Melatonin

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By Nikola · Precision Nutrition L1 · Updated 5 November 2026

Melatonin is a hormone your brain makes in response to darkness; it helps set your body clock, and a synthetic version is used for jet lag and for trouble falling asleep. Light at night blocks its production. The EU allows two health claims: 0.5 mg close to bedtime eases the subjective feeling of jet lag, and 1 mg close to bedtime shortens the time it takes to fall asleep. The effect is modest. In the UK melatonin is prescription-only, and in the EU its legal status differs from country to country. Short-term use appears safe for most adults, but long-term safety data are lacking, and use in children belongs with a doctor.

What the research says

• Jet lag: moderate. In four studies with 142 travellers flying east, melatonin may have beaten placebo for overall symptoms, and two studies with 90 travellers suggested a benefit after flying west. The EU claim: “Melatonin contributes to the alleviation of subjective feelings of jet lag”, with at least 0.5 mg taken close to bedtime on the first day of travel and the following few days after arrival.
• Falling asleep sooner: moderate, small effect. The EU claim: “Melatonin contributes to the reduction of time taken to fall asleep”, with 1 mg close to bedtime. In delayed sleep-wake phase disorder, where the body clock runs late, a 2016 review of 52 people found sleep onset about 22 minutes sooner than with placebo, and a 2018 trial in 307 people found about 34 minutes sooner when melatonin was taken 1 hour before a set bedtime.
• Chronic insomnia: weak. US guidelines from 2016 and 2017 found the evidence insufficient to recommend melatonin. Cognitive behavioural therapy for insomnia (CBT-I) is the recommended first treatment.
• Shift work: weak. One review found about 24 minutes more daytime sleep, with low-quality evidence; another was inconclusive.
• Children with sleep problems: moderate, for specific conditions. A 2019 review of 18 mostly small, short studies with 1,021 children found faster sleep onset and longer sleep: in autism, 37 minutes sooner and 48 minutes longer; in ADHD, 20 minutes sooner and 33 minutes longer. Long-term effects, including on puberty, are unknown.
• Anxiety before surgery: strong. A 2015 review of 12 studies with 774 people found strong evidence that melatonin reduces anxiety before an operation.

Dose and forms

• UK prescriptions (NHS). For short-term insomnia in adults aged 55 and over: one 2 mg slow-release tablet 1 to 2 hours before bed, for a maximum of 13 weeks. For jet lag in adults: one 3 mg standard tablet once a day for up to 5 days, the first dose at your normal bedtime and not before 8 pm or after 4 am; it can go up to 6 mg, with no more than 16 courses a year. Specialists may prescribe up to 10 mg a day for long-term sleep problems in some children and adults.
• Forms. Standard tablets, slow-release tablets, capsules and liquid. The NHS advises taking slow-release tablets with food and swallowing them whole, and standard tablets 2 hours before or after food.
• EU medicines. Since 2007 a 2 mg prolonged-release tablet has been authorised across the EU, on prescription, for short-term primary insomnia in people aged 55 and over, for up to 13 weeks. Since 2018 another prolonged-release medicine has been authorised, on prescription, for children with autism, certain genetic disorders or ADHD when better sleep habits have not helped.

Food sources

Some foods contain melatonin, but in tiny amounts. A 2017 review found eggs and fish to be the richest animal sources and nuts the richest plant source, with some mushrooms, cereals and sprouted legumes or seeds also contributing. Balaton tart cherries had 13.46 ng per gram, about 0.0013 mg in 100 g: roughly 74 kg of cherries for the 1 mg in the EU claim (our calculation). Food can still raise blood melatonin a little: in one study, serum melatonin rose from 48 to 146 pg/mL after eating pineapple. See our entries on eggs, salmon, walnuts, almonds, mushrooms and mung bean sprouts.

Side effects and interactions

• Common. Headache, dizziness, nausea and daytime sleepiness; the NHS also lists stomach ache, restlessness, dry mouth and strange dreams.
• Serious. Rare, in fewer than 1 in 1,000 people: blurred vision, fainting, confusion, or bleeding or bruising that won’t stop. Serious allergic reactions are possible but rare.
• Drowsiness. If you feel sleepy in the daytime, do not drive or use machinery, and avoid alcohol.
• Medicines. The NHS list includes antidepressants such as fluvoxamine, benzodiazepines, blood pressure medicines, NSAIDs such as ibuprofen, oestrogens in the pill or HRT, opiates, some antibiotics, carbamazepine, warfarin and sleeping pills such as zolpidem. Do not combine it with herbal remedies that make you sleepy. People with epilepsy or on blood thinners need medical supervision.

Who should avoid it

• Pregnancy. The NHS does not usually recommend it, because little is known about its effect on babies. When breastfeeding, the NHS says it can be taken if your baby is healthy, but do not share a bed with your baby while taking it.
• Children. Only on a doctor’s advice. In the US, an estimated 11,000 emergency visits between 2019 and 2022 involved children aged 5 and under who swallowed melatonin unsupervised, many of them flavoured gummies. Keep it out of reach.
• Autoimmune, liver or kidney conditions. The NHS asks you to check with a doctor first if you have rheumatoid arthritis, multiple sclerosis, lupus or another autoimmune condition, or liver or kidney problems.
• Older adults with dementia. The American Academy of Sleep Medicine recommends against it. In older people it may act for longer and cause daytime drowsiness.
• France’s advice. In 2018, after 90 reports of side effects, ANSES advised against melatonin supplements in pregnancy and breastfeeding, for children and teenagers, and for people with autoimmune or inflammatory disease, epilepsy, asthma or mood disorders, or on other medicines.

How to choose a good product

• Know your local rules. In the UK you need a prescription. In 2018, Spain and Italy allowed up to 1 mg a day in food supplements, Belgium and Germany treated 0.3 mg a day or more as a medicine, and Denmark and the Czech Republic did not allow it in supplements at all. In several countries outside the US it needs a prescription. Check with a pharmacist.
• Labels can be wrong. A 2023 study of 25 melatonin gummies found 22 inaccurately labelled, with 74% to 347% of the stated amount; one had none. A 2017 study of 31 products found most did not match the label and 26% contained serotonin.
• Check the dose per tablet. The EU claims are based on 0.5 to 1 mg; NHS prescriptions for adults start at 2 to 3 mg. NCCIH notes that safety data for doses above what the body makes are limited.
• Independent testing. Seals from ConsumerLab.com, NSF International or US Pharmacopeia show a product contains what the label says, but do not guarantee safety or effect.

We do not recommend specific products on this page.

FAQ

Does melatonin help you fall asleep?

A little. The EU accepts that 1 mg close to bedtime reduces the time taken to fall asleep, and trials in people whose body clock runs late show sleep onset about 20 to 35 minutes sooner. For long-term insomnia, guidelines do not recommend it; CBT-I comes first.

How much melatonin should I take for jet lag?

The EU claim is based on at least 0.5 mg close to bedtime on the first day of travel and the next few days after arrival. NHS prescriptions use 3 mg once a day for up to 5 days, taken at your usual bedtime.

Is melatonin safe for children?

It can help some children with autism or ADHD fall asleep sooner, but long-term effects are not known. Give it only on a doctor’s advice, and keep gummies out of reach of small children.

Related entries and articles

• Eggs and salmon
• Walnuts and almonds
• Mushrooms
• Other supplements: ashwagandha, magnesium, probiotics
• Why sleep is the cornerstone of a healthy lifestyle

Sources

1. NCCIH: Melatonin: What You Need To Know, updated May 2024. nccih.nih.gov
2. Commission Regulation (EU) No 432/2012 – permitted health claims (melatonin entries). legislation.gov.uk
3. NHS: About melatonin. nhs.uk
4. NHS: How and when to take melatonin. nhs.uk
5. NHS: Who can and cannot take melatonin. nhs.uk
6. NHS: Side effects of melatonin. nhs.uk
7. NHS: Taking melatonin with other medicines and herbal supplements. nhs.uk
8. NHS: Pregnancy, breastfeeding and fertility while taking melatonin. nhs.uk
9. European Medicines Agency: Circadin (melatonin), EPAR. ema.europa.eu
10. European Medicines Agency: Slenyto (melatonin), EPAR. ema.europa.eu
11. Side effects prompt French authorities to issue melatonin supplement warning. NutraIngredients, 23 April 2018. nutraingredients.com
12. Meng X, et al. (2017). Dietary Sources and Bioactivities of Melatonin. Nutrients 9(4):367. mdpi.com
13. NIH Office of Dietary Supplements: Dietary Supplements: What You Need to Know, updated 4 January 2023. ods.od.nih.gov

This page is for information only and is not medical or dietary advice.