- Jet lag symptomsFor every 2 people treated, 1 more improved than with the comparison1 review of trials2 of 3 results reported a benefit2001 study ↗
Also measured alongside: Body clock shift (reported a benefit).
Every resultsupplement
Melatonin
Also known as N-acetyl-5-methoxytryptamine
Hormone released by the pineal gland in response to darkness that signals circadian phase to the brain's suprachiasmatic nucleus; low-dose supplementation can shorten time to fall asleep and ease jet lag.
Reported side effects:HeadacheDaytime sleepiness (somnolence / drowsiness)Sore throat (nasopharyngitis)
Be careful if: pregnant, breastfeeding, certain health conditions, some medical situations, certain ages
Ask first if you take: antidepressants (SSRIs, SNRIs or MAOIs), sedatives or sleep medicines, contraceptives or HRT, blood-pressure medicines, blood thinners (anticoagulants or antiplatelets), epilepsy medicines (antiepileptics), other medicines
Suspect a side effect? Report it to the MHRA Yellow Card scheme ↗
2linked conditions
19linked studies
Evidence
What the research actually shows
We link to relevant studies and leave interpretation to you and your healthcare professional.
What studies found
The headline results, condition by condition
The large figures are what the studies reported for each thing they measured. Open a card for every result.
Colour keyReported a benefitNo clear benefitUnclearPossible harmAmber is for highlights, such as where the most research is. It never means a result was good.
- Total sleep timeLarge effectmuch better than the comparison group1 review of trials2020 study ↗
No figure given: Overall sleep (reported a benefit).
Also measured alongside: Overall thinking skills (reported a benefit); Tiredness (fatigue) (reported a benefit).
Every resultSafety
Safety and considerations
What sources report about side effects, who should be careful, and medicines to ask about first.
Reported side effects
Serious effects reported
Be careful if you…
| Applies to | What sources say | Sources |
|---|---|---|
| pregnant | UK-licensed melatonin (Circadin) is not recommended during pregnancy; the SmPC advises use with adequate contraception in women of childbearing potential. | Circadin 2 mg prolonged-release tablets (melatonin) UK SmPC, emc product 2809 |
| breastfeeding | Not recommended while breastfeeding: melatonin passes into breast milk and the SmPC advises a decision between discontinuing treatment or breastfeeding. | Circadin 2 mg prolonged-release tablets (melatonin) UK SmPC, emc product 2809 |
| certain health conditions | Not recommended in people with autoimmune disorders (SmPC contraindications/warnings section). | Circadin 2 mg prolonged-release tablets (melatonin) UK SmPC, emc product 2809 |
| certain health conditions | Not recommended in hepatic impairment; caution in renal impairment (SmPC). | Circadin 2 mg prolonged-release tablets (melatonin) UK SmPC, emc product 2809 |
| some medical situations | Melatonin can cause drowsiness - take care with driving or operating machinery (SmPC). | Circadin 2 mg prolonged-release tablets (melatonin) UK SmPC, emc product 2809 |
| some medical situations | Avoid alcohol while taking melatonin: the SmPC notes it may reduce melatonin levels and the NHS advises it can worsen drowsiness. | Circadin 2 mg prolonged-release tablets (melatonin) UK SmPC, emc product 2809Melatonin - NHS medicines A-Z (side effects, interactions and who-can-take pages; page last reviewed 2023-02-13) |
| certain ages | Safety of Circadin in children and adolescents has not been established for all ages (SmPC paediatric section); NHS pages advise specialist supervision for children. | Circadin 2 mg prolonged-release tablets (melatonin) UK SmPC, emc product 2809 |
Medicines to ask about
| Severity | Medicine | Sources |
|---|---|---|
| ask first | antidepressants (SSRIs, SNRIs or MAOIs) — Fluvoxamine markedly increases melatonin exposure and the SmPC says concomitant use should be avoided; the NHS also lists amitriptyline-type antidepressants among medicines that alter melatonin effects. | Circadin 2 mg prolonged-release tablets (melatonin) UK SmPC, emc product 2809Melatonin - NHS medicines A-Z (side effects, interactions and who-can-take pages; page last reviewed 2023-02-13) |
| caution | sedatives or sleep medicines — Melatonin may enhance the sedative effect of benzodiazepines (e.g. temazepam, diazepam) and Z-drugs (zaleplon, zolpidem, zopiclone) - additive drowsiness. | Circadin 2 mg prolonged-release tablets (melatonin) UK SmPC, emc product 2809Melatonin - NHS medicines A-Z (side effects, interactions and who-can-take pages; page last reviewed 2023-02-13) |
| caution | contraceptives or HRT — Oestrogens (contraceptives and HRT) increase melatonin exposure and sedation (SmPC; NHS lists oestrogens). | Circadin 2 mg prolonged-release tablets (melatonin) UK SmPC, emc product 2809Melatonin - NHS medicines A-Z (side effects, interactions and who-can-take pages; page last reviewed 2023-02-13) |
| caution | blood-pressure medicines — The NHS lists medicines that lower blood pressure among those that can alter the sedating effect of melatonin. | Melatonin - NHS medicines A-Z (side effects, interactions and who-can-take pages; page last reviewed 2023-02-13) |
| caution | blood thinners (anticoagulants or antiplatelets) — The NHS lists warfarin among medicines that can interact with melatonin - tell your doctor before combining. | Melatonin - NHS medicines A-Z (side effects, interactions and who-can-take pages; page last reviewed 2023-02-13) |
| caution | epilepsy medicines (antiepileptics) — The NHS lists carbamazepine (epilepsy medicine) among medicines that can alter melatonin effects. | Melatonin - NHS medicines A-Z (side effects, interactions and who-can-take pages; page last reviewed 2023-02-13) |
| caution | other medicines — Further NHS-listed medicines that can interact: NSAIDs (e.g. ibuprofen, naproxen), quinolone or rifampicin antibiotics, psoralens, cimetidine, thioridazine and opiates (e.g. codeine, morphine). Tell your doctor or pharmacist. | Melatonin - NHS medicines A-Z (side effects, interactions and who-can-take pages; page last reviewed 2023-02-13) |
How much is too much
When and how to take it
| Guidance | Detail |
|---|---|
| Take | with food |
| Avoid with | sedating — The NHS advises not taking herbal remedies or supplements that make you feel sleepy alongside melatonin - they increase sedation. |
Evidence analytics
Where the evidence is concentrated
Audited published research for Melatonin by condition. Drill into a pair page for the full breakdown.
Melatonin: findings by condition
What this means: Bars count reported findings, not treatment effectiveness or certainty.
One study may report several findings or appear in more than one pairing. Counts do not show the size of an effect. Comparable numerical estimates are not established for this summary.
View the full data table
| Compound and condition | Findings (count) | Studies (count) | Reported results (finding counts) | How sure? |
|---|---|---|---|---|
| Jet Lag | 5 | 3 | Benefit: 3; no benefit: 1; harm: 0; unclear: 1; not recorded / unrecognised: 0 | Not formally graded |
| Sleep Issues | 5 | 2 | Benefit: 4; no benefit: 1; harm: 0; unclear: 0; not recorded / unrecognised: 0 | Not formally graded |
Suggested uses (unproven)
Where people report using it and what trials suggest
- Strong evidenceJet lag / eastward travel
- Strong evidenceDelayed sleep phase disorder
- Moderate evidenceSleep-onset latency (shortens ~10-20 min)
Where the evidence is negative
Common claims the trials do not support
- Inferior to CBT-I for chronic insomnia; long-term benefit unproven.
- No benefit for sleep maintenance (middle-of-night waking) in most trials.
- Consumer products frequently mislabelled (actual dose -83% to +478% in analyses).
Hormone signalling darkness to the body clock. Best evidence is for circadian problems (jet lag, delayed sleep phase) rather than generic insomnia.
Evidence grades reflect study quality and consistency, not marketing claims.
19studies referenced
16journals
2001–2025publication range
Ordered by strength of evidence, then result direction.
01Dysregulation of melatonin rhythm in Parkinson's and Huntington's disease: a systematic review and meta-analysisSuram RP, et al. · Frontiers in aging neuroscience · 2025PMID 41143249 ↗02Sleep disturbances and female infertility: a systematic reviewLi J, et al. · BMC women's health · 2024PMID 39707272 ↗03Clinical efficacy and safety of melatonin supplementation in multiple sclerosis: a systematic reviewMorsali S, et al. · Inflammopharmacology · 2023PMID 37429996 ↗04Blue-light filtering spectacle lenses for visual performance, sleep, and macular health in adultsSingh S, et al. · The Cochrane database of systematic reviews · 2023PMID 37593770 ↗05Effects of exogenous melatonin on sleep quality and menopausal symptoms in menopausal women: a systematic review and meta-analysis of randomized controlled trialsYi M, et al. · Menopause (New York, N.Y.) · 2021PMID 33784263 ↗06Evening wear of blue-blocking glasses for sleep and mood disorders: a systematic reviewHester L, et al. · Chronobiology international · 2021PMID 34030534 ↗Show all 19 studies
07Sleep Disorders in Children and Adolescents with Autism Spectrum Disorder: Diagnosis, Epidemiology, and ManagementCortese S, et al. · CNS drugs · 2020PMID 32112261 ↗08How to manage travel fatigue and jet lag in athletes? A systematic review of interventionsJanse van Rensburg DCC, et al. · British journal of sports medicine · 2020PMID 32303523 ↗09What works for jetlag? A systematic review of non-pharmacological interventionsBin YS, et al. · Sleep medicine reviews · 2019PMID 30529430 ↗10Therapeutic role of melatonin in migraine prophylaxis: A systematic reviewLong R, et al. · Medicine · 2019PMID 30653130 ↗11Is melatonin useful for jet lag?Tortorolo F, et al. · Medwave · 2015PMID 26731279 ↗12Jet lagHerxheimer A · BMJ clinical evidence · 2014PMID 24780537 ↗13Jet lagHerxheimer A · BMJ clinical evidence · 2008PMID 19445780 ↗14Melatonin for the prevention and treatment of jet lagHerxheimer A, et al. · The Cochrane database of systematic reviews · 2002PMID 12076414 ↗15Melatonin for preventing and treating jet lagHerxheimer A, et al. · The Cochrane database of systematic reviews · 2001PMID 11279722 ↗1612-week melatonin intake attenuates cardiac autonomic dysfunction and oxidative stress in multiple sclerosis patients: a randomized controlled trialJallouli S, et al. · Metabolic brain disease · 2024PMID 39630381 ↗17Sleep, Growth, and Puberty After 2 Years of Prolonged-Release Melatonin in Children With Autism Spectrum DisorderMalow BA, et al. · Journal of the American Academy of Child and Adolescent Psychiatry · 2021PMID 31982581 ↗18Resetting the late timing of 'night owls' has a positive impact on mental health and performanceFacer-Childs ER, et al. · Sleep medicine · 2019PMID 31202686 ↗19Phase advance with separate and combined melatonin and light treatmentPaul MA, et al. · Psychopharmacology · 2011PMID 21069516 ↗
Published research results
Reported results grouped by condition. Values and units are preserved as recorded; missing information is not estimated.
How to read this table
- Benefit
- What the trial saw happen: whether the measured outcome moved in the helpful direction in that one study (the tag on each row: “Benefit seen”, “No clear benefit”, “Possible harm” or “Unclear”). It is a study result — not advice, and not a promise it will work for you.
- Evidence
- Study design describes how research was conducted. It is not a formal certainty assessment.
- Effect size
- The result recorded in this summary. “Not reported” means the value is missing from the summary; it does not establish that the publication omitted it.
Reported direction, numerical results and study design are separate. Certainty has not been formally graded in this table.
JET LAG (5 outcomes)
| What was measured | Reported findings | Result and units | Reported sample and duration | Study / source |
|---|---|---|---|---|
| adverse effects | It is unclear if oral melatonin causes adverse effects compared to no treatment in 11 randomized trials, though they would probably be mild.Unclear | Not reported Recorded unit: Not reported | Sample (as reported): 11 Follow-up: Not reported | Meta-analysis · 2015 Study detailsIs melatonin useful for jet lag? Meta-Analysis |
| symptoms associated with jet lag syndrome | Oral melatonin probably reduces jet lag symptoms compared to no treatment in 11 randomized trials.Benefit seen | Not reported Recorded unit: Not reported | Sample (as reported): 11 Follow-up: Not reported | Meta-analysis · 2015 Study detailsIs melatonin useful for jet lag? Meta-Analysis |
| Dose-response of melatonin above 5mg versus 0.5-5mg | Melatonin doses above 5mg were no more effective than doses between 0.5 and 5mg compared head-to-head.No clear benefit | Not reported Recorded unit: Not reported | Sample (as reported): Not reported Follow-up: Not reported | Systematic review · 2001 Study detailsMelatonin for preventing and treating jet lag. Systematic Review |
| Jet lag symptoms after crossing five or more time zones | Melatonin significantly reduced jet lag after crossing five or more time zones compared with placebo (NNT = 2).Benefit seen | 2 NNT Recorded unit: Not reported | Sample (as reported): Not reported Follow-up: Not reported | Systematic review · 2001 Study detailsMelatonin for preventing and treating jet lag. Systematic Review |
| Circadian phase advance with melatonin | Melatonin advanced circadian timing by 0.72 h compared to pretreatment timing. (p<0.005)Benefit seen | 0.72 h Recorded unit: h | Sample (as reported): 11 Follow-up: Not reported | Randomised trial · 2011 Study detailsPhase advance with separate and combined melatonin and light treatment. Randomized Controlled Trial |
Sleep (5 outcomes)
| What was measured | Reported findings | Result and units | Reported sample and duration | Study / source |
|---|---|---|---|---|
| sleep duration | Melatonin increased sleep duration by 44 min compared with placebo in children with ASD. (Hedge's g 1.07 [95% CI 0.49-1.65])Benefit seen | 44 min Recorded unit: Not reported | Sample (as reported): Not reported Follow-up: Not reported | Meta-analysis · 2020 Study detailsSleep Disorders in Children and Adolescents with Autism Spectrum Disorder: Diagnosis, Epidemiology, and Management. Meta-Analysis |
| cognitive outcomes | Limited studies suggested improvements in cognitive outcomes compared to no melatonin over 2 weeks to 12 months.Benefit seen | Not reported Recorded unit: Not reported | Sample (as reported): Not reported Follow-up: 2 weeks and 12 months | Systematic review · 2023 Study detailsClinical efficacy and safety of melatonin supplementation in multiple sclerosis: a systematic review. Systematic Review |
| fatigue | Limited studies suggested improvements in fatigue compared to no melatonin over 2 weeks to 12 months.Benefit seen | Not reported Recorded unit: Not reported | Sample (as reported): Not reported Follow-up: 2 weeks and 12 months | Systematic review · 2023 Study detailsClinical efficacy and safety of melatonin supplementation in multiple sclerosis: a systematic review. Systematic Review |
| safety | No substantial safety issues were found with melatonin compared to no melatonin over 2 weeks to 12 months.No clear benefit | Not reported Recorded unit: Not reported | Sample (as reported): Not reported Follow-up: 2 weeks and 12 months | Systematic review · 2023 Study detailsClinical efficacy and safety of melatonin supplementation in multiple sclerosis: a systematic review. Systematic Review |
| sleep conditions | Limited studies suggested improvements in sleep conditions compared to no melatonin over 2 weeks to 12 months.Benefit seen | Not reported Recorded unit: Not reported | Sample (as reported): Not reported Follow-up: 2 weeks and 12 months | Systematic review · 2023 Study detailsClinical efficacy and safety of melatonin supplementation in multiple sclerosis: a systematic review. Systematic Review |
Important: This page reflects observational, aggregate-only community reporting and independent published research. It is not medical advice, and it does not claim any compound treats, cures, or is effective for any condition. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or treatment.
Outcomes & conditions
Outcomes & conditions →Why people look into Melatonin — and what they report
Associated conditions and community-reported outcomes, wrapped together on one page. Aggregates appear only once enough reports arrive.
Important: This page reflects observational, aggregate-only community reporting and independent published research. It is not medical advice, and it does not claim any compound treats, cures, or is effective for any condition. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or treatment.
Availability
Where to get Melatonin (UK)
How this compound is sold in the UK, and where our readers typically find it.
Prescription-only in the UK
Melatonin can't legally be sold over the counter here. It's available only with a prescription, through a consultation with a doctor or qualified prescriber. We don't sell medicines and never will — our job is the evidence, not the dispensing.
How prescription-only compounds work →