Melatonin for sleep: what it does and doesn't do

Melatonin can help you fall asleep a little faster, but for ordinary insomnia the effect is small, around 7 minutes in pooled trials. Its clearer uses are for problems with the timing of sleep, such as jet lag and a body clock that runs very late. It's a hormone rather than a sedative, so the dose and the time you take it matter, and it's worth checking with a doctor or pharmacist before you start.

What is melatonin?

Melatonin is a hormone your brain makes in response to darkness. The National Center for Complementary and Integrative Health (NCCIH) explains that it helps set the timing of your circadian rhythms, your 24-hour internal clock, and your sleep. Light at night can block its production.

The NHS describes the same pattern: melatonin levels rise at night and fall back during the day, which helps control how and when you sleep. Supplements are mostly made synthetically. In the US they are sold as dietary supplements, while in the UK and several other countries melatonin is prescription only.

Does melatonin help you sleep?

Melatonin helps you sleep a little. A 2013 meta-analysis in PLOS ONE pooled 19 placebo-controlled trials with 1,683 people who had primary sleep disorders. Melatonin shortened the time it took to fall asleep by about 7 minutes and increased total sleep by about 8 minutes. Overall sleep quality also improved compared with placebo.

The authors called these effects modest. They also found the benefits didn't fade with continued use, and that trials using higher doses or lasting longer showed bigger effects on sleep onset and total sleep. They concluded that melatonin may still have a role because its side effects are relatively mild compared with other sleep medicines.

What do sleep experts say about melatonin for insomnia?

The American Academy of Sleep Medicine (AASM) is cautious. Its 2017 guideline on medicines for chronic insomnia suggests that clinicians not use melatonin to treat trouble falling or staying asleep in adults. The recommendation is graded weak, and it's based on trials of 2 mg doses.

NCCIH summarizes the position plainly. According to guidelines from the AASM and the American College of Physicians, there isn't enough strong evidence on the effectiveness or safety of melatonin for chronic insomnia to recommend it. The American College of Physicians strongly recommends cognitive behavioral therapy for insomnia (CBT-I) as the first treatment. Our guide to CBT for insomnia explains how it works.

Where does melatonin work best?

Melatonin works best when the problem is timing. NCCIH lists a few areas where it may help:

• Jet lag. Reviews found melatonin did better than placebo at reducing jet lag symptoms after eastward flights, and in a smaller group of travelers, after westward flights.
• Delayed sleep-wake phase disorder, where people can't fall asleep until very late, often 2 to 6 a.m. In one 4-week trial of 307 people, taking melatonin 1 hour before the desired bedtime alongside a set bedtime helped them fall asleep an average of 34 minutes earlier.
• Anxiety before surgery, where a 2015 review found strong evidence it worked better than placebo.

For shift workers, NCCIH says the studies were generally small or inconclusive.

How much melatonin should you take?

How much melatonin to take is a question for a doctor or pharmacist, because the answer depends on why you're taking it and what else you take. Here is what reputable sources say, as a starting point for that conversation rather than a dosing guide.

In the UK, where melatonin is prescribed, the NHS says it usually comes as 2 mg slow-release tablets. For short-term insomnia in adults, the usual dose is one tablet taken 1 to 2 hours before bed, typically for 1 to 4 weeks and at most 13 weeks. For jet lag, the usual dose is one 3 mg standard tablet a day for up to 5 days. The NHS also says melatonin takes around 1 to 2 hours to work.

US supplements vary much more. The Sleep Foundation says over-the-counter products contain anywhere from about 0.2 mg to 20 mg. It notes that research suggests doses below 1 mg may work as well as higher ones, and advises starting with the lowest dose unless a doctor says otherwise.

Do melatonin supplements contain what the label says?

Melatonin supplements often don't contain what the label says. A 2017 study in the Journal of Clinical Sleep Medicine tested 31 supplements and found melatonin content ranged from 83% less to 478% more than the label claimed. More than 71% of products were outside a 10% margin of their label, and 8 contained serotonin.

Gummies have the same problem. A 2023 study in JAMA tested 25 melatonin gummy products sold in the US and found 22 were inaccurately labeled. One contained no detectable melatonin, and in the rest the actual amount ranged from 74% to 347% of the labeled quantity. The Sleep Foundation suggests looking for a U.S. Pharmacopeia certification on the label or asking a pharmacist to recommend a trusted brand.

Is melatonin safe?

For short-term use, melatonin appears safe for most people, according to NCCIH, though information on long-term safety is lacking. Short-term studies in adults reported only mild side effects, including headache, dizziness, nausea and sleepiness. The NHS adds that some people feel tired, sick or irritable the day after taking it.

Some people should get medical advice first. NCCIH says anyone taking medicine should check with their health care provider, and people with epilepsy or on blood thinners should only take melatonin under medical supervision. There's little research on its safety in pregnancy or breastfeeding. Melatonin may stay active longer in older people and cause daytime drowsiness, and the AASM recommends against its use in people with dementia.

The NHS also warns that drinking alcohol or smoking can stop melatonin working as well, and advises against combining it with herbal remedies that affect sleep, since that may make you very drowsy.

What about melatonin for children?

NCCIH says parents should speak with a health care provider before giving melatonin to a child. There are open questions about the right dose and the long-term effects, and because it's a hormone, it might affect development, including puberty, though this isn't known for sure.

Accidental ingestion is a growing problem. NCCIH cites a CDC estimate of about 11,000 emergency department visits from 2019 to 2022 for children 5 and under who took melatonin unsupervised, many involving flavored products like gummies. Keep it out of children's reach and sight.

What else can you try?

If your main problem is falling asleep, behavioral approaches have stronger evidence than melatonin. Our guide on how to fall asleep faster covers stimulus control, relaxation and other techniques. If late-night phone use is pushing your bedtime later, see do screens before bed really hurt your sleep?.

If you're tired despite a full night in bed, falling asleep may not be the issue at all. Our guide to waking up tired looks at other causes, and snoring vs. sleep apnea explains when snoring needs a doctor.

Read next

• Sleep hygiene: the habits with the best evidence
• How much sleep do adults need?
• Why do I wake up at 3am?

* This content is for informational and educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any disease or health condition. Talk to a qualified healthcare provider about your health.