Quick answer

Melatonin is a hormone your brain makes in the dark to time sleep. Taken near bedtime, it has moderate evidence for falling asleep 4 to 7 minutes sooner and for easing jet lag after long flights. Short-term use appears safe for most adults, but long-term safety is unknown.^1,2,3,4

Key facts

Light at night can block the melatonin your body makes.¹
Jet lag trials used 0.5 to 5 mg at bedtime at the destination, and doses above 5 mg did no better.⁴
In the US melatonin is a dietary supplement, while several other countries sell it only on prescription.¹
In a 2023 test, 22 of 25 melatonin gummies did not contain the amount on the label.⁵
NIH's liver injury database has not linked melatonin to liver damage.⁶

What melatonin is

Melatonin is a hormone your brain produces in response to darkness. It helps with the timing of your 24-hour internal clock and with sleep.¹

Being exposed to light at night can block the body's own melatonin production.¹

A supplement adds to the body's own night-time signal. That is why the trials gave it in the evening, and why the time you take it matters as much as the amount.^1,4

Melatonin supplements can be made from animals or microorganisms, but most are made synthetically.¹

Melatonin is sold as tablets, capsules, liquids and gummies, and US sales rose by about 150 percent between 2016 and 2020.¹

What the evidence shows

Each claim below carries a grade. The grade says how much human research there is and how well it agrees, not how large the effect is. The amount the studies used is shown with each one.

Helps you fall asleep a little sooner on nights of occasional sleeplessness*^2,3,7

Moderate evidence

Pooled placebo-controlled trials show melatonin shortens the time it takes to fall asleep by about 4 minutes (17 studies, 284 people) to 7 minutes (19 studies, 1,683 people, doses of 0.1 to 5 mg). The effect is consistent but small, most trials were short, many enrolled people with diagnosed sleep problems, and the largest 2 mg trials used a slow-release tablet.

Amount studied: 0.1 to 5 mg, almost always taken in the evening

Helps ease the feelings of jet lag after flights across five or more time zones*^1,4,7,8

Moderate evidence

A Cochrane review of 10 trials found that in 9 of them melatonin, taken at bedtime at the destination in doses of 0.5 to 5 mg, reduced jet lag after flights crossing five or more time zones. The trials were small, and a later meta-analysis of 9 trials (427 people) found no effect on how quickly people with jet lag or shift work fell asleep, so the evidence is not unanimous.

Amount studied: 0.5 to 5 mg close to bedtime at the destination

Both effects are modest or narrow. The pooled sleep trials measured a gain of minutes, not hours. The jet lag result comes from travellers crossing five or more time zones who took melatonin near bedtime at the destination, and it was smaller after flights heading west.^2,3,4

How much people take

Sleep trials in adults used 0.1 to 5 mg of melatonin a day, almost always taken in the evening. Several of the largest used 2 mg as a prolonged-release tablet in people aged 55 and over.³

In the Cochrane review of jet lag trials, daily doses of 0.5 to 5 mg worked about equally well, people fell asleep faster and slept better after 5 mg than after 0.5 mg, and doses above 5 mg appeared to be no more effective.⁴

Higher is not clearly better. A 2024 pooled analysis found the effect on falling asleep peaked at about 4 mg a day. The dosage guide sets out the amounts in more detail.⁹

When to take it

Taken at the wrong time, early in the day, melatonin is liable to cause sleepiness and to delay adjusting to local time.⁴

The timing guide covers how long before bed to take it and how to time it around a long flight.

What is in the bottle

In the United States melatonin is sold as a dietary supplement, which is regulated less strictly than prescription or over-the-counter drugs. In several other countries it is available only with a prescription and is treated as a drug.¹

In a 2017 study of 31 melatonin supplements, the amount in most products did not match the label, and 26 percent of them contained serotonin.^1,10

In a 2023 study, 22 of 25 melatonin gummy products were inaccurately labeled. One had no detectable melatonin, and the rest held 74 to 347 percent of the amount on the label.^1,5

The amount printed on a melatonin label is the maker's statement. Studies that measured what was actually inside found it often differed, sometimes by several times.^5,10

What's in ours

What’s in ours

Sleep: Melatonin, 2 mg per serving, from the label

Two capsules of our Sleep formula list 2 mg of melatonin. That is inside the 0.1 to 5 mg range of the sleep trials and the 0.5 to 5 mg range of the jet lag trials. The label does not say whether the melatonin is immediate or slow release.^3,4

Side effects, medicines and who should ask first

Side effects reported in short-term studies in adults were mild: headache, dizziness, nausea and sleepiness.^1,11

Melatonin may stay active longer in older people than in younger people and cause daytime drowsiness.¹

There may be a risk of allergic reactions to melatonin supplements.¹

No upper limit has been set for melatonin. NCCIH says there is not yet enough information on side effects, especially at doses higher than the body makes, for a clear picture of its overall safety, and information on long-term use is lacking.¹

Ask your pharmacist or doctor first

NCCIH says people taking blood thinner medicines need to be under medical supervision when taking melatonin. A Cochrane review noted case reports suggesting that people taking warfarin may come to harm from melatonin, and called for the possible interaction to be studied.^1,4

Reported in studies

NCCIH also says people with epilepsy need medical supervision to take melatonin, and that sleep medicine guidelines recommend against it for people with dementia. Two clinical guidelines, from 2017 and 2019, advised against melatonin for chronic insomnia.^1,12

Ask first if you take a blood thinner, a seizure medicine, sleeping pills or any other prescription medicine¹
Ask first if you are pregnant or breastfeeding, because there has been little research on either^1,11
Ask first if you take birth control pills, which raised blood melatonin 4 to 5 times in one study¹³
See a doctor if poor sleep lasts more than a few weeks, rather than relying on a supplement¹²
Do not drive or use machinery while you feel drowsy¹

Children and melatonin

NCCIH says parents should speak with a health care provider before giving a child melatonin. The right dose, the best time, long-term effects and whether the benefits outweigh the risks are all uncertain in children, and this site gives no amounts for them.¹

A CDC report estimated about 11,000 emergency department visits from 2019 to 2022 for children aged 5 and under who swallowed melatonin without supervision. Many of the cases involved flavored products such as gummies.¹

Keep melatonin, and gummies above all, out of children's reach and sight.¹

Questions people ask

Is melatonin a sleeping pill?

Not in the United States, where it is sold as a dietary supplement and regulated less strictly than a drug. Several other countries sell it only on prescription. It does cause sleepiness, so take the same care as with anything else that makes you drowsy.¹

Can you take melatonin every night?

Most trials lasted weeks, not years. A review of 17 trials found no evidence of harm with use of three months or less, but NCCIH says information on long-term safety is lacking. If you sleep poorly most nights for more than a few weeks, see a doctor.^1,8

Does melatonin do anything besides sleep?

NCCIH says research suggests melatonin has other roles in the body beyond sleep, but these are not fully understood. This site makes no claims about them, including the skin and brain uses some products mention.¹

Can I take melatonin with valerian?

NIH lists melatonin among the supplements that might add to valerian's sedating effects. Our Sleep formula contains both, at 2 mg of melatonin and 150 mg of valerian extract. Ask a pharmacist before adding any other product that makes you drowsy.¹⁴

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Sources

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.