Sleep / circadian supplement
Melatonin
Prepared by the ezGLP team. Sources last checked . Profile reviewed .
Routes represented in the knowledgebase: Oral / Sublingual.
Educational overview
U.S. dietary supplement; evidence varies by sleep condition, product content can vary, and long-term safety is not established.
Melatonin (N-acetyl-5-methoxytryptamine) is a hormone secreted by the pineal gland in a light-sensitive daily rhythm, with blood levels rising in the evening and falling toward morning. It acts on MT1 and MT2 receptors in the suprachiasmatic nucleus and elsewhere, which is why it is classed as a chronobiotic, a timing signal, rather than a conventional sedative. Exogenous melatonin is sold as a sleep and circadian supplement in immediate-release and prolonged-release tablets, capsules, gummies, liquids, and sublingual forms. It is not a peptide and has no pharmacological relationship to the growth-hormone or GLP-1 compounds elsewhere in this knowledgebase, but it is often logged alongside them because of its evening timing.
Human evidence comes from several hundred randomized trials and many meta-analyses, most of them small and short. Pooled analyses report modest reductions in time to fall asleep and small gains in total sleep time in insomnia, with clearer effects in circadian problems such as jet lag and delayed sleep-wake phase disorder. The prolonged-release medicine Circadin was authorised in the European Union in 2007 on the basis of trials in adults aged 55 and older with primary insomnia. Independent laboratory analyses have repeatedly found that over-the-counter products in North America contain far more or far less melatonin than labelled, and some contained serotonin or cannabidiol, which complicates interpretation of supplement-based studies.
Regulatory status differs sharply by jurisdiction. In the United States melatonin is marketed as a dietary supplement, so there is no FDA-approved oral or injectable melatonin drug and content is not verified before sale. In the United Kingdom it is a prescription-only medicine, and in the European Union melatonin medicines such as Circadin are authorised, prescription-only products with defined strengths and release profiles. Other countries fall between these models, licensing it as a natural health product or restricting it to pharmacies. Injectable melatonin is not an approved product in any major jurisdiction; any such preparation is compounded or experimental, and the oral and sublingual routes are the only ones with a meaningful clinical literature.
Most products are stable at room temperature in the original closed container away from heat, moisture, and light; liquids and gummies may carry shorter after-opening periods on their labels. Because labelled and actual content diverge so often, a record of the brand, lot number, stated strength, and release type (immediate or prolonged) is more informative than the milligram figure alone. Clock time relative to intended sleep is the variable most trials treat as decisive, so a dose log that captures administration time alongside the sleep outcome being tracked is the record most useful for review with a prescriber or pharmacist. Product changes between refills are worth noting for the same reason.
- Category
- Sleep / circadian supplement
- Routes represented
- Oral / Sublingual
- Storage context
- Follow the product label; store in the original container away from excess heat and moisture.
Published literature
No verified PubMed or DOI link is available for this entry.
Common questions
Is melatonin a prescription drug or a supplement?
Both, depending on the country. In the United States it is sold as a dietary supplement without FDA pre-market review. In the United Kingdom melatonin is a prescription-only medicine, and in the European Union products such as Circadin are authorised prescription medicines with a defined indication in adults aged 55 and older. The same molecule therefore sits under supplement rules in one jurisdiction and medicines regulation in another.
Does the amount of melatonin in supplements match the label?
Often not. A 2017 analysis of Canadian products found measured melatonin ranging from far below to several times the labelled amount, with lot-to-lot variation and serotonin present in some samples. A 2023 JAMA analysis of melatonin gummies sold in the United States found most were inaccurately labelled and some contained cannabidiol. Regulated medicines in the EU and UK are held to defined content specifications.
Is there an FDA-approved melatonin product?
No. The FDA has not approved any melatonin drug product, oral or injectable, for any indication; melatonin in the United States is regulated as a dietary supplement. Melatonin receptor agonists such as ramelteon and tasimelteon are FDA-approved prescription drugs, but they are different molecules. In contrast, the European Medicines Agency authorised prolonged-release melatonin (Circadin) in 2007 and later a paediatric formulation.
What does the evidence say about melatonin for sleep?
Meta-analyses of randomized trials show modest effects in insomnia: sleep onset is shortened by a few minutes on average and total sleep time increases slightly. Effects are more consistent for circadian rhythm disorders such as jet lag and delayed sleep-wake phase disorder, where timing matters more than amount. Long-term safety data are limited, and most trials lasted weeks rather than years.
Further reading
Summarised from published literature for reference only, with citations to the source. Evidence is graded as reported and is not a recommendation to combine, dose, or use any compound.
For personal tracking and education only. Not medical advice, diagnosis, or treatment, and not a medical device. Peptides may be prescription-only or unapproved where you live. Consult a licensed healthcare professional.