Melatonin is a hormone the pineal gland releases in darkness to cue the body toward sleep. As a supplement it works best as a timing signal — for jet lag and delayed sleep phase — at low doses (about 0.5–3 mg) taken a few hours before the target bedtime. It is not a strong sedative, and higher doses are not reliably better. Supplements are not FDA-evaluated, so potency can vary; third-party-tested products are preferable.

Related terms

Sleep latency: How long it takes to fall asleep after lights out — typically 10–20 minutes in healthy sleepers.
Circadian rhythm: The ~24-hour internal clock that governs sleep, alertness, and hormone release, set mainly by light.
Third-party tested: Independent lab verification that a supplement matches its label and is free of meaningful contaminants.

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