Melatonin Dosage: How Much Melatonin to Take, When to Take It and What the Side Effects Are

The right melatonin dosage for most adults is smaller than the doses many stores sell. The European Food Safety Authority concluded that 1 mg taken close to bedtime reduces the time it takes to fall asleep ³. A 2024 dose-response meta-analysis found that benefits rose up to about 4 mg per day and worked better when taken about 3 hours before bedtime ¹. Doses of 10 mg and more are common on shelves, but no evidence shows they work better.

This guide covers how much melatonin to take, when to take it, what side effects to watch for, why labels are often wrong, and how the rules differ between countries. It is written for adults. Children need a pediatrician's advice, and we do not cover dosing for them here.

What melatonin does

Melatonin is a hormone your brain releases in the evening as light fades. It tells your body that night has started. It is a timing signal. It does not knock you out the way a sleeping pill does.

Supplemental melatonin has two effects:

• A mild sleep-promoting effect for a few hours after you take it.
• A clock-shifting effect. Taken in the afternoon or evening, it moves your body clock earlier. Taken in the morning, it can move it later ⁵.

That second effect is why timing matters so much. For more on the clock itself, see circadian rhythm.

What the research says about melatonin dosage

The effect is modest

A 2013 meta-analysis of 19 trials with 1,683 people with primary sleep disorders found that melatonin shortened the time to fall asleep by about 7 minutes and increased total sleep by about 8 minutes compared with placebo ². Overall sleep quality also improved. The authors called the effects modest, and noted that they did not seem to fade with continued use. Higher doses and longer trials showed somewhat larger effects on sleep latency and total sleep ².

Dose and timing: the 2024 meta-analysis

The most useful recent study is a 2024 systematic review and dose-response meta-analysis of 26 double-blind randomized trials in people with insomnia and healthy volunteers ¹. It found:

• Melatonin gradually reduced the time to fall asleep and increased total sleep time, with the effect peaking at 4 mg per day.
• Taking it earlier relative to bedtime predicted a bigger reduction in time to fall asleep.
• People with insomnia benefited more than healthy volunteers.

The authors suggested that taking melatonin about 3 hours before the desired bedtime at around 4 mg might work better than the common practice of 2 mg 30 minutes before bed ¹. This is a suggestion from pooled data, and it has not yet been tested head to head in a large trial.

The EFSA position

EFSA, the EU's food safety agency, reviewed the evidence for a health claim on melatonin and sleep. It concluded that melatonin reduces sleep onset latency and that 1 mg should be consumed close to bedtime to get the effect ³. In one meta-analysis EFSA considered, the reduction was statistically significant at 1 to 3 mg, but not in the smaller groups of studies that used less than 1 mg or 4 to 5 mg ³.

Jet lag

For jet lag, the Cochrane review found that 0.5 to 5 mg near the target bedtime at the destination worked similarly, with faster sleep onset at 5 mg and no extra benefit above 5 mg ⁴. See melatonin for jet lag for the full plan.

How much melatonin should I take?

A practical approach for adults:

1. Start with 0.5 to 1 mg. Many people do well here, and side effects are less likely.
2. Pick a fixed time. Either about 30 to 60 minutes before bed for a simple sleep aid, or 2 to 3 hours before bed if your problem is a late body clock.
3. Keep your bedtime fixed and your evening light dim. Melatonin competes with bright screens and room lights.
4. Give it one to two weeks and log your sleep.
5. Increase slowly only if needed, staying within the studied range (up to about 4 to 5 mg).
6. Stop if there is no clear benefit.

Use the sleep calculator to choose a consistent bedtime that fits your wake time.

Fast release or slow release?

Immediate-release melatonin gives a quick peak and is what most jet lag studies used. In the Cochrane review, a 2 mg slow-release product worked relatively poorly for jet lag ⁴. Prolonged-release melatonin is used as a prescription medicine for older adults with insomnia. In the EU, Circadin is a 2 mg prolonged-release tablet for short-term treatment of primary insomnia in people aged 55 and over, taken one to two hours before bed after eating ¹⁰.

Melatonin side effects

Melatonin is generally well tolerated in the short term. A systematic review of 37 randomized trials using 0.15 to 12 mg per day found these as the most common side effects ⁸:

• Daytime sleepiness
• Headache
• Dizziness
• Other sleep-related effects
• Feeling cold

Most resolved on their own within a few days or after stopping melatonin. A few more significant effects were reported, including agitation, mood swings, nightmares and palpitations ⁸. Most trials lasted four weeks or less, so long-term safety is less well studied.

Larger doses increase the chance of next-morning grogginess. This matters if you drive early or train in the morning.

Who should be careful

• People taking blood thinners such as warfarin, or with epilepsy: case reports raised concerns, and medical supervision is advised ⁴⁹.
• Pregnancy and breastfeeding: research on safety is lacking ⁹.
• Older adults: melatonin may stay active longer in older people and cause daytime drowsiness ⁹.
• People taking any medication: check with a doctor or pharmacist first ⁹.
• Children: talk to a pediatrician. Accidental gummy ingestion by young children has led to many emergency visits in the US ⁹.

Labels are often wrong

Supplement labels may not match what is inside. An analysis of 31 melatonin products found actual content ranging from 83% below to 478% above the label, with large variation even between batches of the same product ⁶. Serotonin was found in eight products. A US analysis of 25 melatonin gummy products found that actual melatonin ranged from 74% to 347% of the labeled amount ⁷.

What to do:

• Choose products with third-party quality verification.
• Avoid gummies if accuracy matters to you.
• In countries where melatonin is a licensed medicine, the pharmaceutical version is held to drug manufacturing standards.

Rules differ by country

• United States: melatonin is a dietary supplement and is regulated less strictly than drugs ⁹.
• Several other countries: melatonin is available only on prescription and treated as a drug ⁹.
• UK: melatonin is a licensed medicine, including for short-term treatment of jet lag ⁸.
• European Union: prolonged-release melatonin (Circadin) is prescription only ¹⁰. Food supplements with melatonin are allowed in some member states, with national maximum doses that vary, and some countries set low caps around 1 mg. The EFSA claim covers 1 mg close to bedtime ³.

Rules change. Check your national food safety or medicines agency, and ask a pharmacist before you buy melatonin abroad or carry it across borders.

For people who train

• Morning sessions: start at 0.5 to 1 mg and take it no later than your usual bedtime. Higher doses raise the risk of grogginess at an early session.
• Late games or evening races: melatonin will not override the adrenaline and caffeine of a late event. Cool down, dim the lights and see can't sleep after a workout.
• Travel: melatonin is most useful for crossing time zones.
• Doping: melatonin is not known to be prohibited, but supplements can be contaminated. If you are tested, use a third-party certified product such as Informed Sport or NSF Certified for Sport, or a licensed medicine.

Common mistakes

• Starting with 10 mg. The evidence supports much lower doses.
• Taking it at random times. Inconsistent timing can push your clock in the wrong direction.
• Using it nightly for months without review. Recheck every few weeks.
• Ignoring light. Bright evening screens suppress your own melatonin.
• Treating it as a fix for short sleep. In trials, melatonin added only minutes of sleep ². Check how much sleep you need.

The bottom line

For most adults, 0.5 to 1 mg near bedtime is a sensible start, and the evidence suggests benefits rise up to about 4 mg, especially if taken a few hours before bed ¹³. Effects are modest. Labels are unreliable, rules vary by country, and anyone on blood thinners, with epilepsy, pregnant or treating a child should get medical advice first.

Frequently asked questions

Is 10 mg of melatonin too much?

For most adults it is more than the evidence supports. EFSA based its claim on 1 mg close to bedtime, and a 2024 dose-response meta-analysis found that benefits for falling asleep and total sleep peaked at about 4 mg per day. In jet lag research, doses above 5 mg were no more effective. Higher doses raise the chance of grogginess, headache and nightmares without a proven extra benefit.

How long before bed should I take melatonin?

For a simple sleep aid, 30 to 60 minutes before bed is common and matches the EFSA claim of taking it close to bedtime. A 2024 meta-analysis found that taking melatonin earlier, about 3 hours before the desired bedtime, was linked to a bigger reduction in time to fall asleep. If your problem is a late body clock, earlier timing is worth trying.

Can you take melatonin every night?

Short-term trials up to a few months show melatonin is generally well tolerated, and its benefit did not appear to fade with continued use in one meta-analysis. Long-term safety data are limited, though. If you use it nightly, review every few weeks whether you still need it, and see a doctor if you need it to sleep for more than a few weeks.

What are the most common melatonin side effects?

A review of 37 randomized trials found daytime sleepiness, headache, dizziness, other sleep-related effects and feeling cold were the most common. Most were mild and resolved within days or after stopping. Less common effects included agitation, mood swings, nightmares and palpitations. People taking blood thinners, people with epilepsy and pregnant or breastfeeding women should get medical advice before using it.

Is melatonin legal in Europe?

It depends on the country and the product. Prolonged-release melatonin is a prescription medicine across the EU for adults aged 55 and over with insomnia. Lower-dose melatonin food supplements are sold in some EU countries, each with its own maximum dose, and some set low caps around 1 mg. Check your national food or medicines agency before buying or traveling with it.

Sources

1. Cruz-Sanabria F et al. (2024). Optimizing the Time and Dose of Melatonin as a Sleep-Promoting Drug: A Systematic Review of Randomized Controlled Trials and Dose-Response Meta-Analysis. Journal of Pineal Research.
2. Ferracioli-Oda E et al. (2013). Meta-analysis: melatonin for the treatment of primary sleep disorders. PLoS One.
3. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) (2011). Scientific Opinion on the substantiation of a health claim related to melatonin and reduction of sleep onset latency (ID 1698, 1780, 4080) pursuant to Article 13(1) of Regulation (EC) No 1924/2006. EFSA Journal.
4. Herxheimer A, Petrie KJ (2002). Melatonin for the prevention and treatment of jet lag. Cochrane Database of Systematic Reviews.
5. Burgess HJ et al. (2010). Human phase response curves to three days of daily melatonin: 0.5 mg versus 3.0 mg. Journal of Clinical Endocrinology and Metabolism.
6. Erland LA, Saxena PK (2017). Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content. Journal of Clinical Sleep Medicine.
7. Cohen PA et al. (2023). Quantity of Melatonin and CBD in Melatonin Gummies Sold in the US. JAMA.
8. Besag FMC et al. (2019). Adverse Events Associated with Melatonin for the Treatment of Primary or Secondary Sleep Disorders: A Systematic Review. CNS Drugs.
9. National Center for Complementary and Integrative Health (NCCIH) (2022). Melatonin: What You Need To Know. NIH NCCIH.
10. European Medicines Agency (2007). Circadin: EPAR medicine overview. European Medicines Agency.