Systematic review of light exposure impact on human circadian rhythm

This systematic review synthesizes findings from 128 studies on the effects of artificial and natural light exposure on human circadian rhythms, focusing on melatonin suppression and REM sleep impacts. Evening and night-time exposure to blue light (460 nm) suppressed melatonin and delayed circadian phases, disrupting sleep. Shorter wavelengths (424 nm) had the strongest suppressive effects. Light also affected REM sleep timing. Sensitivity to light was influenced by individual factors such as age and chronotype. The review underscores the importance of reducing evening light exposure to mitigate health risks linked to circadian disruption, including sleep disorders and metabolic and mental health issues.

Reduce exposure to bright or blue-enriched light in the evening by using dim lighting or blue-light-blocking filters. Prioritize exposure to natural or bright light in the morning to stabilize circadian rhythms. This recommendation is supported by robust data linking light exposure timing and intensity to melatonin regulation and sleep quality, though individual sensitivity to light varies.