Red Light Therapy: What the Science Says, and How We Use It
Written By Kevin Wallace.
Red and near-infrared light can change how cells make energy. For a handful of uses, including skin aging, pattern hair loss, and preventing mouth sores during certain cancer treatments, there is clinical evidence that it helps. For many of the other claims made for home panels, the evidence is early or mixed. Used sensibly, it is low-risk. It is not a substitute for exercise, sleep, or daylight.
Thea and I bought a full-body red light panel just under a year ago and use it through our long upstate New York winters. Before I would recommend it to anyone, I wanted the research, not the sales page. Here is what holds as of October 2026.
1. What red light therapy is
The scientific name is photobiomodulation, often shortened to PBM. It means using specific wavelengths of red and near-infrared light, at low power, to change how cells behave. It was once called low-level laser therapy. Most home devices now use LEDs instead of lasers.
Two bands do most of the work (1).
Red light, roughly 620 to 700 nm, is visible and reaches the skin and the tissue just beneath it. The 660 nm wavelength in our panel is one of the most studied.
Near-infrared light, from 700 nm up, is invisible and penetrates deeper, into muscle and joints. Around 810 to 850 nm is the other common choice.
This is different from three things it is often confused with: the ultraviolet light in sunlight that tans and burns skin, the bright white light used to treat winter depression, and the heat of a sauna. Red light panels feel only mildly warm. Their effects do not come from heat.
2. How it works
The leading explanation centers on mitochondria, the energy factories in nearly every cell. The main light-absorbing molecule appears to be cytochrome c oxidase, an enzyme in the energy-making chain that absorbs red and near-infrared light (2). The popular theory is that light knocks loose nitric oxide, which can sit on that enzyme and slow it down. Freed of it, the enzyme works faster, and the cell makes more ATP. The released nitric oxide also widens nearby blood vessels, and the cell gets a brief burst of signaling molecules that switch on repair and anti-inflammatory pathways (2).
That is the leading account, not a closed case. A 2023 National Institute on Aging workshop noted that 660 nm light has increased cell proliferation in models where cytochrome c oxidase was not required (3). Other proposed targets include membrane channels and growth-factor pathways. I would not write the mechanism as settled.
The dose matters. Red light follows a biphasic curve: low doses stimulate, the benefit peaks, and higher doses can fade or inhibit the same processes (2, 4). A 2018 parameter review found no single agreed protocol. Some groups recommend under 100 mW/cm² and about 4 to 10 J/cm² at the target tissue. Cellular work often reports stimulation from about 3 to 10 J/cm². In mouse cortical neurons, ATP and mitochondrial signal peaked around 3 J/cm² among tested doses of 0.03, 0.3, 3, and 10 (4). This is the same idea as hormesis. A modest stress triggers repair. Too much does not help. More minutes in front of the panel are not automatically better.
3. Where the evidence is strongest
Skin aging. In a 2014 controlled trial of 136 volunteers, twice-weekly treatments for 30 sessions improved complexion and roughness and increased collagen density on ultrasound, compared with controls (5). Adding a broader near-infrared band, 570 to 850 nm, gave no extra skin benefit over red-only light, 611 to 650 nm. The red-band dose was about 9 J/cm². The limit belongs in the same sentence. Of the 136, 113 were randomized to treatment. The 23 controls were mostly employees of the device company and were not randomized with the treated group. One author worked at that company. The result still favors treatment. It is not a clean independent trial.
Hair loss. For male- and female-pattern hair loss, a 2019 meta-analysis pooled 8 studies that contained 11 double-blind randomized trials. Low-level light increased hair density compared with sham devices, in men and women, and in both comb and helmet devices (6). The authors flagged heterogeneity. Several home devices, mostly combs and helmets made for the scalp, are FDA-cleared for this use. Clearance is a device determination, not a drug approval.
Mouth sores during cancer treatment. This is the most established medical use. MASCC/ISOO guidelines recommend photobiomodulation to prevent oral mucositis in three settings: hematopoietic stem-cell transplantation, head and neck radiotherapy, and head and neck radiotherapy plus chemotherapy (7). They do not recommend it for sores already present, or for chemotherapy alone. The protocols are clinic devices with a set wavelength, power, and time. A door panel is not that protocol.
The eye, in a clinic. On November 4, 2024, FDA granted De Novo authorization, DEN230083, to the Valeda Light Delivery System for specified dry age-related macular degeneration (8). It is a prescription device using 590, 660, and 850 nm. In LIGHTSITE III, treated eyes gained about one line of visual acuity versus sham after about two years. That is a defined dose, in a supervised setting, for early or intermediate dry AMD without center-involving geographic atrophy. A home panel is not an eye treatment. Do not stare into one.
4. Promising, but mixed
Many of the uses people buy home panels for fall here. Encouraging studies, small samples, and devices that do not match a full-body LED panel.
Muscle recovery and performance. Light before or after exercise has been reported to cut soreness. Results vary, and most trials used targeted lasers or clusters, not a door panel.
Joint and tendon pain. Photobiomodulation is used for knee osteoarthritis and tendon problems, with inflammation the likely target (2). Trials are mixed, and dose seems to decide the result.
Wound healing. Long studied, with benefits in some settings, mostly with clinical devices.
The brain. Near-infrared light aimed at the head, called transcranial photobiomodulation, is being studied for injury, dementia, and depression. The human research is still early.
Sleep. A few small studies suggest evening red light may help, in part because red light does not suppress melatonin the way blue light does. The evidence is thin.
The strongest benefits are for tissues the light can actually reach: skin, scalp, and the lining of the mouth. The deeper the target, the weaker and less consistent the evidence.
5. What it does not do, or has not been shown to do
It is not a treatment for winter depression. This matters here, because winter is when we use the panel. The proven light treatment for seasonal affective disorder is bright white light, typically 10,000 lux for about 30 minutes each morning (9). It works through the eyes and the brain’s clock. Blue wavelengths appear to be the active part. Dim red light has been the placebo in many of the trials that established bright light (10). One primary-care trial found similar improvement with bright white light and dim red light, which may mean red is not completely inert, or that expectation is strong (11). Either way, if winter darkness weighs on mood, a 10,000-lux box or morning daylight is the evidence-based choice. A red panel is not a substitute.
There is no good evidence it protects telomeres. I have not found good human research linking red light therapy to telomere length.
Fat loss, detox, and whole-body anti-aging claims are mostly marketing. A few devices have narrow FDA clearances for a temporary change in circumference. That is not weight loss, and it is not reversed aging. Be skeptical of any panel advertised for a dozen conditions at once.
6. Choosing and using a panel
If you try a home panel, a few specifications matter more than the LED count.
| Specification | What it means | What to look for |
|---|---|---|
| Wavelength | The color of the light, in nanometers | Well-studied red, about 630 to 660 nm, and near-infrared, about 810 to 850 nm |
| Irradiance | How much light power reaches the skin, in mW/cm² | Matters more than LED count. Maker figures are often taken very close to the panel and can be optimistic |
| Distance | How far you stand | Irradiance falls quickly as you step back. Follow a measured table, not a slogan |
| Dose | Irradiance times time, in J/cm² | A common target-tissue range is about 4 to 10 J/cm². More is not better |
| Flicker and EMF | Electronics behind the LEDs | Low-flicker designs are preferable. Health effects at these levels are not established |
Dose is irradiance times time. The formula is the same for any panel.
Joules per square centimeter = milliwatts per square centimeter × seconds × 0.001.
Five minutes is 300 seconds, so each 1 mW/cm² delivers 0.3 J/cm². Ten minutes delivers 0.6. A worked check: 50 mW/cm² for 10 minutes is 50 × 600 × 0.001, or 30 J/cm². That is already above the 4 to 10 J/cm² target-tissue range in the parameter review. The ideal dose still depends on the tissue. It does not rise forever with the timer.
Two limits on the arithmetic. Front and back are separate doses. The skin on the chest does not collect the light you give your back. And a flat panel is not a bare bulb, so the light does not fall off as fast as inverse square. Inverse square from the maker’s 6-inch figure is the low estimate. An older distance table, if the maker published one, is the high estimate. A meter at the distance you actually stand is the number to trust.
Safety is simple, and two 2025 findings belong in it.
Protect your eyes. Near-infrared is invisible, so you will not blink it away. Wear the goggles. Never stare into the LEDs. Do not aim a panel into a child’s eyes. Repeated low-level red light is now used in some places to slow myopia. A 2025 cohort in JAMA Ophthalmology found lower macular cone density, and a few retinal abnormalities, in children who had used that eye-aimed treatment for a year or more (12). That is a different device. It is still the reason the goggle rule covers children.
Do not treat a known skin cancer, or an undiagnosed lump, with the panel. Photobiomodulation is used to prevent mouth sores from cancer treatment. It is not a tumor treatment.
Check medications. Some antibiotics, acne drugs, and other medicines make skin more sensitive to light. Ask a pharmacist.
Talk with a doctor first if you have an eye disease, a light-sensitive condition, or are pregnant. Do not aim the panel at a pregnant abdomen.
Watch for heat. High-power panels warm the skin at close range. Step back if it feels hot.
7. Our panel: the Hooga HG1500
The panel Thea and I use is the Hooga HG1500. These figures are the manufacturer’s, from the current product page (13).
| Feature | HG1500, manufacturer figures |
|---|---|
| LEDs | 300 single-chip LEDs, half 660 nm red and half 850 nm near-infrared |
| Irradiance | 115 mW/cm² at 6 inches on the current comparison chart. Independent meters often read lower |
| Size and weight | 35.8 by 11 inches, 33 lb |
| Power | About 585 watts drawn. The 1500 in the name is a series label, not the wall draw |
| Controls | Separate red and near-infrared switches, built-in timer |
| Included | Door-hanging kit and protective goggles |
What I like: the two best-studied wavelengths, a size that covers most of the body, and separate switches for red, near-infrared, or both. It hangs on a door.
What to keep in mind: like most makers, Hooga reports irradiance close to the panel. Independent measurements of consumer panels often come in lower. The current chart gives 115 mW/cm² at 6 inches and does not publish 12 or 18 inches. An older table claimed 65 mW/cm² at 18 inches. That figure is not on the current chart.
How we use it. We stand 18 inches from the panel. Five minutes facing the lights, then five minutes with our backs to the lights. Goggles on. Ten minutes in the room, and each side gets its own dose.
Why that routine. At the claimed 115 mW/cm², 15 minutes at 6 inches was about 104 J/cm² on the facing skin, several times the 4 to 10 J/cm² target-tissue range. The biphasic curve says that is not a better session. Stepping back to 18 inches and cutting the time to 5 minutes a side brings the dose down toward the skin trial, which used about 9 J/cm² in the red band.
| Setup | Irradiance used | Dose on the facing skin |
|---|---|---|
| 6 inches, current chart, for comparison | 115 mW/cm² | about 35 J/cm² |
| 18 inches, older claimed table | 65 mW/cm² | about 20 J/cm² |
| 18 inches, inverse square from 6 inches | about 13 mW/cm² | about 4 J/cm² |
| Our old habit, 15 minutes at 6 inches | 115 mW/cm² | about 104 J/cm² |
At 18 inches for 5 minutes, the low estimate is about 4 J/cm² and the old-table estimate is about 20. The true number is likely between them, and nearer the studied band than 104. Twelve inches for the same 5 minutes would be stronger: about 9 J/cm² on the inverse-square estimate, and about 26 if an older 85 mW/cm² claim at 12 inches were right. We use 18 inches as the default. The two sides do not add. Five minutes on the front plus five on the back is still one dose per side.
I also have a Hooga HG24, a small bulb with 12 dual-chip LEDs at 660 and 850 nm, for a spot treatment. I have used it for an earache or a headache. That is my own practice, not an established treatment. I have not found good evidence that red light treats ear infections or headaches. An earache that is severe, lasts more than a day or two, or comes with fever or drainage needs a doctor. Near the head, keep it out of the eyes or wear the goggles.
8. Honest caveats
Most of the strong evidence comes from clinical devices with a controlled dose on a specific spot. Home full-body panels deliver light differently, and few trials have tested them directly.
Studies use different wavelengths, doses, and schedules. There is no single home protocol.
Placebo effects are real for mood, energy, and pain, and it is hard to blind someone to a bright red light.
Marketing runs ahead of the science. A panel that lists 15 benefits is selling.
It is not a substitute for exercise, sleep, daylight, and a whole-food diet. Those have far stronger evidence for healthy aging.
9. Where we land
Red and near-infrared light can change how cells make energy, most likely through cytochrome c oxidase. That mechanism is the leading theory, not a settled one.
The best evidence is for skin aging, pattern hair loss, and preventing mouth sores in three cancer-treatment settings. An FDA-authorized clinic device exists for specified dry macular degeneration. A home panel is not that device.
Muscle recovery, joint pain, brain health, and sleep are promising and mixed.
It is not a treatment for winter depression. Use a 10,000-lux white box or morning daylight.
Dose matters more than time. We stand 18 inches away, 5 minutes facing the panel and 5 minutes with our backs to it. That is about 4 to 20 J/cm² a side, depending on how fast the light falls off, against about 104 J/cm² for 15 minutes at 6 inches. The studied target-tissue range is about 4 to 10.
Protect your eyes, including a child’s. Do not treat a skin cancer with the panel. Check light-sensitive drugs.
Ignore the long lists. Keep exercise, sleep, daylight, and diet as the foundation.
For us, red light therapy is a pleasant, low-risk part of the winter routine. Worth doing for modest, real benefits, as long as we are honest about what it can and cannot do.
10. Further reading
If you open two, open the parameter review and the MASCC/ISOO mucositis guideline.
Zadik et al., MASCC/ISOO photobiomodulation guideline for oral mucositis, 2019
FDA De Novo letter, Valeda Light Delivery System, DEN230083, November 4, 2024
11. References
Maghfour J, et al. Photobiomodulation CME part I: overview and mechanism of action. J Am Acad Dermatol. 2024. https://www.sciencedirect.com/science/article/abs/pii/S0190962224001865
Hamblin MR. Mechanisms and applications of the anti-inflammatory effects of photobiomodulation. AIMS Biophys. 2017;4(3):337-361. https://pmc.ncbi.nlm.nih.gov/articles/PMC5523874/
National Institute on Aging workshop summary. Light buckets and laser beams: mechanisms and applications of photobiomodulation therapy. GeroScience. 2025. https://link.springer.com/article/10.1007/s11357-025-01505-z
Zein R, Selting W, Hamblin MR. Review of light parameters and photobiomodulation efficacy: dive into complexity. J Biomed Opt. 2018;23(12):120901. https://pmc.ncbi.nlm.nih.gov/articles/PMC8355782/
Wunsch A, Matuschka K. A controlled trial to determine the efficacy of red and near-infrared light treatment in patient satisfaction, reduction of fine lines, wrinkles, skin roughness, and intradermal collagen density increase. Photomed Laser Surg. 2014;32(2):93-100. https://pmc.ncbi.nlm.nih.gov/articles/PMC3926176/
Liu KH, Liu D, Chen YT, Chin SY. Comparative effectiveness of low-level laser therapy for adult androgenic alopecia: a systematic review and meta-analysis of randomized controlled trials. Lasers Med Sci. 2019;34:1063-1069. https://pubmed.ncbi.nlm.nih.gov/30706177/
Zadik Y, Arany PR, Fregnani ER, et al. Systematic review of photobiomodulation for the management of oral mucositis in cancer patients and clinical practice guidelines. Support Care Cancer. 2019;27:3969-3983. https://link.springer.com/article/10.1007/s00520-019-04890-2
U.S. Food and Drug Administration. De Novo classification request for Valeda Light Delivery System. DEN230083. November 4, 2024. https://www.accessdata.fda.gov/cdrh_docs/pdf23/DEN230083.pdf
Maruani J, Geoffroy PA. Bright light as a personalized precision treatment of mood disorders. Front Psychiatry. 2019;10:85. https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2019.00085/full
Effectiveness of visible light for seasonal affective disorder: a systematic review and network meta-analysis. 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC12237333/
Wileman SM, Eagles JM, Andrew JE, et al. Light therapy for seasonal affective disorder in primary care: randomised controlled trial. Br J Psychiatry. 2001;178:311-316. https://www.cambridge.org/core/journals/the-british-journal-of-psychiatry/article/light-therapy-for-seasonal-affective-disorder-in-primary-care/07F5A340400D5BB1F665283EFCAF423C
Liao X, et al. Cone density changes after repeated low-level red light treatment in children with myopia. JAMA Ophthalmol. 2025. https://jamanetwork.com/journals/jamaophthalmology/fullarticle/2832963
Hooga Health. HG1500 red light therapy panel specifications. https://hoogahealth.com/products/hg1500-red-light-therapy-device
