Melatonin

Human RCT Supplementssleep Last reviewed 2026-09-28

Summary

A hormone produced by the pineal gland that regulates sleep-wake timing. Meta-analyses of randomized trials find small reductions in the time needed to fall asleep and small increases in total sleep time compared with placebo.

Mechanism

Melatonin is a hormone secreted by the pineal gland in darkness, signaling nighttime to the brain's circadian pacemaker (suprachiasmatic nucleus) via MT1 and MT2 receptors. Supplemental melatonin shifts sleep timing earlier and shortens the time to fall asleep; it is a chronobiotic signal of darkness, not a sedative.

Reported effects

Ratings are relative to peers in the same category, not absolute claims.

Sleep onset latency★★★☆☆Meta-analyses find roughly 4-7 fewer minutes to fall asleep vs placebo.

Total sleep time★★☆☆☆Small gains of roughly 8-13 minutes in pooled trials.

Overall sleep quality★★☆☆☆Small but statistically significant improvement in pooled scores.

Studied dosing: research context

Trials have used 0.1-10 mg taken before bed, most commonly 0.5-5 mg about 30-60 minutes before the desired bedtime. Meta-analytic data suggest larger effects with higher doses and longer trial durations. These are doses used in research, not guidance.

Research context only. This is not a recommendation.

Safety

Short-term use is generally well tolerated. Commonly reported effects include morning grogginess, vivid dreams, and headache. Data on long-term use, use in children, and use in pregnancy are limited. Interactions are possible with anticoagulants, immunosuppressants, and diabetes medications.

Limitations

Absolute effects are modest, and trial populations and doses vary widely. Long-term efficacy and safety are less studied than short-term use. Melatonin is less effective than prescription sleep medications, and its advantage is mainly a relatively benign side-effect profile.