What research shows

136 participants received 30 sessions, twice a week, with red light (611–650 nm) or broadband light. Compared with the control group, skin became smoother and collagen density increased, measured with ultrasound. Participants were also more positive about how their skin looked and felt. Red light alone worked as well as broadband light.

76 participants received light at 830 nm, 633 nm, a combination of both, or a placebo, twice a week for four weeks. Wrinkles decreased by up to 36% and skin elasticity rose by up to 19%. Skin biopsies contained more collagen and elastic fibres. No side effects were reported.

137 women aged 40 to 65 received ten sessions in four weeks: red light (660 nm) on one half of the face and amber light (590 nm) on the other. Wrinkle volume around the eyes decreased by 31.6% with red and by 29.9% with amber light, at a dose of 3.8 J/cm².

Researchers followed the effects of red light on signs of skin ageing, including after the sessions had ended. The improvements lasted up to a month after stopping.

In a cultured skin model, pulsed 660 nm light increased production of procollagen, the precursor of collagen, by 31%. An enzyme that breaks down collagen decreased by 18%. The researchers compared this with a clinical study in people.

30 participants received yellow light at 570 or 590 nm, combined with red and infrared light. Both groups improved on pores, wrinkles, skin texture and pigment spots.

93 people with different skin types received pulsed amber light at 590 nm. In 90%, signs of skin ageing improved, such as fine lines around the eyes, skin texture, redness and pigmentation.

Caveat: there was no control group, so this is an indication rather than firm evidence. The device also used a special pulse pattern.

This review article brings together clinical research on 830 nm LEDs immediately after aesthetic treatments. Redness, swelling and bruising subsided more quickly, and the skin recovered faster.

Caveat: this is a summary of earlier research, not a study of its own. The research took place in clinics, after treatments.

This review brings together research on whole-body light therapy around exercise and recovery. Of all sources on this page, it comes closest to using a panel.

An overview of 37 studies with 586 participants. Light improved muscular endurance and time to exhaustion on the bike. The effect was in endurance, not in maximal strength or sprinting.

An overview of 13 good-quality randomised studies. In 12 of them the light was applied before exercise, and 10 found significantly better performance.

An overview of 46 studies with 1045 participants, using red light, near-infrared and combinations. According to the authors, light can increase the gain in muscle mass after training and lower inflammatory markers and oxidative stress. They even ask whether it should be allowed in competitive sport.

An overview of 39 studies with 861 healthy participants on muscle performance and fatigue during exercise. The outcomes favoured light.

20 elite female basketball players received 30 minutes of whole-body red light at 658 nm every evening for 14 days. Compared with a group receiving no light, they slept better, had more melatonin in their blood and performed better on an endurance running test.

Caveat: a small group, and the comparison group received no sham treatment but no light at all.

28 high-level football players received 810 nm light on their thigh before an intense leg exercise, at three doses or placebo. At the highest dose, their muscle strength recovered better, and blood markers of muscle damage and inflammation were lower. There was no effect on muscle soreness.

Caveat: a laser was used, aimed at a single muscle group, and the middle dose showed no effect.

In a double-blind study, 17 healthy, active men received combined LED light at 660 and 850 nm on their thigh muscles, or placebo. After a fatiguing exercise, they retained more strength with light than with placebo.

Caveat: a small group, and the two wavelengths were given together.