Know2eat

Melatonin

Isolated Compounds

What melatonin may help with

Ranked by how strong the human evidence is — best supported first.

Best supportedSleep qualityStrong evidence· 2 sources

Then, in order

About Melatonin

A hormone secreted by the pineal gland in darkness, synthesised commercially and sold as tablets, gummies, sprays and prolonged-release forms. It signals biological night rather than inducing sleep directly.

Melatonin is the rare supplement where the mechanism is genuinely understood, and understanding it changes how you read the label. It is a circadian timing signal, not a sedative: the effect on when you fall asleep is driven far more by when you take it than by how much. The dose-response curve is remarkably flat — 0.5 mg shifts circadian phase about as well as 5 mg — while the phase-response curve to timing is steep and has a direction, advancing sleep when taken in the early evening and delaying it when taken in the morning. Meta-analyses support a reduction in the time taken to fall asleep and a real effect on jet lag when timing follows the destination clock. Against this sits a product-quality problem that is among the worst in the supplement industry, and a paediatric exposure problem that has grown sharply.

Sold as
Immediate-release tablet, Prolonged-release tablet, Gummy, Sublingual, Liquid spray
Standardised to
Milligrams of melatonin; retail products in the US are frequently far from their label — a product without this marker may not resemble what was studied.
Also known as
N-acetyl-5-methoxytryptamine, Circadin (prolonged release), The sleep hormone

Regulation: Sold over the counter as a dietary supplement in the US with no pre-market review. In the UK, most of the EU, Japan and Australia it is a prescription medicine for most uses, with prolonged-release 2 mg licensed for insomnia in older adults. That regulatory difference is why American product quality and European product quality are not comparable.

What the research used

The amounts, forms and durations published trials of Melatonin actually administered.

These are the amounts published trials administered — not a recommendation, and not a dose to copy. Trial participants were screened, supervised and given a characterised preparation. What is in a retail bottle is frequently not what was studied, and the amount that suits one person is not general advice.

  • Studied for Delayed sleep onset

    0.5–5 mg

    Strong

    Immediate-release, 30–60 minutes before intended sleep · Days to weeks

    Meta-analysed doses span this whole range with little difference in effect, which is the important fact: higher is not better, and doses at the top end raise the chance of next-day grogginess without shortening sleep onset further.

  • Studied for Jet lag

    0.5–5 mg

    Moderate

    Immediate-release, at destination bedtime · 2–5 days after arrival

    Effect depends on taking it at local bedtime at the destination, not on the dose. Eastward travel responds better than westward in the trials.

  • Studied for Insomnia in adults over 55

    2 mg

    Moderate

    Prolonged-release tablet, 1–2 hours before bed · 3–13 weeks

    The licensed European product and dose. It was studied in an older population with low endogenous melatonin and should not be read across to younger people.

  • Studied for Circadian rhythm disorders in children with neurodevelopmental conditions

    2–10 mg

    Moderate

    Immediate or prolonged release, clinician-supervised

    Studied in specialist settings under clinical supervision. This is not a template for giving melatonin to a child who will not settle.

This is general information about food, not medical advice. It cannot diagnose, treat or replace guidance from a clinician who knows your history.

When it was taken

Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.

Each timing below was actually compared against an alternative in a trial, which is unusual.

  • Evening

    Strong

    Timing is the whole mechanism, and it has been directly tested. Human phase-response curve studies show melatonin taken in the hours before habitual bedtime advances the body clock, while the same dose taken in the morning delays it — the opposite of what most people want. For sleep onset the studied window is roughly 30 to 60 minutes before the intended bedtime; for shifting a delayed body clock, several hours before it. This is the clearest case in the whole catalogue where the timing question has a real answer and the dose question mostly does not.

    Timing was tested. A trial compared this window against another and reported a difference.

  • Evening

    Moderate

    For jet lag the reference point is the destination clock, not the departure clock. Trials dose at local bedtime on arrival and for a few nights afterwards; taking it at the old bedtime can push the body clock the wrong way.

    Timing was tested. A trial compared this window against another and reported a difference.

The evidence in depth

Best supported: Strong

What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how promising the supplement sounds. How we rate evidence.

Sleep quality

Sleep
Strong evidence

Meta-analyses of randomised trials consistently show melatonin shortens the time taken to fall asleep, by an average of roughly ten to twenty minutes, and modestly increases total sleep time. The effect is reliable but smaller than the marketing implies, and it is larger in people whose sleep timing is shifted than in people with classic insomnia.

What may be going on: Melatonin binds MT1 and MT2 receptors in the suprachiasmatic nucleus, the body clock, where it acts as the chemical signal for darkness and shifts the phase of the circadian rhythm.

Strong evidence. Consistent findings across multiple good-quality human studies.

View the 2 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Alertness and energy

Energy & Metabolism
Moderate evidence

Trials in travellers crossing several time zones report reduced jet lag symptoms and better daytime function when melatonin is taken at destination bedtime. Benefit grows with the number of time zones crossed and is clearer eastward.

Moderate evidence. Several human studies point the same way, with real caveats.

View the 1 source

Deep research mode adds each paper’s own conclusion and stated limitations.

Mood

Mental Wellbeing
Not enough evidence

There is not enough human evidence to say melatonin affects mood independently of its effect on sleep. Trials in depression are small and confounded by the sleep improvement itself.

Not enough evidence. Not enough human research to say anything useful yet.

View the 1 source

Deep research mode adds each paper’s own conclusion and stated limitations.

Things to know

Interactions, contraindications and dose limits, most serious first. Concentrated extracts interact with medication in ways the whole plant does not, so this section carries more weight here than it does on a food page.

  • Worth knowing

    Paediatric poisoning calls have risen sharply

    US poison-centre reports of children ingesting melatonin increased several-fold over the decade to 2021, running to hundreds of thousands of exposures, with thousands of hospital admissions, a small number of children requiring ventilation and reported deaths. Gummies are the central problem: they look and taste like sweets, they sit within reach, and a child can eat many at once. Melatonin should be stored like a medicine, not like a vitamin.

  • Worth knowing

    US products are wildly mislabelled

    Independent assays of retail melatonin have repeatedly found content bearing little relation to the label — from a small fraction of the stated amount to several times it, with the largest analyses finding most products outside a reasonable tolerance. One Canadian analysis also found serotonin, an unlisted and pharmacologically active contaminant, in roughly a quarter of the products tested. A 2023 analysis of gummies found the great majority inaccurately labelled, including one containing no melatonin at all. This is why a "1 mg" gummy is not a reassuringly small dose.

  • Worth knowing

    Not a benign sleep aid for children

    Melatonin in children has been studied mainly in neurodevelopmental conditions, under clinical supervision, with dose and timing chosen deliberately. It is a hormone given to a developing endocrine system, long-term data are limited, and giving it nightly to a child with ordinary bedtime resistance is not what the trials did. This warrants a conversation with a paediatrician rather than a purchase.

  • Too much

    Next-morning grogginess and vivid dreams

    Hangover-like drowsiness, headache and unusually vivid dreams are the common complaints, and they track with dose and with taking it too late at night. Because the dose-response for the actual effect is flat, most of this is avoidable by taking less.

  • Interaction

    Interacts with several drug classes

    Interacts withFluvoxamine and other CYP1A2 inhibitors, benzodiazepines, sedatives, warfarin, antihypertensives

    Fluvoxamine strongly inhibits melatonin metabolism and can multiply blood levels several-fold. Sedatives, benzodiazepines and alcohol are additive. Melatonin may also affect blood glucose and blood pressure control, and there are case reports of altered anticoagulation on warfarin.

  • Worth knowing

    Do not drive after taking it

    Melatonin causes drowsiness, and driving or operating machinery within several hours of a dose carries the same risk as any sedating medicine. Prolonged-release forms extend that window.

Evidence ratings on this page: 1 strong evidence, 1 moderate evidence, 1 not enough evidence.

Supplements are sold in the US without pre-market review of efficacy or safety. Nothing on this page is a recommendation to take Melatonin, or a dose to follow.