What is the Best Time of Day to use Red Light Therapy?
Most medicines may prescribe a certain “dosage”, but they may also indicate a time of day to take the medicine. Sometimes the drug may need to be taken on an empty stomach, or with food, or with other considerations with other drugs or activities.
In that way, we must consider what the best time of day to do red light therapy? Are there certain times of days that are more beneficial, or even doing red light therapy relative to other activities may help optimize the effectiveness of the therapy?
What we will review:
- Mechanisms of action during any time of day.
- Morning and Evening exposure for evolutionary timing.
- Strategic timing of Red/NIR for performance boosts.
- Optimal timing around cryotherapy and sauna.
- Optimizing sleep and circadian rhythms with proper red light timing.
As always, there are many different perspectives we can take and appreciate certain nuances about red light therapy and our chronobiology.
1. Can we do Red Light Therapy anytime?
Most of the cellular mechanisms for photobiomodulation appear to be independent of timing.
For example, absorption into CCO, dissociation of NO, producing EZ water, and up-regulating ATP production all do not have any particular circadian cycle that would affect red light therapy effectiveness.
As far as we can find, most studies of red light therapy do not even take note of the timing or time of day. We might presume they are conducted in clinics during normal business hours.
Thus we can safely assume that we can do red light therapy nearly any time of day for most applications. So as much as we want to get into the nitty-gritty of the “optimal” timing, don’t let that stop you from using red light therapy when it is most convenient for you.
2. Evolutionary Sunlight Timing for Red Light Therapy
We know that sunlight delivers proportionally more Red/NIR during the early morning or evening closer to sunrise and sunset.
One study even notes that from an evolutionary standpoint we may assume our cellular circadian mechanisms would be preferentially tuned to receiving red and NIR light in the mornings and evenings. 
That same study refers to red light therapy in the morning as "PBM Pre-Conditioning" and evening as "PBM-Repair".  Which might indicate that photobiomodulation is beneficial in the mornings to help prevent damage during the day, and in the evenings that repair the damage that has taken place during the day.
Additionally, recent research showed that benefits for the eyes with red light therapy were only obtained by treatment in the morning. Treatment later in the day produced no results. (2)
Another recent study conducted on flys with 670nm light found that the timing of the light therapy between 8am to 11am showed the biggest improvement in ATP production. Where dosing in the afternoon and evening there was no significant change from normal ATP cycles. (7)
One study used full-body red light therapy in the evenings and showed an improvement in sleep.(3)
3. Strategic Timing of Red Light Therapy
One study indicated the best time to do red light therapy before athletic performance or fitness training is 3-6 hours before the event. This is because the peak of ATP production comes 3-6 hours after treatment and they showed muscle performance increases by 300-600%! The benefit can come as soon as 40-60 minutes after irradiation as well. (4)
Similarly, the same study notes that long-term studies with athletic training programs also do well with red light therapy after the workout.(4)
Another study showed that transcranial photobiomodulation before an activity could reduce the strain of the brain while conducting challenging cognitive tasks. (5)
Thus, we can conclude from this section that we should do red light therapy before any strenuous physical or mental activity to boost performance, and perhaps ideally between 3-6 hours after treatment to give us the biggest ATP boost in that window.
4. Keeping Cool for Red Light Therapy
Applying ice or cryotherapy before red light therapy treatments has been shown to improve skin penetration of the treatment. (6)
This is likely due to the cryotherapy effects to draw away circulation, reduce blood vessels, and overall make the skin thinner and more transparent. Which we know by understanding the skin optics is very important for penetration and effectiveness.
Conversely, too high of skin temperature may increase blood flow and change tissue optics in a way that hinders photobiomodulation penetration and treatment.
Thus, this answers two big questions for “stacking” our red light therapy with other health activities.
- Cryotherapy, icing, cold showers, and cold plunges should be done before red light therapy to help optimize the penetration of the light.
- Red Light Therapy should be done before sauna sessions while the skin is still relatively cool.
5. Bright Red Light Therapy and Circadian Rhythms
Not directly a photobiomodulation effect, but still a major part of Red Light Therapy devices that is often overlooked is the effects on circadian rhythms.
- Early morning exposure of the face and eyes to bright light therapy, even bright red lights, may help increase wakefulness and alertness in the mornings and subsequently improve sleep at night.
- Conversely, bright lights (even red light) at night will reduce melatonin production and could negatively affect sleep or keep us too stimulated at night.
So it can be quite beneficial to do facial/eye treatments with red light therapy in the mornings, not only for the anti-aging benefits, but also getting bright light therapy benefits in the morning as well.
When we look at all of the factors mentioned above, we might assume that doing red light therapy in the mornings may be the optimal time of day!
- Morning treatments help simulate the evolutionary sunrise and cellular pre-conditioning.
- Doing red light therapy in the mornings will give us an ATP boost 3-6 hours later to help us improve physical and mental performance for the inevitable challenges we will face during the day.
- Our body temperature is still relatively cool in the morning to allow for good penetration, and a cold shower in the morning before red light therapy can enhance this further.
- Treatments for eye health specifically found it was more beneficial for the eyes in the mornings, not later in the day. As well as studies on flies showed significant improvement when treating in the mornings between 8am-11am.
- Morning treatments for the face and eyes (being mindful of intensity) act as a type of bright light therapy that can help with wakefulness, alertness during the day and help with sleep and circadian rhythms at night.
- We can also appreciate some anti-aging benefits while getting the bright red light therapy on the face in the mornings, where treating the face in the evening could be too stimulating and stunt melatonin production.
Red light therapy treatment in the evenings is also nearly equally as optimal, as it also helps simulate sunset as well as boosts repair mechanisms from the day. However, we should be mindful that bright red lights at night could be stimulating and adversely affect melatonin and sleep. Some people might want to experiment with treatments in the evenings, as everyone responds differently if it helps sleep or harms it.
There is plenty of evidence for red light therapy to be very effective any time of day. We find that truly the “best” time of day is to find what time is convenient for you to do consistent doses, even if not in the mornings or evenings.
The difference between getting benefits from red light therapy vs “optimal” benefits is usually marginal. So, if you can’t fit red light therapy in the mornings or evenings, don’t let that stop you from reaping the benefits in a different part of the day.
As always, these tips can give you guidance on how to optimize your routines, but ultimately you must experiment and find what fits best into your lifestyle.
Barolet D, Christiaens F, Hamblin MR. Infrared and Skin: Friend or Foe. J Photochem Photobiol B. 2016.
Harpreet Shinhmar, Chris Hogg, Magella Neveu, Glen Jeffery. Weeklong improved colour contrasts sensitivity after single 670 nm exposures associated with enhanced mitochondrial function. Scientific Reports, 2021; 11 (1) DOI: 10.1038/s41598-021-02311-1
Zhao J, Tian Y, Nie J, Xu J, Liu D. Red light and the sleep quality and endurance performance of Chinese female basketball players. J Athl Train. 2012;47(6):673-678. doi:10.4085/1062-6050-47.6.08
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
Chan, A.S., Lee, Tl., Hamblin, M.R. et al. Photoneuromodulation makes a difficult cognitive task less arduous. Sci Rep 11, 13688 (2021). https://doi.org/10.1038/s41598-021-93228-2
Disclaimer: All information in this article and website are intended for educational purposes only. It is not intended to treat, diagnose, or cure any ailment. Please consult with your doctor or trusted wellness practitioner before starting any new health activity including Red Light Therapy.