What melatonin is — and isn't
Melatonin is a hormone the body makes to signal nighttime; supplements aim to nudge sleep timing. It's widely treated as a general 'sleeping pill,' but NCCIH's summary of the evidence is more nuanced [1].
Where it has reasonable evidence
- Jet lag: melatonin may help, per medium-sized reviews, though effects vary by travel direction [1] — relevant for [travelers](/learn/supplements-for-frequent-travelers).
- Delayed sleep timing: evidence is mixed; one trial found people fell asleep about 34 minutes earlier, with weak overall recommendations [1].
Where it falls short
For chronic insomnia, NCCIH notes 'there's not enough strong evidence on the effectiveness or safety of melatonin,' and professional guidelines generally don't recommend it as a primary treatment [1]. So melatonin is better thought of as a circadian-timing aid than a reliable sleep inducer for ongoing insomnia.
Safety realities
- Short-term use is generally well tolerated, with mild effects like headache or daytime drowsiness [1].
- Long-term safety data are limited [1].
- It's a hormone, so possible effects on hormonal development in children are a concern, and pediatric use should involve a clinician.
- Mislabeling is common: an analysis found many gummy products contained far more melatonin than labeled [1], and unsupervised pediatric ingestion has risen sharply (see [supplement safety for children](/learn/supplement-safety-for-children)).
Dosing and expectations
More is not better — lower doses (often a fraction of a milligram to a few milligrams), taken earlier in the evening, generally suit circadian effects better than large bedtime doses. Set expectations around timing help, not sedation, and address sleep habits first.
Practical guidance
- Best for jet lag and shifting sleep timing, less so for chronic insomnia.
- Start low, take it earlier, and don't expect a knockout effect.
- Use children's melatonin only with a clinician, and store it safely.
- Choose third-party-tested products given mislabeling.