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Melatonin

Also known as: N-acetyl-5-methoxytryptamine, Sleep hormone

The sleep-wake hormone, taken as the most popular OTC sleep aid in the US — best for jet lag and falling asleep faster.

Nighttime still life with an amber dropper, plain tablet, book, and paper moon
Editorial illustration

Melatonin is a circadian signal rather than a conventional sedative. Evidence is strongest for correctly timed jet-lag use and selected circadian-delay problems; average insomnia effects are modest, and dose timing, product accuracy, and long-term pediatric safety remain important uncertainties.1, 3

  • Hormone released in darkness that regulates the circadian rhythm1, 3
  • Strongest evidence: jet lag and shifted sleep schedules1, 3
  • Typical useful dose: 0.5–3 mg, taken 30–60 minutes before bed1, 3
  • More is not better — high doses raise side effects without better sleep1, 3

What is Melatonin?

Melatonin is often called the sleep hormone, but its real job is subtler: it is the chemical signal of darkness. When evening light fades, the pineal gland releases melatonin, telling your body's internal clock that night has begun. Supplementing it does not sedate you like a sleeping pill — it nudges your circadian rhythm, which is exactly why it shines for jet lag and schedule shifts, and why its effect on ordinary insomnia is modest.1

Where it comes from

Natural sources

  • Produced endogenously by the pineal gland in darkness
  • Tart cherries and a few foods contain trace amounts (too little to matter clinically)
  • Supplemental melatonin is produced synthetically, not extracted from animals

How it's made

Commercial melatonin is synthesized in laboratories; doses on labels are often inaccurate, so third-party testing matters.

What it does in products

  • Signals nighttime to the circadian clock
  • Slightly lowers core body temperature, part of the sleep-onset cascade
  • Phase-shifts the sleep-wake cycle (moves it earlier or later depending on timing)

Benefits

Jet lag

strong evidence

Meta-analyses consistently find melatonin reduces jet lag symptoms when taken near bedtime at the destination, especially crossing five or more time zones.2, 1

The Cochrane review supports correctly timed melatonin for jet lag, especially after crossing several time zones; timing is central to the effect.

Delayed sleep phase (night owls)

moderate evidence

Small doses taken hours before habitual bedtime can shift sleep earlier in people with delayed sleep-wake phase disorder — one of its clearest clinical uses.1, 3

Circadian-timing evidence supports use in delayed sleep-wake phase, but dose and clock time should not be inferred from a generic bedtime instruction.

Falling asleep faster

moderate evidence

In people with insomnia, melatonin shortens the time to fall asleep by roughly 7–12 minutes on average and slightly improves total sleep time — real but modest.3, 4

Meta-analyses find modest average effects on sleep onset; product variability and the cause of insomnia limit generalization.

Children's sleep

limited evidence

Melatonin helps some children with ADHD or autism-spectrum conditions fall asleep, and short-term use under pediatric guidance is common — though long-term safety in children is not fully established.1

Short-term pediatric studies show benefit in selected neurodevelopmental populations, but long-term safety and over-the-counter product consistency remain concerns.

Evidence scope and limitations

The review covers oral melatonin for jet lag, circadian delay, insomnia symptoms, and selected pediatric settings; it does not treat every sleep complaint as one condition.

  • Dose and timing interact with circadian phase, so more milligrams do not necessarily produce a better result.
  • U.S. supplements may differ from their labels, and long-term safety evidence is more limited than short-term evidence.

Evidence last checked: 2026-09-26

Side effects & safety

Morning grogginess (uncommon)More common at doses above 5 mg; lowering the dose usually fixes it.
Vivid dreams or headache (uncommon)Usually transient.
Accidental ingestion by children (rare)Gummy formulations look like candy and are a leading cause of pediatric poison-center calls — store locked away.

Safety considerations

  • Melatonin has limited safety data in pregnancy; consult your provider before use.
  • Adds to the effects of sedatives, alcohol, and other sleep medications.
  • May affect immune function — caution with immunosuppressant therapy.
  • May raise blood pressure slightly if taken with certain blood-pressure medications (timing matters).
  • Not for: Autoimmune conditions (use under supervision only)
  • Not for: Unsupervised use in young children
1, 4

Amounts studied & product use

These figures describe research or common product use, not a personal dose or treatment recommendation.

In supplement studies and products

Sleep and jet-lag trials use varied timing and amounts, commonly from sub-milligram doses to several milligrams. Product content can differ from the label, and the evidence does not establish one nightly dose for long-term self-treatment of insomnia.

1, 3

Regulatory status

  • Dietary supplement under DSHEA. Unlike prescription sleep aids, it is not FDA-approved as a treatment for insomnia, and label quality varies — independent testing (USP/NSF) is recommended.
5

Why less melatonin is often more

A landmark MIT analysis found peak physiological effect at roughly 0.3 mg, and clinical reviews consistently find no additional sleep benefit above 3 mg — while next-day grogginess rises with dose. The 10 mg gummies on shelves reflect marketing, not pharmacology. If 3 mg does not help, the problem may be sleep hygiene or timing, not the dose.

1

Frequently asked questions

What is the best time to take melatonin?

For sleep onset, 30–60 minutes before bed. For shifting a late sleep schedule earlier, tiny doses (0.3–0.5 mg) several hours before your current bedtime are more effective than a big dose at bedtime — timing determines whether you shift earlier or later.1, 3

Is melatonin safe to take every night?

Short-term nightly use (weeks to a few months) appears safe for most adults. It is best used as a rhythm corrector rather than a permanent crutch; if insomnia persists beyond a few weeks, see a doctor rather than escalating the dose.1, 3

Is melatonin addictive?

No. Melatonin does not cause physical dependence or withdrawal like prescription sedatives, though some people become psychologically reliant. Tolerance is not a known issue — ineffectiveness usually reflects wrong timing or an underlying sleep problem.1, 3

The bottom line

With melatonin, timing often matters more than milligrams. It has credible circadian uses, but it is not a universal answer to every cause of poor sleep.

References

  1. Melatonin: What You Need To Know. National Center for Complementary and Integrative Health (2025) · government guidance
  2. Melatonin for the prevention and treatment of jet lag. Cochrane Database of Systematic Reviews (2002) · systematic review · PMID 12076414
  3. Optimizing the time and dose of melatonin as a sleep-promoting drug: a systematic review and dose-response meta-analysis. Journal of Pineal Research (2024) · meta analysis · PMID 38888087
  4. Efficacy of melatonin for chronic insomnia: systematic reviews and meta-analyses. Sleep Medicine Reviews (2022) · systematic review · PMID 36179487
  5. Dietary Supplements. U.S. Food and Drug Administration (2025) · government guidance

Revision history

  1. Replaced search-result citations with exact sources, mapped claims to evidence, and reassessed evidence strength.