Red light and mood: early research, read carefully

Salehpour and colleagues (2019) later pooled studies on thinking skills in healthy adults. Only nine publications qualified, and six were used in the main analysis. They found a benefit for cognitive tasks in young adults, but also signs of publication bias, high variation between studies and modest study quality. Their own conclusion was that these shortcomings should be addressed before calling light a cognitive enhancer.

Some of the authors of that review reported advisory or consulting roles with light therapy companies. That doesn't make the findings wrong, but it's worth knowing.

Studies in people with depression

We include these because they're a large part of the research. We are not suggesting anyone use a home device for depression.

Schiffer and colleagues (2009) gave a single near-infrared treatment to the forehead of 10 people with major depression, most of whom also had anxiety. Depression and anxiety scores fell over the following weeks. Each person also had placebo sessions with the light off, but the longer-term changes weren't compared with a separate control group, and the authors called it a feasibility study.

Cassano and colleagues (2018) ran a double-blind, sham-controlled pilot called ELATED-2. People with major depression had 823 nm near-infrared light to both sides of the forehead twice a week for eight weeks, alongside their usual care. The results favoured light, but only 21 people were in the main analysis and 13 completed the trial. The authors said replication was needed because of the small sample. The lead author disclosed a provisional patent and links to light therapy companies.

Caldieraro and Cassano (2019) reviewed 17 animal and human studies on light and depression. They described the evidence as preliminary and noted that clinical studies varied widely and most lacked an appropriate control.

The most recent review we found, Seok and colleagues (2026), pooled 18 trials and reported a moderate overall effect on depressive symptoms. Lasers did better than LEDs, and systemic approaches, where the light wasn't aimed at the head, showed larger effects than transcranial ones. The authors called for large trials to set standard protocols.

Stress

We found very little on everyday stress. The clearest data point is from Forsey and colleagues (2023), a trial of 20 minutes of whole-body light in 48 active adults. Compared with placebo, there was no difference in how stressed people said they felt.

Why the specific devices matter

The transcranial studies above used research lasers or purpose-built devices, aimed at set points on the forehead, at doses the researchers measured and reported. ELATED-2, for example, reported its wavelength, power per area and session length precisely. A home panel or mask isn't designed or tested for this. Even if the research matures, it won't automatically apply to consumer devices.

How to read this

This is early research. The sample sizes are tiny, the methods vary, several key researchers have commercial interests, and reviews keep calling for larger, better-controlled trials. That's a reason for curiosity, not for buying anything.

Who should check with a doctor first

If you have depression, anxiety or any mental health condition, speak to your GP before trying any light device, and don't change any treatment you're on. Talk to your GP or pharmacist first if you're pregnant, take medicine that makes your skin sensitive to light, or have an eye condition. If you have epilepsy, the Epilepsy Society notes that flashing or flickering lights can trigger seizures in people with photosensitive epilepsy, so check with your doctor before using any light device. Our pages on eye safety and side effects cover more.

What we won't say

We won't say our devices lift mood, reduce stress, ease anxiety, sharpen thinking or help with depression. There's no evidence for that about our devices, and the wider research is too early to support it for home use.