inform us how to optimize treatments with LED panels. It is important to look at studies that use relevant devices to the types of panels we see on the market to learn how to properly use them.
There is a common theme that non-contact treatment is used for superficial treatments and systemic therapy, rather than direct deep penetration targets. This is consistent with our understanding that non-contact treatment has poorer penetration.
Studies that are non-contact include eye health, wound healing, skin ulcer healing, skincare, cellulite, fibromayalgia, sleep, and athletic performance and recovery. Many of which are superficial or systemic in nature, which seems clear the researchers understand that non-contact therapy is appropriate mostly for superficial applications.
There are obvious advantages to non-contact LED light therapy treatments like convenience, being hands-free, covering large areas of the body comfortably, reducing heat exposure from devices, reducing contamination, and reducing the likelihood of overdosing especially for new users at home.
As always, users should be aware of all their options for therapeutic treatment, understand the pro's and con's of different types of treatment, learn the real science, and utilize honestly advertised devices responsibly.
Hopefully more studies on non-contact red light therapy will be conducted to futher our understanding of this mode of therapy. But we need to be clear-minded about the true nature of non-contact treatment and how the mechanisms and targets are different than therapeutic skin-contact treatment.
[1]
https://pubmed.ncbi.nlm.nih.gov/17566756/
https://pubmed.ncbi.nlm.nih.gov/30227084/
https://pubmed.ncbi.nlm.nih.gov/19764893/
https://pubmed.ncbi.nlm.nih.gov/16414908/
[7-10]
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4292127/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3680844/
https://pubmed.ncbi.nlm.nih.gov/28265648/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3799047/
[11]
The point of 3rd party data is not just to "have" it and still lie about intensity anyway like many companies are doing now. It was about following basic advertising law and delivering the product that is specified on the product page.
It is not a marketing gimmick to be honest in advertising, in fact it is the bare minimum to conduct a legal and ethical business.
For example:
- If MitoRed advertises delivering >170mW/cm^2 at 6 inches away but they have 3rd party data that says it emits 73 mW/cm^2 at 6 inches away.
- If RedLightRising advertises delivering 161mW/cm^2 at 15cm away but they have 3rd party data that says it is 65.51mW/cm^2 at 15cm away.
Clearly this is a massive discrepancy of over 2x that should be easily corrected by updating the advertised numbers on the product page as soon as they obtained the 3rd party results. They could have even done it quietly, with no fuss, but they choose not to.
No amount of excuses, using asterisks that contradicts your advertising, using different units, using fine print, links to other documents, or burying the accurate data in supplementary materials; there are clear guidelines and precedents that these are misleading tactics.
If a company does not deliver the product as advertised on the product page, then the consumer has been mislead when shopping and purchasing.
It doesn't matter if the product was measured by a 3rd party, by a calibrated laser power meter, a solar power meter with a correction factor, or if you asked a ouija board for the intensity. What matters is the end result of honest advertising on the product page.
Normally 3rd party testing is only required in industries where you don't trust the companies to begin with, or the equipment and expertise required to do the testing is too expensive. In this industry it is a little bit of both.
Once again, the actions of the "top" brands have left another negative stain on the industry by losing trust in 3rd party testing claims. Many brands "have" 3rd party data, but utilize it as another deception to build trust with the consumer and then lie to them about intensity anyway on their product pages.
Exposing the truth is always a positive experience in the long run, and we believe these companies will eventually do the honourable thing by correcting their advertising and apologizing to their customers. We are just giving them a polite nudge in the correct direction.
Alex Fergus has done this industry a great service by measuring and comparing so many different brands of panels. However, the industry shouldn't rely on him to "vet" all brands. Each brand should take responsibility to accurately represent their products on their own websites.
Alex has become a crutch for this industry because no one trusts the advertised specifications from red light panel manufacturers.
In 2019, during his review, Alex discovered a grave deception. All of the brands he measured were falsely advertising their intensity by a wide margin.
In 2021, Alex did another big review. Yet again most of the intensity claims were falsely high by a wide margin.
Because of this, Alex has occasionally implied in his content that he does not trust the advertised intensity on any red light panel brand. This includes even his top recommended brands and even GembaRed ourselves.
However, when Alex measured our Reboot panel he emailed us this.
"Hey mate,
Just finished testing your panel.
A few things:
1) Peak power was 50.1 - that is the absolute highest figure I saw. But 'average' peak would be mid to high 40's. I just looked on your site at the 6 inch reading was 44 mw so that aligns well."
Which may be one of the first panels he had ever measured that his measurements "aligns well" with what is advertised. I wonder what kind of feedback he gives his top paying companies when he observed their websites do not "align well" with his measurements? Did he kindly ask them to correct it so he wouldn't be complicit with endorsing misleading advertising?
Alex's measurement's aligning with our measurements is actually more of a validation of his measurement technique. Since we are advertising the 3rd party measurements, and his tool is not necessarily NIST calibrated or operated by a trained expert in photometrics. So it is a good confirmation that his tool and techniques are relatively accurate if it matches our advertised numbers.
If we had our own ranking, then we would rank honest advertising as #1, since that will have the greatest impact on proper dosing and safety.
So, we have compiled Alex's measurements of intensity and compared it against the advertised intensity measurements.
We will be ranking the discrepancies of Alex's 2021/22 peak intensity measurements versus the current advertised intensities on those company websites. We will highlight in RED if there is a discrepancy greater than +/- 30% of the actual value. And GREEN if it is within the +/-30% range.
Alex's measurements were at 6 inches away from the panels. Some companies use Metric where 10-15 cm is the nearest equivalent. Some companies don't mention the distance at all, but we assume the intensity claim is some relevant distance about 6 inches away.
Note that ">100" is not a real number. The symbol ">" means "greater than". This means the actual number could be anywhere from 101 to infinity. So be weary of companies using meaningless ">" symbols.
Yet ironically Joovv is sticking so hard to their false narrative that their panels magically emit the "best" intensity of ">100mW/cm^2" that they are accidentally the 2nd most accurately advertised. As we said it doesn't necessarily matter how it is accomplished, what matters is getting closer to honest advertising.
No surprise that GembaRed is the closest at 12% difference and we are actually advertising a number lower than Alex measured. Unfortunately, most companies are over by 2x (100%+) higher!
Note that Alex is using a Hopoocolor Spectoradiometer. While it isn't a NIST calibrated device, it likely isn't routinely checked for calibration, and Alex is not a professional for taking photometric measurements. So that is why we left a wide range to account for measurement variability, a generous window of 60% (+/-30%).
Any complaints for these measurements can be filed to Alex Fergus directly, we had no involvement with these independent measurements from Alex. We are just reporting these numbers from his review and from companies' own websites. As far as we know no one has publicly disputed the accuracy of validity of Alex's measurements.
If Mito Red Light or RedLightRising were to simply advertise their 3rd party measurements on their actual product pages, then the error percentage would be extremely low and we would have happily highlighted them as Green. But instead they are still advertising false numbers on the product pages that are nearly over 2x the reality of the products that they deliver.
All company product pages were saved to the WayBack Machine on 1/22/2023, which is a part of the Internet Archive so we always have a 3rd party reference for the numbers in this page.
For example, here is the link to RedLightRising's archived page (and they recently edited the page, where we gave them the opportunity to amend it but they choose to add more misleading information). This way even if RedLightRising updates the advertising after this date, we know our numbers were correct at the time of publishing and backed up by an independent reference on the archive.
Notice that RedLightRising's 3rd party test report is dated February 09 2021, so they have been knowingly false advertising on their product pages for nearly 2 years (which means they also have been accidentally false advertising ever since they started their business too)! Joovv and Mito Red Light have had 3rd party data for even longer.
Yet RedLightRising and Mito Red Light think that using asterisks and hyperlinks to other information can outwit basic advertising laws, despite clear precedent that it does not. Advertised product pages must be accurate, even if you have "fine print" that contradicts your advertised specifications.
This begs some obvious questions:
The science and technology of Red Light Therapy has rapidly evolved over the past decade. Many facts we know now may be obsolete in the near future.
This industry needs brands, scientists, and experts that are brave enough to admit when they made mistakes or that their old statements have been incorrect.
The problem when "marketing experts" run medical businesses is that they never want to admit they made a mistake. Especially if that means consumers would start to ask questions about the validity of their other claims or their status of being a false authority.
Perhaps it was a genuine mistake that most brands used Solar Power Meters to false advertise intensity. Most people can forgive a genuine mistake especially if people are humble enough to admit they were wrong (in a timely manner).
However, it is inexcusable that many brands "have" 3rd party data for years, yet refuse to change the advertised intensity on the product pages or notify their customers of a massive issue with the advertised intensity on their so-called medical devices.
Every single day they don't update their website, they are making a conscious choice to lie to every visitor to their product pages, and deceive purchasers by not delivering the advertised intensity in the actual products.
If companies want to be true leaders of making medical devices, then they need to lead by example by being honest and transparent with the market. If Joovv or any "top" company were to start being more honest, many other companies would follow.
Even the Liver King was wise enough to make a public apology when he was caught red-handed lying. He could have emphatically denied the allegations, and threatened to sue everyone that exposed him. But he knew that would be very negative and actually tarnish his reputation further. He even thanked the guy that exposed him!
The most positive thing anyone can do when they make a mistake is to apologize, correct the advertising, and move on. Even if it seems temporarily negative and a blow to their ego to admit they did something wrong. As well they fear it might hurt their profits and position as an authority in the market.
Being vulnerable actually builds trust with the consumer that companies are honest enough to do the hard things. This is clearly counter-intuitive to the many companies spending a lot of effort trying to cover-up that they made a mistake with misleading intensity claims.
]]>The popularity of near-infrared therapy has rapidly increased in recent years, especially from recent YouTube videos that claim it helps reduce inflammation for a recent viral outbreak of unknown origin, and helps reduce neuroinflammation.
As well, a popular new study showed Near-Infrared light stimulates subcellular (a.k.a. extrapineal) melatonin production.[8] Which is not only a hormone for sleep, but an important and powerful antioxidant.
Infrared Heat Lamps are often used for purposes such as workout recovery, skin health, energy, circulation, wound healing, and more!
These types of heat lamps are also made into the popular DIY Near-Infrared Sauna! This was popularized by Dr. Lawrence Wilson’s book and website. And you can find some other DIY guides on Quantified Bob’s website and from the Certified Saunas website.
DIY infrared heat lamp saunas can promote sweating, detox, and cardiovascular health! And you can save a lot of money by using affordable bulbs that we recommend in this blog.
It is good to note that although general-service incandescent lighting are being banned in the USA by 2/28/2023, that it seems heat lamps will be excluded from the ban and still be available for the foreseeable future. So no need to stock up… yet!
Precaution: These Incandescent Heat Lamps are much hotter than LED Red Light therapy. You cannot touch the bulbs for risk of burns, you must use them at a sufficient distance away to not overheat the skin, and consider putting a metal mesh in front of them in case they shatter.
Incandescent bulbs are a cheap, simple way to implement red and near infrared light therapy. However, a more recent scientific term for the research is called Photobiomodulation.
Photobiomodulation (PBM) is the study of the non-thermal interactions of light and biology. One article notes that this definition specifically excludes any heating devices like NIR heat lamps:
"The use of this term is key, as it distinguishes photobiomodulation therapy, which is nonthermal, from the popular use of light-based devices for simple heating of tissues as can be accomplished using near-infrared (NIR) lamps" [1]
Red and Near-Infrared light tends to be the most widely studied wavelengths for photobiomodulation due to their safety, effectiveness, therapeutic value, and penetration into the body.
Wavelengths from about 600nm to 1100nm are typically considered the optical therapeutic window where these wavelengths penetrate deeper into the body and activate several mechanisms that improve cellular and mitochondrial function.
"Red light or near-infrared light (NIR) are the most commonly used wavelengths in PBM (600–1100 nm)" [2]
However, several studies observe PBM effects from longer-wavelength Mid-Infrared and Far-Infrared.[3] Even at sufficiently low intensities that are non-thermal, there are often mechanisms like producing EZ Water that confer the PBM benefits.
One study using Carbon Arc incandescent lamps for wound healing stated the following about the effects of broad-spectrum incandescent therapy:
Compared with the low level laser with its narrow spectrum and monochromatic light source, the carbon arc is a broad-spectrum light source that may provide the therapeutic effect of integrated light." [5]
We need to appreciate that incandescent lamp therapy is not the same as PBM and LLLT, and the effects of combined light and heat are different than applying light alone like in PBM. It is generally accepted that incandescent therapy is beneficial, but we cannot oversimplify it to just it's basic components. It should be studied and considered as a whole.
250W Incandescent Heat Lamps emit a broad spectrum as defined by Plank’s Laws. It is often difficult to measure the entire spectrum directly, but Plank’s theories have been widely accepted as being an accurate depiction of incandescent radiation for over 100 years.
One study managed to use 3 different spectrometers to measure the range of a standard incandescent bulbs, and even then, they only measured from 300nm to 2500nm. [4] Which the curve does resemble what Plank’s theory tells us.
However, Plank’s equation would be applicable to a standard clear incandescent bulb. The red coating used on these incandescent bulbs modify the spectrum by blocking the blue and green light.
Here is the spectrum we calculated by combining Planks equations with our measurements of the red-coated heat lamps later in this review.
So, we can see from this chart that about 23% of the spectrum from a Red 250W IR Heat Lamp is in the ideal 600nm-1100nm therapeutic range for photobiomodulation.
Unfortunately, as we discussed in a previous blog, these wavelengths suffer high reflection from the skin and only confer deep penetration when Laser or LED devices are held in contact with the skin. Which, you cannot do with a heat lamp because you would get burned.
Contrary to popular belief, the real workhorse of benefits from these incandescent heat lamps is the 77% of the spectrum that is 1100nm+. These wavelengths get superficially absorbed by the water in the skin, leading to heating and the EZ water mechanism effects. This is key for sauna efficiency since you want that heating effect on the body.
As well we can calculate the Near Infrared (IR-A) region of the red incandescent bulb spectrum from 780nm to 1400nm is about 38% of the spectral intensity. Which this is the traditional range used in physics to define Near Infrared (IR-A), not necessarily relating to biological effects.
It is important to appreciate the benefits of the entire spectrum of exposure, and realize there has been too much focus on the “PBM wavelengths” that are poorly absorbed and highly reflected from the skin with non-contact treatment.
Spoiler alert: these are listed in order of our opinion and analysis from best (1) to worst (8).
*SaunaSpace automatically gets the lowest ranking because they are too expensive.
**note, we have no affiliation with any of these brands, and purchased these bulbs for testing purposes.**
Here is where we found the ones we reviewed (click the highlighted word for hyperlink):
So we can see there are many places to purchase these bulbs from.
One major problem is light uniformity was not consistent for many of the bulbs. The bulbs have a “shadow” in the center of the target area, and a ring of a hot spot surrounding the shadow. This can be inconvenient for trying to use them for consistent dosing.
So, the primary ranking for this review is based on the light uniformity more than any other factor. The lamps with the best concentration of light in the center predictably have higher intensity measurements.
The Philips Bulb (left) has a wider beam spread and more pronounced shadow in the middle. The GE Bulb (right) has a narrower beam spread and more concentrated light in the middle.
If you want a red heat lamp outside of what we have reviewed, you can do a basic check yourself by aiming it at a wall and observing if it has a shadow pattern as we describe. But it should not really be a dealbreaker anyway.
Measuring red light therapy intensity accurately has been elusive in recent years.
Many self-proclaimed “experts” and brands have erroneously used cheap solar power meters. Which solar power meters rely on photodiodes that have limited narrow wavelength ranges of measurements and are calibrated to estimate sunlight intensity, measuring only Red and NIR gives falsely high readings.
A Thermopile Power meter is traditionally used to measure broadband incoherent incandescent sources and is more reliable for higher powered heat sources. The concept was invented in 1831 by Macedonio Melloni, long before the invention of the laser in the 1960s. Although many modern Optical Power Meters are often mislabeled as laser power meters, leading to some confusion about their application.
Thermopile power meters were commonly used for measuring Carbon Arc and Xenon lamps, which were the incandescent predecessors that were used for therapy a long time ago. Like these three studies mention the usage of thermopile power meters for incandescent sources. [5][6][7]
Here is one quote:
With our new VLP-2000-3W from Beijing Ranbond Technology Co., Ltd. on Alibaba; we can perhaps be the first in the industry to offer accurate intensity measurements for incandescent heat lamps! Now we can't guarantee the absolute accuracy of this tool either, but it is a small step forward for this industry to pioneer finding better tools and treating heat lamps like medical devices for proper phototherapy dosing.
This meter has a mostly flat spectral absorption from 355nm to 10,600nm; which is what makes it ideal to measure and represent broad spectrum incoherent light from incandescent or LED sources.
The intensity measurements from the thermopile represent the entire spectrum from the incandescent bulb. As well we will report the milliwatts (mW) that our sensor displays, but then also divide it by the sensor area to estimate the intensity (the sensor area is 3.14159).
So when we want to know the popular photobiomodulation range from 600nm-1100nm, we multiply the result by the 23% factor from the spectral analysis we did earlier. This should give a good approximation of the intensity in popular PBM wavelength range.
These measurements were taken at 18 inches away from the bulbs and the sensor at the center point from the bulb. This means if the bulbs are casting a big shadow in the middle, it will seem to be emitting less intensity.
Brand |
milliWatts |
Total Intensity mW/cm^2 |
Calculated 600nm-1100nm intensity (mW/cm^2) |
Therabulb |
264 |
84 |
18.5 |
GE |
248 |
79 |
17.4 |
Saunaspace Thermalight |
176 |
56 |
12.3 |
Feit Electric |
108 |
34 |
7.6 |
Philips |
104 |
33 |
7.3 |
Rubylux |
76 |
24 |
5.3 |
Westinghouse |
72 |
23 |
5.0 |
Satco |
68 |
22 |
4.8 |
Halco |
68 |
22 |
4.8 |
Although all the bulbs consume similar electrical power and theoretically are all emitting the same total optical power, the measurement at the center point shows how the light uniformity plays a big role. Having a big shadow in the middle led to many bulbs having seemingly low intensity with this method of measurement.
If you want more concentrated single-bulb targeted treatments, then you would choose one of the top 3. All of the other ones would be fine for a multiple-bulb setup or sauna because the overlapping rings of hotspots should “fill in” the shadows and ensure more coverage. The Feit and Philips brands emit a good balance of intensity and coverage area and are great for any purpose.
With our HopooColor 350-SF we can measure the spectrum from 350-1100nm from each of the bulbs. We normalized the curves so they all fit on the same graph, and we are just comparing the relative spectrum.
We can see how the Halco, Therabulb, and SaunaSpace Thermalight all deliver the optical illusion of a deeper red by blocking more orange light in the beginning. This is an asthetically pleasing result, but would not theoretically alter the benefits much.
The irregular squiggles on the graph at 950nm+ would likely be more of a failure of the measurement tool, and not represent the actual spectrum. A much wider range spectrometer would need to be used to properly measure the full spectrum.
But we can confirm that all of these bulbs are emitting essentially the same spectrums, with small variances based on the tint of the glass.
All 250W Near-Infrared heat lamps with a red coating are fundamentally the same.
We consider that all of these bulbs in this review are the best, and the performance difference between the bottom-ranked ones to the top-ranked is only marginal. If you happen to have a bottom-ranked one already, it is not worth throwing out to replace for a top-ranked one. If you are shopping and can only find one of our bottom tier units, get it!
The only difference we found was in the optics of how the light spreads. Some lamps had wider spreads and more of a shadow in the middle, while others were more concentrated in the center - perhaps explaining why some brands claimed to have defied physics to make their lamps more powerful. When really it could be simple optics. We would like to see better diffusers in the front of these lamps like how many incandescent flood lights use, which would improve beam uniformity and maybe even be easier on the eyes.
Don't fall prey to fancy marketing of medical claims, magical spectrums that defy the basic laws of physics, or overpriced products giving the illusion of superiority.
A generic-looking GE Bulb can perform even better than most of the brands with fancy packaging. And remember this is the same GE that makes aircraft engines and GE has been producing light bulbs for over 130 years. So if anyone deserves brand recogniton, it is them.
Truly, the only thing you should avoid is heat lamps labeled as “Shatterproof” or with a special coating that prevents shattering. That usually uses PTFE (aka Teflon), PFA, or Silicone which is a nice concept to prevent glass shards when they break, but people are concerned the plastic coating would off-gas due to the extreme heat.
If you can find alternative brands other than the ones we reviewed, as long as they do not use a “shatterproof” plastic coating, then basically any red 250W incandescent bulb can be equivalent.
So hopefully this helps explain the science, make it easier to find incandescent heat lamps, and learn some tips for evaluating them for shadows and uniformity.
[1]
Bontemps B, Gruet M, Vercruyssen F, Louis J. Utilisation of far infrared-emitting garments for optimising performance and recovery in sport: Real potential or new fad? A systematic review. PLoS One. 2021 May 6;16(5):e0251282. doi: 10.1371/journal.pone.0251282. PMID: 33956901; PMCID: PMC8101933.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8101933/
[4]
Elvidge CD, Keith DM, Tuttle BT, Baugh KE. Spectral Identification of Lighting Type and Character. Sensors. 2010; 10(4):3961-3988. https://doi.org/10.3390/s100403961
https://www.researchgate.net/publication/223137703_Spectral_Identification_of_Lighting_Type_and_Character
[5]
[8]
Zimmerman, S. and Reiter, R. 2019. Melatonin and the Optics of the Human Body. Melatonin Research. 2, 1 (Feb. 2019), 138-160. DOI:https://doi.org/https://doi.org/10.32794/mr11250016.
https://www.melatonin-research.net/index.php/MR/article/view/19
Eyesight is often rated as our most valued sense.
A 2016 US survey study in JAMA found that Losing Eyesight is a bigger concern than Memory Loss, Losing a Limb, or losing hearing or speech. [1] Participants were more concerned with getting Blindness than Alzheimer’s, Cancer, or Heart Disease. [1]
A recent 2019 UK survey in JAMA also confirmed that vision was voted the most important sense. [2] They learned that people would rather live a shorter life with good eyesight, than to live longer without eyesight. [2]
Obviously, many people have an irrational fear that they would prefer Heart Disease, Alzheimer's, or even Death over living with Blindness.
To support eye health, many people are rightfully aware that Red and NIR light therapy is an obvious clinically-studied method to support the mitochondria of the eye.
Conversely, there is still lingering fear that Near Infrared (NIR) light, and Infrared light in general, may be causing an insidious gradual progression of cataract formation.
The confusion and dual nature of NIR on the eyes would incite enough fear for people to avoid the potential benefits of NIR completely from red light therapy devices.
So once again we look at the science and official guidelines so that we can be well-informed and make reasonable decisions for eye health and safety.
A cataract is a condition where the lens of the eyes becomes clouded, reducing vision and causing blurriness. The proteins in the lens of the eye have broken down and clump together.
The NIH estimates that more than half of adults over the age 80 will have or have had cataracts. Indeed, cataract surgery is one of the top operations conducted in the USA.
The NIH also lists some of the top contributing factors to developing cataracts including:
The mainstream list of causes of cataracts do not directly mention infrared light as a factor.
So where has this fear of infrared light causing cataracts come from? Is it relevant to Near-Infrared LED light therapy panels?
Let’s take a look at the mechanisms, history, current science, and relevant exposures that infrared could be impacting the eye.
Here are the top reasons as to how and why infrared light, particularly Near-Infrared (NIR), is associated with cataract formation.
And the research we found on these topics:
Conversely, the positive benefits of low-intensity NIR light to the eye should not be overlooked and will be reviewed at the end.
Disclaimer: There are many other eye hazards to watch out for, particularly acute damage caused by high-intensity collimated beams like from a laser or narrow beam angle lenses, and other high-risk wavelengths for the eyes like UV and Blue light. So, we should always be responsible with our eye exposure to light, check with your doctor about photosensitivity or pre-existing conditions, and understand the safety guidelines from individual device manufacturers.
Scope: In this blog we are only investigating if we can be absolutely certain that even low-level NIR exposure from LEDs does not cause a gradual formation of cataracts.
Several studies and guidelines have stated that a NIR exposure intensity to the eye of up to 10mW/cm^2 has no risk of cataract formation especially for long-term chronic (daily) exposure over 1000 seconds (16.67 min). [3][4][6] The ICNIRP notes that higher intensities than 10mW/cm^2 are safe for shorter time periods or in cold environments.
They specifically note the guidelines are set to avoid cataractogenesis (formation of cataracts):
"To avoid thermal injury of the cornea and possible delayed effects on the lens of the eye (cataractogenesis), infrared radiation (770 nm - 3 m) should be limited to 100 W/m^2 (10 mW/cm^2) for lengthy exposures ( >1,000 s), and to 1.8 t^3/4 W/cm^2 for shorter exposure durations" [4]
To be clear these guidelines are intended to include incoherent (non-laser) exposures to near-infrared light including incandescent bulbs, infrared heaters, industrial furnaces, and LEDs. And this calculation is for Cornea and Lens safety only and they have other calculations for different wavelength ranges and different parts of the eye.
For shorter exposure times less than 1000 seconds, they give us this formula such that higher intensities can be tolerated according to the guideline.
E < 1.8 (t) ^-3/4 (W/m^2)
From this calculation we can find that 100mW/cm^2 can be tolerated for up to 47 seconds before potential damage could occur according to the ICNIRP.
Other researchers have noted that 100mW/cm^2 of NIR would not cause significant temperature increase in the eyes to cause damage, but the ICNIRP comments that such a high intensity from an incoherent source is impractical because it would felt as “painfully warm” on the face. [3] [5][16]
"Vos and van Norren (1994) argued that an irradiance of 1 kW mj2 would not increase the temperature of the anterior segment of the eye by more than 1-C.
However, 1 kW mj2 on the face would be painfully warm and not tolerated in a warm environment."[16]
Good thing nobody makes “painfully warm” intensity panels that emit >100mW/cm^2 at 6 inches away. However, feeling too much heat on the face is a good warning to move further away, and we are reassured by this data that we don’t immediately get damage from such a high exposure.
Based on the ICNIRP equation above, we made this calculator to enter in the intensity of your device to tell you the amount of exposure time that is generally safe for the eyes in the NIR range according to ICNIRP guidelines.[4]
We recommend using the total combined intensity of both Red and NIR for added safety since even Red light can contribute to the total heat load on the eye.
We don't recommend "testing" the limits of this calculator on yourself, but remain well below the levels of either intensity or time as noted by these ICNIRP equations. Use our other eye safety tips in another blog for simple ways to use red light therapy panels responsibly.
Always check with your doctor if you have any pre-exisitng conditions or medicines that would cause photosensitivity which would mean certain individuals would need to be even lower exposures than the general guidelines here.
Where did the fear of Near-Infrared and Infrared light causing cataracts come from?
There is a long history of cataracts in glassblowers, steelworkers, metalworkers, welders, and other workers in hot environments near furnaces and kilns that are emitting infrared, even documented back to 1739. [6]
However, several articles including one from Nature persistently note that there is a thermal or heating component, high temperature environments, a lot of Far-Infrared, exposure during an entire work shift (8 hours); such that the damage is never from NIR alone and from excessive exposure. [6] [7]
One study measured the daily Infrared radiation exposed to glassblowers working near the furnace. Those glassblowers were exposed to 2000-3000 J/cm^2 per day, an estimated 40-80 mW/cm^2 every day for 10-15 years to develop cataracts (and only 10% of that total IR is estimated to be IR-A Near-Infrared). [6]
This is a tremendous amount of dosage that you would never get from responsible use of a LED panel. Even a high intensity hot-spot of a panel may produce up to 80mW/cm^2, but even if there is 20 minutes of direct exposure to the face that would be only 96 J/cm^2, which is less than 5% of the exposure given to glassblowers every day.
However, that same article aptly titled "Determination of infrared radiation levels for acute ocular cataractogenesis" published in 1981 mentions from their research that the 10mW/cm^2 standard could be higher.
"The data in this study indicate that the 10mW/cm^2 figure is conservative and could be increased. We recognized that ACGIH recommendations are intended for delayed effects of chronic exposure while the data of this study concern from acute exposures; however, we are certain that our exposures were only to IR...." [6]
So we can appreciate that even in the early 1980's research has been conducted on this topic, and they were also aware of a potential "delayed effects" which would be the gradual building of cataracts. However, these researchers did not seem concerned by relatively low intensities in normal environments.
UV and Blue light are regarded as causing a gradual degradation of the lens by a photochemical effect. [8] Where UV and Blue are shorter wavelength and higher frequency photons that will slowly accumulate the damage on the lens. Eventually leading to the age-related cataract formation.
The hypothesis has been that Near-Infrared light may have the same effect, that it is a slow accumulation of damage associated with long-term chronic low-dose exposure.
That is to say, even if we stay below non-thermal exposures recommended by the ICNIRP to the eye; there still could be a very slow progression of lens degradation that would manifest decades later as Cataracts.
The theory is summarized well in this quote:
"If IRR causes damage photochemically, repeated below threshold exposures could accumulate over time to cause cataract." [11]
This appears to be the real fear of NIR - since it is a slow, insidious, unmeasurable gradual progression of the disease state until it is too late.
In a recent 2015 experiment, researchers put this hypothesis to the test. They exposed rat eyes to a NIR laser of 1090nm at 96 W/cm^2 (yes, 96,000 mW/cm^2 intensity). They controlled the exposure so the lens temperature would not exceed 8 C. In this experiment, they found no signs of cataract formation, even at such a excessively high intensity of Near-Infrared light. [9]
This means there is no gradual accumulation of cataract from high intensity NIR in a controlled trial. The authors concluded that they debunked the theory of a photochemical effect from NIR, but it is only a thermal effect if there is excessive heat or intensity for too long.
The article in Nature titled "Does infrared or ultraviolet light damage the lens?" comments on this great experiment, but recommends that more wavelengths and experiments should be conducted. [11] Which of course there should always be more experiments to keep confirming that the lens damage is a thermal effect and not a cumulative photochemical effect.
The rumor persists that Near-Infrared LED technology is “new” to human existence. That perhaps long-term safety analysis has not been assessed.
Security cameras often have Near-Infrared LEDs that are useful for the "night vision" survalence. Could these also be a risk to the eyes?
This of course is also a false rhetorical argument; humans have been exposed to infrared light for eons both indoors and outdoors:
Clearly near-infrared light has been a natural part of human evolution, society, and even modern indoor lifestyles. Near-Infrared wavelengths are ubiquitous and unavoidable and there is nothing new about it to human or animal existence.
To fully avoid all Near-Infrared exposure, one would need to wear high-end laser goggles all the time. Especially outdoors.
So, if people are fearmongering that infrared light causes cataracts, just ask them if they are wearing Welding Goggles or NIR Laser Goggles all day every day, both indoors and outdoors (normal sunglasses aren't rated to block IR). If not, then they clearly don’t understand the science or they are simply hypocrites.
Sunlight has long been associated as a major risk factor for cataracts.
Many studies have surveyed populations of people to correlate lifetime sunlight exposure to cataracts. Here are just 6 of them.
However, the common knowledge is that the shorter UV (Ultraviolet) wavelengths of light are the main cause of cataracts from sunlight, due to the gradual photochemical breakdown we mentioned eariler.
This is why sunglasses are actually regulated by the FDA to ensure they properly block UV as advertised, yet there are no requirements or guidlines for sunglasses to block any form of infrared. Which reinforces that there is no mainstream acceptance that everyday levels of NIR does not cause direct eye damage, which if that were the case sunglasses would need to block NIR too.
Indeed, we reviewed 6 studies above on associations of Sunlight and cataracts, and not a single one even mentioned that Infrared light had any contribution to the condition, despite the large amount of NIR we know is emitted by the sun.
The study titled "Determination of infrared radiation levels for acute ocular cataractogenesis" comments on the studies comparing Sunlight to Cataracts:
"If sunlight were a causative agent, UV radiation would necessarily be implicated..."[6] The same study observes many early researchers used Xenon and Carbon Lamps which erroneously reported cataracts from the IR but there is massive UV exposure also from those types of lamps. [6]
But once again we can be comforted that our human eye can certainly tolerate the intensity of NIR from the sun (but never stare at the sun) of about 32mW/cm^2. An early estimation assumes that 10mW/cm^2 is natural from sunlight (because we have eye sockets and eyebrows and eyelashes and aversion reflexes that ensure we get indirect exposure). [3]
Which may play into the prevalence of this 10mW/cm^2 as being a safe level of NIR exposure for the eyes amonst these studies - because it is presumed to be a natural ambient level.
The article in Nature notes the obvious concern that the implementation of NIR LEDs in all facets of modern life is a new potential threat to the eyes.
“The current frequent use of near IRR for remote control and sensing demands verification that near IRR does not cause cataract photochemically. If IRR causes damage photochemically, repeated below threshold exposures could accumulate over time to cause cataract.” [11]
The modern world is increasingly using NIR LEDs for security cameras, face and eye scanners, remote controls, and other invisible sensor applications.
An important article on this topic is titled "Eye Safety Related to Near Infrared Radiation Exposure to Biometric Devices" and investigates this concern even in the year 2011. [13]
Ultimately they conclude that guidelines such as from the ICNIRP and IEC must be followed to prevent eye risks, as well they state that the current LED technology (in 2011) is not powerful enough to cause much risk to the eyes. [13]
However, this article had the foresight to note that the power of LEDs is increasing exponentially over time, as well arrays of LEDs (i.e. LED panels) would increase the intensity and potential risks. [13] So now in the year 2022 we should consider the serious risks of utilizing "the highest intensity" panels as a marketing gimmick that ignores safety for sales.
An old article from Dr. Mercola’s website reviewed how Near-Infrared light is beneficial to the mitochondria in the human eye. He argued that the removal of incandescent lighting being replaced with blue-rich LEDs devoid of NIR was a main culprit of modern eye problems. So we can appreciate a reversal of perspective, that he is promoting more NIR exposure to the eye by switching back to incandescent bulbs in the house. A copy of the article was found here: https://globalpossibilities.org/how-led-lighting-may-compromise-your-health-2/
Indeed, a recent 2021 article titled “Near Infrared (NIR) Light Therapy of Eye Diseases: A Review” was resoundingly positive towards the use of NIR to support eye health through all of the same mechanisms that we understand Red Light Therapy benefits the mitochondria. [14]
Cells with the most mitochondria are highly responsive to Red and NIR light therapy. However this also means they will reach a biphasic dose response sooner so lower intensities and doses are required. This is usually mitigated by the skin for other organs, but eyes can get direct exposure.
The article concludes that NIR LEDs are safe and beneficial by saying “Nevertheless, LEDs only produce negligible heat, impossible for thermal injury”. [14] However, this statement assumes that medical devices are not making recklessly high intensity products and that the consumer is aware to avoid heating devices for the eyes.
A 2008 study on Age-related Macular Degeneration (AMD) recruited 193 patients that had cataracts and treated them with a NIR laser of 780nm. [15] Which of course would be contraindicated and unethical to treat people with cataracts with NIR laser according to the myths we have covered so far. Luckily, the researchers don’t listen to fearmongers on social media, and 95% of the patients with cataracts reported improved visual acuity from the study treatment with Near-Infrared laser light.[15]
Eye health and eye safety of course is one of our top priorities especially since it is often rated as the most important human sense. Unfortunately the extreme fear of losing eyesight can make our minds clouded from the real rational science.
The industrial revolution had workers exposed to massive levels of heat, infrared, and NIR light for many hours a day without much protection or restrictions. Some were quick to place the blame entirely on the NIR exposure as causing cataracts in those industries.
One review notes that by the 1920's safety standards had improved such that:
"workers in the "heat industries" show equal or fewer cataracts than control population". [6]
We can even appreciate that perhaps lower, controlled exposures to NIR in these industries now potentially have "fewer cataracts" than the control population.
The research is positive that low-intensity Red and NIR light on the eyes is beneficial to the mitochondria and general eye health.
Like all things, the dose makes the poison. Drinking too much water will kill us, inhaling too much oxygen will kill us. Yet we critically need those things to survive.
Like water and oxygen, Near-Infared light has been a natural part of life since organisms manifested in the primordial goo. Humans clearly require NIR light for proper mitochondrial function especially in the eyes, but like all things we need moderation.
Many reports and guidelines show the human eye can tolerate up to 10mW/cm^2 for an infinite amount of time without any risk of damage. However, this may be an overly conservative estimate and we can likely tolerate higher intensities for short timeframes in cool environments.
An ancestral perspective of NIR exposure would make the threshold of closer to 30mW/cm^2, where sunlight, fire, and even incandescent bulbs have rarely been blamed for causing cataracts (from the infrared component).
While intensities up to 100mW/cm^2 may not be immediately dangerous to the eyes, we don’t want to push our luck with “painfully warm” intensities that wouldn’t benefit us anyway due to the dose-rate response. A heating sensation on the face and eyes is a good indication to move further away or to use eye protection.
As always, having realistic and honest intensity data is the first step towards responsible, safe, and effective red light therapy usage. Note that these safety guidelines are all based on Intensity so it is imperative that responsible manufacturers disclose thier actual intensity numbers to the consumer.
Listen to the guidelines from your device manufacturerers if they require goggles or protective eyewear during usage for their products, especially for high-intensity panels or lasers. However, we feel when people are properly educated about the risks - they will be more compliant to wear the neccesary safety gear.
And we are continuously re-examining the literature for safety guidelines that we can always offer you the best education for awareness to make smart choices for your eyes and body.
Disclaimer: This article is for education purposes only and does not provide medical advice for the treatment, diagnosis, or prevention of disease. Consult with your doctor and qualified professionals before implementing any of the information contained in this blog.
References:
[1]
Light penetration through the skin is generally discussed as being wavelength dependent. Where longer wavelengths like Near-Infrared (800nm to 1100nm) offer the best penetration, and shorter wavelengths like Red (600-700nm) has relatively shallow penetration for superficial treatment. We dove into this topic more deeply in a previous article here.
However, this perspective ignores the importance of making skin contact during treatment to optimize absorption and penetration.
Many leading researchers and articles have explicitly stated their preference for skin contact treatment with properly measured devices.
This blog we till take another look at new publications and even more sources that talk about contact treatment - such that we can be properly informed when using consumer grade red light panels.
Unfortunately, the new generation of red light therapy “experts” have been biased by non-contact LED panels advertised to be used 6 inches away. They all conveniently overlooked the differences between skin contact and non-contact delivery while they wrote their original books and blogs with their affiliate promotions.
In the peer-reviewed literature, we see the opposite preference. Most studies, clinicians, researchers, and experts like Dr. Hamblin and James Carroll are all biased towards using skin contact with red light therapy devices. And for good reason.
The reason isn’t just reflection losses, but we can see a common theme that non-contact treatment has significantly less penetration due to how the optics works.
In this blog we will take a deeper look at the non-contact vs contact method treatments in the clinical research. It becomes clear that the researchers aren’t merely talking about reflection and absorption losses, but a massive difference in penetration depth with non-contact treatment.
The goal isn’t to entirely denounce non-contact LED panels (in fact we sell some), but we need to approach them with the proper mindset if we ever want to dose them properly.
When we first researched this question in the literature, it became clear the question itself is a Catch-22. If you are even asking the question of “what distance to use red light therapy”, you are already contradicting the bulk of the published science.
Just as important as intensity, time, dose, and repetition - researchers understand there is a significant difference between skin contact treatment versus non-contact treatment.
In fact, there is massive debate and inconclusive evidence about the “best” parameters in terms of wavelengths (nm), dose (J/cm^2), or intensity (mW/cm^2) for different conditions.
Astonishingly, the only treatment parameter that is well-settled in the science – is that skin contact is the ideal way to administer red light therapy.
Let’s take a deeper look into these studies and find out the truth about non-contact treatments.
Let’s let one author define these terms for us in this quote:
“Treatment may be done with the applicator either in direct contact with the patient or at a distance away from the skin surface. The former is referred to as contact mode of treatment while the latter is the noncontact mode of treatment.” [1]
It goes on:
“Whenever possible, the contact mode of treatment is preferred for the simple reason that the loss of energy is minimal—virtually every photon emanating from the applicator enters the patient’s skin or tissue. This is not the case with the noncontact mode of treatment, in which some of the photons are reflected or refracted from the surface of the skin resulting in loss of energy and diminishing the intended amount of treatment energy.” [1]
This is a big deal that Dr. Chukuka S Enwemeka would directly tell us that skin contact is preferred “whenever possible.” We should understand that with few exceptions, skin contact is the ideal method of treatment.
This is essentially common knowledge to the researchers and clinicians to prefer skin contact treatment whenever possible, but is still a shock to the modern consumer who has been biased towards thinking standing 6 inches away from a fancy retrofitted grow light is the “true medical grade” treatment for Photobiomodulation.
It may be impossible to correlate non-contact studies to our commercial LED panels that promote being >6 inches away.
Human biology is much more complex than merely extrapolating conditions completely out of context from one device to another. Especially if that effort is done by ignorant marketers to sell books and products.
For example, one study measured that skin contact delivered 5 times more penetration than non-contact treatment. [2] So, if you absolutely needed to treat the deeper tissue, no extra dosing time or compensation factor could ever help reach the required treatment depth with non-contact treatment.
Another study makes this comment about why they use skin contact treatment:
“The [contact] pressure technique eliminates any power loss due to air gap and reflection from the stratum corneum, physically places the probe head nearer the target tissue, and blanches out the superficial microvasculature, thereby removing a possible absorbing medium to give better penetration and thus deeper absorption of a more clinically viable photon density.” [3]
In a March 2015 article authored by Dr. Hamblin, Dr. de Sousa, Dr. Arany, James Carroll, and Dr. Patthoff (many of the current leading researchers in PBM right now) they had this to say about their bias torwards skin contact treatment.
"When a light source is applied to the skin in contact mode more light penetrates due two 2 reasons: (a) compression of the tissue reduces optical interference by blood flow; (b) diffuse reflectance by the skin is reduced." [7]
So note how explicitly clear that we aren't just losing absorption of photons to reflection losses, the penetration of light into the skin is impacted as well.
This emphasis cannot be understated that the leading researchers have all come together in agreement on this method of treatment.
It is not only the reflection losses we need to worry about (which are already significant at about 60% for Caucasian skin), but even the optics for how the light penetrates and diffuses through the skin is completely different for non-contact treatment. Leading to researchers directly telling us about the penetration loss.
So, we cannot simply take the dosing from a Contact Mode study and sloppily add an additional factor to overcompensate just for the reflection losses. Since that would be ignorant of the change in diffusion and penetration.
A similar diagram can be found in this blog.
A recent article published November 17th 2022 by Dr. Hamblin was analyzing the potential therapeutic intensity gotten from sunlight.
“Assuming that the spectral range between 600 and 900 nm that penetrates deeply into tissue is 20% of this 50 mW/cm2 value, then we have the same value of 10 mW/cm2 incident on the head” [4]
Notice the careful wording Dr. Hamblin when he says that 20% of the non-contact sunlight "penetrates deeply" in the ideal optical window range of 600-900nm commonly used in PBM. It is not just accounting for reflection losses, but accounting for penetration losses too. So ultimately according to Dr. Hamblin’s recent estimation – about 80% of non-contact treatment intensity will NOT penetrate very deeply.
Dr. Hamblin’s assumption of 20% deep penetration is somewhat in correlation with the study that observed a 5x loss of penetration with non-contact treatment. Since 20% is equal to one fifth (1/5), so it is essentially the same factor calculated a different way.
While Dr. Hamblin’s estimation that a factor of 80% intensity losses sounds reasonable and plausible, it would need to be thoroughly studied in different contexts to verify.
Could we increase the intensity of non-contact panels by 80% to compensate for the losses? Probably not, since that just would lead to overheating problems and your product would just be a glorified heat lamp.
Could we increase the time or dose? Perhaps, but since the delivery is inherently superficial we wouldn't want to overdose the skin just for a hypothetical correction factor.
You won't have much doubt if you try skin contact and see the penetration yourself, even with a red wavelength like this picture. Does your hand glow like this when you hold it 6 inches away from a LED panel?
Finding proper dosing for non-contact treatment is entirely its own new set of parameters that need to be discovered through new controlled studies. Not through oversimplified mathematical guesswork or charlatain booksellers making up their own compensation factors.
A recently published review of PBM in Sports Medicine had some sobering commentary about the repeated failed usages of full-body LED devices in clinical studies.
“Therefore, we consider that whole-body PBMT has as its main limitation the lack of contact with the target tissue, and the optical profile (or focus on different deep tissue) affects substantially the power density in the muscles and the modulation of the mitochondrial activity, and so the effects of the whole clinical trial are corrupted.” [5]
In a recent talk, Dr. Hamblin notes that “full body panels” are more of a systemic (indirect) treatment. This would imply a knowingness that non-contact panels lack the penetration that would be achieved with skin contact, but the overall power at the surface of the skin is giving us at least a systemic benefit.
https://youtu.be/XAHpmZc4f7U?t=1476
Oversized "modular" panels are designed to benefit the bank accounts of the business, not actually deliver more therapy to the user.
While non-contact treatment with LED panels certainly can be effective– we need to re-frame our biases to understand how it really works. We should appreciate it is more of a superficial and systemic benefit and utilize this new knowledge properly.
Dr. Hamblin’s reference to the therapeutic potential of sunlight rouses an interesting point.
From another perspective, we could say that Sunlight and the infamous 250W Near-Infrared Heat lamps are also forms of non-contact red light therapy.
The major factor that made so many LLLT and PBM studies special was the penetration depth delivered by skin contact. Otherwise, it would be no different than ambient sunlight or incandescent lights that we are normally exposed to.
This puts LED panels used several inches away on the same level as Sunlight and 250W Heat Lamps in terms of therapeutic value. They all suffer the same reflection and penetration losses.
And Sunlight can be utilized for free and Incandescent Heat Lamps can be purchased much cheaper than a big LED panel.
The real differentiating factor and clinical therapeutic advantage of LASERS and LED for all of these years was perhaps the skin contact.
In the unscientific arms race to make "the highest intensity" LED panels for some vaguely defined "value proposition" of dollars to optical watts - most of the current generation of LED panels on the market are indeed unsuitable for contact method treatment.
The Western mindset of "value" has been heavily manipulated to promote over-consumption and hoarding.(i.e the Value Meal from Fast Food Restaurants)
Could the emphasis on red light device "value" lead to unnecessary overdose of intensity and power with oversized modular panels?
The many brands that paradoxically all claim to be the "highest intensity" as some sort of meaningless marketing fluff are indeed too intense to be used directly on the skin (and too high EMF). Which could lead to unwanted skin overheating or biphasic dose response.
The PBM literature and textbooks are clearly against the notion of "more intensity is better". Which destroys any "dollars-to-watts" value proposition since we should look for effective intensity and not "the highest intensity".
In a 2017 handbook of phototherapy, the chapter on Dosing Parameters (page 42) written by James Carroll of NovoThor notes the following:
"It is argued (by sales and marketing people) that more power means the required "dose" is achieved in less time, and mathematically that is true; however, it has been shown many times that there is a "dose-rate effect" and if the dose is delivered too quickly the beneficial effects are diminished. This is because the intensity (irradiance/power density) is too high." [8]
So we shouldn't listen to salepeople who use rhetorical arguments that imply "more intensity is better"? That would make us have to ignore the marketing of 99% of the red light therapy panel brands and influencers, including all of the most popular ones. What a shame.
However, we want to be very clear that if a device is not made for skin contact then you should listen to the guidelines of the original device manufacturer to make sure you use them safely.
The clinical research is resoundingly clear for this one parameter of Photobiomodulation – using skin contact over non-contact treatment.
Not only do we suffer reflection losses of an estimated 60%, but perhaps only one fifth (20%) of non-contact intensity are considered to “penetrate deeply”. Which is why the scientists are so biased towards using skin-contact method “whenever possible”,
The benefits of non-contact LED Red light therapy panels is through superficial absorption of a large amount of power which leads to systemic effects. Non-contact LED panels likely don't offer significant direct penetration (regardless of Red or NIR wavelength) despite the marketing otherwise.
False illustrations like this one imprinted a false expectation of penetration depth of non-contact red light therapy panels. This bias has been hard to shake for many "experts" whose first education was by LED panel marketing.
Certainly, many consumers are using non-contact LED panels with great success – although perhaps accidentally with improper perspective of the true science and mechanisms for how it works.
Our blogs are not to denounce any particular type of device or treatment. Indeed, the science does recognize that non-contact therapy is a viable option. There may indeed be cases where non-contact therapy is preferred, especially if the device itself is purposefully designed to be used at a distance.
Since our blogs highlighting non-contact treatment there has been a resurgence of acceptance for LED torches (flashlights), handheld LED cluster units, flexible pads, and low-EMF LED panels used on the skin.
Nowadays the consumer is aware that these are effective options because of the contact method, despite the overwhelming marketing of the "red light panel" industry claiming you need super high intensity to be effective.
This has allowed consumers to utilize more options for therapeutic treatment with red light therapy, and ultimately balances out the previous bias that dominated the industry for several years.
Designers of red light therapy devices may opt to make lower intensity, lower EMF products that can be safely used for skin contact - rather than following the echo chamber of nearly identical rebranded non-contact panels with tons of power.
Ultimately cognizant consumers, doctors, and researchers will need to evaluate on a case-by-case basis of when to non-contact treatment and contact method.
The good news is that a recent study was published that successfully used full-body LED light therapy for fibromyalgia patients! [6]
So, in the near future we will soon get scientific resources to properly dose non-contact full body devices.
However, the LED Panel industry must be ready by offering accurate 3rd party intensity numbers rather than blatantly lying with solar power meters.
As a minumum standard we should match the measurement methods used in clinical studies, utilize professional light measurement laboratories, or follow Dr. Hamblin's advice to discard solar power meters for better optical power meters like thermopile type laser meters.
The value of the NovoThor is in its effectiveness to deliver the right amount of intensity for a beneficial effect, not having some arbitrary dollars-to-watts or "highest intensity" sales pitch.
For example, the study on fibromyalgia used a full-body LED bed at 28mW/cm^2 which is properly measured by industry leader NovoThor. This would be incompatable with unrealistic ">100mW/cm^2 at 6 inches away" claims by major manufacturers. If we are to believe the claims by Joovv, MitoRed, and PlatinumLED then they could be delivering 3 to 5 times the intensity that is documented as effective in studies. And the previous quote just told us that you can't just decrease the time to get the same effect with a mathematical calculation of dose due to the dose-rate response.
So if we want even a slim chance to ever properly dose non-contact red light therapy panels, we need to start with accurate measurement techniques.
Industry authorities like the PBM Foundation will easily classify LED Panels as non-medical grade merely because of the false intensity claims. So while the lies about intensity are clearly profitable for scammers, it will hurt the medical acceptance of these devices in the long run.
The scammers selling LED panels have a clear choice. Cash in on an easy gimmick of "high power is better" and false advertised intensity - or get proper measurements and re-educate the consumer the nuances about realistic intensity exposure.
Essentially, the "true medical grade" photobiomodulation according to the research establishment is 1) Skin Contact and 2) Accurate Power/Intensity Measurements. Both of which are crucial for proper dosing and both of which the mainstream LED Panels are failing.
Is it a "marketing gimmick" when Dr. Hamblin, James Carroll, and other leading researchers state they generally prefer skin contact with properly measured devices? Of course not, only a belligerent scammer would out themselves by making such a claim - especially when they are obviously biased towards promoting brands that lie about intensity.
When we look for value, we want evidence based effectiveness - not just a blinding amount of power for a sales fallacy.
For real dosing information, you can visit this blog to see how we compiled ALL of the published full-body red light therapy studies in one place. These are the most relevant studies so far to help us understand proper dosing of large LED panels (hint, none of them used ">100mW/cm^2 at 6 inches away").
At GembaRed, we will continue to review the published literature and seek relevant studies that inform us how to use red light therapy panels. Rather than fraudulent companies that use irrelevant contact-method laser studies to market their giant non-contact false advertised LED panels.
[1]
Kampa N, Jitpean S, Seesupa S, Hoisang S. Penetration depth study of 830 nm low-intensity laser therapy on living dog tissue. Vet World. 2020;13(7):1417-1422. doi:10.14202/vetworld.2020.1417-1422
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7429387/
[3]
Chiyuki Shiroto, Misako Yodono, Shigeyuki Nakaji, PAIN ATTENUATION WITH DIODE LASER THERAPY: A RETROSPECTIVE STUDY OF THE LONG-TERM LLLT EXPERIENCE IN THE PRIVATE CLINIC ENVIRONMENT, LASER THERAPY, 1998, Volume 10, Issue 1, Pages 33-39, Released on J-STAGE July 16, 2011, Online ISSN 1884-7269, Print ISSN 0898-5901, https://doi.org/10.5978/islsm.10.33, https://www.jstage.jst.go.jp/article/islsm/10/1/10_1_33/_article/-char/en
[4]
https://journals.sagepub.com/doi/full/10.1177/20406223221078095
[7]
Hamblin, Michael & Sousa, Marcelo & Arany, Praveen & Carroll, James & Patthoff, Donald. (2015). Low level laser (light) therapy and photobiomodulation: The path forward. Progress in Biomedical Optics and Imaging - Proceedings of SPIE. 9309. 10.1117/12.2084049.
https://www.researchgate.net/publication/281708244_Low_level_laser_light_therapy_and_photobiomodulation_The_path_forward
[8]
Hamblin, de Sousa, Agrawal. Handbook of Low-Level Laser Therapy. Pan Stanford Publishing Pte. Ltd. (C) 2017
Here is a quick summary of the main practical differences of our red light therapy panels, and make sure to look at the pictures to help see how they are different.
Remember to check each individual product page for the full list of specifications and details, which includes 3rd party professionally measured intensity and power output. All of our products have also been industry-leading low EMF and low flicker since we started in 2018 so we won't be worrying about that either in this quick summary guide.
All of our mini panels need to be plugged-in to run. None of them have internal battery supply.
New! GembaRed Spazer 2.0:
The GembaRed Spazer delivers 5 wavelengths of Red and Near-Infrared in a convenient hand-held or table-top unit (with built-in kickstand). It's dimpled convex lenses protrude slightly from the surface of the panel to optimize penetration with the skin contact technique. The intensity is high for this one with only needing 1 minute treatments per area with skin contact. This is preferred for advanced users needing deep penetration. Priced at $299.
Our most affordable mini LED panel at $159 with only one Red wavelength of 660nm. But don't let it's small size and single wavelength fool you, it is great for targeted treatment, as bright light therapy and skincare in the mornings, supporting eye health, targeting male fertility organs, and much more.
It can be used with Skin Contact or Non-Contact with narrow focused beam angle lenses and a convenient built-in stand.
GembaRed Vector Red&NIR Panel:
Our original Vector panel offers 4 wavelengths of Red and Near-Infrared in a convenient mini size. It has advanced features like select-able Red or NIR (we always recommend using both simultaneously).
Having 2 wavelengths of Red and 2 wavelengths of NIR makes sure this Vector panel is versatile for the widest range of benefits. So if you are unsure what you are treating or want the most possible applications with a mini panel, choose this one.
All of the Vector series panels have an automatic 10-minute shut-off to protect from overheating and overdosing, but can be immediately turned back on for another treatment area if needed. Just be mindful of the device heating up with repeat uses and allow it to take a break when it feels too hot.
All Vector panels are all suitable for skin contact treatment and non-contact treatment. Skin contact treatments will be 5-10 minutes per area. The Vector panels have a built-in kickstand for easy tabletop setup for skincare.
All of our Vector panels are competitively priced at $249.
GembaRed Vector 670nm Red-Only Panel:
This special variant of the Vector panel uses only 670nm with unique diffused lenses. This configuration is in league with some popular studies showing red light therapy can support eye health. Using Red Light Therapy on the eyes for 3 minutes per day in the mornings can support eye health, be great for bright light therapy for circadian rhythms, as well it can support skin health at the same time during treatment with this panel.
GembaRed Vector 810nm NIR-Only Panel:
This GembaRed Vector focuses on using mostly invisible 810nm Near-Infrared LEDs (check the picture above to see all of the invisible LEDs ,no light emitted). The 810nm wavelength is well-accepted in the clinical literature as being one of the best wavelengths for deepest penetration. Add to it the Vector series can be used with skin contact, this makes this panel one of the best on the market for offering the deepest penetration.
This Vector 810nm panel uses only 4 Red 660nm LEDs in the corners to help you see that it is On and properly functioning easily.
New Product! GembaRed Improve NIR & Red LED Panel:
The Improve panel is similar to the Rex and Groove panels in terms of size and power output. However, the Improve Panel now has 5 wavelengths, even lower EMFs than the predecessors, and comes with a convenient on/off switch and stand.
GembaRed Rex vs GembaRed Groove Panels:
The GembaRed Groove and GembaRed Rex are our most popular models that we started our business with. They are essentially the same power, intensity, size, lightweight plastic enclosure, and used very similarly. They are easily used by laying them directly on the skin for 10-20 minutes per treatment. Or for skincare use them 6-12 inches away for 5-10 minutes per treatment.
Visit this YouTube video that shows a demonstration how easily the Rex and Groove panels are used.
If you want to stand the panels on a table to do facial treatments then you can buy a stand separately like this one on Amazon.
https://www.amazon.com/
The Groove and Rex panels do not have built-in switches, so for convenience you can get a power strip with individual switches like this one to control it.
https://www.amazon.com/OUTLET-
The GembaRed Groove is our first panel and at a very affordable $299 price. It uses 2 wavelengths of Red and 1 wavelength of NIR. The Groove panel uses 66.6% Red wavelengths making it the preferred panel for supporting skincare and superficial treatments.
The GembaRed Rex is a bit more expensive at $379 and uses 4 wavelengths of Red and Near-Infrared - adding more range and versatility to the treatments. Having proportionally more Near-Infrared (invisible) LEDs than the Groove, the Rex is preferred for deeper penetration treatments.
GembaRed Beacon vs GembaRed Rex:
The GembaRed Beacon shares the same 4 wavelengths as the Rex, but is designed more like many other panels on the market. The Beacon has nicer features like an on/off switch, metal enclosure, built-in stand, and external power adapter.
The Beacon panel is more suitable for non-contact treatment with narrow beam-angle lenses and higher intensity output at greater distances away, where the Rex and Groove panels are more ideal for closer skin-contact treatment.
GembaRed Reboot vs GembaRed Overclocked:
The GembaRed Reboot and GembaRed Overclocked are our full-body panels that are best used upright and standing in front of them at 6-24 inches away for 10-20 minute treatments. This might be inconvenient for some people to be standing for so long, so a smaller panel might be preferred for people that want to do seated treatments.
So, in terms of coverage area the OverClocked panel is preferred for taller people and the Reboot is efficient for smaller frames. However the Reboot panel is a great affordable way for anyone to get started as it is similar size to many 36 inch tall panels on the market.
The OverClocked panel offers an impressive 5 wavelengths of Red and NIR, along with advanced features like select-able Red or NIR (again, both simultaneously is almost always best), and built-in timer. The OverClocked panel has mounting holes on the back to purchase a wheeled stand for it separately.
The Reboot panel uses the same 4 wavelengths as the Rex and Beacon, and has a single simple switch at the top, so both wavelengths are always on simultaneously with no selection option. The Reboot panel does not have any mounting holes on the back, so it must be hung on a door or wall with the hanging accessories provided.
Both the Reboot and OverClocked panels have similar intensity output, but the OverClocked is emitting proportionally more power because of it's larger size.
Make sure to check our FAQ and the product pages for the products you are interested in.
We have a vast blog covering many topics in-depth around red light therapy, and you can also check our YouTube channel and Facebook or Instagram to keep up to date with us. You can sign up to our email list at the bottom of the website for our newsletter.
Any other questions feel free to email us gembared@gmail.com
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In our last part in this series about the Tenmars TM-206 we detailed how we have sent several cheap solar power meters to our 3rd party lab to develop correction calculators so you can take accurate measurements at home!
This time we will look at the 2nd most popular solar power meter used by manufacturers and self-styled experts - the TES 1333 Solar Power Meter!
To save you even more money, we bought the General Tools DBTU1300 Solar Power Meter on Amazon, which is an even cheaper rebranded TES 1333.
https://www.amazon.com/General-Tools-DBTU1300-Digital-Solar/dp/B001TOJG10/
We confirmed the TES 1333 and General Tools DBTU1300 solar power meter measure similarly, so these calculators can be used for both tools.
Like last time, just follow these steps:
The TES 1333 model (including General Tools brand, but we will just call them both TES 1333 for the rest of this blog) includes an interesting feature to re-calibrate the sensitivity!
In the wrong hands, this is dangerous because we can now increase the sensitivity to display even more falsely high intensity numbers.
However, now if you want to impress your friends at parties or pretend to be a red light therapy expert online - you can re-calibrate the sensitivity lower to display instantly accurate numbers!
For example, since we know from the data the TES 1333 measures falsely high by about 2x, then we simply adjust the sensitivity factor down to 0.547 for Red+NIR. For Red-only set it to 0.83 and for NIR-only set it to 0.386 based on our data.
Here is how to re-calibrate it:
Of course there are drawbacks that this linear sensitivity adjustment does not account for the non-linear measurements that the solar power meters take.
So still the most accurate way to use the TES 1333 is use the standard sensitivity (1.0) and put the numbers into our calculators above.
Once again you might not even need to buy your own solar power meter. If a manufacturer shows you pictures of their measurements with a TES-1333 then you can just put those numbers right into the calculator.
To be clear, the consumer should never have to measure their own intensity, similar to how you shouldn't have to measure the horsepower of your car to see if you have been scammed by an automotive dealer.
To expand on this metaphor. Lets say you got a Truck that lied about horsepower. However, you never measured it yourself and the Truck worked well for your activities for years. You enjoyed the truck and never had any issues with it. Were you scammed? If you get a red light panel that lied about intensity but you enjoy it anyway, is that a scam? Yes, of course it is.
You can note that MitoRed had extensively catalogued their intensity measurements with the Tenmars TM-206. So you should use our first calculator in the other blog to get an understanding of their realistic intensity outputs.
However, now they seem to be telling people that their advertised measurements were taken with a TES 1333. Which only reinforces how meaningless MitoRed's intensity claims really are if they can flip flop between wildly disparate tools.
Imagine if the effort manufacturers use to deceive people was applied to offering honest information instead? We could be in a golden age of red light therapy if that happened.
So look carefully at the model of solar power meter when manufacturers take pictures and videos, because it is important to use the correct calculator to get an accurate result.
Head back to our first blog with tips on how to re-calibrate your mindset to understand that no red light panels on the market deliver the fabled "100mW/cm^2". And that seeking 100mW/cm^2 would likely lead to undesirable results anyway.
Using these solar power meter correction calculators are the best way to take intensity measurements for yourself at home. They are cheap and easy to use, and you can finally understand realistic intensity numbers for safety and efficacy.
Unfortunately, many manufacturers and brands initially used Solar Power Meters without knowing that they measure Red/NIR wavelengths falsely high by about 2x. So they gleefully reported these unrealistically high numbers without any technical scrutiny that a real engineer or scientist would apply towards a measurement tool.
Since 2016 the so-called "experts" and consumers have only been presented with a single narrative about how ">100mW/cm^2 at 6 inches away" is the gold standard for red light therapy administration. It has established a strong bias for all consumers since this is the first and only narrative they have ever seen.
It is clear that only when these biased companies and individuals can face the truth about accurate intensity and non-contact delivery that the real science around proper understanding of dosing of red light panels can even begin to happen. Until then we will still be in the dark ages dominated by false narratives and marketing fallacies - and when that fails - resorting to attacks against GembaRed's credibility.
]]>Should you choose a Full-Body LED therapy panel or a Far-Infrared Sauna? A Near-Infrared sauna? What about LED Pads, Infrared Pads, LED Bulbs or Infrared bulbs?
Generally Far-Infrared technology is used for heat therapy and detox, while Red and Near-Infrared is used for the non-thermal application of light for deeper penetration and sub-cellular up-regulation. This may be all people need to know for a basic understanding of the differences, however this blog will dive much deeper.
The main problem is that the benefits of Red, Near-Infrared, and Far-Infrared are very similar and often overlapping. People and companies are purposely conflating terms or making up new classifications like "full spectrum infrared" with no clear definition. This makes a very confusing situation, and we will attempt to sift through the data to find the truth.
So, with the popularity of alternative red and infrared light therapies soaring, it is important to clearly define the what these technologies are, the spectrums they emit, the penetration depths, the mechanisms for how they benefit the body, the types of devices, and how they are used.
“Red Light Therapy” often refers to usage of non-thermal LEDs or (cold) Lasers to deliver Red and Near-Infrared (NIR) wavelengths. The more precise term preferred by scientists is Photobiomodulation, where Photobiomodulation is specifically the science of the non-thermal interaction of light on the cells.
“Infrared Light Therapy” tends to use more heating devices like incandescent heat lamps, infrared heating pads, infrared domes, infrared saunas, and infrared sauna blankets. For Infrared, scientists prefer to term different ranges of Infrared by IR-A, IR-B, and IR-C instead of non-specific terms like “near-infrared” and “far-infrared light”.
The 250W Red Incandescent Heat Lamps are often marketed as "Red Light Therapy" or "Near-Infrared Light Therapy" as a misnomer since they emit a wide spectrum from Red to Far-Infrared. Regardless of the multiple inaccurate names, incandescent heat lamps can indeed be used as a cheap hack therapeutically, but there isn't much of a clear scientific category for them.
Thermal Image (Top) versus Picture (bottom). - A Red & NIR LED Bulb (Left) versus a 250W Incandescent Heat Lamp (Middle) Versus a 100W Far-Infrared Reptile Heat Bulb (Right). The LED light emits some brightness but produces very little heat. The Heat Lamp emits some visible light and a lot of heat. The Far-Infrared Bulb emits no light but only heat.
The solidification of the term Photobiomodulation in the medical literature clearly separates using optical radiation for non-thermal responses. So the first distinction we should make is that regardless of wavelength, the scientists are trying to create two categories of thermal and non-thermal light therapies.
And we can appreciate we even use the term “light” loosely because infrared is invisible to the human eye and doesn’t actually deliver any brightness.
Sunlight has been the ultimate life-giving source of energy for billions of years; it is only within the past 80 years that humans have noticed the profound influence of the sunlight spectrum on our health.
The official “optical radiation” spectrum is between 100 nanometers (nm) to 1,000,000 nm. We can only observe the “visible spectrum” between 400nm (Violet/Blue) to 780nm (Red).
Even amongst different textbooks and publications and standards - the ranges for Red and Infrared can vary greatly (creating more inconsistencies and confusion). We will use the definition used in a new textbook on infrared light therapy, since those are ranges most relevant to distinguishing biological effects.
https://library.oapen.org/handle/20.500.12657/54423
Red light is between 600nm to 780nm
Near-Infrared or IR-A (Infrared-A, IR-A) is between 780nm to 1,400nm
Mid-Infrared or IR-B (Infrared-B, IR-B) is between 1,400nm to 3,000nm
Far-Infrared or IR-C (Infrared-C, IR-C) is between 3,000nm to 1,000,000nm
When only discussing infrared light ranges, we switch to talking about “micron” ranges. Where micron is short for micrometer with abbreviation μm (notice the prefix is the Greek letter “μ” spelt as “mu” and pronounced like "mew" and not a typical “u”). So, when you see “μ” just think “micro”, which is shortened to micron when talking about distance.
1 micron (μm) = 1000 nanometers (nm)
In other words, a micron is 1000 times longer than a nanometer. So when we talk about the Far-Infrared range, the wavelengths are much longer than when we typically talk about Red or Near-Infrared so we use the micron units instead.
Articles on infrared light might say that the entire Infrared range is from 0.78 microns to 1000 microns, and that also means it is 780nm to 1,000,000nm because we just multiply by 1000. And vise-versa if people are talking about nanometers, you just divide the number by 1000 to know the micron equivalent.
It is important to understand this these definitions and terminology especially when diving into the literature yourself and needing to understand the comparisons between microns and nanometers.
What is the spectrum of Infrared Light Therapy? The theoretical spectrum of infrared emitters has been well defined since the year 1900 by Max Plank.
The spectrum of an infrared emitter is directly determined by its temperature according to Plank’s laws and equations. All objects above 0 Kelvin (absolute zero) emit some infrared, which is why we can measure human skin temperature with an infrared sensing gun.
Infrared Thermal Cameras display the optical range between 7.2 and 13 microns, showing what the world looks like if we could "see" only infrared. This "infrared selfie" was taken in a mirror, showing that mirrors reflect infrared well too.
The theories set by Plank tells us that the light spectrum from a glowing piece of metal, from a hot stone, from our body, from a carbon infrared panel, the sun, and an incandescent bulb are all related by the same equation. The type of material used roughly determines the operating temperature of the infrared emitter in the devices, and thus the spectrum.
The glow of a infrared space heater or toaster oven element indicates the partical visible light from hot infrared emitters following Plank's laws. Infrared therapy is just a medical application of these common household technologies.
A carbon panel heater operates about 150-230 F (~360K), a ceramic heater about 350-450 F (~470K), and a tungsten incandescent bulb is 2700K.
Now let’s overlay some LED spectrums of 660nm and 850nm, and remember that LEDs are quasimonochromatic (quasi meaning “partly”) so even though the peak might be at 660nm or 850nm – there is some spectrum +/- 15 nm that you see sloping from both sides of the peak.
Then let’s overlay the ASTM Sunlight spectrum because we are often vying to re-create nature.
And we are going to “normalize” the spectrums (make the Y-axis meaningless by setting the height to 1) – this way we are just comparing spectral distributions – and we can discuss intensity separately later.
The chart is also on a logarithmic scale (not a typical linear scale) due to the extremely wide range of the infrared spectrum.
The peaks calculated by Wien’s Displacement Law are
Even though some Infrared emitter companies can squabble about their supposed peaks and micron ranges, we can see the tremendous broad wavelength ranges for the Carbon and Ceramic heaters that overlap a lot. Where the LED will have distinct ranges that are more interesting to study to isolate biological responses to specific wavelengths.
One thing that makes Photobiomodulation (non-thermal) therapy so effective is the penetration into the body which we covered in-depth in a previous blog. The “optical window” of the skin is roughly defined as between 600nm to 1300nm, and beyond 1300nm water absorption takes over and leads to more superficial absorption.
This means we expect IR-B and IR-C to have much less penetration than the typical Photobiomodulation wavelength ranges – like noted in studies with diagrams like below.
A similar diagram is found here:
One study notes that the Red (633nm) penetration is about 3.5mm, the Near-Infrared 820nm penetrates to 8mm, and 10,600nm (10.6 microns) is only 20μm. So, we could say that Near-Infrared light has about 400 times more penetration than Far-Infrared wavelengths.
However, a recent editorial by Dr. Hamblin notes that even though the “ballistic” penetration of Far-Infrared (IR-C) is very shallow at only a few micrometers (μm), the effective penetration depth is 2 to 4 cm. [2] Authors theorize that the energy is transferred by the water molecules more indirectly that explains the non-photon penetration effects.
Many other studies on Far-Infrared light therapy also seem to corroborate that the effective penetration of far-infrared is 3 to 4 cm, despite its very shallow photon penetration. [3] [4]
This is similar to how researchers often note that Red and NIR LED benefits structures deeper into the body than the actual penetration depth [5], or how UV light can help promote Vitamin D synthesis which obviously affects the function of the whole body despite the lack of penetration.
So, for most light therapy effects, we need to be looking more at the biological mechanisms and benefits of these wavelengths rather than fixating on just the photon penetration depths.
When comparing Red Light Therapy and Far Infrared Light – the intensity or power output of these devices must be considered as a big part of the difference. Although strangely the intensity is overlooked when talking about Red vs FIR.
Remember that Joules are a unit of energy. 1 Joule is the amount of energy that raises 239 mg of water by 1 degree Celsius.[18] Where we should be familiar with the term Joules and how it relates to Power (Watts) from dosing calculations for photobiomodulation.
So, regardless of wavelength, absorbed radiation always has the capacity to raise the temperature of an object. Our skin and blood is uniquely designed to promote thermoregulation and will also excreet sweat when needed to cool off.
One Photobiomodulation study measured skin temperature increases with 810nm and 904nm lasers with increasing Joules and Watts. As they increased dose from 2 to 6 to 9 to 12 Joules, they found an increase in skin temperature of a total of 4 degrees C at the highest dose. They also found the 904nm had a much higher propensity to heat the skin than 810nm, which makes sense because 904nm has slightly higher water absorption and less penetration than 810nm. The point of the study was to understand safety of high intensity lasers, since they worried the "more power is better" marketing gimmick could eventually cause painful or deleterious skin overheating. [17]
Another study suggests to use photobiomodulation (Red and NIR 600-1400nm) with intensities less than 50mW/cm^2 to avoid skin hyperthermia (overheating). [13]
Much lower intensities of Far-Infrared are needed to produce heating in the skin due to its superficial absorption in the water. One study notes only "tens of mW/cm^2" is required to induce heating effects with Far-Infrared. [1] And that a non-thermal intensity of Far-Infrared would need to be only 0.1 to 5 mW/cm^2. [1]
So we can see that a thermal intensity of Far-infrared would be possibly greater than 5 mW/cm^2, and a thermal intensity of Red or NIR would be greater than 50 mW/cm^2.
Lets take a look at the power (Watts) of a few common devices for comparison.
Full Body Photobiomodulation vs Far-Infrared Sauna:
A typical single-person Far-Infrared Sauna utilizes 1300 W to 1500W, most of which we can assume is being converted to heat and infrared rays inside a decently insulated sauna.
Let’s say you have two “Joovv Elite” setups (on for the front and one for the back) for a total of 2x 248W (496W) of optical watts according to the manufacturer’s website.
Then we know that Red and Near-Infrared light is poorly absorbed and about 60% is reflected from the skin especially if standing 6 inches away. So perhaps only 200 Watts is absorbed, where more of the Far-Infrared is absorbed by water in the skin.
So, we have a potential difference of about 7x the absorbed power in an infrared sauna versus a typical full-body-LED-panel setup.
Are the heat effects from the Far-Infrared alone, the much higher power, or both? Probably both.
"NIR" Heat Lamp vs LED Lamp:
A typical “Near-Infrared” incandescent red heat lamp is 250 Watts. A LED Red Light Therapy Lamp from Amazon consumes an average of 20 Watts, and we assume at best only emits about 30% as optical energy so about 6 Watts emitted.
Once again, for a similar size bulbs we have the optical output difference of about 41 times the power from the LED versus incandescent. Can we even believe that the heat effects are only from the wavelength, and ignore the massive difference in power?
Infrared Pad vs LED Wrap:
The DGYao LED pad only consumes about 12 Watts. We know LED pads actually do warm up because they have no heat sinks or fans, but the DGYao pad runs "cooler" than most of the other pads we tested.
A similar size HealthyLine 1818 Far-Infrared mat is rated for 45 Watts and actually consumes about 54 Watts when we measured it with a Kill-A-Watt meter.
So even with infrared pads versus LED pads we observe a large difference in power output of 4.5 times more power. And we have heard reports that the LED pad users enjoy the heat effects more dominantly than the light effects.
*Case Study: I gave my mom the DGYao LED pad and the HealthyLine 1818 infrared mat. She has been using both regularly for over 6 months. She prefers the infrared heating mat more to relax her muscle pain.*
We can see a pattern that the “heating” infrared devices not only deliver longer wavelengths, but much more power. Biological heating is always a function of power and intensity first, not wavelength.
For example, there are far-infrared textiles (clothing) that do not emit heat on their own, but are considered to be a far-infrared therapy regardless.[3]
And of course, we can appreciate that many “high power” LED Panels are vying to deliver instant gratification with feelings of warmth from high intensity.
So, if we want to control whether we want a thermal response or non-thermal response, then we need to understand the power and intensity of these devices, not just the wavelength. Some far-infrared technologies don’t illicit heat, and some high intensity red light devices will induce heating.
In understanding the differences between Far-Infrared versus Near-Infrared many people fixate on the wavelengths but seem to forget about intensity and power of these devices is a major factor.
Generally “red light therapy” photobiomodulation is considered very safe not only because of the wavelengths, but because it is low intensity delivered by non-coherent divergent beam LEDs. There are very rare cases of contraindications or risks, and are usually associated with excessive intensity as can be seen in our previous blog.
Far-infrared saunas are intended to induce sweating - so replacing water, minerals, and electrolytes is important – especially if it is a person’s first time they could become faint from dehydration or lack of minerals.
Repeated heating from any form including infrared devices can cause rare skin heating issues like erthyma ab igne, hyperpigmentation, or other skin irradiation issues. [7][16]
One study notes:
"IR-induced heat action can be pathological for the skin. When the skin temperature exceeds 39 C during IR irradiation, it can induce ROS generation and pathological effects through changes in structural integrity caused by enzyme induction in the skin. "[1]
Cheap infrared devices may lack temperature safety controls and overheat the skin, where it is documented that repeated or sustained skin temperature elevation can cause issues.
Even with intentional far-infrared heating, the medical applications of infrared heating devices are often careful not to exceed skin temperatures of 40 C for sustained periods (often lower), where at 45 C or higher is documented that skin damage occurs. [1] [10]
The risks with Red to Infrared for the eyes are also in cases of excess intensity, power, and heating called photothermal damage (as opposed to UV and Blue light causes photochemical damage even at low intensities). It is well documented that an increase of eye retinal temperature above 10 degrees C causes irreversible damage. [6] [8]
High heat and intensity is usually easy to avoid because your skin will give you warnings that it feels it is being overheated, however, extra precautions should be taken for individuals if they lack heat sensations.
The primary mechanism of most Infrared therapies is indeed heating. Which doesn’t always sound glamorous, but it does feel very nice and is often overlooked as a powerful healing modality.
Heat associated with Far-Infrared is known to relax muscles, reduce stiffness, improve circulation, activate metabolism, stimulate nociceptive receptors, and relieve pain. [9]
The FDA often approves/clears/registers infrared heating devices “for the temporary relief of minor muscle and joint pain and stiffness, or muscle spasm, the temporary increase in local blood circulation; and/or the temporary relaxation of muscle.”
https://www.accessdata.fda.gov/cdrh_docs/pdf10/K102149.pdf
Those are just the immediate, targeted benefits for far-infrared heating. We also know in the context of full-body infrared exposure like a sauna confers many more benefits. Infrared sauna therapy raises the core body temperature, induces sweating, and can assist in cardiovascular health, immune health, brain health, detox, and improve athleticism. [4][10]
While heat effects doesn’t sound like an enticing marketing ploy, we can appreciate the vast benefits it can deliver.
Several studies have noted that Far-Infrared confers both thermal and non-thermal effects, especially in the cases of far-infrared textiles that don’t emit heat. One study mentions the non-thermal mechanisms of Far-Infrared as:
“FIR may, therefore, excite molecules and cells (i.e. cytochrome-c-oxidase and intracellular water) and alter biological functions.” [11]
This revelation is mind-blowing, because these are exactly the same mechanisms that we thought were exclusive to non-thermal photobiomodulation such as LEDs and Lasers.
Indeed with longer-wavelength infrared preferentially being absorbed by water in the body, it can create EZ Water (Exclusion Zone Water) in the cells as defined by Gerald Pollack’s research group. This work is consistently cited in the infrared therapy literature as a primary mechanism for the non-thermal effects of infrared to improve cellular function. [12]
Where is it commonly accepted that Red and Near-Infrared have deeper penetration and direct actions on the Cytochrome C Oxidase to improve mitochondrial function, the Far-Infrared delivers similar non-thermal effects but focuses more on EZ Water mechanism.
There are more similarities than there are differences in the benefits of Red & NIR versus Far-Infrared. Benefits we commonly associate with LED red light therapy like skincare, brain health, and wound healing can also be found for Infrared therapies too. [13][14][15]
One study also Co-Authored by Dr. Hamblin plainly describes this dillema:
"how can the biological effects of red and NIR absorption be so similar to those seen with FIR ?" [1]
Which is part of the confusion that we find very similar benefits for Red, NIR, and FIR – so it makes it harder to distinguish what we should choose as the “best” thing for a specific ailment.
So generally we should prefer Far-Infrared when needing direct tissue heating or detox with full-body devices. The usage of non-thermal Red and Near-Infrared LEDs and Lasers is used for deeper direct photon penetration and more subtle cellular mechanisms of healing.
The good news is that we if we have to choose only one modality, we shouldn’t worry about “missing out” on benefits of another - when used properly Red, NIR, and FIR can all deliver similar non-thermal benefits.
"Full Spectrum Infrared" has become a popular term especially when selling saunas. Now that you are an expert in all of the information presented above, we can break it down.
The claim implies that Full Spectrum Infrared includes some Near-Infrared, Mid-Infrared, and Far-Infrared wavelengths. Manufacturers seem to achieve this with a smattering of different types of emitters in a single sauna like incorporating carbon, ceramic, quartz, or even tungsten infrared heaters, and maybe even throwing in a few Red or NIR LEDs in there as well.
Having all types of infrared would imply that you won't be missing out on any potential benefits as well as saving time by getting the full spectrum all from one device. Which of course we can find no study that verifies that "full spectrum sauna" delivers superior benefits to standard far-infrared sauna, or any studies about full-spectrum infrared sauna therapy at all.
The drawback of haplessly adding Near-Infrared into a Sauna is that Near-Infrared is poorly absorbed by the body and much is reflected away from the skin. In other words, Near-Infrared is an inefficient way of trying to heat the body, which may detract from the primary goals of sauna to induce sweating and detoxification.
Likewise, the clinical application of Near-Infrared is usually with skin-contact while the skin is still room temperature to allow for the best penetration and absorption. Using a vaguely defined 'full spectrum emitter" that you don't even know the intensity of Near-Infrared that even reaches the skin does not give much confidence that you have any chance of getting real Near-Infrared therapy benefits.
So, too much emphasis on "Full Spectrum Infrared" not only detracts from the heat therapy offered by Far-Infrared alone, but it likely does not mimic the clinical settings for the benefits of Near-Infrared in the photobiomodulation context.
As a counter point, we will end with a quote from Dr. Hamblin's recent editorial commenting on the existence of full-spectrum sauna brands that add in Red and NIR LED panels:
"The combination of FIR wavelengths and PBM wavelengths may provide additional physiological benefts." [2]
And we can note that this is an editorial (Opinion) article and this opinion was not backed up with any study or reference. In the disclosure statement he acknowledges that he is a scientific advisor for a brand that manufactures "full-spectrum" infrared saunas.
So the consumer is in the same boat as the top researcher in the field. We like to speculate that combining Red, NIR, and FIR in sauna could give an additional benefit - but we have no studies to back it up yet and we don't want to detract too much from the efficient heating provided by FIR alone.
Lets look at the more practical aspects of some realistic devices, rather than getting caught up in studies and mechanisms and lists of benefits.
Red and Near-Infrared LED devices are extremely convenient, affordable, and deliver profound benefits without heat (or minimal heat). They don’t take up much space and can often be used anywhere in the home conveniently. LEDs can be used instantly and treatments can be as short as 5 minutes to 20 minutes. Delivering light therapy from LEDs is extremely safe and using skin contact also helps with photon penetration. However, LED light therapy is very subtle because you don't feel anything during treatment, and the benefits will also be subtle and occur after consistent repeated usage. Often the overlooked immediate benefit of LED light panels is the bright light therapy aspect and improved sleep cycles.
Incandescent Heat Lamps are extremely cheap and a great way to experiment with heat and red light therapy. Finding a good grounded lamp and setting it up properly is important to avoid EMFs and burning yourself as these aren’t necessarily made with any safety considerations. Incandescent bulbs themselves heat up instantly, but will take time to heat up the body or the room if making a DIY sauna.
Far-Infrared devices like saunas, lamps, and mats are usually more expensive for the medical grade technologies. Saunas take up a lot of room, and even infrared pads must be laid out on a bed, couch, or floor. Infrared saunas and pads usually require some heat-up time of up to 20 minutes or more, then the session is usually at least 30 minutes. All of the costs and inconveniences of proper Far-Infrared therapy are certainly worth it for the immediate benefits like pain relief and long-term benefits like cardiovascular health and detox. But it does seem to take more cost and effort to get proper Far-Infrared into your routine.
Comparing Red, Near-Infrared, and Far-Infrared wavelengths is difficult due to the complexities, nuances, and lack of thorough clinical research comparing them.
Trying to distinguish the differences of Red Light Therapy and Infrared Light Therapy in terms of penetration, mechanisms, and benefits is challenging due to the vast overlapping mechanics for how these light wavelengths interacts with the body.
The clear differences between Red, Near-Infrared and Far-Infrared therapies is with the total power (Watts) of the devices and the thermal effects. The thermal effects enable more circulation, skin and body temperature increases, temporary muscle and pain relief, and ultimately the cardiovascular and detox (sweating) benefits that far-infrared saunas are well known for.
However, heating is powerful and must be used cautiously to not overheat the skin, eyes, or cause potential unwanted effects.
Red and Near-Infrared LED devices are incredibly convenient for the low cost, low space needed, no heat-up time, and extremely safe and comfortable low intensity output. The profound benefits of low-intensity Red and Near-Infrared light delivered comfortably non-thermally cannot be understated, which makes it very easy to do routinely several times a week for long term benefits.
We found that instead of getting nerdy about wavelengths which often leads to confusing conclusions and the uprising of "full spectrum" gimmicks, we need to take a practical perspective on the actual devices that deliver these wavelengths.
Ultimately the best thing to do is to try these technologies yourself and start to feel the differences and see what works best for you. LED Bulbs, Incandescent Bulbs, and Infrared Bulbs are all cheap and easy to try. Then you can graduate to larger full-body devices or pads of your preferred technology.
A good resource for low-EMF far-infrared saunas is the Certified Saunas website.
A good place for affordable low-EMF infrared heat mats is HealthyLine (don't get the PEMF mats, just filter for Far-Infrared only).
https://healthyline.com/products/
Until then, we hope this blog filled with scientific references, pictures, diagrams, and practical device analysis can help close the knowledge gap to feel more confident to start trying and implementing any from of red and infrared light therapy to enrich your life, since they all clearly offer immense benefits.
[1]
Vatansever F, Hamblin MR. Far infrared radiation (FIR): its biological effects and medical applications. Photonics Lasers Med. 2012 Nov 1;4:255-266. doi: 10.1515/plm-2012-0034. PMID: 23833705; PMCID: PMC3699878.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3699878/
[2]
Hamblin MR. Traditional or Infrared Saunas and Photobiomodulation: What Do They Have in Common? Photobiomodul Photomed Laser Surg. 2022 Sep;40(9):595-596. doi: 10.1089/photob.2022.0078. Epub 2022 Aug 30. PMID: 36040391.
https://pubmed.ncbi.nlm.nih.gov/36040391/
[3]
Bontemps B, Gruet M, Vercruyssen F, Louis J. Utilisation of far infrared-emitting garments for optimising performance and recovery in sport: Real potential or new fad? A systematic review. PLoS One. 2021 May 6;16(5):e0251282. doi: 10.1371/journal.pone.0251282. PMID: 33956901; PMCID: PMC8101933.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8101933/#pone.0251282.ref002
[4]
Mero A, Tornberg J, Mäntykoski M, Puurtinen R. Effects of far-infrared sauna bathing on recovery from strength and endurance training sessions in men. Springerplus. 2015 Jul 7;4:321. doi: 10.1186/s40064-015-1093-5. PMID: 26180741; PMCID: PMC4493260.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4493260/
[5]
Lee SY, Park KH, Choi JW, Kwon JK, Lee DR, Shin MS, Lee JS, You CE, Park MY. A prospective, randomized, placebo-controlled, double-blinded, and split-face clinical study on LED phototherapy for skin rejuvenation: clinical, profilometric, histologic, ultrastructural, and biochemical evaluations and comparison of three different treatment settings. J Photochem Photobiol B. 2007 Jul 27;88(1):51-67. doi: 10.1016/j.jphotobiol.2007.04.008. Epub 2007 May 1. PMID: 17566756.
https://pubmed.ncbi.nlm.nih.gov/17566756/
[6]
Youssef PN, Sheibani N, Albert DM. Retinal light toxicity. Eye (Lond). 2011 Jan;25(1):1-14. doi: 10.1038/eye.2010.149. Epub 2010 Oct 29. PMID: 21178995; PMCID: PMC3144654.
https://pubmed.ncbi.nlm.nih.gov/21178995/
[7]
Haleem Z, Philip J, Muhammad S. Erythema Ab Igne: A Rare Presentation of Toasted Skin Syndrome With the Use of a Space Heater. Cureus. 2021;13(2):e13401. Published 2021 Feb 17. doi:10.7759/cureus.13401
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7971733/
[8]
http://photobiology.info/Rozanowska.html
[9]
Park YJ, Lee HK, Cho JH. Analysis of muscular elasticity according to infrared and ultrasound therapy by sonoelastography. J Phys Ther Sci. 2018 Aug;30(8):1024-1029. doi: 10.1589/jpts.30.1024. Epub 2018 Jul 24. PMID: 30154594; PMCID: PMC6110236.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6110236/
[10]
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4935255/
[11]
Bontemps B, Gruet M, Vercruyssen F, Louis J. Utilisation of far infrared-emitting garments for optimising performance and recovery in sport: Real potential or new fad? A systematic review. PLoS One. 2021 May 6;16(5):e0251282. doi: 10.1371/journal.pone.0251282. PMID: 33956901; PMCID: PMC8101933.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8101933/
[12]
Of course we can't talk about intensity without acknowledging the scam that most red light panel manufacturers are lying about intensity with cheap solar power meters.
But lets, just for this blog, imagine a world where manufacturers aren't lying about intensity. That we are all seeking the common goal of scientifically analyzing these panels so we can offer the most evidence-based understanding of these products.
How would we truly quantify the intensity output from a red light panel in an honest multiverse world? Lets take a look.
We covered Beam Angles in a previous blog with some nice illustrations of the differences between narrow beam angles and wide beam angles.
However, we did not clearly separate the differences between Beam Angle of the entire panel, versus the Lens Angle of the individual LEDs.
Most companies are referring to the Lens Angle of the individual LEDs when they are making claims about having 30 degree, 60 degree, or 90 degree beam angles.
The Beam Angle for the entire panel is the aggregation of all of the LEDs in the arrangement on the panel, the lens angles, the spacing between the LEDs, and how all of the light converges together.
For example, our GembaRed OverClocked and Reboot panels use 60 degree lenses but according to our 3rd party lab the beam angle of the entire panel is only 20 degrees.
Obviously this makes a big difference in how we plan our coverage area for treatment. And we have seen many times how other brands are over-exaggerating their coverage area by referencing the lens angles and not the actual beam angle of the panel.
Most Red Light Panel companies will offer a single intensity number that represents the entire coverage area that they claim.
You might recognize a diagram like this being shown on many websites, which helps illustrate the intensity at various distances, as well as how the coverage expands with distance.
According to some companies, somehow a 3 foot tall panel emits 72 inches tall of coverage at only 18 inches away. This is only possible if they are confusing Beam Angle of the entire panel with Lens Angle of the individual LED lenses.
We can appreciate that many companies have claimed exorbitant coverage areas for their panels. For example, the PlatinumLED BioMax 600 currently claims to emit 130mW/cm^2 and a coverage area of 72 x 45 inches (6 foot by 3.75 foot) at 18 inches away.
With a blazing inferno of 130mW/cm^2 and a coverage area much larger than most humans, then there wouldn't be any need for additional "modular" panels.
Yet, most people who own the BioMax 600 quickly realize it actually emits a very narrow coverage area, and they do indeed need to purchase 3 more panels just to get the actual coverage that a single panel claimed to emit.
Lasers have been the forerunners of the Photobiomodulation (LLLT) industry, and we need to understand them but also appreciate the massive contextual differences between LED and Laser.
Lasers have a long history of having non-homogenous outputs. We can only "see" a small dot of a laser. And we falsely assume that the laser output is a perfect circle of even distribution.
We can't really tell by eye if a laser dot is a perfect circle or has an uniform distribution, even though that is what is commonly assumed.
For example, a 5mW laser with a 0.2 cm diameter. Typically researchers will simply divide 5 by pi*(0.2/2)^2 = 159 mW/cm^2.
(notice a 5mW laser is very low power [a typical pen laser], but companies can cherry pick this large intensity number to sell their falsely advertised intensity panels and imply that is a good idea to engulf an entire human body in the intensity of a laser)
With this simplistic math, the researchers have assumed that the Laser beam is perfectly distributed over the area of the circle. And that it is a perfect circle the first place.
In reality, it is widely accepted that this is not the case with most lasers. Lasers are known to emit a Gaussian Distribution where there is a hot spot in the very center and lesser intensity around the edges.
Then there are many lasers that don't even follow a Gaussian distribution, they have irregular distributions, or they aren't even perfect circles and are oval or irregularly shaped.
Researchers can employ not only power measurements, but devices called "beam profilers" that are designed to elucidate the true beam pattern of lasers. The Blog at Thor Photomedicine has much more detailed examples of laser beam profiles.
So even with a laser, we can start to appreciate the many layers of potential inaccuracies with assumptions about the intensity distribution.
Some studies have started to use truly uniform laser beams. The researchers note that they get much more consistent results with uniform beam distribution, rather than inconsistent results with Gaussian or haphazard distributions.[1]
An advanced form of analysis that can be done by 3rd party test labs is called Iso-Irradiance plots. The lab measures the total power output and true beam angle output and can calculate these isoplots of intensity.
3rd Party Isoplot Analysis of the GembaRed Overclocked Panel at 6 inches away.
The picture above shows the isoline analysis for the GembaRed OverClocked panel at 6 inches away. Think of it like a topography map except for intensity.
At the center, the green oval shows us the average intensity of 40 mW/cm^2 in that area, reaching a maximum at the center of the panel of 47mW/cm^2.
The red boundary line the intensity drops to 20mW/cm^2. So we can see even at the perimeter of the panel the intensity has already dropped by nearly half.
Then outside the perimeter, the purple line drops to 10 mW/cm^2, then the next green line is 5 mW/cm^2, then the outer brown line is only 1mW/cm^2.
So we can see even though the panel width is about 9 inches, we really only get about 12 inches of coverage. But the intensity outside of the perimeter of the panel dramatically decreases.
Accurate intensity measurements are the basis for safe and effective red light therapy dosing.
Now that we know red light panels have a much more complex intensity distribution, how do we properly use this knowledge? Should we adjust our dosing strategy?
Probably not. But like how laser studies have evolved to preferring uniform distributions, perhaps red light panels should consider the intensity distribution as an important part of the design.
Eye safety is interesting, for example obviously we wouldn't want to put our face in the middle of a panel and stare directly at it, since that is the highest spot of intensity. If we position the height of our panels just a few inches below the eye-line, that will help ensure we don't get as much intensity as the rest of the body, while still enjoying a low beneficial dose of indirect light to the eyes.
Using just one intensity number to represent an entire coverage area rarely shows the entire story. Especially when companies use solar power meters, only advertise the intensity of a single hot spot, and make outrageous claims about coverage area.
Lens Angle and Beam Angle have big differences that manufacturers need to learn so they don't mis-calculate the coverage area. The Beam Angle of panels should be measured by an accredited 3rd party lab so we can calculate more accurate coverage areas.
The beam distribution issue is not new to the LLLT community. There have been similar issues with Laser dot assumptions, however with LED Panels the intensity distribution can be much more complex because they have many light sources over a wide area.
Advanced analysis by professional 3rd party labs provides intensity distributions of red light panels similar to how lasers should be analyzed with beam profilers. It really shows us the "full story" when it comes to intensity distribution and coverage area. This is possibly the best way to start to fully understand intensity output from these devices.
Joovv had briefly posted their own isoirradiance analysis plots in 2019, however they must have realized if anyone ever figured out how to read the plots then they would have incriminated themselves. Since their own 3rd party isoirradiance plots showed their panels had an average intenstiy of 20mW/cm^2 at 6 inches away. Don't worry, we have the screenshots.
We can see Joovv posted isoirradiance plots of their competitors (RedRush 360 and SaunaSpace) on Ben Greenfield's blog, but they cleverly didn't publish their own product analysis to continue to obscure the truth about their own panels. Joovv still displays the SaunaSpace graph on their own website, but is too cowardly to offer a plot of their own product as a fair comparison. Notice the pattern of Joovv hiding the truth about their own products while discrediting others?
Most red light panel companies seem to be on a quest to come up with the most misleading representations of intensity and often coverage area. But we present a potential world where we can do deep analysis of red light therapy panels so we can properly understand dosing, safety, and effectiveness.
So let us know what you prefer; challenging technical analysis or convenient marketing lies?
[1]
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8346075/
]]>The signature feature of the next-next-gen red light panels is the inclusion of pulsing!
And handles on the back apparently.
As predicted in our previous blog on pulsing, the advent of Joovv incorporating a pulsed mode in their panels has led the way for copycat brands to start incorporating the same features.
The shameless "Equate" or "Kirkland" generic type brands of this industry like RedTherapyCo (RedRush) and infraredi are the first major brands to add pulsed features to their panels, and they will be generous enough to offer it at a lower price than Joovv. We expect Mito Red Light to be quick to follow.
Recently, we have found many Alibaba manufacturers are also adding pulsed features to their next-generation panels, which will soon trickle down to many more of the generic re-branders and resellers of panels.
We will review several of these next-generation pulsed panels from Alibaba later in this blog.
But first, a rant.
Several years from now, when most red light panel companies are offering pulsed modes, the average consumer will naturally assume that pulsing is the standard for red light therapy.
Similar to how people falsely assumed that standing 6 inches away is the gold standard, or that 660nm+850nm are the best wavelengths, or that >100mW/cm^2 at 6 inches away is a good idea - the way things are proven in this industry is if everyone just keeps repeating the same thing.
Regardless of what the science actually says, or what the products actually deliver. This industry is trapped in a painful cycle of not following the science, but instead just copying each other and leveraging marketing fallacies.
So we can stop and appreciate that we are witnessing a slow-motion example of how features become "standard" in this industry regardless of science.
Companies like Joovv are again reaching deep to extract studies on pulsing with completely different devices than their own - often lasers, LED pads, or cluster units held in contact with the skin.
Joovv has branded their pulsed mode as Recovery+. But remember we live in a society where a Footlong Subway Sandwich isn't actually a foot long, and an Oreo Double-Stuf cookie doesn't actually have double the stuff.
Those are just trademark names with no connection to the product they deliver - just like how Joovv can name something Recovery+ but not actually prove that it delivers superior recovery. In fact it could have less benefits.
Of course companies like Subway and Nabisco had to pay a lot for lawyer fees to defend their misleading naming convention. But Joovv's owners coming from the pharmaceutical industry know that we live in a society where paying fines and fees for false adverting are just a normal line item on the profit sheet.
The dead giveaway that a company is using pseudoscience to market pulsed panels is that they completely forget about the dosing parameters.
They will make claims about the pulsed light entirely on the Hz alone, but never mention the intensity or exposure time it takes to reach a beneficial dose.
The successful studies on pulsing will increase the peak intensity dramatically to offset the loss of power and penetration that pulsed modes inherently cause.
The peak power is not increased with pulsed LED panels, so randomly pulsing panels at any Hz will mostly work as a detriment to the dosing strategy.
For example, Joovv panel pulses only the NIR LEDs leaving the Red mode on as continuous. If we assume the duty cycle is 50%, that means the average power output in the Recovery+ mode is expected to be 75% of its total output, compared to the normal continuous mode.
In panels that pulse both Red and NIR, or if a user only uses the NIR of a Joovv in pulse mode, then the average power is expected to be only 50% of its potential power output.
The guidelines for companies selling pulsed panels would logically be to increase the exposure time to offset the loss of average intensity in the pulsed modes.
Which of course is contradicting the years of claims that more power equals less exposure time. Not that they ever proved the implied claim that "more power is better" anyway, so I guess it doesn't matter if they contradict an old claim that was never proven, with a new claim that will never be proven.
Without increasing the peak intensity or exposure time, what is called Recovery+ pulse mode would theoretically provide less benefits according to the science, not more.
Pulsing has traditionally been used to reduce the heat effects from higher-powered lasers and devices - which of course is mostly irrelevant to red light panels that we mentioned.
However, with many brands have been recklessly increasing intensity of their panels and more consumers are reporting skin redness, sunburn type effects, erthyma, skin burn sensations, skin peeling, pigmentation issues, "herx" reactions, and incredible warmth - then perhaps now pulsing can help reduce the detrimental effects of the high intensity panels.
If pulsed panels turn out to be more beneficial, it will be a testament to what we have been saying all along - that using less intensity is more beneficial than having "the highest intensity".
One study we stumbled across did note that they were intentionally using combined continuous and pulsed wavelengths in an effort to activate different cellular mechanisms. [3] Of course this study was with 808nm and 905nm light, not the cheap 660nm and 850nm LEDs that Joovv prefers.
This would be a good study to highlight a rationale for using both continuous and pulsed light in red light therapy panels, but instead Joovv lazily redefined the word "quench" to suit their marketing strategy.
Those who have pre-existing photosensitive epilepsy would need to exercise caution and possibly avoid pulsed red light therapy products. As well there may be more likelihood of other photophobia, photosensitivity, and flicker-effects like headaches, dizziness, nausea, anxiety, and other mood issues.
We note that Joovv, RedRush, and RedDot have all decided to only pulse the Near-Infrared (invisible) wavelengths to perhaps lessen the stress and discomfort that would be put on the eyes and the brain.
Did these companies really figure out on their own to only pulse the NIR for safety? Or were they mindlessly copying Joovv? Could there be some other reason they only pulse the NIR, hopefully something that was clinically studied?
The brain has been found to operate as several different "frequencies" named Alpha, Beta, Delta, Theta that corresponds to certain Hz that can be measured via EEG. If the brain is suffering from some disruption, then we can play god and force our brain into different states with modulating frequencies of light, sound, electrical stimulation, or PEMFs.
Many studies have used visible light flashing at 10Hz or 40Hz to induce brainwave entertainment. If red light therapy panels are only pulsing Near-Infrared, then they are sacrificing the most effective form of brainwave entertainment for safety. [1] [2]
Amazingly consumers still get good results from red light therapy panels. Not "because of" the diligent evidence-based products and protocols, but "in spite of" their blatant manipulation of science and falsely representing their products.
One author notes that the selection of pulse frequencies seem mostly arbitrary.[4] If the goal is to reduce heating by cutting the average intensity in half, this can be achieved with any random Hz frequency at a 50% duty cycle.
We could create the GembaRed Pulse frequency of 1234 Hz (also the combination for my luggage), and start experimenting on people by making outrageous claims for it. Some of those people will get good results, and we will start cherry-picking those testimonials to reinforce our magical healing protocol.
If you can obtain a red light therapy panel that pulses the red light, or any pulsed visible light product - you can prepare yourself for a psychedelic experience.
Yes, it is well-studied that flickering or pulsed light induces hallucinations. Not like a scary drug-induced situation, but the user will observe geometric patterns that are seemingly impossible.
My earliest experience with pulsed light several years ago - I noticed these unique geometric patterns with a pulsed 10Hz red light with my eyes closed.
Like any good engineer, after making an observation - I proceeded to research this phenomenon. I was amazed to find that many studies even had pictures and illustrations of the hallucinations that I was seeing.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1088430/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1895977/
Studies find that closed-eyes exposed to pulsing or flicker between 5Hz to 30Hz will evoke visual hallucinations. They note the frequency closest to the Alpha frequency (10Hz) is the most likely to induce the hallucinations, which confirms my experience. The researchers even liken it to an Altered State of Consciousness.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8248711/
Just search for terms like "flicker hallucinations" on Pubmed and you get 37 results, with many more studies in the references.
Here are a few more:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7741072/
https://pubmed.ncbi.nlm.nih.gov/11860679/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3182860/
It might be important for sellers of pulsed red light therapy to educate themselves on these flicker effects and hallucination phenomenon, so they can pretend like they are experts when their customers ask about their strange experiences.
Perhaps people who are susceptible to the influences of mind-altering brain-states would want to exercise caution if inducing hallucinations from pulsed light.
I was told that I am blacklisted from SGrow after my YouTube review where I point out how similar SGrow panels are to Mito Red Light.
Which didn't deter me from obtaining the new SGrow A1200 for this review, but only confirmed that SGrow and Mito Red Light are likely working together.
With SGrow offering the new A1200 and E2400 series panels with pulse and dimming features, we expect that Mito Red Light will soon release panels with similar features.
But hopefully they can correct the issues we found in the A1200 panel before it is released.
Lets take a look at these panels! We selected panels that would be similar size range to keep the comparison consistent. They are all similar to the standard "body-light" size panels of about 3 feet tall (36 inches, 900mm) and about 9 to 12 inches wide.
Generally the larger or smaller model of the same "series" from these suppliers will be proportionally more or less powerful. So feel free to decide which size fits best for you.
Price:
Price is tough while shopping on Alibaba, since you have to prepare yourself to incur the high shipping costs. I usually paid between $150 to $180 for the shipping cost of each panel on express shipping.
These are the prices that I paid for just the panels:
Red Dot RD1500W: $399
SGrow A1200: $259
Idea Light RL300MAX: $350
Sunglor SG-AL-1000: $448.9
SAIDI BS1000: $295
Dimmable:
Red Dot RD1500W: Red and NIR independantly, 0% to 100%
SGrow A1200: Red & NIR together, 25%, 50%, 75%
Idea Light RL300MAX: Red & NIR together - 1% to 100%
Sunglor SG-AL-1000: No
SAIDI BS1000: No
Pulse Modes:
Red Dot RD1500W: NIR Only - 1 Hz to 20 Hz
SGrow A1200: Both Red & NIR - 10 Hz, 20Hz, and 40 Hz
Idea Light RL300MAX: Both Red & NIR - 1 Hz to 9999 Hz
Sunglor SG-AL-1000: Both Red & NIR - 73 Hz, 146 Hz, 293 Hz, 587 Hz (Nogier frequencies only - I told them to add normal science based frequencies in the future)
SAIDI BS1000: Both Red & NIR - 1 Hz to 9999 Hz
Wavelengths:
I usually ask manufacturers for their "stock" or "standard" wavelengths for these reviews, but they could always have different variants or you can ask them for custom wavelengths.
Red Dot RD1500W: 660nm & 850nm
SGrow A1200: 660nm & 850nm
Idea Light RL300MAX: 660nm & 850nm
Sunglor SG-AL-1000: 630, 660, 830, & 850
SAIDI BS1000: 660nm & 850nm
Intensity at 12 inches away (continous mode):
Measured with our new prototype PBM Meter that is NIST calibrated specifically for the Red Light Therapy wavelength range.
We took the measurements at 12 inches away because they are all very high intensity and narrow beam angles.
Red Dot RD1500W: 62 mW/cm^2
SGrow A1200: 55 mW/cm^2
Idea Light RL300MAX: 64 mW/cm^2
Sunglor SG-AL-1000: 44 mW/cm^2
SAIDI BS1000: 73 mW/cm^2
EMF at 12 inches away:
Measured the Milligauss with an AlphaLabs UHS2 3-axis meter.
Red Dot RD1500W: 1.6 mG
SGrow A1200: 1.0 mG
Idea Light RL300MAX: 0.6 mG
Sunglor SG-AL-1000: 0.5 mG
SAIDI BS1000: 0.9 mG
*the Ambient mG reading was 0.38 with all of the devices off.
Flicker Percentage:
We do the flicker percentage measurement with the Radex Lupin.
Red Dot RD1500W: 1.1 %
SGrow A1200: 0.5 %
Idea Light RL300MAX: 0.6 %
Sunglor SG-AL-1000: 3.1 %
SAIDI BS1000: 0.9 %
As if measuring all of those parameters wasn't exausting enough, as we mentioned most companies selling pulsed panels are conveniently omitting re-taking all of these measurements again during the pulsed mode. Which is a tell-tale sign they are only interested in pseudoscience marketing tactics.
Are they trying to hide that the power and intensity dramatically decreases while pulsing? Yes.
Should we be concerned that the EMF potentially increases during pulsed mode due to the fancy electronics? Yes.
We know the flicker measurements will be expected to be 100%, since pulsing is just a fancy form of flicker especially in LED panels. Or we should say "temporal modulation of light" as the experts we have consulted call it.
Flicker and EMF: We know that flicker will be high since that is the point of pulsing. We were surprised to note that the magnetic field measurement actually decreases most of the time during pulsing mode. Which perhaps is due to the drop in power from the panels.
Just like companies should verify the intensity and wavelength of their panels with 3rd party measurements. They should at least verify if the Hz is correct.
When you set the panel to 40 Hz, then we should be able to measure a 40 Hz output.
This seems painfully obvious that companies should check this and deliver what the setting says, but remember we are in an industry where most companies still incorrectly advertise the most important parameter of red light therapy, intensity.
We can measure the Hz with our Radex Lupin meter connected to the PC software.
Red Dot RD1500W: Hz matches the setting
SGrow A1200: Hz does not match. 10Hz = 8Hz, 20Hz = 15 Hz, and 40Hz = 21 Hz. Watch the video.
Idea Light RL300MAX: Hz matches the setting up to 70, then at 71Hz and above switches to continuous output, also the Duty Cycle is super short which will be important later. Watch the video.
Sunglor SG-AL-1000: Hz does not match. Watch the video
SAIDI BS1000: Hz matches the setting up to about 400Hz, then above switches to continuous mode (or maybe that is a limitation of the flicker meter).
So we can see the disturbing results from the SGrow and Sunglor. If we wanted special benefits from 10Hz, 40Hz, or Nogier frequencies but the panel doesn't actually deliver the proper frequency output - then obviously you may not get the intended benefits. Especially for brainwave entrainment that can be a very bad thing.
The Idea Light panel does output the correct settings (only at the lower frequencies), but the duty cycle is very short. So you don't get the reduced heating or reduced average intensity like is expected from pulsed mode.
So even if you get a "pulsed" panel, the consumer needs to demand professional verification that they are even getting the Hz output that is supposedly programmed into the panel.
The consumed power is the electrical watts consumed by the panel. Sometimes called the "actual watts", where most of the panels will claim a number like 1000W, 1200W, or 1500W as a mostly meaningless "rated watts". Read our other blog about Watts for more info.
Red Dot RD1500W: 526 W Continuous, 427 W Pulsed - 19% Reduction
SGrow A1200: 401 W Continuous, 209 W Pulsed - 48% Reduction
Idea Light RL300MAX: 509 W Continuous, 466 W Pulsed - 8.4% Reduction
Sunglor SG-AL-1000: 396 W Continuous, 222 W - 44% Reduction
SAIDI BS1000: 365 W Continuous, 336 W - 7.9% Reduction
The consumed watts is usually directly proportional to the optical watts output, minus some inefficiencies and power to the fans and controller.
We can see the Red Dot, SGrow, and Sunglor behave nearly as expected. The Red Dot only pulsing the NIR mode means we expect close to 25% reduction and we observed 19%. The SGrow and Sunglor pulsing both Red&NIR we observed nearly 50% reduction, and the difference is likely due to those panels still using the same watts to power the fans and controller.
The Idea Light and SAIDI had barely any power reduction at only about 8% when we should expect 50%. We noted in the video about Idea Light that the duty cycle is very small, not the normal 50% duty cycle like most pulsed devices do. The SAIDI also seems to have a strange pulse waveform that could explain the lack of change.
So even when panels behave predictably, it gets very complex to understand if we should increase the exposure time to offset the loss of power. If panels use strange duty cycles or pulse structure, then how do we know if that is a good or bad thing?
When we see in a few years that many red light panels are offering pulsed modes, the average consumer will take for granted that the science has been settled. Like most things in Red Light Therapy, the science is not settled about anything like wavelengths or dosing or pulsing, nor do we expect it to be anytime soon.
The Pulsed LED Panels would theoretically need to increase the exposure time to offeset the loss of average intensity and power. Otherwise we could expect getting less benefits if they are dosed incorrectly.
Ultimately if pulsing is just a fancy way to reduce the intensity, then that will also serve to improve the benefits of Red Light Panels, which were getting too intense anyway.
Pulsing visible light is a double edged sword. It can offer superior brainwave entrainment and some interesting hallicination experiences. However, care must be taken by flicker sensitive people and those at risk of photosensitive epilepsy.
Reputable brands (if they exist) would need to do additional 3rd party testing, quality controls, and additional transparancy and education to properly implement pulsing. They could claim to deliver certain Hz, but the panel might not actually output it correctly.
Hopefully by reviewing these panels, educating the consumer, and providing feedback to the Alibaba suppliers early on, then we can attempt to improve the quality of the devices that are inevitbly re-branded by non-experts.
[1]
Tian T, Qin X, Wang Y, Shi Y, Yang X. 40 Hz Light Flicker Promotes Learning and Memory via Long Term Depression in Wild-Type Mice. J Alzheimers Dis. 2021;84(3):983-993. doi: 10.3233/JAD-215212. PMID: 34602491.
https://pubmed.ncbi.nlm.nih.gov/34602491/
[2]
Zheng L, Yu M, Lin R, Wang Y, Zhuo Z, Cheng N, Wang M, Tang Y, Wang L, Hou ST. Rhythmic light flicker rescues hippocampal low gamma and protects ischemic neurons by enhancing presynaptic plasticity. Nat Commun. 2020 Jun 15;11(1):3012. doi: 10.1038/s41467-020-16826-0. PMID: 32541656; PMCID: PMC7296037.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7296037/
[3]
Kuryliszyn-Moskal A, Kita J, Dakowicz A, Chwieśko-Minarowska S, Moskal D, Kosztyła-Hojna B, Jabłońska E, Klimiuk PA. The influence of Multiwave Locked System (MLS) laser therapy on clinical features, microcirculatory abnormalities and selected modulators of angiogenesis in patients with Raynaud's phenomenon. Clin Rheumatol. 2015 Mar;34(3):489-96. doi: 10.1007/s10067-014-2637-8. Epub 2014 May 13. PMID: 24820143; PMCID: PMC4348551.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4348551/
[4]
Tunér J, Hode L. Low-level laser on hearing: is there an effect? ISRN Otolaryngol. 2013 Nov 11;2013:839256. doi: 10.1155/2013/839256. PMID: 24319598; PMCID: PMC3844230.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3844230/
]]>
Hanging red light panels on doors is what made them such a viral "hack" for getting affordable full-body red light therapy. It is cheap, simple to set up, and can get you doing full-body red light therapy in just minutes.
However, we often notice that doors aren't always the best place to hang a red light therapy panel. Sometimes there aren't any convenient doors to put it on, the outlet isn't nearby, the cord causes a trip hazard, or the panel can flop around on a door especially if it is a high-traffic area.
An alternative would be to mount a hook or bracket to the wall, then hang the red light panel from the wall. This is a simple task that can be done by a handy-person. However, not everyone likes to drill holes in their walls.
Naturally we have seen a big demand for wheeled floor stands for red light panels. Some companies have made cheap and affordable brackets that sit on the floor, but then they portray consumers sitting or laying on the floor in front of them.
Large wheeled stands have become available but they often cost around $300 from most of the major brands. Even if you can source a red light therapy stand from Alibaba, the cost of shipping is very high because of the sheer size of the package.
However, upon looking closely at the stands being offered by many brands, they appear to be simply re-purposed TV Stands. These are easily obtainable on Amazon and other online retailers at very low prices.
The biggest downside to using a wheeled stand like we will show is that they take up a lot more space! The base of the stands are usually around 3 feet wide and 2.5 feet deep - and also can be a trip hazard if not placed out of the way.
We tested over a dozen TV stands and are recommending just a few of the best ones. The TV Stand kits come with large baggie of different sized screws which are compatible for a range of different TVs, but also that is what makes them adaptable to most LED Panels.
We didn't want to charge high prices for stands, or deal with the logistics and let stands take up our precious inventory space. So we found some stands on Amazon that are compatible with our panels, but also will work with many other panels on the market!
We will be recommending the PERLESMITH stand for the GembaRed OverClocked panel now!
Mobile TV Cart with Wheels for 32-85 Inch Flat Curved Screen TVs PSTVMC01
Assemble the TV Stand normally per the instructions included. Do not assemble the small tray table since that would get in the way of hanging the panel later.
Instead of mounting the bracket onto a TV, we mount it onto the back of the panel. The PERLESMITH includes an assortment of screws and tools to make sure it is compatable with a wide range of TVs, but also works for most LED panels that have mounting holes on the back like the OverClocked panel.
In the PERLESMITH kit the tools used for mounting the panel are F1, B1, and C1. For other kits or models then look at the dimensions of the washers and screws and spacers and use the appropriate sizes. The screw size for the OverClocked panel is M4.
Then simply hang the panel onto the assembled TV Stand!
The TV Stand does have instructions about how to adjust the height (remove the panel first before adjusting the height).
You can also use our Multiple-Panel guide in the below sections for how to get additional mounting brackets for cheap and then add more panels! You can get more GembaRed OverClocked panels, or mix and match basically any panels that have mounting holes.
The GembaRed Reboot panel, like many 1st generation body-lights, does not have mounting holes on the back for a TV bracket. So generally the Reboot panel works best if you are planning to mount it on the door or on a wall.
If you are planning using a GembaRed body-light with a stand, then we recommend getting the OverClocked panel instead.
However, there is a way to "MacGyver" the GembaRed Reboot to hang it on a TV stand.
Mobile TV Cart with Wheels for 32-85 Inch Flat Curved Screen TVs
https://www.amazon.com/gp/product/B07FXMX241/
For this stand you assemble it normally, and then for the Reboot panel you need to remove some of the screws from the back of the frame, or remove the back bumper. Then use those same screws to attach the mounting bracket.
You will need Metric M2 Allen Wrench (Hex head) screwdriver to remove the screw. Then fitting the screw back in can be tricky.
We recommend also getting new screws with slightly longer length than comes with the Reboot, and some washers to match. This way it can secure the Reboot to the bracket easier.
Here is the list of recommended tools:
2.5mm Allen Key - https://www.mcmaster.com/6958A12/
M3 Screws - https://www.mcmaster.com/97763A421/
Oversized Washers for the M3 Screw - https://www.mcmaster.com/98040A101/
2.0mm Allen Key for the new M3 screw - https://www.mcmaster.com/6958A11/
This makes the Reboot mounting not as easy as the Overclocked or other new-generation panels, but it is possible!
Some companies can sell large oversized panels, and this is where a heavy duty TV stand becomes very useful.
For example, these big stands are perfect for our new oversized GembaRed BFP 9000 full body panel!
Here are a few that we tested. Even these TV Stands they all seem nearly identical with different brands and packaging - similar to all of the rebranded panels we see in the red light therapy industry.
Mount Factory Rolling TV Cart Mobile TV Stand for 40-65 inch Flat Screen, LED, LCD, OLED, Plasma, Curved TV's - Universal Mount with Wheels
https://www.amazon.com/gp/product/B00RH46N6M/
NB North Bayou Mobile TV Cart Rooling TV Stand with Wheels for 32 to 70 Inch LCD LED OLED Plasma Flat Panel Screens up to 100lbs AVA1500-60-1P (Black)
https://www.amazon.com/gp/product/B00GQLLCTA/
These heavy-duty stands appear to be the exact same types being resold by red light panel brands for almost $300, as it is also helpful to use a heavy-duty stand for modular panel setups.
Here is a hack to hang multiple panels on a single stand. Especially if you have a variety of different panels from different manufacturers.
This setup seems to be the best for the widest variety of different brands of panels we have tested it on.
Start with the PERLESMITH wheeled stand that we referenced earlier for the Reboot panel.
Mobile TV Cart with Wheels for 32-85 Inch Flat Curved Screen TVs PSTVMC01
That kit only comes with one set of mounting brackets. So if we wanted to mount more panels, we don't want to buy more of the full-sized kit.
We tested a lot of different smaller kits just to find ones with brackets that would be compatible with that stand. Here are the 3 that fit, in order of lowest price at the top.
PERLESMITH Swivel Universal TV Stand / Base - Table Top TV Stand PSTVS09
https://www.amazon.com/dp/B07TK2KWVJ
TAVR Universal Swivel TV Stand Base Tabletop TV Stand
https://www.amazon.com/TAVR-Universal-Adjustable-400x400mm-UT1002X/dp/B07CGK9TN5/
PERLESMITH Universal TV Stand Table Top TV Base PSTVS11
https://www.amazon.com/dp/B07XLMQ39D
Here we can mount both a GembaRed Reboot Panel (left) and GembaRed Overclocked panel on the same stand!
This unfortunately means the rest of the stand kit goes unused. But even to get the stand and 1 of these kits to mount an extra panel, then you are still spending less than $300 on the whole setup.
End of Guide! Hope that helps everyone. Check out our YouTube video to see some of the stands in action!
Despite being an "Amazon Basics" product - this stand was put out of stock shortly after we made this guide and hasn't come back for months. We will keep this section here at the bottom in case it ever comes back.
The GembaRed OverClocked panel is a very practical size at about 42 inches tall by 9 inches wide. This is a great size for covering most of the body without being overly bulky or heavy.
We found the perfect compliment to the Overclocked Panel is the following stand from Amazon. It is a sturdy heavyweight stand, but isn't as much of an eyesore as many of the bulky stands offered by our competitors.
Amazon Basics TV Trolley for 24 - 43'' TVs with Swivel Feature, Black
Just assemble the stand as the instructions tell you to, then the only difference is that instead of mounting to a TV, the mounting bracket gets attached to the back of the panel.
We use the smallest screws that were provided in the kit, and bolted it right to the back of the panel with the provided washers. That is it, the only tool needed is a screwdriver!
The only downside to this particular stand is that it is limited by the height it can go up to. At the fullest height the OverClocked Panel reaches just over 5 feet from the floor, which is fine even for me at 6 foot tall and covering most of my torso and providing indirect light therapy to my eyes and face.
If you are much taller, then you might need one of the other stands mentioned below that can reach higher.
Like we mentioned these TV stands are Universal! So the kit comes with many different screws and mounting holes which could work for other red light panels you can find too.
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A big decision for science-minded consumers is which wavelengths to get in a red light therapy device.
The wavelengths are considered the “active ingredient” for red light therapy.
Where other parameters like intensity, time, and energy are considered the “dose” – we want to make sure we have the correct “active ingredient” or wavelength to treat the condition that we want.
The “standard formula” of 660nm (Red) and 850nm (NIR) is offered by nearly every red light panel brand. This creates a strong echo chamber and confirmation bias for the consumer.
These same brands will make claims like:
"we use best wavelengths of 660nm and 850nm"
"clinically proven wavelengths of 660nm and 850nm with over 4,000+ published studies"
These are bold claims that need to be broken down:
So far we haven't seen these claims definitively substantiated with relevant evidence, despite how often we see them repeated.
Recently, other wavelengths are becoming available like 630nm, 670nm, 810nm, 830nm, 880nm, 904nm, 940nm, 980nm, 1064nm, and others. In addition, red light therapy panels are offering 2 wavelengths, 3 wavelengths, 4 wavelengths, 5 wavelengths and more!
Naturally this creates some decision-fatigue and analysis paralysis when shopping for red light therapy products, and people might retreat to the “standard” wavelengths that are more familiar.
Worse, companies might only include 2-5% of an alternative wavelength in their panels, yet cherry-pick the benefits from single-wavelength studies that used that wavelength. Even the casual consumer can tell that this is a pseudoscience marketing gimmick, creating extra skepticism around the introduction of *new* wavelengths.
*note, these wavelengths aren’t actually new to the clinical science, they are just new to the commercial red light panel marketplace.*
Are adding new wavelengths really offering additional benefits? Or are they potentially “diluting” the popular formula and just a gimmick?
One 2020 study tells us the imperative for needing more multiple-wavelength studies:
“These questions are not new. Manufacturers are beginning to incorporate multiple wavelengths in their PBM devices. If combinations of wavelengths were found to have synergistic (or detrimental) effects on NO release, our results would have substantial implications for clinical applications.” [1]
The implication here is that the “manufacturers” are releasing multiple-wavelength devices, yet the science needs to catch-up. The worst possibility is that these combinations are detrimental, and not synergistic like is commonly assumed.
In this blog we will take a look at:
Lets dive into the literature and see what conclusions about wavelengths we can come up with.
We know that Joovv established their version of red light therapy about 6 years ago with extremely strong marketing campaigns. Even Joovv's initial claims of being "clinically studied" were undermined by their claims that their device was patent-able. Since, according to the definition, being patentable means the device is "novel" or "new" to the market, which also means nothing like it could have possibly been clinically studied before they existed.
Subsequent copy-cat brands came in and started offering similar red light panels as Joovv, including the wavelengths. Thus, we find ourselves in a marketplace saturated with 660nm+850nm combination panels, without much memory if those wavelengths were even rooted in science to begin with, or if the science has changed over the past 6 years.
Vladimir Heiskanen’s photobiomodulation database of 6,602 peer-reviewed articles (at the time of this blog) published in the literature holds some simple answers.
https://docs.google.com/spreadsheets/d/1ZKl5Me4XwPj4YgJCBes3VSCJjiVO4XI0tIR0rbMBj08/
Applying some search and filter functions for the “+” sign on the wavelengths column yields 379 results. So, we assume only 379 studies used multiple combined wavelengths, and the rest are single-wavelength studies (sometimes broad-spectrum studies too).
Using some search functions for “660nm + 850nm” yields us 27 results. Yes, out of thousands of studies, only 27 of them actually use these popular wavelengths together.
Only two of those 660+850nm studies were full-body light therapy. Both of those studies failed to show statistically significant improvement. No surprise both studies were released several years after Joovv existed.
The majority of the 25 other studies using 660nm+850nm used handheld clustered LED units held in contact with the skin. Which we know using skin contact is contextually very different than using a red light panel at 6 inches away.
It is rather disturbing to find that out of over 6,600 studies, only 27 of them used 660nm+850nm. Which seems to poke a hole in the claims that many red light panel companies have thousands of studies backing them up.
Going back to the basic mechanisms for Red and Near-Infrared quickly makes clear why we like to combine Red and Near-Infrared wavelengths.
The “Optical Window” for the skin is often referred to by the studies as the range between 600nm to 1100nm.[2] This range offers the best penetration of light of the entire “sunlight” spectrum, and is a primary reason why we use Red and Near-Infrared light for photobiomodulation.
And generally Red wavelengths have more superficial penetration, and NIR wavelengths reach deeper tissues. Which makes Red light preferred for skin care, and NIR is preferred to for deeper tissues like muscles and brain.
One study states the obvious clearly about why we combine Red and NIR wavelengths in devices:
protocols based on multiple-wavelength radiation sources can present a therapeutic advantage by providing concurrent energy delivery to biological tissues at different depths” [2]
Even from this rudimentary perspective, it is clear why we would combine Red and Near-Infrared wavelengths to help cover a wider range of penetration depths.
The mechanisms for how Red and Near-Infrared light are absorbed by our cells reveal more compelling reasons why we would want to combine wavelengths.
The most commonly accepted mechanism is that Red and NIR light is absorbed by Complex IV in the electron transport chain in the mitochondria.
When the enzyme Cytochrome C Oxidase (CCO) absorbs Red or NIR light, then it activates many beneficial mechanisms such as releasing Nitric Oxide, producing more ATP, beneficial ROS, DNA transcription factors, etc.
What is rarely mentioned is that there are also 4 different peak absorption ranges for CCO. [3] And each “peak” also corresponds to different biological states of the Copper (Cu) center of the CCO enzyme - 620nm, 680nm, 760nm, 820nm. One study tells us that the combination of copper states and heme centers gives 16 different possibilities for absorption bands. [2] [3]
More info about this chart is on this blog.
A 2016 review article on athletic performance summarizes why Red and NIR are often used in combination:
“It is important highlight the scientific rationale for the use of red and NIR wavelengths at the same time. Our research group already reported previously that irradiations with red and NIR wavelengths at the same time possibly offer advantages based on the absorption bands of the chromophores in the cells that absorb light, in special cytochrome c oxidase in the mitochondrial electric transport chain, resulting in even more synthesis of ATP than either red or NIR used alone.” [4]
Since we don’t know what “state” our copper molecules are in during treatment, it may be prudent to cover the range of wavelengths that can be absorbed into a variety of the 16 different possibilities.
Two other important mechanisms should be shared that impact our perspective for why we care about both Red and NIR light combined. And they primarily reside in the Near-Infrared region of the spectrum.
The first is that above 720nm+, water absorption slowly increases for longer wavelengths. Water absorption into interstitial mitochondrial areas is known to produce EZ Water (structured water) in the cells. This EZ Water improves cellular functions in similar ways as CCO absorption does. [3]
Perhaps related to the water-absorption – are the mechanisms of heat and light gated ion channels in the cells. This too is considered a primary mechanism for the near-infrared wavelengths. Referred to simply as IR (infrared) in the following quote:
“In addition PBM absorption of IR radiation by structured intracellular water, may produce additional changes in molecular vibrational energy and affect the tertiary conformation of enzymes, ion channels and other proteins.” [3]
Remember that all of this is on a “spectrum” of absorption ranges, where one study notes that 810nm wavelengths (in addition to having the best penetration), act on both the CCO and water absorption mechanisms. [3]
And we can appreciate in the graph above there is another valley of water absorption in the 1000-1100nm region, which is why 1064nm is gaining in popularity as an effective wavelength especially for deep penetration.
So particularly the Red-NIR range from 600nm-850nm focus on different CCO molecular states, while wavelengths above 810nm also impact water absorption and ion channels. [7]
We summarize all of these mechanisms of penetration depths, CCO absorption bands, water, and heat and light channel wavelengths are put together in a single chart below:
The Theraputic Optical Window for the Skin is 600nm-1100nm [study] [2][6]
The official definition of Red light is 600nm-780nm. The scientific definition of Near-Infrared is referred to more precisely as Infrared-A (IR-A) range is 780nm to 1,400nm. [IR-A Reference]
The Most Bioactive Ranges are Red Range 600-700nm and NIR 780nm-950nm. With 700nm-780nm being insignificant. [study]
The 600-850nm range is for ideal CCO Absorption [study]
Above 810nm+ Increases Heat and Light Ion Channel Activation [study]
Wavelength absorption above 720nm+ increases EZ water production [study]
One 2020 review article on the mechanisms of red light therapy really highlights the importance of understanding the different wavelength absorption ranges and their mechanisms.
"The application of red light (600–810 nm) is absorbed by the enzyme cytochrome c oxidase, which is located in the unit IV respiratory chain of the mitochondria. Nitric oxide (NO) is then displaced and activates the enzyme and this leads to a proton gradient. Consequently, calcium ions (Ca2+), reactive oxygen species (ROS), and ATP production levels are increased. On the other hand, the application of near-infrared light (810–1064 nm) activates light-sensitive ion channels, and increases the levels of Ca2+. ROS and cyclic AMP (cAMP)then interact with the calcium ions." [5]
We can quickly visualize from this chart that if we have multiple wavelengths that intersect several of these key regions of penetration and absorption, then we would theoretically be better situated for giving us the best probability for results with photobiomodulation.
The theory clearly points to the benefits of having multiple wavelengths, now let’s look at a few studies that actually compared multiple-wavelengths to single wavelengths.
For skincare a study found that simultaneous 633nm and 830nm wavelengths performed better than the individual wavelengths. [9]
A study on diabetic wound healing found that the 660nm and 808nm combined wavelengths performed synergistically over the individual wavelengths. [10]
The study on skin health noted that 633nm alone reduced melanin and improved skin brightening. The 830nm alone offered improved skin elasticity increase. Overall, the 633nm and 830nm gave the best objective and subjective results. [9]
Another interesting combination used often in studies is 808nm and 904nm. Where the 808nm is for the CCO absorption. and 904nm focuses more on water absorption. [12] The study notes this, similar to many of the multiple-wavelength studies:
“Two emissions are absorbed by different mitochondrial complexes and can affect cellular energy metabolism by acting on multiple sites in the cellular respiratory chain at the same time.” [12]
We can see from above that multiple wavelengths are highly regarded an improvement over the individual wavelengths, and these comparative studies used a variety of different wavelengths other than just 660+850nm and got great results.
Photobiomodulation relies on a range of wavelengths between 600nm to 1100nm that generally offer similar benefits to our mitochondrial function. Single-wavelength studies with a wide-variety of wavelengths have produced fantastic results and comprise the majority of the 6,600+ studies seen on the topic.
Some have assumed that the benefits of combining wavelengths is merely additive. That 850nm and 660nm simply gives you the benefits of each individual wavelength. When spun the other way by marketing experts, that means substituting “other” wavelengths would be a subtractive result.
However, one study suggests that we should be considering combined wavelengths as their own entity, rather than the composite of individual wavelengths:
"These results suggest that exposure to dual-wavelength radiation could produce different effects compared to those induced by single-wavelength radiation." [2]
So far, the combinations of multiple wavelengths have proven to be complimentary and synergistic, particularly when combining Red and NIR wavelengths that cover a range of different penetration depths and absorption chromophores including different CCO states and water absorption.
The researchers have been very optimistic towards using multiple-wavelength devices, which has only been limited by the prior technologies only providing single-wavelengths.
One study says it best:
“Possibly motivated by the desire to “get the best of both worlds” there has been an increased use of mixed red and NIR wavelengths recently made possible by newly developed clusters and arrays of laser diodes or LEDs for PBM.” [4]
Additional wavelength combinations of 3, 4, or 5 wavelengths are theoretically adding more penetration bands and have slightly different absorption targets – so we are essentially “hedging our bets” and increasing the odds of affecting the structures needed and increasing actions along different mechanisms simultaneously.
A consumer must naturally be skeptical of any companies that claim to have the perfect wavelength formula, whether it is the commercially popular 660nm+850nm or any new combination of wavelengths.
In addition, we can keep an eye out for gimmicky tactics like using a low % of alternative wavelengths, or using very narrow 30 degree beam angles or lenses with dramatic "hot spots". In those cases you may not be getting concurrent wavelength exposure as described in the literature. You would need to stand much further away to allow the concurrent wavelength blending.
Until we have more data, the science is not settled about the optimal wavelength combinations for photobiomodulation, and there is no overwhelming evidence that says the combination of 660nm and 850nm is the best in the first place.
Clearly 660nm+850nm has worked well due to its commercial success and easy accessibility to these mass-produced LED chips. As the technology evolves and new LEDs become available, we need to continually re-examine the science and question the “established” assumptions.
Overall, the studies we have reviewed imply that additional wavelengths are a welcomed synergistic benefit to red light therapy treatments, as long as they are in the effective ranges that have been identified.
[1]
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7423318/
Pope NJ, Powell SM, Wigle JC, Denton ML. Wavelength- and irradiance-dependent changes in intracellular nitric oxide level. J Biomed Opt. 2020 Aug;25(8):1-20. doi: 10.1117/1.JBO.25.8.085001. PMID: 32790251; PMCID: PMC7423318.
[2]
https://pubmed.ncbi.nlm.nih.gov/31523781/
Lima, Andrezza & Sergio, Luiz Philippe & Fonseca, Adenilson. (2020). Photobiomodulation via multiple-wavelength radiations. Lasers in Medical Science. 35. 10.1007/s10103-019-02879-1.
[3]
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5505738/
Tsai SR, Hamblin MR. Biological effects and medical applications of infrared radiation. J Photochem Photobiol B. 2017 May;170:197-207. doi: 10.1016/j.jphotobiol.2017.04.014. Epub 2017 Apr 13. PMID: 28441605; PMCID: PMC5505738.
[4]
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5167494/
Ferraresi C, Huang YY, Hamblin MR. Photobiomodulation in human muscle tissue: an advantage in sports performance? J Biophotonics. 2016 Dec;9(11-12):1273-1299. doi: 10.1002/jbio.201600176. Epub 2016 Nov 22. PMID: 27874264; PMCID: PMC5167494.
[5]
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8887026/
Austin E, Geisler AN, Nguyen J, Kohli I, Hamzavi I, Lim HW, Jagdeo J. Visible light. Part I: Properties and cutaneous effects of visible light. J Am Acad Dermatol. 2021 May;84(5):1219-1231. doi: 10.1016/j.jaad.2021.02.048. Epub 2021 Feb 25. PMID: 33640508; PMCID: PMC8887026.
[6]
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7356229/
Dompe C, Moncrieff L, Matys J, Grzech-Leśniak K, Kocherova I, Bryja A, Bruska M, Dominiak M, Mozdziak P, Skiba THI, Shibli JA, Angelova Volponi A, Kempisty B, Dyszkiewicz-Konwińska M. Photobiomodulation-Underlying Mechanism and Clinical Applications. J Clin Med. 2020 Jun 3;9(6):1724. doi: 10.3390/jcm9061724. PMID: 32503238; PMCID: PMC7356229.
[7]
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4348551/
For Red Light Therapy (Photobiomodulation), knowing the intensity is important to make sure it is not too high that could cause eye or skin damage. And of course, we don’t the intensity too low that the light therapy device has no effect.
Knowing the correct intensity allows you to properly calculate your dosage or exposure time especially if you are trying to follow a protocol seen in a clinical study.
Unfortunately, even if you bought from a “major brand” – you probably don’t know the real intensity of your red light therapy panel.
Nearly all brands (big and small) have used inaccurate solar power meters to false advertise the intensity of their LED panels, and are continuing to be misleading about intensity today despite knowing better.
However, in this blog we have devised a way to convert solar power meter measurements to more accurate numbers for intensity!
You will notice the Solar Power Meter units are in W/m^2, so just enter the whole number into our calculator, because it also converts it to mW/cm^2, in addition to the correction calculation.
Perhaps you purchased a cheap red light panel from a dubious reseller and need to measure the intensity yourself.
Maybe you are a red light therapy enthusiast and want to correlate the clinical science (where they never use Solar Power Meters) to your device and dosing protocol.
More likely; you purchased from a major brand who are surprisingly dodgy about sharing their true intensity measurements. They use asterisks, fine print, and sneakily reveal in their blogs that they are knowingly false advertising their intensity.
Many major brands are proudly brandishing solar power meters as their evidence for their intensity claims, but we know that solar power meters measure falsely high by a wide margin.
If an advertised claim is wrong by 2x; that is not just some mundane measurement error due to lack of standardization, that is false advertising.
There are standards for light measurements set by the NIST and IES that professional 3rd party laboratories do follow.
When cornered, brands will deflect and tell you that intensity doesn't matter anymore. Instead look at Total Watts or Fluence of J/cm^2 per minute - pay no mind to the fact that they are lying about intensity. Which of course is not only false, but contradictory to their own marketing where misleading intensity always has been front and center on thier product pages.
Our attempt with this blog is to present a breakthrough by using the same cheap solar power meters used for false advertising, and applying a correction calculation to make them more accurate.
We noticed a long time ago that most solar power meters measure about 2x the real-world intensity when measuring Red and Near-Infrared LED Panels.
As the name implies, Solar Power Meters are cheaply designed for a singular purpose of measuring full-spectrum sunlight. Solar Power meters use a silicone photodiode and they have more responsiveness when measuring longer wavelengths like Red and NIR light.
A typical silicone photodiode responsivity curve from Wikipedia Commons. Look closely how the sensitivity greatly increases as the wavelength it measures increases, especially around 850nm. [1]
So, when you try to measure an LED panel that has Red+NIR wavelengths with a solar power meter, it is not surprising that we get falsely high measurements.
Many laser power meters also use this same silicon photodiode technology, but apply correction factors based on the wavelength being measured and the sensitivity curve.
Solar Power Meters provide no such correction factor which further implies they were never intended for measuring red light therapy.
This is why we have 3 different calculators for Red+NIR, Red-only, and NIR-only.
Where we have occasionally heard some brands and "experts" claiming that NIR LEDs are much stronger intensity than Red LEDs, but that was due to the measurement error with the solar power meter sensitivity, and not a real phenomenon.
We knew ahead of time to design our experiment separating Red, NIR, and Red+NIR because we understand the reality of how these solar power meters really work.
Most Red Light Panel companies have measurements obtained by solar power meters. So, you can just request them to send you pictures of the measurements at various distances, and ask for the specific model of the solar power meter used.
For example, MitoRed provides many measurements with a Tenmars TM-206 solar power meter in their blog. So, you can just plug those numbers into our calculators and get a better estimation of intensity from their products.
This way, you don’t even need to buy your own solar power meter, just ask manufacturers to send you pictures of their measurements and then put those numbers into our conversion calculators!
Like any power measurement, even with expensive laser power meter brands, there are important contexts and limitations to consider.
That is why there are so many types of laser power meters, because they all have slightly different applications and limitations.
The older solar power meters tend to measure slightly lower than the new ones. Perhaps it is measurement drift, or that the units were calibrated slightly differently to begin with, or the conditions they have been stored or used.
Overall, the potential drawbacks and errors are minor, especially considering this is a big leap of improvement of accuracy versus not using any correction factor at all.
In fact, this method of using a Tenmars TM-206 with our conversion calculator is likely more accurate than our previous recommendations to use a Laser Power Meter. Since this new method derives a direct correlation between the Tenmars-TM206 and the 3rd party measurements, and we used the same wavelengths that are commonly used in LED Panels.
Data Analysis:
For the Red/NIR measurements we used a Gerylove COB light because that would eliminate issues if the Red and NIR is not perfectly mixed like in some panels with narrow beam angles or “hot spots”. It also has a wide angle beam so we could measure a wide range of intensities without needing large distances.
For the individual Red and NIR measurements we used a SAIDI BS301 panel for it's high intensity.
Taking the raw data, we compiled it into a Microsoft Excel spreadsheet. We make a simple scatter chart with the ILT950 (professional measurement) as the Y axis, and the Tenmars TM-206 measurements as the X axis.
Then we use the "fit trendline" function in Excel to produce an equation to fit the data. We found the polynomial equation gave the best fit (not a simple linear equation).
A good way to visualize the data is in the graph below, this time we put the 3rd Party Measurements on the X axis, and the corresponding Tenmars TM-206 measurements on the Y axis.
So we can see the experiment matches the theory here. The Red-Only measurements are lower than NIR-Only measurements because it is following along the sensitivity curve that we have shown earlier. The Red+NIR response predictably is in between those two responses since it is now a mix of both wavelengths.
The polynomial response (the slight nonlinear upwards curvature you see in the graphs) also validates why solar power meters have been very unreliable even for "comparison" purposes. Which has led many companies to make the false comparative statement that they were "Twice the Intensity as Joovv", but it was due to this non-linear response by the solar power meters.
For years we have recommended that consumers divide the advertised intensity numbers of red light therapy panels by 2, or if they are using a solar power meter then just to divide that number by 2.
That seemed unsatisfactory for many people, since people prefer to trust a number that appears on the screen of an unthinking machine. Especially if that number confirms their bias that they have a “powerful” product.
In engineering, scrutinizing measurements and applying logical interpretations to them is a normal part of the job. If we were to believe an inaccurate measurement, then massive problems inevitably arise.
With this blog, we spent a hefty chunk of money to have solar power meters professionally validated. Technically, we professionally invalidated them to show how wildly inaccurate they are.
“As you can see, there are significant differences between our ITL950 and all three of the meters. While these meters may work for solar irradiance measurements, they are not suitable for red, and particularly NIR measurements.”
However, by noticing a trend that solar power meters are consistently wrong by a predictable factor, then we can apply a correction factor to this measurement.
Even one professional laser power meter brand recently posted a video of how to apply a correction factor if their power meter is out of calibration or being used in a context that would knowingly alter the power measurement.
Applying empirical correction factors is a normal part of many engineers’ and scientists’ jobs, especially if it means improving an inaccurate measurement.
This is the first-ever side-by-side measurement comparison with solar power meters compared to a professional spectroradiometer.
By having a 3rd party take the measurements, it makes sure the comparison was conducted as accurately as possible and removes our bias from the situation.
And we hope consumers get some gratification by taking their own measurements and using our interactive calculators to produce more accurate results.
Don’t be shocked that the intensity numbers from your LED Panel are much lower than you expected after using these calculators.
The numbers are usually about half of what has been claimed or measured by a Solar Power Meter, which is what we have been saying for years.
You can look at Alex Fergus’ reviews which show that nearly all of the brands deliver much less intensity than they claimed (except us, but I guess we don’t get bonus points for being honest).
Now that you know more accurate intensity numbers for your red light therapy panel, you also need to “re-calibrate” your mindset about what is an effective amount of intensity.
The narrative of “you need >100mW/cm^2 to be effective” has been repeated by so many brands and affiliate influencers that it is hard to believe that companies are not only delivering much less than 100mW/cm^2, but that people are getting good benefits from those lower intensities.
Perhaps check our other science-based blogs for references to re-contextualize the intensity that you are actually getting:
These correction calculators should help red light panel customers obtain more accurate intensity measurements at a small fraction of the cost of getting a decent laser power meter or spectroradiometer.
Of course we always advise true professionals, experts, resellers, brands, and manufacturers to get 3rd party data from a certified light laboratory (and be honest about it). But this blog should help the average consumer or enthusiast to take more accurate intensity measurements.
Knowing the intensity is only half the battle. There are still big questions about how to properly “dose” red light therapy even if we know the true intensity. That perhaps the exposure duration, how often it is used, and distance used – all play important roles for proper dosing.
But we do know clear clinical information like how full-body red light therapy studies have never used anything higher than 50mW/cm^2 on humans.
Which means that companies claiming the “highest intensity in the market” with outrageous intensity numbers are also implying that their products have never been tested for safety and effectiveness.
This is why it is important to use these conversion calculators or more accurate power meters to help consumers understand the real intensity from red light panels.
Until companies start abiding by federal advertising laws to stop misleadingly intensity claims, we have offered a lot of tools and education to help empower consumers to measure and understand the real science on their own.
[1] KaiMartin
https://commons.wikimedia.org/wiki/File:Response_silicon_photodiode.svg
*used under Creative Commons Attribution-Share Alike 3.0 Unported license.
]]>Naturally, the opposing media have torn the entire notion of Red Light Therapy apart. That this prospect of “testicle tanning” is not only a scam and quackery, but potentially harmful when carelessly promoted. They theorize that the mere mention of alternative health modalities is part of a grand misinformation campaign.
Like most polarized news coverage, the truth usually resides somewhere in-between. Both sides have conveniently mis-represented the prospect of Red Light Therapy to serve their own bias and agenda.
Lets see if we can clearly define what they are even talking about, and if there is any credence to either sides’ claims.
If you are familiar with our blog you know that we dig into the peer-reviewed science available to us and see if there are any practical conclusions.
This blog will cover:
Lets get started with the first two sections trying to unravel what we think both sides are saying on this topic.
The right-wing media used the inaccurate term “tanning” when describing Red Light Therapy. It is clear from the documentary trailer they are using a“Red Light Therapy” panel device. There is no UV light that comes from these devices, and thus is in no way considered “tanning”.
The interviewee in the recent news piece, a fitness trainer named McGovern, was quick to plug his affiliated company’s name, Joovv, and laugh along with the incorrect terminology of “tanning”. He could have saved the industry a lot of embarrassment if he offered a polite correction to the misuse of the word “tanning” rather than focusing on endorsing his brand.
The “would you like to supersize your meal” moment also comes when McGovern up-sells us not only to treat the testicles, but your entire body. If curiosity got the better of you, then you would find that his affiliated company’s “Elite” full-body panel is currently selling for $9,499.00.
This is an unfortunate perfect storm of ways to misinterpret the very premise of “testicle tanning” that they are trying to promote. From using the wrong terminology like “tanning” to shilling a nearly ten thousand dollar system to treat an issue that isn’t even accepted as being a problem in the first place.
The other side of the media took no time to tear down the entire concept of “testicle tanning” to improve testosterone, and add that is could be unsafe.
Several articles including now WebMD have noted that there is no such thing as a “safe tan” due to the risks of developing skin cancer and melanoma. Which is purposefully misinterpreting the devices that McGovern was referring to because they do not emit UV, thus do not produce a tan or carry any risk of cancer.
In fact, a recent peer-reviewed article notes a slowing of tumor progression and reduction of associated inflammation in skin cancer in mice when treated with red light therapy. [1] As well, initial discovery of Red Light Therapy is attributed to Endre Mester in the 1960’s who failed to produce skin cancer in rodents, but instead noted the rodents had improved hair growth and healing.[2]
A more logical risk is connecting Red Light Therapy with excessive heating of the testicles. Naturally the testicles are outside the body to keep cooler, and heat is associated with declined function. The clever science-minded fearmongering will tell you that Infrared therapy is associated with heat, and that is bad for your testicles.
Late night television shows compared "testicle tanning" to dropping your balls in a toaster. Which evokes a powerful image of fearmongering, but is far from reality of comparing LEDs to a toaster.
However; Photobiomodulation, is by definition, the non-thermal application of light for biological effects. [2] The devices and research clearly prefer wavelengths in the range of 600nm to 900nm which are well-regarded as producing the least amount of heat in the body. We do find the range of 800nm to 900nm are indeed technically called “infrared”, but more scientifically known as Near-Infrared. Where Near-Infrared is not considered as heating, but it’s neighbor “Far-Infrared” is more commonly accepted as the heating range of wavelengths.
Thus we see the convenient conflating of “Red Light Therapy” with UV, Far-Infrared, and Heat – although it is technically none of those things, thus carrying none of the supposed risks. If you are still concerned about potential risks we have an extremely thorough blog of the potential risks and contraindications that have been noted in the research so far.
The science of Low Level Laser Therapy (LLLT), predecessor for what is now called Photobiomodulation (PBM), has taken off since the 1960’s. A quick search on PubMed.gov for a keyword like LLLT, a governmental website that aggregates peer-reviewed journal articles, will yield thousands of results. In fact, the trend is that more studies on LLLT and PBM are being published every subsequent year.
The mere reason that Red Light Therapy has even broached mainstream news is indeed due to its scientific and commercial successes recently. Readers of Mens Health are already familiar with the notion of applying red light therapy for testosterone support. And even a popular CNN article has touted the potential beneficial effects of red light therapy for the eyes.
Olympians have used Red Light Therapy for athletic performance and recovery in 2016. Red light therapy is regarded as such a large advantage in athletic performance that one peer-reviewed article notes that it should be addressed by the International Olympic Committee (IOC).[3]
A NASA LED device has been developed and tested for applications of pain management. Where is seems NASA had also been researching LED therapy for wound healing especially to offset the slow healing experienced in space.
The FDA has cleared or approved dozens of various “Red Light Therapy” devices for purposes of treating a range of conditions such as wrinkles, hair loss, and pain. Of course the FDA is the ultimate authority when it comes to determining if a medical technology is legitimate.
Although it is expected to have skepticism, red light therapy has been firmly established in peer-reviewed science for nearly 80 years with notable applications and approvals from NASA and the FDA.
Although Photobiomodulation has been established as its own science with some governmental regulatory nods, the application of photobiomodulation directly to treat testosterone gets flimsy. Of course there has not yet been any FDA filings for the usage of red light therapy for the gentiles, so we must tread lightly.
Reports of testosterone improvements by red light therapy have been mostly anecdotal in nature, and often touted by fitness influencers who have strong financial ties to the brands that they conveniently got the benefits from. Many of these fitness influencers were already quite healthy and fit before using this intervention, which is suspicious because the science tells us that healthy, young cells do not gain much benefit from photobiomodulation. [4]
Many of my competitors have already cashed in on this trend by writing “educational” articles about how red light therapy can boost testosterone. Although we want it to be true, the studies they reference are small and were conducted on animals, not humans.[5]
A more recent study used the same full-body red light therapy brand that McGovern was endorsing. They measured the testosterone levels in athletes before and after treatment with the full-body device. They found no statistically significant change in testosterone. [6]
Unfortunately the only science we have shows that there was no effect of red light therapy on testosterone. Of course we should remain open minded that more rigorous research should be conducted with larger trials and different contexts.
Red light therapy has does not have solid science for supporting testosterone, nor are there many reasons to specifically target male genitalia yet in the science.
So where would they have gotten this notion of “tanning” and testosterone in the first place?
There are well established positive associations between Vitamin D levels and testosterone in the scientific literature. [7] [8] Vitamin D is regarded as the “sunshine hormone” as it can be produced naturally by our skin from sensible sunlight or UVB exposure.
A properly researched UVB lamp or sensible sunlight exposure would have been more science-based to promote to support testosterone.[12]
A more recent December 2021 peer reviewed article looked at the association of Vitamin D deficiency, depression, and serum testosterone levels in middle-aged and elderly men. Due to the clear interrelationship of those 3 factors, the conclusion was that Vitamin D supplementation or sensible sunlight exposure could reduce depression associated with low testosterone. [9][10]
One study did use a form of “light therapy” which is instead known as Bright Light Therapy. They used 10,000 lux white light on subjects for 30 minutes per day between 7am and 8am. They found an improvement in testosterone levels, which they associated with the interaction between melatonin (which is directly modulated by bright light) and sexual hormones.[11]
Indeed even WebMD and several other news outlets at the time picked up and reported on the study with bright light therapy in 2016. There wasn’t as much of a political overtone or controversial stance as we are seeing now.
Although sunlight, Vitamin D, and bright light therapy have been associated with testosterone improvements, we cannot seem to find any peer-reviewed published research with actual red light therapy affecting testosterone in humans.
Red Light Therapy is indeed an exceptional wellness modality with rapidly expanding scientific research and ever-growing regulatory approvals. It is certainly not a fad and the interest will only grow in mainstream interest the coming years.
The term “testicle tanning” is very much a farce, in many aspects of the sensational phrase. It was incorrectly used to describe red light therapy, although it has no UV and does not tan the skin. As well there is not enough peer-reviewed published evidence that directly treating human testicles with any form of light therapy would produce a response in testosterone.
However, the science is clear that sensible sunlight exposure, being mindful of Vitamin D levels, and even Bright Light Therapy can support healthy testosterone levels. So, there is a shred of truth buried beneath all of the controversy and pandering. Of course, this sunlight and bright light exposure does not need to be applied to the testicles, those can be covered for modesty.
Red light therapy via LED panels is certainly safe, and quite possibly offers one of the safest forms of a “light therapy”. Since LED-based Red light therapy does not use UV which is associated this skin cancer, nor does it use Far-Infrared which is associated with heating tissue. LEDs are low cost and safer than the lasers that were predominantly used in the original research on LLLT.
When there aren’t highly-compensated influencers pushing their brands, LED light therapy can be quite affordable with “starter” level devices easily found on Amazon that people can try out.
Having proper expectations of what Red Light Therapy can and can not do based in rigorous science is the only way that this industry can gain mainstream acceptance. Hopefully this has helped clairfy this nuanced issue.
Toaster Photo by Photography Maghradze PH from Pexels: https://www.pexels.com/photo/toasted-bread-3997309/
[1]
Park, Hyeong Ju et al. “Treatment with Light-Emitting Diodes of Wavelength 863 nm Delays DMBA/TPA-Induced Skin Tumor Formation and Decreases Proinflammatory Cytokine Levels in ICR Mice.” BioMed research international vol. 2022 4400276. 23 Feb. 2022, doi:10.1155/2022/4400276
[2]
Chung, Hoon et al. “The nuts and bolts of low-level laser (light) therapy.” Annals of biomedical engineering vol. 40,2 (2012): 516-33. doi:10.1007/s10439-011-0454-7
[3]
Ferraresi, Cleber et al. “Photobiomodulation in human muscle tissue: an advantage in sports performance?.” Journal of biophotonics vol. 9,11-12 (2016): 1273-1299. doi:10.1002/jbio.201600176
[4]
Cardoso, Fabrízio Dos Santos et al. “Photobiomodulation of Cytochrome c Oxidase by Chronic Transcranial Laser in Young and Aged Brains.” Frontiers in neuroscience vol. 16 818005. 18 Mar. 2022, doi:10.3389/fnins.2022.818005
[5]
Alves MB, de Arruda RP, Batissaco L, Florez-Rodriguez SA, de Oliveira BM, Torres MA, Ravagnani GM, Lançoni R, de Almeida TG, Storillo VM, Vellone VS, Franci CR, Thomé HE, Canella CL, De Andrade AF, Celeghini EC. Low-level laser therapy to recovery testicular degeneration in rams: effects on seminal characteristics, scrotal temperature, plasma testosterone concentration, and testes histopathology. Lasers Med Sci. 2016 May;31(4):695-704. doi: 10.1007/s10103-016-1911-1. Epub 2016 Feb 25. PMID: 26914685.
[6]
Zagatto AM, Dutra YM, Lira FS, Antunes BM, Faustini JB, Malta ES, Lopes VHF, de Poli RAB, Brisola GMP, Dos Santos GV, Rodrigues FM, Ferraresi C. Full Body Photobiomodulation Therapy to Induce Faster Muscle Recovery in Water Polo Athletes: Preliminary Results. Photobiomodul Photomed Laser Surg. 2020 Dec;38(12):766-772. doi: 10.1089/photob.2020.4803. PMID: 33332232.
[7]
Nimptsch K, Platz EA, Willett WC, Giovannucci E. Association between plasma 25-OH vitamin D and testosterone levels in men. Clin Endocrinol (Oxf). 2012 Jul;77(1):106-12. doi: 10.1111/j.1365-2265.2012.04332.x. PMID: 22220644; PMCID: PMC3712348.
[8]
Tak YJ, Lee JG, Kim YJ, Park NC, Kim SS, Lee S, Cho BM, Kong EH, Jung DW, Yi YH. Serum 25-hydroxyvitamin D levels and testosterone deficiency in middle-aged Korean men: a cross-sectional study. Asian J Androl. 2015 Mar-Apr;17(2):324-8. doi: 10.4103/1008-682X.142137. PMID: 25532570; PMCID: PMC4650484.
[9]
Amini S, Jafarirad S, Abiri B. Vitamin D, testosterone and depression in middle-aged and elderly men: a systematic review. Crit Rev Food Sci Nutr. 2021 Dec 14:1-12. doi: 10.1080/10408398.2021.2015284. Epub ahead of print. PMID: 34904472.
[10]
Pilz S, Frisch S, Koertke H, Kuhn J, Dreier J, Obermayer-Pietsch B, Wehr E, Zittermann A. Effect of vitamin D supplementation on testosterone levels in men. Horm Metab Res. 2011 Mar;43(3):223-5. doi: 10.1055/s-0030-1269854. Epub 2010 Dec 10. PMID: 21154195.
[11]
D. Koukouna, L. Bossini, I. Casolaro, C. Caterini, A. Fagiolini,
P.4.b.010 - Light therapy as a treatment for sexual dysfunction; focus on testosterone levels,
European Neuropsychopharmacology,
Volume 26, Supplement 2,
2016,
Page S606,
ISSN 0924-977X,
https://doi.org/10.1016/S0924-977X(16)31685-6.
(https://www.sciencedirect.com/science/article/pii/S0924977X16316856)
[12]
Dabai, Nicholas S et al. “The effect of ultraviolet radiation from a novel portable fluorescent lamp on serum 25-hydroxyvitamin D3 levels in healthy adults with Fitzpatrick skin types II and III.” Photodermatology, photoimmunology & photomedicine vol. 28,6 (2012): 307-11. doi:10.1111/phpp.12000
]]>
To figure out how often to use red light therapy, we must understand important concepts like the Cumulative Dose and Rest Periods between doses. We will dive into the important mechanisms of how red light therapy works after a treatment has ended.
Although these concepts seem to be common-knowledge in the scientific literature, we have seen very little coverage of these important aspects of proper dosing protocols in other blogs.
We will cover:
Perhaps you received a red light therapy device with some guidance for the distance to stand away from the panel and how long to use the panel. However, the guidelines on “How Often” we should use a red light therapy panel at home often seems vague.
By now, many of our readers appreciate the intricacies of intensity, time, energy fluence, and even skin contact for an effective dose of red light therapy. However, it is often only implied that Red Light Therapy should be administered at a routine interval.
One study that we will be referencing explains it nicely:
“While selection of the correct wavelength and power density (W/cm2) is important, consistent application of the necessary dose (energy density or fluence: in joules per cm2 [J/cm2]) is required if the best therapeutic effects are to be achieved.” [1]
This is a profound statement that reminds us that we need consistent applications of red light therapy to achieve the best benefits, and perhaps we often get too fixated on the individual parameters of a single dose.
But now we have opened yet another can of worms. It begs the question of what we define as “consistent application”?
Should we do red light therapy only once a day or can we do it twice a day? Is 3 times a day is too much? Perhaps we should only do it once every other day? Once a week? Or once a month?
Remember the Biphasic Dose response of Red Light Therapy tells us that too little of a dose leads to no response, but too much leads to an inhibitory response. We usually want to stay in the beneficial middle-range called the stimulatory response.
Does the Biphasic Dose Response play a role in how often we should use Red Light Therapy? Logically, if we do 10 doses a day, that seems like too much. Will the cumulative dose force us to cross the threshold into a lack of benefits?
Looking at it another way, we ask how long should we wait in between red light therapy treatments? If we “pause” a treatment for 5 minutes and then return to finish it, then logically we would consider that as a continuation of the original treatment. If we wait 12 hours to return to the treatment, then perhaps that is a new dose all together.
This helps formulate our concept and definition of Cumulative dose for red light therapy. Where the cumulative dose describes the raising level of red light therapy effects that accumulates across multiple doses during a relatively short time span.
Cumulative dose is probably a new term for most people in this Red Light Panel industry, since it also implies that we need to restrain ourselves from excessive treatments or too high of a dose. Which may hurt the bottom line of some business models that promote “more is better”.
Although the dosing interval has not been thoroughly studied in the science, once again we have dug up many interesting articles that can help us provide a framework of understanding of this important aspect of Red Light Therapy dosimetry.
Let’s jump right into defining and explaining what the Cumulative Dose is, since that is the crux of what we need to understand for the correct dosing interval.
Cumulative Dose tells us that there is a building or stacking of effects in the body that accumulate across separate treatments. Especially if doses of red light therapy are administered multiple times in one day or on consecutive days.
One study informally defines the cumulative dose as:
“The dose from one treatment lasts some time and what “remains” of the dose is added to the dose at the next treatment. Adequate time between doses is essential to allow the cells time to respond to the initial dose and will also avoid a situation where the accumulated dose eventually ends up above the bio-stimulating range or even in the bioinhibitory range, with consequently poorer results.” [1]
Another study tells us this about cumulative dose:
“this therapy produces effects on muscle tissue lasting 24 to 48 hours, suggesting possible cumulative effects if applied repetitively.” [2]
Now that we have roughly defined what Cumulative Dose is, let’s take a look at some of the science that explains why it is so important.
Thinking about Cumulative Dose forces us to appreciate that Red Light Therapy is doing its work in our cells long AFTER the treatment session has ended. The typical western mindset makes us assume we are only getting benefits DURING the treatment, but this certainly is not the case.
Remember that upregulated Adenosine Triphosphate (ATP) production in the mitochondria is the principal mechanism of benefits for doing red light therapy in the first place. However, has anyone told you that the ATP increase not only happens during treatment, but ATP production is increasing to a peak at about 6 hours after the Red light therapy session ended? They can still find remains of the effects of the LED therapy up to 24 to 48 hours after the dose was administered! [2] [3]
Cytochrome C Oxidase (CCO) enzyme activity is also considered a primary mechanism for red light therapy. Researchers have repeatedly found elevated activity of CCO for 24 hours AFTER treatment ended. [4]
Even more metabolites of red light therapy effects found 24-48 hours after treatments include Nitric Oxide (NO), Heat Shock Protein (Hsp70), Interleukin-2 (IL-2) and Calcium release. [1][5]
Some studies have graphed or visualized the cellular response in a similar way that we show below.
In the graph above, after a single dose of Red Light Therapy there are several cellular responses that peak several hours after treatment. Then the response tends to diminish back to baseline after about 48 hours. Keep this graph in mind for the next section.
Similar to the rest periods between exercise, where after exercise many of the repair mechanisms take place for building muscle tissue – we should also be considering rest periods between red light therapy doses.
Let’s say we are doing a daily dose of red light therapy, exactly every 24 hours we do another dose. According to our theory in the previous section, many of the cellular responses like ATP, CCO, NO, and Calcium are still at an elevated level. Since it perhaps takes over 48 hours for those effects to subside.
Now we have a building of these cellular responses and the cumulative dose starts to take over.
The graph above, which is similar to the graphs seen in PocketDentistry.com and this study, shows us how the cumulative dose of stacking cellular effects could start to cross the line into the inhibitory region. [1]
Ideally, if the doses are adequately spaced apart, there is less risk of the Cumulative dose crossing the line to the cellular inhibition range.
Several studies, usually longer-term studies, have mentioned that they are particularly mindful of not allowing the cumulative dose to reach a point of cellular inhibition, meaning they crossed the line to the higher end of the biphasic dose response.
For our all-important ATP production, one study noticed a biphasic dose response as the cumulative dose progressed. Obviously, it is quite important to keep our most important biomarker of red light therapy effectiveness in the stimulatory range.
“The ATP results support published findings that suggest that the cumulative dose administered determines the biostimulatory or bioinhibitory effect of the laser irradiation.” [1]
One long term study on muscle performance had this to say about the possible negative response from the cumulative dose.
“It could be envisaged that cumulative exposure or excessive light doses could produce an inhibition or a lack of positive effects on human skeletal muscles based on the biphasic dose response” [2]
Another study mentions the possible danger of the suppressive effects when a treatment is administered repeatedly (chronically) every other day for 30 days.
“…showing the depletion in the adaptive cell response under increased cumulative dose. Similar effects were observed for the NO and IL-2 production. Taken together, these dose response relationships show the risks of possible danger of chronic treatment with the low-energy laser light.” [5]
Another study has noticed the potential issue that clinical doses combined with too much sunlight exposure in one’s daily lifestyle may affect the cumulative dose, thus leading to a biphasic dose response.
“Equally, the potential of sunlight to deliver significant light doses of red to near-infrared wavelengths means that additional exposure to sunlight might need to be restricted when using LED or laser light sources to deliver controlled light doses. Given the reported biphasic response of some models to light therapy (Huang et al., 2011), too much light may be as ineffective (and possibly even detrimental) as too little light. We think that this is a potentially important aspect of light therapy that has been somewhat overlooked with respect to clinical use.” [6]
As far as we can tell, the cumulative dose response has indeed been largely overlooked in the current state of this industry.
Many studies on red light therapy have been short-term, and have used higher doses to illicit a healing response in just a few treatments. Which is a big opportunity for manufacturers to cherry-pick the higher-intensity and higher-dose studies to sell their overpowered products.
However, with the cumulative dose and biphasic dose response in mind, some researchers reconsider the intensity and dose to lower levels when designing longer-term studies.
One study noted that while a single treatment for TBI in rats was effective at 50mW/cm^2 and 36 J/cm^2, for the longer-term study they decided to use only 25 mW/cm^2 and 18 J/cm^2 per dose. [7] That is a dramatic difference of cutting the dose and intensity per session in half, simply because the researchers were concerned of the biphasic dose response of the cumulative doses.
This is also very clever because they acknowledge the importance of time and they didn’t want to simply cut the dose and the time in half. They wanted to cut the dose in half, but keep the time the same. So, they also reduced the intensity.
These are a very important considerations, that using a device longer-term (like a red light panel that you own at home and plan you use for many years) should consider either spacing the dose apart further, or decreasing the intensity and dosage. Whereas most of the dosing recommendations you have received so far have likely come from shorter term studies so companies can upsell you on higher intensity products.
Not to worry, most human studies on Red Light Therapy do not report negative outcomes based on cumulative dose response. As shown earlier, researchers are mindfully designing their protocols appropriately to avoid too much cumulative dose.
Here we will take note of a few long-term studies and how often they used their devices.
Hair Growth Dosing Interval:
Skin Dosing Interval:
A recent long-term at-home study for reducing wrinkles around the neck used daily dosage frequency. They reported an improvement in skin, but more importantly noted that there was no long-term issues for thyroid function. Now that you understand the cumulative response, this is a very good thing that the thyroid was safe for daily treatments of red light therapy in this case. [9]
Athletic Performance Interval:
Brain Interval:
At Home Devices Review:
One publication reviewed all articles on at-home usage of red light therapy. They noted that most of the treatments were done daily. Although one study was done twice a day and another was 3 times a day. [11]
Full-Body Red Light Bed Interval:
The only long-term study protocol (just a protocol, not yet conducted) for full-body light therapy plans to use a full-body pod to treat fibromyalgia syndrome 3 times a week. [13] Obviously, they haven’t completed the study yet, but at least this shows the researchers have confidence that 3 treatments per week should be sufficient to treat this condition.
However, we might assume they only do 3 times a week for the convenience of the patients to not have to drive to the clinic too often. Perhaps if they had at-home units they might want to do it more often.
In the course of understanding "how often" we should do red light therapy revealed some very important concepts. We learned about the cumulative response, cellular effects after treatment, biphasic doses across multiple treatments, how longer-term treatments may reduce the intensity or dose per treatment, and looked at some real examples of long-term repeated dosing protocols.
Here are a few of the conclusions of optimal dosage protocols we can be confident about:
We postulate that many of the “high intensity” panels on the market may give customers instant gratification with feelings of warmth and benefits that come quickly. However, they should be mindful of the long-term effects of repeated usage, and take note if there is a decline in those benefits over time. That would be the inhibition taking over per the cumulative dose concepts we learned here.
While there still is a lot we need to learn about proper dosing protocols, it is clear that daily usage of low intensity red light therapy can be the ideal way to do treatments. If you are short on time or do higher intensity, then perhaps only 2-3 times a week is sufficient. Typically for only severe or acute issues would do treatments more than once a day.
As with most of our blogs, it is a story of moderation with dosing red light therapy. This time we need to consider how red light therapy affects us across multiple doses with long-term usage. We don’t always give you an exact prescription, but these are important mechanisms to be aware of so you can customize your dose to make red light therapy work for you.
[1]
Hawkins D, Abrahamse H. Effect of multiple exposures of low-level laser therapy on the cellular responses of wounded human skin fibroblasts. Photomed Laser Surg. 2006 Dec;24(6):705-14. doi: 10.1089/pho.2006.24.705. PMID: 17199470.
https://pubmed.ncbi.nlm.nih.gov/17199470/
[2]
Ferraresi, Cleber et al. “Effects of Light-Emitting Diode Therapy on Muscle Hypertrophy, Gene Expression, Performance, Damage, and Delayed-Onset Muscle Soreness: Case-control Study with a Pair of Identical Twins.” American journal of physical medicine & rehabilitation vol. 95,10 (2016): 746-57. doi:10.1097/PHM.0000000000000490
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5026559/
[3]
https://pubmed.ncbi.nlm.nih.gov/25700769/
[4]
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]]>LEDs are the wave of the future for lighting due to their high efficiency, long lifespan, and economical costs. However, there has still been uncertainty in the health community if LEDs can be safe to use at home. Many influencers have preached that LEDs are inherently and irredeemably dangerous for several reasons.
Can we find high quality LED bulbs that are a safe alternative to Incandesent?
However, it isn't practical anymore to stockpile banned incandescent bulbs, or smuggle them into your home from other states or countries. LEDs aren't just the future, they are the present! Its the year 2022! We need to find a way to embrace LEDs and promote the brands that are making healthy lighting.
So we decided to compile a list of some of the healthiest LED light bulbs, and along the way explain why they are much healthier than their problematic predecessors from a decade ago.
Although this blog isn't specifically about red light therapy, interest in Red Light Therapy often acts like a gateway drug that makes people realize that all of the lights around them can be important for their health. They may even be more open minded to how even more fringe health effects like from EMFs or pulsing.
Many people realize that excessive blue light disrupts our circadian rhythm and can cause declining eyesight. On the other hand, Red Light Therapy is becoming newsworthy for it's potential eye benefits. The irony is that we could be improving our eyes every morning with 670nm lights, and then throughout the day accosting our eyes with blue-rich LED lighting and digital screens.
Especially in the "new normal" where many people are working from home and realizing that they need to improve their light bulbs in their office. The right light bulbs will provide energy and alertness, the wrong lighting can cause tiredness and anxiety.
We already have a blog post on the best ambient red light bulbs for sleep, and due to popular demand we have compiled a list of the best white LED light bulbs!
Here are the bulbs we tested (actually we tested a lot more, but these are the good ones). Ranked from best to worst in terms of overall performance (not price) according to our testing and preferences.
Click the name of the bulb mentioned to see where to purchase it!
2700K Category:
3000K Category:
*CRI measurements were performed with a HopooColor 0HSP-350SF and flicker percentage with a Radex Lupin meter.
The 2700K Bulbs (left) will have a slightly more "yellowish" hue, giving it the name "warm white" and also confirming it is low in blue light. 3000K bulbs (right) have a bit more blue light and have a nice balanced "soft white" color to it.
You can watch many of our measurements on our YouTube video!
Runner ups: The TCP Elite bulb and Sunlite LED bulb both have impressively low flicker of less than 1%, but only have mediocre CRI of 80.
Tested but excluded: We tested the GE Relax and Feit Electric bulbs which got good reviews on other sites like Wirecutter and CNET. They offer good CRI values and low Kelvin, but our testing of flicker showed they were too high.
Excluded: We might have tested Hyperikon LED bulbs but apparently they are out of business now, and according to some pictures we have seen online they seem to have high flicker also.
Usage Tips: Don't just choose bulbs entirely based on our "top" ranking.
Lower wattage (40W equivalent) and lower kelvin (2700K) is more ideal for bedrooms, living rooms, bedside lamps, or anywhere you will be in the evenings.
Higher wattage (60W or more) and kelvin (3000K) would be better for office, kitchen, studio, task lighting, and working areas during the daytime.
Higher wattage provides more lumens (brightness) which may be needed for bigger rooms. Lower wattage provides less lumens (brightness) which is important to use in bedrooms and bathrooms and living areas.
We mention high quality dimmable bulbs later in this review.
No matter what type of bulb from Incandescent to LED, we want similar criteria to determine the quality and usability. Our top requirements are:
Color Temperature tells us how well the light bulb simulates an incandescent "black body" spectrum. For example a typical incandescent bulb is 2700K, and sunlight at noon is about 5500K.
So especially for LEDs, we want lower Kelvin which helps minimize the blue light that many people have had issues with LEDs in the past. For this review we mostly selected 2700K LEDs as it usually has a natural feeling balanced spectrum that is lower in Blue light. But for office areas during the daytime the 3000K versions might be better.
The graph above shows the dramatically increasing "blue peak" as you use higher-kelvin bulbs. Typically sticking to only 3000K or 2700K is important to reduce the blue light exposure.
CRI is the Color Rendering Index. This tells us how "complete" the spectrum is for a light, and if it is deficient in any colors. This can lead to an unpleasant viewing experience or feeling unnatural. Sunlight has a CRI of 100, Incandescent is 99, and generic LEDs are 80. LEDs usually lack some of the deeper-red wavelengths, leading to the poor CRI of only 80. For this review all of the LEDs we recommend are higher than 90 CRI or higher which gives us more of those important Red wavelengths (especially which can balance the blue light).
The graph above shows the peak of Red moving to longer wavelengths with higher CRI. So for this context, higher CRI means getting proportionally more longer-wavelength Red light, which tremendously helps balance the blue light exposure further.
Flicker is one of our favorite topics we covered in depth in a previous blog. LEDs have been historically demonized for being high flicker. Of course sunlight is a continuous, no flicker light source. Generic incandescent bulbs are usually 6 to 12% flicker. The LEDs we recommend in this ranking have LOWER flicker than typical incandescent bulbs.
Some of the LEDs we found are almost indistinguishable from incandescent bulbs in terms of color quality, and have less flicker! On the left is an incandescent bulb. The middle is Sylvania LED, and on the right is the Satco LED. All are 2700K.
LEDs typically don't have much issues with emitting unwanted EMFs, unlike some of the fluorescent predecessors with magnetic ballasts. However, there can be some "dirty electricity" because LEDs utilize electronics that rectify the AC to DC to power the LEDs (and this is how LEDs eliminate flicker). Typically this isn't a big issue as the dirty electricity travels through the walls and out the neutral wires. If you turn your lights off at night, they don't emit anything while you sleep. However some health enthusiasts may still find a concern with this so we test it anyway on our YouTube videos! Those same health enthusiasts should know they can also easily clean up the dirty electricity with dirty electricity filters from Greenwave, Stetzer, and Satic. Which also cleans up the dirty electricity coming from your neighbors, the power grid, TVs, computer adapters, USB chargers, and other appliances.
Waveform Lighting and Yuji lighting offers some of the most ideal light bulbs to meet the above criteria. They offer Low Kelvin, Low Flicker, and Very High CRI bulbs. These criteria aren't necessarily made for healthy people, but because they are important for Videography! Poor color rendering (CRI) and flicker can be devastating to photographs and video quality. However, people can benefit from these high quality LEDs too!
However, there are a few drawbacks to their Waveform and Yuji LED bulbs.
The standard Waveform lighting bulb we use is a 10 Watt, 800 Lumen, 60-Watt Equivalent bulb. This is great for bigger rooms. But smaller rooms, bedrooms, bedside lamps, and even bathrooms can easily be overpowered by brightness.
That is why you will find many of the other LEDs we chose for this review are lower watts, 450 Lumens, 40-Watt Equivalent bulbs. So even if the Waveform lighting bulbs are superior in many categories, it is often better to use a lower brightness bulb in some parts of the house.
The high expense of $18-20 per bulb is self-explanatory why this is a problem, especially to outfit an entire house with them. Some areas of the house might not need so much brightness, or other areas aren't critical to have super sophisticated bulbs in.
The real quest for this entire blog was for us to find suitable substitutions for our Waveform Lighting bulbs, especially where cost and brightness is a problem.
Often times we fear that LED bulbs will exacerbate their flicker and EMF issues when you attempt to dim them. This is because the electronics in LEDs may not be compatible with the old dimmer switches that were designed for incandescent bulbs.
This may have caused massive (visible) flicker and EMF noise with older LEDs and CFLs which weren't designed right for dimmer switches. But now we have found several LED bulbs that perform exceptionally without significant flicker!
2. Sylvania TruWave series
The GE bulb that ranked #2 above starts out with low flicker and continues to be low flicker even when dimmed!
The Sylvania TruWave series uses impressive technology where the flicker actually reduces while dimming! They offer a very wide range of dimmability even with old style dimmers. All of the Sylvania bulbs in our first list are the Truwave series, or just search for them on LightBulbs.com
Watch our video on the best dimmable LED bulbs on YouTube!
There was a push by many health influencers to demonize LEDs and revert back to incandescent. However, many of the original problems with LEDs have been resolved. Or quite frankly, the health influencers didn't really try very hard to find high-quality LEDs.
We have shown repeatedly that LEDs actually can have less flicker than incandescent bulbs. The high amount of Blue light from LEDs is easily avoided with either low Kelvin, High CRI bulbs, or simply using an Amber, Orange, or Red LED bulb entirely.
Early introductions of Fluorescent, CFL, and LED bulbs did have problems with EMF interference, dirty electricity, and flicker. However, most notoriously this was a problem with the CFL style bulbs and these fears carried on towards the LEDs. And now in 2022 there are regulations and standards for LEDs to be lower in flicker, and not emit any disruptive EMF per FCC and CE requirements.
As well the Materials of Concern (MOC) with mercury being used in Fluorescent bulbs were also giving rise to concerns in LEDs. LEDs certainly do not contain mercury, as well they must be compliant with RoHS, REACH, and other directives to not contain heavy metals which may be bad for disposal in the environment.
We do think that incandescent heat lamps can be used therapeutically in close proximity to the body, but it isn't very practical to use incandescent bulbs for general lighting. They tend to high higher flicker than the LEDs we recommend, need to be replaced often, and waste electricity.
With incandescent bulbs being phased out and even banned in some regions, finding healthy LED lighting is more important than ever.
We know many LED lights have been problematic in the past for blue light emissions, flicker, EMFs, and unpleasant light spectrum. The "healthy" LEDs seemed to always be too expensive and packed with more marketing gimmicks than focus on the important criteria (remember SORAA?).
Here we dug through dozens of LED light bulb descriptions and tested many of them to find some of the most ideal white LED bulbs for practical usage. We are very happy with what we have found, and many of them have exceeded our expectations and can be very affordable.
Thanks for reading!
-Andrew
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