Melatonin

Detailed overview

Melatonin (N-acetyl-5-methoxytryptamine) is a hormone secreted by the pineal gland in darkness that signals biological night and regulates the sleep-wake rhythm. Acting on MT1 and MT2 receptors in the brain's master clock (the suprachiasmatic nucleus), it works as a chronobiotic rather than a classic hypnotic: it primarily tunes the timing of sleep onset instead of suppressing consciousness like a sedative. Meta-analyses of randomized trials show a modest but consistent reduction in sleep-onset latency and improved sleep quality, and it is particularly effective for jet lag and circadian misalignment. It is also a direct free-radical-scavenging antioxidant. Smaller doses often work as well as large ones, and excess mainly causes next-day grogginess.