Melatonin is a hormone produced by the pineal gland that regulates the sleep-wake cycle. Its production rises in the evening as light decreases, signalling to the body that it is time to sleep, and falls in the morning as light increases.
Blue wavelength light (from screens, LED lighting, and natural daylight) is the most effective suppressor of melatonin production. Exposure to bright light in the 1–2 hours before bed delays melatonin onset by 30–90 minutes, pushing back natural sleep time and reducing total sleep duration. This is the mechanism behind the NHS recommendation to avoid screens before bed.
Low-dose melatonin supplements (0.5–1mg) are available without prescription in the UK and can help with jet lag and circadian rhythm disruption. They are not as effective as sleep hygiene improvements for chronic poor sleep. The timing of supplementation matters — it should be taken 30–60 minutes before the desired bedtime.
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