The short version: red and near-infrared light are absorbed by the energy centres in your skin cells. In controlled trials, regular sessions over four weeks to about four months led to measurable improvements in fine lines, wrinkles and skin texture. The changes are gradual, and they depend on getting two things right: the wavelength and the dose.
What red light therapy is
Red light therapy (researchers call it photobiomodulation) shines low-level red and near-infrared light onto the skin. It isn't UV, so it won't tan or burn you. And unlike lasers and peels, it doesn't work by wounding the skin to trigger repair. The light is kept at levels too low to heat or damage tissue. The aim is to help your cells work better, not to injure them.
How it works
Scientists are still filling in the details, but the leading explanation goes like this. Inside your cells are mitochondria, the parts that turn food and oxygen into energy. One of their enzymes, cytochrome c oxidase, absorbs red and near-infrared light. When it does, it appears to release nitric oxide that had been slowing it down, so the cell can make more energy and send signals that switch on repair and renewal.
In skin, the cells that respond include fibroblasts, which make collagen and elastin, the proteins that keep skin firm and springy. In one placebo-controlled trial, skin biopsies taken after treatment showed more collagen and elastic fibres, and highly active fibroblasts.
Why the nanometres matter
Light is measured in nanometres (nm), and the number tells you its colour. It also decides two things that matter for your skin: how deep the light travels, and whether your cells can use it.
Research focuses on two bands: red, from about 600 to 700 nm, and near-infrared, from about 780 to 1,100 nm. Light travels furthest through tissue in this range, and it's where cytochrome c oxidase absorbs. The stretch in between, roughly 700 to 780 nm, does much less.
Red light: 630–660 nm
A deep, visible red. It passes through the thin outer layer of skin into the dermis, where collagen is made. The trials below used 633 nm, 660 nm and 611–650 nm. It's also where our name comes from: 630 nm.
Near-infrared: 810–850 nm
Invisible to the eye, and it travels deeper than red. It's often paired with red. In one placebo-controlled trial, 830 nm on its own, 633 nm on its own and the two together all reduced wrinkles.
Blue light: around 415 nm
Blue light is mostly absorbed near the surface, so it isn't used for collagen. It has been studied for breakouts instead. Our face devices have a blue setting, but at 460 nm it isn't the wavelength used in that research, so we don't claim it helps with breakouts.
More colours isn't better
Some masks advertise seven colours. More isn't automatically better. In one trial of 136 people, a broad-spectrum light covering 570–850 nm did no better than red light alone. What counts is the right wavelength at the right dose.
Dose: the number worth asking for
Wavelength tells you what kind of light it is. Dose tells you how much of it reaches your skin. Dose is measured in joules per square centimetre (J/cm²) and comes from two numbers: power density (irradiance, in mW/cm²) and time.
Dose (J/cm²) = irradiance (mW/cm²) × time (seconds) ÷ 1,000
So a device delivering 30 mW/cm² for 10 minutes (600 seconds) gives 18 J/cm².
Light therapy follows what scientists call a biphasic dose response. Too little light does nothing. More helps, up to a point, but past that point extra light stops helping and can even work against you. That's why a brighter device or a longer session isn't automatically better, and why showing up regularly beats overdoing it.
We publish the wavelengths, irradiance and recommended session time for every device on its product page, so you can work out the dose for yourself.
What the research shows
These are three of the better-designed trials. The results come from the studies named, not from tests of our devices.
Lee et al., 2007
76 people with facial wrinkles. Randomised, placebo-controlled, double-blind and split-face. 633 nm, 830 nm or both, twice a week for four weeks, followed up for three months.
Found: wrinkles reduced by up to 36% and skin elasticity improved by up to 19%, measured with instruments rather than by eye. Biopsies showed more collagen and elastic fibres. No side effects were reported.
Wunsch & Matuschka, 2014
136 people. Randomised and controlled. Red light (611–650 nm) or broad-spectrum light (570–850 nm), twice a week for 30 sessions.
Found: better complexion and skin feel, smoother skin on profilometry and higher collagen density on ultrasound. Assessors judging photos without knowing who had been treated rated the treated groups as improved compared with untreated controls. Broad-spectrum light did no better than red alone.
Mota et al., 2023
137 women aged 40 to 65. Randomised and split-face, comparing red (660 nm) and amber (590 nm) light over 10 sessions in four weeks.
Found: wrinkle volume around the eyes fell by 31.6% with red and 29.9% with amber. Skin hydration and elasticity didn't change.
The honest caveats
The evidence is encouraging but still young. A 2018 review of 31 randomised trials of LED light in dermatology found that some studies had fewer than 20 people, lacked blinding or had no sham control, and used widely varying settings. Cleveland Clinic notes that home devices may be less powerful than clinic ones, and that the long-term safety of red light devices isn't yet known. Results vary from person to person.
What it can help with
Based on the trials above, regular red and near-infrared light may help:
- soften the look of fine lines and wrinkles
- make skin feel smoother
- improve your overall complexion
It won't:
- lift sagging skin or replace lost volume
- replace daily sunscreen
- treat skin conditions. If something on your skin worries you, see your GP or a dermatologist.
Using it well
- Be consistent. The trials above used two to three sessions a week. Follow your device's instructions for session length.
- Give it time. Studies measured results after four weeks to about four months. Take a photo in the same light each fortnight so you can see the change.
- Start with clean, dry skin.
- Protect your eyes. Keep them closed during a session and don't look directly into the lights.
- Check first with your GP or pharmacist if you take medicine that makes you sensitive to light, you're pregnant, or you have an eye or skin condition.
- Stop if your skin or eyes feel irritated.
Why we're called Six Thirty
630 nm sits right in the red band that skin research focuses on. 6:30 pm is when we think it fits best: ten minutes, lights down, phone away. The name is a reminder of both. The right light, used consistently.
References
- Lee SY, et al. A prospective, randomized, placebo-controlled, double-blinded, and split-face clinical study on LED phototherapy for skin rejuvenation. Journal of Photochemistry and Photobiology B. 2007;88(1):51–67. PubMed
- 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. Photomedicine and Laser Surgery. 2014;32(2):93–100. PubMed
- Mota LR, et al. Photobiomodulation reduces periocular wrinkle volume by 30%: a randomized controlled trial. Photobiomodulation, Photomedicine, and Laser Surgery. 2023;41(2):48–56. PubMed
- Jagdeo J, et al. Light-emitting diodes in dermatology: a systematic review of randomized controlled trials. Lasers in Surgery and Medicine. 2018. PubMed
- de Freitas LF, Hamblin MR. Proposed mechanisms of photobiomodulation or low-level light therapy. IEEE Journal of Selected Topics in Quantum Electronics. 2016;22(3):7000417. PubMed
- Huang YY, Chen AC, Carroll JD, Hamblin MR. Biphasic dose response in low level light therapy. Dose-Response. 2009;7(4):358–383. PubMed
- Cleveland Clinic. Red light therapy. clevelandclinic.org