Melatonin Dose & Timing Calculator

The NHS’s timing for its 2 mg slow-release tablet is “1 to 2 hours before bedtime”; the 2018 trial of 0.5 mg gave it 1 hour before the bedtime people wanted. A standard tablet peaks about 50 minutes after you swallow it, and about half of that is gone 45 minutes later. There is no official US dose — melatonin is sold as a supplement — so this page shows what the sources used, not a dose of its own.

How to use it

Pick why you take it, set your bedtime, choose what it is (a standard tablet or capsule, a slow-release tablet, or a gummy) and type the milligrams on the label and how many you take. You get the clock time the source’s timing gives for your bedtime, where your milligrams sit among the doses those sources used, and — for a standard tablet or gummy — when it peaks and how long it lasts. Pick “Child or teen” and the page gives no time and no dose: NCCIH and the American Academy of Sleep Medicine both send that question to a pediatric health care professional.

When to take melatonin

The sources print three timings. For short-term sleep problems, the NHS: “The usual dose is one 2mg slow release tablet taken 1 to 2 hours before bedtime.” For a late body clock (delayed sleep-wake phase disorder), NCCIH describes the trial: “A 2018 randomized controlled trial that lasted 4 weeks and included 307 people with DSWPD found that taking melatonin 1 hour before the desired bedtime combined with going to bed at a set time led to several improvements.” The trial’s own paper says people were “randomised to 4-wk treatment with 0.5 mg fast-release melatonin or placebo 1 h before DBT for at least 5 consecutive nights per week”, and “sleep onset occurred 34 min earlier”. The AASM’s 2015 guideline, on older trials: “Positive results were obtained with a 5 mg dose timed between 19:00–21:00 (no circadian-based timing), for a period of 28 days.” For jet lag, the NHS: “When you arrive at your destination, take your first dose at your normal bedtime. This should not be before 8pm or after 4am.”

How much: the doses the sources used

NCCIH’s melatonin page (last updated May 2024) prints no dose, and the NIH’s Office of Dietary Supplements has no melatonin fact sheet. What exists is what trials and other countries’ health services used:

Two things the honest version has to say. First, for ordinary insomnia the American Academy of Sleep Medicine’s 2017 guideline is against it: “We suggest that clinicians not use melatonin as a treatment for sleep onset or sleep maintenance insomnia (versus no treatment) in adults.” — a weak recommendation, and “This recommendation is based on trials of 2 mg doses of melatonin.” NCCIH agrees that “there’s not enough strong evidence on the effectiveness or safety of melatonin supplementation for chronic insomnia to recommend its use”, and adds: “The American College of Physicians guidelines strongly recommend the use of cognitive behavioral therapy for insomnia (CBT-I) as an initial treatment for insomnia.” Second, on the NHS melatonin is a prescription medicine (“Melatonin is available on prescription only.”), and the 10 mg figure is a specialist’s maximum, not a target: “The maximum dose is 5 tablets (10mg) once daily.” Above 10 mg this page says so. NCCIH: “For melatonin supplements, particularly at doses higher than what the body normally produces, there’s not enough information yet about possible side effects to have a clear picture of overall safety.”

How long melatonin takes to work, and how long it lasts

A systematic review of 22 pharmacokinetic studies (Harpsøe and colleagues, 2015) concluded: “Tmax was approximately 50 min following oral immediate-release formulations of melatonin.” and “T1/2 was 45 min in both administration routes.” Tmax is the time to the highest blood level; T1/2 is the half-life. Both vary a lot between studies: “Tmax ranged between 15 (2 mg) and 210 min (10 mg). T1/2 ranged from 28 (0.005 mg, IV) to 126 min (4 mg, oral)”. The review also found that “Bioavailability of oral melatonin was approximately 15%.” and that “Pharmacokinetics was affected by age, caffeine, smoking, oral contraceptives, feeding status, and fluvoxamine.”

So a standard tablet swallowed at 10:00 pm peaks at about 10:50 pm, about half of that peak is left at 11:35 pm and a quarter at 12:20 am. A slow-release tablet is different by design — the NHS: “Melatonin usually comes as 2mg, slow release tablets. These release melatonin gradually into your body during the night.” — and for those the NHS’s own line is “Melatonin takes around 1 to 2 hours to work.” Food matters too: “It’s best to take standard tablets 2 hours before or 2 hours after food.” And age: NCCIH says “Melatonin may stay active in older people longer than in younger people and cause daytime drowsiness.”

What the label may not tell you

NCCIH: “A 2023 study found that 22 out of 25 over-the-counter melatonin gummy products were inaccurately labeled.” One had no detectable melatonin; “In the remaining products, the melatonin levels ranged from 74 to 347 percent of the labeled quantity”. On that range a 5 mg gummy could hold 3.7 to 17.35 mg — pick “Gummy” above and the page works it out for your label. An earlier study of 31 supplements found the same pattern: “For most of the supplements, the amount of melatonin in the product didn’t match what was listed on the product label.” The AASM’s advice for parents applies to anyone: “Parents should select a product with the USP Verified Mark to allow for safer use.” The Is It Third-Party Tested? tool shows what that mark checks and how to look a product up.

Children and teenagers

This page gives no dose and no time for a child. NCCIH: “Parents considering giving their children melatonin should first speak with a health care provider about melatonin use in children.” It says of the research that “there are uncertainties about what dose to use and when to give it”. The American Academy of Sleep Medicine’s 2022 health advisory: “Before starting melatonin or any supplement in their children, parents should discuss this decision with a pediatric health care professional.” and “If melatonin is used, the health care professional can recommend the melatonin dose and timing for the sleep problem.” Both stress storage: “Melatonin should be handled as any other medication and kept out of reach of children.” (AASM) and “Parents need to ensure safe storage and appropriate use of melatonin supplements.” (NCCIH). In the UK, the NHS says “Longer-term treatment for children and teenagers is usually prescribed by a specialist.”

Worked examples

• Bedtime 11:00 pm, trouble sleeping, one 3 mg tablet (the page’s example): the NHS’s timing is 9:00 pm to 10:00 pm, and 3 mg is more than the NHS’s usual 2 mg and under its 10 mg maximum. Taken at 10:00 pm, a standard tablet peaks around 10:50 pm.
• Bedtime 11:00 pm, a late body clock, one 5 mg gummy: the 2018 trial’s timing is 10:00 pm, with 0.5 mg — a tenth of that gummy’s label, which on the 2023 study’s range could hold 3.7 to 17.35 mg.
• Jet lag, bedtime 10:30 pm at the destination, one 3 mg tablet: the NHS’s timing is 10:30 pm, for up to 5 days.
• Two 10 mg tablets: 20 mg is above the highest dose the NHS prints for anyone, and the page says so.

Common mistakes

• Taking it as you get into bed. Every timing above is before bedtime, and a standard tablet needs about 50 minutes to peak.
• Assuming more works better. The trial NCCIH describes used 0.5 mg; the dose the AASM’s insomnia review looked at was 2 mg. No source here says a bigger dose puts you to sleep faster.
• Trusting a gummy’s number. 22 of 25 gummy products were inaccurately labeled in the 2023 study.
• Using it for months without asking. NCCIH: “Short-term use of melatonin supplements appears to be safe for most people, but information on the long-term safety of supplementing with melatonin is lacking.”
• Not telling your pharmacist. NCCIH: “In particular, people with epilepsy and those taking blood thinner medications need to be under medical supervision when taking melatonin supplements.” It also notes “There’s been a lack of research on the safety of melatonin use in pregnant or breastfeeding women.” and that “The 2015 guidelines by the American Academy of Sleep Medicine recommend against melatonin use by people with dementia.”

Frequently asked questions

For the other common sleep supplements, trial by trial: Magnesium for Sleep, Valerian for Sleep, Chamomile for Sleep and Glycine for Sleep.

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This is not medical advice, and nothing here diagnoses or treats anything. It shows the timing and doses published sources print; whether melatonin is right for you, and how much, is a conversation with your doctor or pharmacist — especially with blood thinners, antidepressants or blood-pressure medication. Some links on this site are affiliate links: I buy what I review at full price, and a commission never changes a verdict.