MELATONIN & SLEEP: SCIENCE-BACKED, PLAIN-LANGUAGE GUIDE “Sleep is not just rest; it synchronizes systems from hormones to immunity.” Melatonin is a hormone released by the pineal gland mainly in darkness, signaling the body that “biological night” has begun. Its key role is regulating circadian timing—your internal clock. That’s why melatonin is most useful for circadian misalignment such as jet lag or delayed sleep–wake phase disorder. It does not “knock you out” like many sedatives; instead, it provides a timing cue that can make falling asleep easier. Evidence suggests it can shorten sleep-onset latency in some people, but response varies widely. In practice, timing matters more than mega-dosing. For circadian disorders, earlier evening dosing is often used; for jet lag, timing depends on destination schedule and travel direction. For chronic insomnia, melatonin alone is rarely a complete solution unless sleep hygiene (light exposure, caffeine, bedtime routine), stress factors, and coexisting medical issues are addressed. People who are pregnant or breastfeeding, on anticoagulants, or on immunosuppressive therapy should seek medical advice before use.