Melatonin is often presented as the “sleep hormone”. In France, around 1.4 million boxes were already sold annually in 2016, according to an estimate cited by ANSES. Yet melatonin is not a sleeping pill: it signals to the body that it is night. Here is what it really does, what studies show, what regulations allow and what is recommended for insomnia.
Key takeaways
- Secreted at night, melatonin regulates the internal clock: it is more a darkness signal than a sleeping pill.
- On average, it shortens sleep onset by around seven minutes in people with primary sleep disorders.
- Two claims are authorised: time to fall asleep (1mg before bed) and jet lag (at least 0.5mg).
- ANSES advises against it particularly during pregnancy and breastfeeding, in children and adolescents, and in inflammatory or autoimmune disease.
What is melatonin?
Melatonin is a hormone made mainly by the epiphysis, a small brain gland also called the pineal gland. The body produces it from serotonin, itself derived from tryptophan, an amino acid supplied by food. Serotonin is made using an enzyme that requires vitamin B6 as a cofactor.
Its secretion is controlled by an internal clock in the hypothalamus and inhibited by light. It begins in the evening, lasts around ten hours and peaks around 3 or 4 a.m. According to ANSES, blood concentration rises from around 10 pg/ml during the day to 60 pg/ml at night.
A hormone that tells the time more than inducing sleep
Melatonin acts on two receptor types: some promote drowsiness, others shift the internal clock. That is why it is called a chronobiotic: it resets the clock.
Timing therefore makes all the difference. Taken in the afternoon or evening, it advances the clock and facilitates sleep onset. Taken in the morning, it tends instead to delay it, with the transition around 3 p.m. depending on chronotype. A 1mg dose is enough to exceed natural night-time concentrations, and its half-life ranges from around half an hour to two hours.
Which claims are authorised for melatonin?
Regulation (EU) No 432/2012 authorises two melatonin health claims. Each is tied to a specific dose and intake time.
| Authorised health claim | Dose per serving | Timing |
|---|---|---|
| “Melatonin contributes to the reduction of time taken to fall asleep” | 1mg | Before bedtime |
| “Melatonin contributes to the alleviation of subjective feelings of jet lag” | At least 0.5mg | Close to bedtime on the first day of travel and for the few days after arrival |
These wordings do not make melatonin a solution for chronic insomnia, which requires medical care.
Melatonin and sleep: how large is the actual effect?
The short answer: a real but modest effect. In 2013, a meta-analysis pooled 19 placebo-controlled trials involving 1,683 children and adults with primary sleep disorders. Melatonin reduced sleep onset by an average of seven minutes and increased total sleep by eight minutes, with a slight improvement in quality. The effect did not fade over time but remained smaller than that of other insomnia medicines.
A 2005 meta-analysis found a similar effect in insomnia: around seven minutes gained. The gain reached 39 minutes in delayed sleep phase syndrome, a disorder in which the internal clock shifts towards night, but based on only two trials. Melatonin shows its clearest value in these clock shifts.
In 2024, a meta-analysis of 26 trials sought the optimal dose and timing. The effect increased up to around 4mg daily and appeared better when taken around three hours before bedtime. These results need confirmation, and such a dose exceeds the French food supplement framework.
Jet lag
For jet lag, evidence is more favourable. A Cochrane review analysed ten trials: in nine, melatonin taken at local bedtime, between 10 p.m. and midnight, reduced jet lag after flights crossing at least five time zones. Doses of 0.5 to 5mg had comparable efficacy, with slightly faster sleep onset at 5mg; no further gain was observed above that.
The benefit is greater when more time zones are crossed, especially eastward. Conversely, taking it too early in the day can cause drowsiness and delay adaptation to local time.
What professional societies recommend
International guidelines are cautious. In 2017, the American Academy of Sleep Medicine suggested not using melatonin for adult insomnia (weak recommendation).
The 2023 European guideline takes the same direction. It does not recommend immediate-release melatonin for insomnia, but accepts prolonged-release melatonin for up to three months in people aged 55 or over. Above all, it places cognitive behavioural therapy for insomnia (CBT-I) first-line for adults of all ages, in person or online.
In France: food supplement or medicine?
The distinction depends on dose and use. According to ANSES, melatonin has been on list II of poisonous substances since 2011. A prescription 2mg prolonged-release medicine is authorised for short-term primary insomnia in people aged 55 or over.
Food supplements providing less than 2mg per dose are authorised by DGCCRF decision. Elsewhere in Europe, rules varied in 2017 according to ANSES: in Germany and Belgium, products supplying 0.3mg or more daily were considered medicines, while melatonin was banned in supplements in Denmark and the Czech Republic. ANSES calls for a harmonised European framework.
Who should avoid melatonin according to ANSES?
Based on reported adverse effects and scientific data, ANSES advises against melatonin supplements in:
- pregnant or breastfeeding women;
- children and adolescents;
- people with inflammatory or autoimmune diseases;
- people who must remain alert when driving or at work, where drowsiness would pose a safety problem.
It requires medical advice in epilepsy, asthma, or mood, behavioural or personality disorders. Melatonin may also interact with medicines broken down by certain liver enzymes and with sleeping pills. The agency recommends occasional use, without exceeding 2mg daily, and simple formulas without other ingredients.
Adverse effects and product quality
Between 2009 and May 2017, ANSES received 90 reports of possible adverse effects: headache, dizziness, drowsiness, nausea, nightmares or irritability. Product quality also raises questions. A Canadian study of 31 supplements found contents from 83% less to 478% more than the stated dose, and serotonin in eight products.
In 2025, a medical record analysis presented at a conference associated use for at least one year with more heart failure among over 130,000 adults with insomnia. Such an observational study does not prove causation, and its results were not published in a journal when presented. It nevertheless highlights the lack of long-term use data.
Chronic insomnia: what should be tried first?
The French National Authority for Health (HAS) notes that sleep hygiene should be checked first in all insomnia cases. The main points are:
- get up and go to bed at regular times;
- avoid naps longer than one hour or after 4 p.m.;
- limit noise, light and heat in the bedroom;
- avoid caffeine, alcohol, nicotine and large evening meals;
- be active during the day rather than in the evening.
These measures sometimes suffice in mild insomnia. For chronic insomnia, HAS considers cognitive behavioural therapies most appropriate. CBT-I combines stimulus control, restriction of time in bed, relaxation and work on sleep-related thoughts.
Adjustment insomnia, lasting a few days to three months, is linked to a stressful event or new situation, HAS notes. For ingredients studied in this area, with uneven evidence and no authorised sleep claim, see our analyses of stress and ingredients studied for it, passionflower, ashwagandha and different magnesium forms.
When should you seek care?
See a doctor if sleep difficulties last more than a few weeks or affect the daytime: fatigue, drowsiness, irritability, concentration difficulties. Advice is also necessary for snoring with breathing pauses, restless legs in the evening, persistent sadness or marked anxiety, which may indicate another disorder.
Also seek advice before melatonin if taking medication, during pregnancy or for a child. If short nights affect concentration, see our article on methods to maintain memory.
Frequently asked questions
What is the maximum melatonin dose for adults?
ANSES recommends not exceeding 2mg daily, and supplements sold in France supply less than 2mg per dose. Authorised claims rely on 1mg before bedtime or at least 0.5mg for jet lag. More is not necessarily better: for jet lag, no dose above 5mg performed better.
Can melatonin be taken every day?
Because sufficient long-term data are lacking, ANSES recommends occasional use. Melatonin safety is well documented only over short periods of around three months. If the need becomes daily, discuss it with a doctor to identify the insomnia's cause.
Why does melatonin not make me sleep?
First, its average effect is measured in minutes. Second, poorly timed intake can shift the clock in the wrong direction. Finally, many cases of insomnia have other causes, such as anxiety or sleep-disordered breathing.
Spray, gummy or tablet: does the form matter?
The form mainly affects absorption speed. According to ANSES, sublingual intake markedly raises the blood peak because it partly avoids first-pass liver metabolism, while prolonged-release forms spread the delivery. Whatever the form, actual content may differ from the label, with no relation to product type in the Canadian study cited above.
Is melatonin dangerous for the liver?
The US NIH LiverTox database classifies it as an unlikely cause of liver injury: despite widespread use, no convincing case has been reported. The liver nevertheless eliminates around 90% of circulating melatonin, explaining interactions with certain medicines. Liver disease therefore warrants medical advice before use.
Can melatonin be combined with alcohol or sleeping pills?
Not without medical advice. ANSES notes possible interactions with substances acting on the central nervous system, particularly hypnotics, potentially increasing drowsiness. Alcohol is among the products HAS recommends avoiding for good sleep.
Can melatonin be given to a child?
Not as a food supplement: ANSES advises against it in children and adolescents. In certain children with neurodevelopmental disorders, melatonin may be prescribed as a medicine within medical care. Disrupted sleep in children first warrants paediatric advice.
Conclusion
Melatonin is first and foremost a clock signal. In studies, it shortens sleep onset by a few minutes; its clearest results concern jet lag, with an authorised claim (at least 0.5mg close to bedtime), and delayed sleep phase syndrome, a disorder requiring medical care. In France, ANSES advises occasional use and discourages it in several populations. For chronic insomnia, guidelines prioritise sleep hygiene and CBT-I and do not recommend immediate-release melatonin.
Sources
- Commission Regulation (EU) No 432/2012 of 16 May 2012 establishing a list of permitted health claims made on foods. Official Journal of the European Union, L 136, 1-40. eur-lex.europa.eu
- ANSES (2018). Opinion on the risks associated with consuming food supplements containing melatonin (request No 2016-SA-0209). anses.fr
- Ferracioli-Oda E, Qawasmi A, Bloch MH (2013). Meta-analysis: melatonin for the treatment of primary sleep disorders. PLoS One, 8(5), e63773. doi:10.1371/journal.pone.0063773
- Buscemi N et al. (2005). The efficacy and safety of exogenous melatonin for primary sleep disorders. A meta-analysis. Journal of General Internal Medicine, 20(12), 1151-1158. doi:10.1111/j.1525-1497.2005.0243.x
- Cruz-Sanabria F et al. (2024). Optimizing the Time and Dose of Melatonin as a Sleep-Promoting Drug: A Systematic Review of Randomized Controlled Trials and Dose-Response Meta-Analysis. Journal of Pineal Research, 76(5), e12985. doi:10.1111/jpi.12985
- Herxheimer A, Petrie KJ (2002). Melatonin for the prevention and treatment of jet lag. Cochrane Database of Systematic Reviews, (2), CD001520. doi:10.1002/14651858.CD001520
- Sateia MJ et al. (2017). Clinical Practice Guideline for the Pharmacologic Treatment of Chronic Insomnia in Adults: An American Academy of Sleep Medicine Clinical Practice Guideline. Journal of Clinical Sleep Medicine, 13(2), 307-349. doi:10.5664/jcsm.6470
- Riemann D et al. (2023). The European Insomnia Guideline: An update on the diagnosis and treatment of insomnia 2023. Journal of Sleep Research, 32(6), e14035. doi:10.1111/jsr.14035
- HAS, SFTG (2006). Management of adult patients reporting insomnia in general practice. Clinical practice guidelines. has-sante.fr
- Erland LA, Saxena PK (2017). Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content. Journal of Clinical Sleep Medicine, 13(2), 275-281. doi:10.5664/jcsm.6462
- LiverTox (2020). Melatonin. National Institute of Diabetes and Digestive and Kidney Diseases, NCBI Bookshelf. ncbi.nlm.nih.gov
- American College of Cardiology (2025). Research Suggests Long-Term Melatonin Use For Insomnia Increases HF Risk (report on an abstract presented at AHA Scientific Sessions 2025). acc.org
Food supplements do not replace a varied, balanced diet or a healthy lifestyle. Ask a healthcare professional for advice if you are taking medication, pregnant or breastfeeding.
