Melatonin: Benefits, Dosage, Forms & Research

What the Research Says

Melatonin is one of the most extensively studied sleep supplements. Ferracioli-Oda et al. (2013) published a pivotal meta-analysis of 19 RCTs involving 1,683 subjects, demonstrating that melatonin significantly reduces sleep onset latency (weighted mean difference -7.06 min), increases total sleep time (+8.25 min), and improves overall sleep quality. Herxheimer & Petrie (2002) conducted a Cochrane review of 10 trials confirming melatonin's efficacy for jet lag prevention and treatment. Brzezinski et al. (2005) meta-analyzed 17 studies confirming melatonin's sleep-promoting effects and noted that efficacy did not diminish with continued use over weeks. A key finding across the literature is the absence of a clear dose-response relationship — Zhdanova et al. (2001) demonstrated that physiological doses (0.3mg) were as effective as pharmacological doses (3mg) for improving sleep in older adults with insomnia.

Benefits of Melatonin

• Sleep onset — a 2013 meta-analysis of 19 RCTs (Ferracioli-Oda et al.) found melatonin supplementation significantly reduced sleep onset latency by a weighted mean of 7.06 minutes compared to placebo, with improvements in total sleep time and sleep quality
• Sleep quality — melatonin improved subjective sleep quality scores across studies, with benefits most pronounced in primary sleep disorders and delayed sleep-wake phase disorder
• Jet lag treatment — a 2002 Cochrane systematic review (Herxheimer & Petrie) of 10 trials found melatonin remarkably effective for preventing or reducing jet lag, particularly when crossing 5 or more time zones and traveling eastward
• Circadian rhythm resetting — melatonin acts as a chronobiotic, shifting the phase of the circadian clock, making it the treatment of choice for delayed sleep-wake phase disorder and shift work sleep difficulties
• Antioxidant effects — melatonin is a potent direct free radical scavenger and also stimulates antioxidant enzymes (superoxide dismutase, glutathione peroxidase), providing neuroprotective effects beyond sleep

Side Effects and Safety

Safety profile: Generally Safe

Potential Side Effects

• Generally very well tolerated at standard doses
• Morning drowsiness or grogginess (more common at higher doses >3mg)
• Vivid dreams or nightmares (uncommon)
• Headache (uncommon)
• Mild dizziness (rare)
• Temporary feelings of depression (rare, at higher doses)
• May suppress endogenous production temporarily with long-term high-dose use (though evidence for this is weak)

Drug & Supplement Interactions

• Sedative medications (benzodiazepines, zolpidem) — additive sedation effects, use caution
• Anticoagulants (warfarin) — melatonin may increase bleeding risk
• Immunosuppressants — melatonin has immunostimulatory properties that may counteract immunosuppression
• Diabetes medications — melatonin may affect blood sugar levels
• Fluvoxamine — strongly inhibits melatonin metabolism (CYP1A2), dramatically increasing melatonin levels
• Caffeine — may reduce melatonin production; avoid caffeine after 2 PM