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Also: the sleep hormone · melotonin
Four separate measurements, never averaged. Independent evidence counts only studies with no sponsor attached. Methodology version v2.0-2026-10 · how we grade evidence
Claimed to shorten time to fall asleep, improve sleep quality and duration, treat insomnia and jet lag, and deliver antioxidant, anti-ageing and metabolic benefits. The size of the sleep effect is the whole story: across 19 placebo-controlled trials in 1,683 people with primary sleep disorders, sleep onset latency shortened by 7.06 minutes (95% CI 4.37–9.75). Total sleep time gained 8.25 minutes under a fixed-effects model but 8.48 minutes (95% CI −4.02 to 20.98), p=0.184 under random effects — the result does not survive the more conservative model. Sleep quality improved by SMD 0.22 (0.12–0.32), a small standardised effect. The authors concluded the effects were smaller than those of other insomnia drugs.
The American Academy of Sleep Medicine, reviewing the same literature, makes a weak recommendation against using melatonin for either sleep onset or sleep maintenance insomnia. That recommendation does not speak against melatonin for circadian problems such as jet lag or shift work, which are different indications — and the chronobiotic mechanism is the better-supported one.
The dominant risks are product quality and paediatric exposure rather than pharmacology. In an analysis of 31 commercial products from 16 brands, over 70% fell outside 10% of the label claim, content ranged from 83% below to 478% above label, one chewable tablet labelled 1.5 mg contained 9 mg, serotonin was detected in 26% of products, and lot-to-lot variation within a single product reached 465%. US poison control centres recorded 260,435 paediatric ingestions from 2012 to 2021, a 530% rise, with 4,097 hospitalisations, 287 intensive-care admissions and two deaths in children under two. No hepatotoxicity signal; short-term tolerability in adults is generally good. The regulatory split is the sharpest in this dataset: a dietary supplement in the United States, a prescription-only medicine in the United Kingdom.
At a glance
A pineal hormone under suprachiasmatic-nucleus control. It agonises the MT1 and MT2 G-protein-coupled receptors in the suprachiasmatic nucleus, producing circadian phase shifts and a mild sleep-promoting signal. The chronobiotic phase-shifting mechanism is confirmed in humans, which is why the jet-lag claim is the better supported of the two the European Union authorises. But confirming a mechanism says nothing about the magnitude of the hypnotic effect, which is seven minutes.
Dated determinations, each flagged for whether it is final and whether it covers safety only. A safety review is not an efficacy finding, and most reporting in this category conflates the two.
The absence of mandated potency verification is not an abstraction: in 31 analysed products, over 70% fell outside 10% of the label claim, content ranged from 83% below to 478% above label, and lot-to-lot variation within one product reached 465%.
The MHRA told *Which?*, in an article dated 10 February 2026, that "Melatonin is considered to pose an identifiable risk to public/patient safety" because of its effects on the body, and that melatonin sold as a supplement in the UK is being listed illegally. The sharpest regulatory divergence in this dataset: an unscheduled gummy in one country, a prescription medicine in another.
Recorded by the report from a secondary source and not further verified — carried here with that caveat attached rather than dropped, since it shows a Member State acting below the EU claim threshold.
In the Annex to Regulation (EU) 432/2012: the food must contain at least 0.5 mg of melatonin per quantified portion, taken close to bedtime on the first day of travel and the following few days. Underlying assessment EFSA Journal 2010;8(2):1467, entry 1953. This is the better-supported of the two claims, because the chronobiotic phase-shifting mechanism is the one confirmed in humans.
In the Annex to Regulation (EU) 432/2012: the food must contain 1 mg of melatonin per quantified portion, taken close to bedtime. Underlying assessment EFSA Journal 2011;9(6):2241, entries 1698, 1780, 4080. The authorised effect is real and, in pooled trials, 7.06 minutes (95% CI 4.37–9.75) — while the American Academy of Sleep Medicine suggests clinicians not use melatonin for sleep onset or maintenance insomnia.
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