Red light and sleep: a small and mixed set of studies

Red and near-infrared as a therapy

The basketball study

Zhao and colleagues (2012) is the study most often quoted. Twenty female basketball players were split into two groups of 10. One group had 30 minutes of whole-body red light every night for 14 days; the other had no light at all. The light group reported better sleep on a questionnaire and had higher blood melatonin and better 12-minute run results.

What it doesn't tell you: 20 people is small, the comparison group got no light rather than a convincing fake, and the paper describes itself as a cohort study. Without a sham, it's hard to separate the light from the attention and expectation that come with a nightly routine.

Near-infrared in older adults

Chen and colleagues (2026) randomised 59 adults aged 60 and over with early waking and broken sleep to one of three options for an hour each night over two weeks: 850 nm near-infrared to the neck, white light to the eyes, or both.

Sleep questionnaire scores improved in all three groups. People reported sleeping longer, by about 0.4 hours with white light, 0.8 with near-infrared and 1.1 with both. But wrist-worn sleep trackers showed no significant change, and neither did melatonin. There was no sham group, and one author worked for the company that supplied the equipment.

Transcranial light in insomnia

Mehdizadeh and colleagues (2025) gave 30 adults with chronic insomnia either 810 nm near-infrared light to the front of the head or a sham, for 10 minutes a day over three days. A week later, the active group had better sleep questionnaire scores, less daytime sleepiness and changes in brain wave activity compared with sham.

That's a sham-controlled design, which helps. It's also 30 people, a three-day course, one week of follow-up, and a specific research device delivering a set dose to the forehead. It tells you nothing about a panel or mask at home.

What the meta-analysis found

Vital de Azevedo and colleagues (2026) searched for randomised controlled trials of light therapy and sleep up to September 2025. Only five met their criteria, with 240 participants in total.

Pooled together, light improved scores on the Pittsburgh Sleep Quality Index, a standard sleep questionnaire, by about 1.25 points compared with sham. The authors pointed out that the wide confidence interval means the size of the effect is uncertain. They described the evidence as limited, said it should be interpreted with caution, and called for larger, standardised trials.

How to read this

Five trials and 240 people is a very small evidence base. Most outcomes are questionnaires, which is why a convincing sham matters so much. Where objective measures were used, as in the Chen trial, they didn't always move. The devices, wavelengths, body areas and timings all differ.

A fair summary: red light at night may be less disruptive to melatonin than blue light, and red or near-infrared therapy has shown small, uncertain effects on self-reported sleep in a few trials. That's interesting, and it's early.

Who should check with a doctor first

If poor sleep is affecting your days, the NHS insomnia page sets out what you can try yourself and when to see a GP. Talk to your GP or pharmacist before using any light device if you're pregnant, take medicine that makes your skin sensitive to light, have an eye condition, or have epilepsy triggered by flashing lights. Read our pages on eye safety and side effects as well.

What we won't say

We won't say our devices help you sleep, fix insomnia or raise melatonin. If you do use a red light device in the evening, use it as its instructions say, follow its eye protection advice, and fit it into a routine you'll keep. Our guide to planning a routine may help.