Melatonin Dosage: 0.3 mg or 4 mg? What Trials Used vs 917 Labels

Melatonin is the rare supplement where taking more is not obviously better, and where the bottle on the shelf rarely matches the dose a trial used. In the United States it is sold as a dietary supplement, so there is no official dose on any label to compare against.

So this page puts two things side by side: the doses that were tested, and the doses that are sold.

What the trials used

Study	Who	Dose	Result
Zhdanova 2001	Adults over 50, 15 with insomnia, 15 normal sleepers	0.1, 0.3 and 3 mg, 30 min before bed	0.3 mg restored sleep efficiency; 3 mg helped but lowered body temperature and kept melatonin raised into daylight; normal sleepers were unaffected by any dose
Ferracioli-Oda 2013	19 trials, 1,683 people with primary sleep disorders	Various	Fell asleep 7.06 minutes sooner and slept 8.25 minutes longer; higher doses gave larger effects on those two measures
Cruz-Sanabria 2024	26 randomized trials, 1,689 observations	Various	Benefit rose with dose up to a peak at 4 mg a day; a longer gap before bedtime (about 3 hours) was associated with a larger effect
Vural 2014	16 studies in people aged 55 and over	0.1 mg upward	Older adults reached higher levels than younger adults; advice: lowest possible immediate-release dose

The two numbers that matter look like they disagree. They mostly answer different questions.

0.3 mg comes from one carefully measured trial in people over 50 whose sleep efficiency was low. At that dose, blood melatonin rose into the normal night-time range and sleep efficiency recovered. The larger 3 mg dose also improved sleep, but left melatonin raised into the next day.

4 mg comes from pooling 26 trials across insomnia patients and healthy volunteers. The pooled benefit kept rising until about 4 mg a day and did not grow after that.

Neither study supports the idea that 10 mg works better than 4 mg. And the effect at any dose is modest: the 2013 meta-analysis measured it in minutes, about 7 minutes faster to fall asleep.

What the shelf sells

We downloaded every on-market product in the NIH Dietary Supplement Label Database with melatonin in its name and as a listed ingredient. 917 state how much melatonin a serving contains.

Melatonin per serving	Products	Share
Under 1 mg	27	2.9%
1 to under 3 mg	187	20.4%
3 to under 5 mg	296	32.3%
5 to under 10 mg	225	24.5%
10 mg or more	182	19.8%

The single most common serving is 3 mg (291 products), followed by 5 mg (205), 10 mg (144) and 1 mg (121). Only 24 products (2.6%) sell 0.5 mg or less, the range of the dose that worked in the older-adult trial. 410 products (44.7%) sell 4 mg or more, the point where the pooled benefit stopped rising.

The largest single serving we found was 60 mg.

The dose on the label may not be the dose in the bottle

Two laboratory studies measured what was actually inside.

• 31 melatonin supplements: content ranged from 83% below to 478% above the label. More than 71% were outside a 10% margin, and lot-to-lot variation within one product reached 465%. Eight contained serotonin.
• 25 US melatonin gummies (JAMA, 2023): melatonin ranged from 74% to 347% of the labeled amount, and 22 of the 25 were inaccurately labeled. One contained no detectable melatonin.

That is a reason to choose a product whose label you can actually count, and to start low: if a 3 mg tablet can contain several times that, the margin for error is in the dose you choose.

When to take it

Most labels say 30 minutes before bed, which is also the schedule the 2024 authors describe as most used in practice. Their meta-regression found that the gap between taking melatonin and the sleep episode predicted how quickly people fell asleep, and they suggest about 3 hours before the desired bedtime.

Older adults

This is the group where the evidence argues most clearly for a low dose. The review of studies in people aged 55 and over found higher blood levels than in younger adults at the same dose, and higher doses kept levels raised for longer. Its advice was the lowest possible dose of an immediate-release product.

NCCIH adds two cautions: melatonin “may stay active in older people longer than in younger people” and cause daytime drowsiness, and the 2015 American Academy of Sleep Medicine guidelines recommend against melatonin for people with dementia.

Children

This page does not give a children’s dose. NCCIH says there are uncertainties about “what dose to use and when to give it” in children, and about long-term effects. Reports of pediatric melatonin ingestions to US poison centers rose 530% between 2012 and 2021; five children needed mechanical ventilation and two died. Of the 17 products in our download named for children, 12 contain 1 mg per serving. Ask a pediatrician before giving any.

How to use this

1. Start low. 0.5 to 1 mg sits within the range the trials tested, and you can move up if it does nothing.
2. There is little reason to go past 4 mg. The pooled benefit stopped rising there.
3. Try taking it earlier, not just more of it.
4. Over 55, stay at the lowest dose that works, in an immediate-release form.
5. On other medicines, pregnant, or for a child, ask a clinician first; NCCIH lists interactions and gaps in safety data.

For whether melatonin is a good choice for chronic insomnia at all, see our page on what the sleep guideline says about melatonin. For pairing it with magnesium, see magnesium and melatonin together.

We do not link to any product on this page. Label accuracy varies too much between lots for a product pick to carry the dose it promises.