Melatonin: Evidence for Sleep, Studied Doses and Safety

What is Melatonin?

Melatonin is a hormone produced by the pineal gland that signals darkness to the body and helps regulate the sleep–wake cycle. Supplemental melatonin is synthetic and is regulated in the US as a dietary supplement, not a medicine.

How it is used in supplements

It is marketed for falling asleep faster, jet lag, shift-work adjustment and general sleep quality, and appears in many multi-ingredient sleep formulas.

What the research shows

Evidence is strongest for circadian timing problems — jet lag and delayed sleep–wake phase — where research shows meaningful benefit. For ordinary chronic insomnia, average effects in studies are real but modest, typically shaving minutes off the time to fall asleep rather than transforming sleep. NCCIH maintains an accessible evidence summary.

Typical studied amounts

Studied doses commonly range from 0.5 mg to 5 mg taken before bedtime; research does not show that larger doses work better, and many products contain far more than studies used. Actual melatonin content in supplements has been found to vary from label claims, which makes third-party-tested products preferable.

Safety and side effects

Short-term use appears well tolerated; drowsiness, headache and vivid dreams are the common complaints. Long-term safety data is limited. Next-morning grogginess can affect driving.

Medication interactions

Melatonin can interact with blood thinners, immunosuppressants, diabetes medication and contraceptives, and adds to the effect of sedatives and alcohol.

Who should be cautious

Pregnant and breastfeeding women, people with autoimmune conditions, and anyone on interacting medication should consult a professional first. Persistent insomnia and snoring-with-gasping warrant medical evaluation, since disorders like sleep apnea do not respond to melatonin.

References

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