Melatonin
Melatonin
Key Benefits
Sleep Onset
Reduces time to fall asleep, especially effective for delayed sleep phase and jet lag.
Circadian Rhythm
Regulates internal clock, helpful for shift workers and travelers.
Antioxidant
Powerful antioxidant that protects neurons and supports cellular health.
Activation Synergies
Magnesium supports melatonin production and enhances GABA function. Together they promote deeper, more restorative sleep.
Glycine lowers core body temperature while melatonin regulates circadian rhythm. Combined, they support both sleep onset and sleep quality.
B6 is required for converting tryptophan to melatonin. Adequate B6 supports natural melatonin production.
Deficiency Indicators
- Difficulty falling asleep
- Jet lag or shift work fatigue
- Delayed sleep phase (night owl)
Scientific Citations
Melatonin: Research Summary
Research & Sources
What the evidence says — with links to the original studies
Melatonin is one of the better-evidenced sleep supplements, but its benefits are specific and modest rather than sweeping. Multiple systematic reviews and meta-analyses of randomized controlled trials show that exogenous melatonin reliably shortens sleep-onset latency (the time it takes to fall asleep) and shifts the circadian clock, making it genuinely useful for circadian-rhythm problems: jet lag, delayed sleep-wake phase disorder, and sleep-onset insomnia. The pooled effect on falling asleep faster is statistically robust but small in absolute terms (on the order of 7 minutes in the general primary-insomnia population, larger in circadian and pediatric/ASD populations). Effectiveness depends heavily on dose and, critically, timing: low physiological doses (0.5-3 mg) taken at the correct time relative to the individual's circadian phase generally work as well as or better than large doses, and mistimed dosing can be counterproductive. Evidence is strongest for sleep initiation and circadian realignment and notably weaker for sleep maintenance (staying asleep) and total sleep time, where effects are marginal. Melatonin shows a favorable short-term safety profile with mild, infrequent adverse events (most commonly daytime sleepiness/next-day grogginess, headache, dizziness), though long-term safety data, especially in children, remain limited.
Supporting Evidence
19 RCTs, 1,683 subjects. Melatonin reduced sleep-onset latency by a weighted mean of 7.06 min (95% CI 4.37-9.75), increased total sleep time by 8.25 min, and improved sleep quality (SMD 0.22). Higher doses and longer duration produced larger effects on latency and total sleep time. Open access.
Landmark Cochrane review concluding melatonin is remarkably effective at preventing/reducing jet lag, especially crossing 5+ time zones and traveling east. Doses of 0.5-5 mg are similarly effective (5 mg helps people fall asleep a bit faster); timing near destination bedtime is critical, and mistimed early-day dosing can delay adaptation. Occasional short-term use appears safe.
9 RCTs (91 adults, 226 children). Melatonin advanced endogenous (dim-light) melatonin onset by 1.18 h, advanced clock-hour of sleep onset by 0.67 h, and reduced sleep-onset latency by 23.27 min. Wake time and total sleep time were not significantly changed, underscoring it acts as a chronobiotic (phase-shifter) rather than a hypnotic. Full text on PMC (PMC2982730).
Meta-analysis of RCTs in children with ASD; melatonin significantly improved sleep-onset latency and total sleep time versus placebo with good tolerability. Consistent with the broader pediatric/ASD literature (e.g., Rossignol & Frye 2011) supporting melatonin as a first-line pharmacologic option for ASD-related sleep-onset problems. Open access.
Systematic review of 37 RCTs. Most frequent adverse events: daytime sleepiness (1.66%), headache (0.74%), other sleep-related AEs (0.74%), dizziness (0.74%), hypothermia (0.62%). Very few serious AEs; melatonin 'generally regarded as safe and well tolerated.' Documents next-day drowsiness/grogginess as the leading side effect. Notes scarcity of long-term safety data.
Opposing / Critical Views
AHRQ/University of Alberta meta-analysis found the reduction in sleep-onset latency, while statistically significant, was small and judged not clinically meaningful for most primary sleep disorders, with no meaningful effect on sleep efficiency/maintenance. The companion 2006 BMJ analysis found melatonin ineffective for secondary sleep disorders. Tempers claims of broad hypnotic efficacy.
GRADE-assessed review highlighting that evidence on long-term safety of pediatric melatonin use is limited and of low certainty. A caution rather than a refutation of efficacy: raises concerns about routine long-term use in children given sparse follow-up data. Open access.
Full-text & official documents
Educational summary of published research — not medical advice. Consult a qualified professional before supplementing.
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