Is red light therapy good before bed?

Circadian signalling is driven largely by intrinsically photosensitive retinal ganglion cells, which peak in sensitivity around 480 nm — blue. That's why evening phone and overhead lighting are the usual sleep culprits.

Red light at 630–660 nm and near-infrared at 810–850 nm sit far from that peak, so equivalent brightness has much less circadian effect. This is also why red-tinted evening lighting is a common sleep-hygiene recommendation.

Less effect is not zero effect. A very high-output full-body bed is extremely bright, and brightness itself is arousing for some people regardless of colour.

There is published work reporting improved sleep quality and, in some athlete studies, improved sleep and recovery measures with regular red light exposure. The literature here is younger and smaller than the skin and soreness research.

Proposed explanations include effects on melatonin production and general reductions in muscle discomfort making it easier to settle. Both are plausible; neither is settled.

Treat it as a promising habit rather than a treatment. If sleep is your main goal, the honest expectation is a modest improvement layered onto ordinary sleep hygiene, not a replacement for it.

Start with a session that finishes 30–60 minutes before bed. That leaves room for the brightness to wear off and for your normal wind-down.

If you feel wired afterwards, move the session earlier — late afternoon or straight after dinner — rather than abandoning it.

Keep the rest of the evening dim. A red light session followed by an hour of bright overhead lighting and a phone at full brightness is working against itself.

Keep the timing consistent. Regularity is a bigger lever on sleep than the exact hour you pick.