How Many Wavelengths do you Need for Red Light Therapy? Optimal Nanometer Ranges Reviewed.
How many wavelengths do you need for red light therapy? Is it always better to have more wavelengths? Or just stick to the popular ones?
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.
The Standard Wavelengths vs New Wavelengths:
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:
- Are 660nm and 850nm really the best wavelengths?
- Is the combination of 660nm and 850nm really backed by thousands of papers in clinical research?
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 10% 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?
Why We Need to Study Multiple-Wavelength Devices
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.” 
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:
- Are 660nm and 850nm the Best Wavelengths according to the Literature?
- Why Different Penetration Depths of Red and Near-Infrared Light Matter.
- The Mechanisms of Combining Red and Near-Infrared Light.
- How Combining Wavelengths creates a Synergistic Response.
Lets dive into the literature and see what conclusions about wavelengths we can come up with.
Is 660nm and 850nm Supported by the Science?
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.
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 surpise 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.
Penetration Depths for Red and Near-Infrared Light
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. 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” 
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.
Mitochondrial Mechanisms for Red & NIR Light
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.  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.  
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.” 
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.
Intracellular Mechanisms for Red & NIR Light Therapy
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. 
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.” 
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. 
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. 
Ultimate Red and Near-Infrared Photobiomodulation Penetration and Absorption Mechanisms Cheat-sheet
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] 
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." 
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.
Combined Wavelengths vs Individual Wavelengths:
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.
- One study found that Nitric Oxide production was much greater for simultaneous usage of 635nm and 808nm than using them individually or even sequentially. 
- For brain health studies have found sequential or simultaneous 670nm and 810nm performed better than either wavelength alone. 
For skincare a study found that simultaneous 633nm and 830nm wavelengths performed better than the individual wavelengths. 
A study on diabetic wound healing found that the 660nm and 808nm combined wavelengths performed synergistically over the individual wavelengths. 
- A study on wound healing in rats found that combined 685nm and 830nm light provided additional benefits than single wavelength treatment. They specifically cited the theory that it was the differing penetration and absorption bands that likely enhanced the treatment. 
More Effects of Combined Wavelengths:
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. 
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.  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.” 
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.
Combined Wavelengths: Additive or Synergistic?
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." 
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.
Conclusion: Are More Wavelengths Better?
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.” 
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.
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