Full profile
| Also known as | N-acetyl-5-methoxytryptamine |
|---|---|
| Best for | Falling asleep faster (reducing sleep-onset latency) · Re-aligning a shifted body clock — jet lag, shift work, delayed sleep phase · Occasional sleep support, evening use |
| Evidence grade | Grade B — Moderate — several human trials, some mixed results |
| Studied dose range | 0.5–5 mg taken 30–60 minutes before the target bedtime (Health Canada permits up to 10 mg/dose for adults). More is not better: low doses (0.5–1 mg) are often as effective as higher ones with less next-morning grogginess. For circadian shifting, the timing of the dose matters more than its size. |
| Time to effect | Acute — the sleep-onset effect is the same night, typically within 30–60 minutes; circadian re-alignment builds over several nights. |
| Best form | Plain immediate-release melatonin at a stated milligram dose; avoid high-dose (10 mg) products by default. Prolonged-release forms are studied more for sleep maintenance in older adults. |
| Food sources | Tart cherries, Pistachios, Eggs and fish (trace amounts, far below a supplemental dose) |
Evidence, honestly graded
Claim-specific B, and — unlike several branded ingredients in this library — it rests on independent, non-sponsor evidence. A meta-analysis of 19 randomized trials in 1,683 people (Ferracioli-Oda 2013) found melatonin reduced sleep-onset latency and modestly increased total sleep time and sleep quality versus placebo. The honest caveats that keep it at B rather than higher: the effect sizes are small (sleep onset shortened by roughly 7 minutes on average), and the American Academy of Sleep Medicine's 2017 guideline (Sateia et al.) issued a weak recommendation *against* melatonin for chronic sleep-onset or sleep-maintenance insomnia, citing low-quality evidence. Read together, the fair reading is a real, well-replicated but modest effect — strongest for sleep-onset timing and circadian realignment, weakest as a treatment for chronic insomnia.
See the full grading rubric — study type, replication, population match, and dose adequacy — in The Evidence Standard.
79 licensed natural health products in Health Canada's LNHPD list Melatonin as a medicinal ingredient.
That makes Melatonin a recognized, licensable medicinal ingredient in Canada — regulated by Health Canada's Natural and Non-prescription Health Products Directorate, which issues each licensed natural health product a Natural Product Number (NPN). Search the LNHPD to verify.
Side effects
- Next-morning grogginess or drowsiness, especially at higher doses
- Headache, dizziness, or nausea in some users
- Vivid dreams
Who should avoid it or check first
- Before driving or operating machinery after a dose
- Pregnant or breastfeeding without clinician guidance
- Children and adolescents without clinician guidance (Health Canada has moved pediatric sleep use toward prescription oversight)
- Autoimmune conditions or on immunosuppressants without review
Interactions
- May add to the effects of sedatives, benzodiazepines, alcohol, and other CNS depressants
- Fluvoxamine and other CYP1A2 inhibitors can sharply raise melatonin blood levels
- May interact with anticoagulants/antiplatelets, blood-pressure and diabetes medication, and some contraceptives — discuss with a clinician
Stacks well with
- Glycine (evening slot)
- Magnesium L-Threonate (evening slot)
Use caution stacking with
- Daytime stimulant-free focus actives — this is an evening-only ingredient
- Other sedating sleep agents without clinician guidance
What to look for on a label
- Health Canada has a dedicated Melatonin (Oral) monograph — adult-only, up to 10 mg/dose — permitting sleep-onset, sleep-quality, and jet-lag / sleep-wake-cycle claims. Keep claims inside it and confirm the current monograph before filing.
- Lead with the lowest effective dose and a clear evening-use, do-not-drive-after statement rather than a bigger number.
References
- Ferracioli-Oda E, Qawasmi A, Bloch MH (2013). PLoS One, 8(5):e63773Reduced sleep-onset latency (~7 min) and increased total sleep time (~8 min) versus placebo, with an overall sleep-quality improvement.
- Sateia MJ, Buysse DJ, Krystal AD, Neubauer DN, Heald JL (2017). Journal of Clinical Sleep MedicineSuggested clinicians not use melatonin for chronic insomnia (weak recommendation) due to low-quality evidence.
- Health Canada NNHPD — Melatonin (Oral) monograph (2024). Dedicated adult-only monograph permitting sleep-onset, sleep-quality, and jet-lag / sleep-wake-cycle claims, up to 10 mg/dose. Basis for Canadian regulatory defensibility. webprod.hc-sc.gc.ca/nhpid-bdipsn (atid=melatonin.oral). Confirm the current version before filing.
Entries above without a linked identifier are either editorial summaries of a wider body of literature or references to a named authority (a regulator or government monograph) cited by name rather than by a single paper.
Grades and studied doses are our conservative reading of the human research, shown for education. They are not product claims, and a studied dose is not a recommended dose.
Revision history
Every change to this ingredient's evidence status, dated and explained. The full cross-library log lives at Evidence Updates.
- 2026-07-12New profile
New profile, published at Grade B on independent (non-sponsor) evidence: a meta-analysis of 19 randomized trials found melatonin reduced sleep-onset latency and modestly increased total sleep time. Graded for sleep onset specifically — not as a daytime nootropic.
See how Melatonin compares on grade, dose, and goal in the Evidence Explorer.