The Benefits of Near Infrared Light

We have a great respect for the influence of light upon health. We’ve blogged and spoken about the importance of blue light for circadian rhythm entrainment, and ultraviolet light for production of vitamin D and nitric oxide (for example, in “Nitric Oxide and AO+Mist Skin Probiotic at the Perfect Health Retreat”; use the coupon code phd25 for 25% off AOBiome’s nitric oxide enhancing skin probiotic).

However, red and near infrared light are healthful too. Vladimir Heiskanen (also known as “Valtsu”) is a Finnish blogger and intelligent young scholar who has been researching the effects of red and near infrared light, and he wrote a post on his blog which deserves greater exposure. Vladimir has graciously allowed me to revise his post for PHD readers. – Paul Jaminet

I (Valtsu) used to spend a lot of time reading Ray Peat’s articles, trying to make sense of his ideas. In many of his articles, Peat praised red light. For example (from here):

Old observations such as Warburg’s, that visible light can restore the activity of the “respiratory pigments,” showed without doubt that visible light is biochemically active. By the 1960s, several studies had been published showing the inhibition of respiratory enzymes by blue light, and their activation by red light.

Peat didn’t give many references to justify his claims, but after doing some searches on PubMed, I realized that there are thousands of papers supporting his views.


Activation of cytochrome c oxidase (Cox), the mitochondrial respiratory enzyme discovered by Nobel laureate Otto Warburg, seems to be the primary mechanism by which red light enhances mitochondrial function. [1] [2] [3] [4] [5] [6]

Cox is the centerpiece of the last stage of mitochondrial energy production, Complex IV. Cox utilizes energetic electrons and protons from opposite sides of the inner mitochondrial membrane to turn one molecule of oxygen (O2) into two molecules of water (H2O), in the process contributing the energy required to form ATP.

But a number of small molecules can displace the O2, spoiling the reaction and acting as inhibitors of ATP synthesis. These include cyanide (HCN), carbon monoxide (CO), hydrogen sulfide (H2S), and nitric oxide (NO). If too much oxygen is displaced, as in cyanide or carbon monoxide poisoning, cells die from chemical asphyxiation.

Nitric oxide is a native molecule of crucial importance for health, especially cardiovascular health. Nitric oxide generation by ultraviolet light (UV-A) is probably a major reason for the healthfulness of sunshine. Nitric oxide is commonly generated by stressed cells (for example, during the heat shock response) to support cellular health, in part by increasing blood flow.

However, the binding of NO to Cox, inhibiting mitochondrial respiration, can be an unwanted side effect. It turns out, fortunately, that red and near infrared light photodissociate NO from Cox, leading to its release from mitochondria back into circulation with beneficial effects on blood flow.

Removal of NO from mitochondria appears to be the mechanism by which red light phototherapy enhances mitochondrial respiration [2] [7a] [7b] [8] [9] [10] [11]. Supporting evidence: provision of NO abolishes the cellular effects of red and near infrared light.

Visible light doesn’t penetrate the body well, but infrared light does. Near infrared light is only reduced in intensity by about half after passage through 2 mm of tissue, and in daytime outdoor environments may dissociate NO and promote mitochondrial respiration at a depth of 2-3 cm beneath the skin. [13] [14] [15]

This image, from here, is illuminating:

Valtsu image 01

First, it illustrates the relative transparency of human tissue in the red (and even greater transparency in the infrared). Transparency in this frequency range appears to have been evolutionarily selected, to the point that one molecule – cytochrome c oxidase in mitochondria – absorbs 35% or more of red light. If it was so important to let red light reach mitochondria that other human molecules had to evolve transparency in the red, then it is surely important for us to provide our mitochondria with red light.

Second, when tissues are injured, they release extra nitric oxide, and NO bound to Cox absorbs red light, making the injured tissue more opaque in the red. In this case the middle finger had been jammed; due to the injury it passes significantly less red light than the fingers on either side.

The History of Red Light Therapy

There is nothing new under the sun, and when a simple activity is beneficial for health, we often find that somebody discovered the effect long ago. So it is with red light.

Niels Ryberg Finsen won the Nobel Prize for Medicine in 1903 for his explorations of the therapeutic effects of light, notably the use of ultraviolet light to treat lupus and other diseases; but he had also found that red light could be beneficial, and had published an article titled “The Red Light Treatment of Smallpox” in 1895.

The idea of using red light for therapy was picked up by John Harvey Kellogg, who published a 200-page book titled Light Therapeutics in 1910. Kellogg had long been famous as one of the first vegetarian doctors, leader of the Battle Creek Sanitarium for the Seventh Day Adventist Church from 1876 until 1933, and as the inventor of corn flakes breakfast cereals (in 1878). Kellogg recommended light therapy for diabetes, obesity, chronic fatigue, insomnia, baldness, and cachexia. [18]

After the invention of lasers, it was found that red laser light could accelerate wound healing in animals, and in the 1970s similar results were obtained in humans. [2]

The most interesting work on phototherapy, however, has been conducted recently. It is becoming a hot field: a Pubmed search for LLLT (an acronym for “low-level laser therapy” or “low-level light therapy”) generates about 10 papers per year in the 1990s, 100 per year in the 2000s, and 400 per year in the 2010s.

Therapeutic Benefits from Local Application of Red Light

Therapeutic benefits from local application of red or near infrared light to injured tissues have been reported for several conditions:

  • Age-related macular degeneration. The eyes of 200 elderly subjects with age-related macular degeneration were exposed to near infrared light of wavelength 780 nm. Visual acuity was improved in 95% of the subjects; most were able to see two rows lower on an eye chart. Results achieved in two weeks of treatment were maintained three to thirty-six months. [65]
  • Knee osteoarthritis. Application of near infrared (830 nm) light to the knees of osteoarthritis patients dramatically reduced knee pain scores. [73]
  • Herpes labialis. Cold sores around the lips caused by herpes simplex virus 1 were treated with red laser light. Time to recurrence was a median 37.5 weeks in the treatment group, 3 weeks in the placebo group. (Subjects wore masks and couldn’t tell which group they were in.) [61]
  • Hypothyroidism. Hashimoto’s hypothyroidism patients were exposed to near infrared (830 nm) radiation of the skin over the thyroid gland. Nine months later, 48% of the treatment group had been able to stop taking thyroid hormone, and the average T4 dose had dropped from 93 mcg to 39 mcg. In the control group, the average T4 dose had increased from 90 mcg to 107 mcg. [37] Similar results have been reported in other studies. [36] [37] [38] [40]  [41] [42] [43]
  • Cognitive dysfunction following traumatic brain injury. Eleven patients with continuing cognitive dysfunction following traumatic brain injury (from motor vehicle accidents, sports injuries, and an improvised explosive device detonation) were treated with red and near-infrared light to the scalp. They experienced improvements in executive function, learning, and memory, as well as improved sleep and fewer post-traumatic stress disorder symptoms.
  • Cellulite. This is more speculative, but there are indications that red and near infrared light can help reduce cellulite.
  • Hair loss. Use of a laser hair comb led to fuller and thicker hair in hair loss patients.

Systemic Benefits of Phototherapy

Even when light is applied locally, some of the benefits may be shared systemically.

For instance, exposure to light causes release of NO from mitochondria and also an increase in NO levels due to photoactivation of nitric oxide synthase. Elevation of NO anywhere increases blood flow throughout the body. In one experiment, one hand was irradiated with white light; blood flow rate increased 45% in the irradiated hand and 39% in the non-irradiated hand.

Irradiation with white light has been found to increase antibody production, presumably improving immune function.

Light exposure has also been found to have anti-inflammatory effects. For example, white light exposure reduces levels of the pro-inflammatory cytokines TNF- α, IL-6, interferon-gamma, and interleukin-12 and increases levels of anti-inflammatory cytokines interleukin-10 and TGF-beta.

Other studies have found that UV radiation increases TNF-α, IL-6 and other pro-inflammatory cytokines. [90] [91] So it is likely that the anti-inflammatory effects of the white light were chiefly due to its red and near infrared components.

These anti-inflammatory effects may shed light on the improvements hypothyroid subjects experienced from near infrared phototherapy. TNF-α and IL-6 suppress peripheral thyroid hormone metabolism by decreasing T3 and increasing rT3. [92] [93] Inflammation seems to commonly trigger hypothyroidism, while anti-inflammatory strategies are almost always therapeutic for hypothyroidism.

Epidemiological evidence suggests that light exposure improves serum lipid profiles. At mid-latitudes, serum cholesterol levels typically rise 5% to 10%, but HDL cholesterol levels decrease, in winter. Blood pressure is also higher in winter. [97] [98] [99] [100] [101] [102] Lack of red light may be the reason. In a pilot study, red light exposure reduced serum cholesterol levels in 84% of subjects.

Widespread Deficiencies in Light Exposure

It’s likely that our modern environments lead to systemic deficiencies in light exposure. It’s common for health to worsen in low-light locations or seasons, as Ray Peat observed:

Many people who came to cloudy Eugene to study, and who often lived in cheap basement apartments, would develop chronic health problems within a few months. Women who had been healthy when they arrived would often develop premenstrual syndrome or arthritis or colitis during their first winter in Eugene.

Since the last ice age ended, humanity has populated more northerly latitudes and moved indoors. We are getting far less light than our ancestors. The evolutionary mismatch principle suggests that humans will be optimized for ancestral light levels, and that we moderns can improve our health by getting more light.

Health Risks of Blue-Only Light

While red light tends to enhance mitochondrial function, high intensities of blue light can damage mitochondria by triggering oxidative stress. Blue-only light can kill retinal cells. Exposing rats to blue-only light or to “white” LED light that peaks unnaturally strongly in the blue led to retinal damage. LED lights are the worst, due to their concentration at single frequencies, but compact fluorescent lights which have peaks in the blue can also generate mild to moderate retinal damage. A commentary on the research is here.

Reactive oxygen species are generated in mitochondria when they can’t dispose of electrons in the manufacture of ATP. For this reason, NO binding to Cox promotes oxidative stress, and release of NO from Cox by red and infrared light reduces oxidative stress. It is probably by this mechanism that red and near infrared light protects against retinal injury.

Because of this research, we don’t recommend using blue-only light boxes for circadian rhythm entrainment; rather, use full spectrum white light.

Incandescent lights, which produce a smooth spectrum including red and near-infrared wavelengths, are probably safest for eye health. Some researchers, such as Richard Funk and Alexander Wunsch, who appeared in the Bulb Fiction documentary, assert that increased CFL usage may be harmful to eyes. Of course, governments are here to help us, and have banned incandescent lighting.

Circadian Rhythm Considerations

There are hints that bright red and near infrared light exposure should occur in the daytime.

Night-time levels of melatonin, but not day-time levels, have been shown to abolish the effects of red and infrared light on cellular function, just as nitric oxide does.

This shows that melatonin, a circadian rhythm hormone, evolved to inhibit red light influences at night. If our “night hormone” is trying to block the influence of red light, we probably shouldn’t willfully expose ourselves to bright red light at night.

What to Do

If fluorescent lights are problematic, how should we get adequate red and near infrared light, while getting sufficient blue in the daytime to entrain circadian rhythms?

The general lighting types that provide the most red and near-infrared are incandescent lights, heat lamps, and LEDs.

Heat lamps by Philips or Osram  generate little blue light but, thanks in part to their high power levels (up to 250 W), provide significant red and near-infrared light. However, only ~12% of the power is emitted at therapeutic wavelengths (600-1070 nm); most of their power is emitted at the warming IR-B wavelengths. In fact, these lamps emit so much heat that they can substitute for central heating in the winter. Most people will find they produce too much heat for summer use. Although we recommend using red or orange lighting at night, heat lamps are not really suitable for night use; ambient temperature is a zeitgeber and our exposure to warmth should occur in the daytime. Moreover, as noted above, it might be best to get red light exposure in the daytime, when melatonin levels are low. So heat lamps are best used in the daytime as a complement to other broad-spectrum lighting.

Incandescent lights (including halogen lights), which produce a blackbody spectrum, can generate a significant amount of red and near infrared and are excellent daytime light sources. A color temperature of 5500 K mimics the sun and provides substantial amounts of red and near infrared; a color temperature of 4100 K is also excellent in the red and near infrared, but is rather weak in the blue and ultraviolet for daytime circadian rhythm entrainment. A look at blackbody spectra as a function of color temperature:

Valtsu image 02

LEDs are another possibility. One of their virtues is that it’s possible to obtain monochromatic LEDs with frequencies optimized for Cox-NO photodissociation (680 and 820 nm work best; inexpensive LEDs are available at 630, 660, 850, and 880 nm. Here is a video of a fellow who created a homemade LED helmet:

A variety of commercial light devices have been used in LLLT/light therapy studies: AnodyneBioptronHairMax LaserCombOmniluxNoveon NaiLaserBiolightQuantum WarpSyrolight BioBeamHIRO 3.0Picasso LiteHELBO® TheraLite Laser and Mustang 2000.


Exposure to sunshine on bare skin, which was common in our ancestral environment, is something we need to obtain or mimic if we want optimal health.

Unfortunately, it’s hard to reproduce the many facets of sunshine in indoor environments. Blue light (for daytime circadian rhythm entrainment), UV-A light (for nitric oxide), UV-B light (for vitamin D), red light (for nighttime circadian rhythm entrainment), and now red and near infrared light in the daytime (for mitochondrial respiration) all seem to be important.

Awareness is the first step toward optimization. Thank you, Vladimir, for sorting through this research for us!

Leave a comment ?


  1. Would be really interesting to see if people with chronic fatigue syndromes show blockage of light in fingers, from capillary hypoperfusion.

    Some practitioners (e.g., Shoemaker) think that CFS is primarily brought on by hypoxia, due to a type of inflammation that causes capillaries to tighten. Tissues do not get oxygen.

    Could an infrared light be partly diagnostic for this?

  2. Red Light tubes are now being retro fitted into some solarium beds. So rather than the extremely high UVA/B output of regular solariums tubes/lamps, lamps are being replaced with Red Light wavelenghths620-750 nm tubes. These tubes also produce some uvb for vitamin D production and a small amount uva for NO.
    Check this site for great article on RED LIGHT THEROPY IN TANNING BEDS.

  3. Thanks for the article!
    If this is true “Hashimoto’s hypothyroidism patients were exposed to near infrared (830 nm) radiation of the skin over the thyroid gland. Nine months later, 48% of the treatment group had been able to stop taking thyroid hormone” then whyyyy wasn’t this all over the news, it’s so sad! But when I get it right, you can’t do this at home because you can’t buy these 830nm lights? Still… exciting.

    • Hi Anja,

      I also wonder why so few people are talking about that study result by Danilo B. Höfling (et al.). The study isn’t even that bad quality, and similar results were also observed in the pilot study of the same researchers.

      Also, Russian and Ukrainian researchers have also reported very good results with 890nm. I haven’t read all of the Russian reports, so that’s something I will do during this summer.

      And yes, these studies were conducted with laser, so it’s not completely clear to me, whether normal light would have the same effect.

      However, some people in Ray Peat groups have reported good effects from heat lamps and I believe it could be potentially possible to achieve similar effects with halogen lamp, heat lamp or incandescent lamp (or LED lamp), without the use of expensive laser. But I can’t give any kind of a guarantee of such effects.

      • I said: “The study isn’t even that bad quality”

        I should have said: “It’s a good study.”

        • Valtsu, in another article you wrote,
          “I think one needs to be careful about the dosing, as photobiomodulation is characterized by the biphasic dose response, where either too little or too much light might be ineffective.”
          Also, the researchers were very careful to irradiate the thyroid and only the thyroid. They had the anatomical knowledge to do that – most people don’t.

    • 🙂 Google near infrared lamps and red lights. You can pick up some pretty cheep ones at a hardware store and I have seen some on amazon. I have seen some already configured too. I just bought a single red light for just $35.

  4. Vladimir,

    Thanks for the report. I used philips red and clear heat lamp bulbs this winter as well as a 500 watt halogen work light. I filtered the light thru a rectangular glass milk bottle filled with water and a small hole in the plastic cap at the top. (the bottle is the type requiring a deposit so it is hefty.)

    Do you think the filtering is an improvement in reduced UVA and B?

    I can say I noticed a benefit in fatigue and neuropathy symptom reduction which always recede in the summer when I move standing workstation outside into indirect sunlight. So the indoor winter light did help in bringing me closer to how I feel during the summer.

    I was also wondering if you know of a way to measure light frequency? Can a camera white balance function be a help with its color temperature measurement in kelvin? Thanks so much.

    • Hi Perry,

      I think filtering might be a good idea. Can’t say for sure, and it probably depends on the exposure (duration&distance) 🙂 Water also absorbs much of the far-infrared so the lamp doesn’t heat your skin so strongly.

      Do you have any photos of your bottle? I can’t really imagine what it looks like.

      Nice to hear about your (subjective) benefits. 🙂 That’s what I’ve heard from people on “Ray Peat Fans” group on Facebook, and some other people as well.

      I don’t know how to measure light frequency/wavelength. Maybe camera experts have the answer to the question.

      Thanks for the comment. 🙂

  5. I have used Luxmeter Pro (free) on iphone to measure color temperature in K mostly to see if f.lux was working. Does anyone know how to convert K to nm? Also, are there better apps for measuring color temperature? And how does glass affect all this? What aspect of sunlight is blocked by glass?

    • Hi Yaniv,

      Color temperature can’t be converted to wavelength. Typically, if the color temperature is high, then the light source emits more UV/blue than red/infrared wavelengths.

      Wikipedia says: “Ordinary window glass passes about 90% of the light above 350 nm, but blocks over 90% of the light below 300 nm.”

      So, the effect is strongest on UV-C (and UV-B).

      Water also blocks (absorbs) far-infrared (FIR), so glass+water combination blocks both UV+FIR.

  6. Because I work in an office all day, I use short sessions in the tanning beds at Planet Fitness to make Vitamin D. After reading this post I was inspired to try their “Total Body Enhancement” which is a Beauty Angel RVT30 full body red light therapy booth.

    I couldn’t find any specifications, but their FAQ page states “The spectrum used in the Energizing Light Technology within the near-infrared range up to a maximum of 850 nm” and also uses visible light, no UV.

    Assuming the spectrum is right, I wonder what kind of dosage should I use. Each session is 12 minutes. Beauty Angel recommends 3 times a week but since I go to the gym 5 days/week I could potentially do more. I’m also curious if I should do my UV tanning and Red light back to back to counteract possible negative effects from the UV beds.

    • Hi Alex,

      Unfortunately I don’t know what would be a good dose. In some cases, “less is more”.

      There is one scientific paper called “Biphasic Dose Response in Low Level Light Therapy”, in which they show that in some studies, results are worse when the dose is higher. I don’t believe this is always true, since in some studies the doses are quite high and the effect is still very positive. Example:

      Also, in their Laser Phototherapy book, Jan&Hoder mention that having many treatments within a short time might have a smaller effect than having less treatments.

      Especially if it’s expensive, I would try 1-3 treatments per week first. But I don’t really have a clue which is the most healthy option.

      • Interesting information. Thankfully the treatments are completely free. In theory, as long as I maintained this gym membership I would do the red light therapy for life for the health and potential anti-aging effects. In which case, 3 treatments a week forever is probably good enough. It’s hard to resist the urge to do too much of a good thing.

  7. Also, I forgot to ask. If I do both artifical UV light and red light in the same day, which one should I do before the other?

    UV first, because it is pro-inflammatory followed by the anti-inflammatory red light? Or, do I follow recommendations commonly seen on tanning salon websites to do red light first based on claims of more blood being brought to the surface and leads to more melanin oxidation.

    Since tanning is just a nice side effect to me, I’m looking for the health-promoting answer 🙂

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  10. Do infrared saunas have the same benefits?

  11. I’m wondering what y’all think of this study (link below), which found that compared blue enriched white light (at 17,000K) to white light (at 4,000K) on office workers. The study found that the workers who used blue light-enriched full spectrum light had better alertness, mood, sleep quality, and many other outcomes.

    Vladimir mentioned the possible retinal damage that blue enriched white light might cause, however, so I don’t know how to reconcile these findings. Perhaps moderate blue light enrichment can produce the aforementioned benefits without causing the retinal problems.

    I look forward to your response.

    Rob Palmer

    • They’re both consistent. Office light is normally too dim to entrain circadian rhythms adequately; blue light is the most effective frequency for entraining daytime rhythms; so blue enriched light is an efficient way to get better entrainment.

      However, it risks eye injury over a period of months or years, so it’s important to have the red light with it.

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  14. I have have been contemplating getting glasses with Sharper Image’s Tech Shield for reducing blue light, since I work at a computer all day and thought it would reduce eye strain and damage…but would this be a bad idea because it would eliminate blue light’s roles in circadian rhythm entrainment altogether? How do all-day computer users prevent eye damage then?

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  16. The abstract about melatonin vis IR you posted does not seem to support your warning about using IR at night. The study was on human cancer cells in a glass dish. Very hard to generalize from that point about what people should or shouldn’t do.

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