What melatonin dose and safety considerations are recommended for an adult with difficulty falling asleep (or jet‑lag or circadian‑rhythm sleep disorder) after optimizing sleep hygiene?

Melatonin for Sleep-Onset Insomnia, Jet Lag, and Circadian Rhythm Disorders

Start with 3 mg of immediate-release melatonin taken 1.5–2 hours before your desired bedtime; if ineffective after 1–2 weeks, increase by 3 mg increments up to a maximum of 15 mg, but recognize that higher doses increase side effects without improving efficacy and that melatonin should not be used beyond 3–4 months for chronic insomnia. 1, 2, 3

Dosing Algorithm

Initial Dose and Timing

• Begin with 3 mg immediate-release melatonin administered 1.5–2 hours before target sleep time (approximately 6:00–8:00 PM if bedtime is 8:00–10:00 PM). 1, 2, 3, 4
• This timing capitalizes on melatonin's circadian phase-shifting properties rather than just its mild hypnotic effect. 1

Dose Escalation if Needed

• Assess response after 1–2 weeks using sleep diaries to track sleep-onset latency, total sleep time, and night awakenings. 1
• If sleep latency remains >30 minutes or symptoms persist, increase by 3 mg increments (to 6 mg, then 9 mg, then 12 mg, with a ceiling of 15 mg). 1, 3
• Do not exceed 15 mg; doses above 10 mg may cause receptor desensitization and increase adverse effects (morning grogginess, headache, gastrointestinal upset) without added benefit. 1, 3

Duration of Treatment

• Limit continuous use to 3–4 months maximum for chronic insomnia due to insufficient long-term safety data beyond this period. 1, 5
• For circadian rhythm disorders (delayed sleep-wake phase disorder, jet lag), ongoing use may be appropriate as these conditions require chronic chronobiotic therapy. 1, 2

Expected Efficacy

• In adults with delayed sleep-wake phase disorder, melatonin reduces sleep-onset latency by approximately 38 minutes and increases total sleep time by 56 minutes. 2, 3
• For primary insomnia (not circadian-based), the American Academy of Sleep Medicine recommends against melatonin as first-line therapy because benefits roughly equal harms. 1

Safety Profile and Adverse Effects

Common Side Effects

• Daytime sleepiness (1.66%), headache (0.74%), and dizziness (0.74%) are the most frequently reported adverse events. 1, 2, 6
• These effects are dose-dependent and more common at doses ≥10 mg. 1, 7

Serious Adverse Events

• No life-threatening or serious adverse reactions have been documented across age groups when melatonin is used at appropriate doses. 1, 3, 6

Special Populations and Contraindications

• Use with caution in patients taking warfarin due to case reports of potential drug interactions. 1, 2
• Exercise caution in patients with epilepsy based on isolated case reports. 1, 2
• Avoid in elderly patients with dementia and irregular sleep-wake rhythm disorder; the American Academy of Sleep Medicine recommends against this use due to lack of benefit and potential harm (detrimental effects on mood and daytime functioning). 1

Product Quality Considerations

• Melatonin is regulated as a dietary supplement in the U.S., not as a medication, raising concerns about purity and dose accuracy. 1, 2
• Choose formulations with the United States Pharmacopeial Convention (USP) Verified Mark to ensure the product contains the labeled amount of melatonin. 1, 3

Common Pitfalls to Avoid

Timing Errors

• Do not take melatonin in the morning or afternoon; this worsens circadian misalignment and can paradoxically delay sleep onset. 1
• Avoid taking melatonin immediately before bed (within 30 minutes); this timing is too late to shift circadian phase effectively. 1, 4

Dose Misconceptions

• Higher doses are not more effective; receptor saturation occurs around 3–5 mg, and doses above 10 mg increase side effects without improving sleep outcomes. 1, 3
• Prolonged-release formulations are less effective than immediate-release for sleep-onset problems; reserve prolonged-release for sleep-maintenance issues in elderly patients (≥55 years). 3

Drug Interactions

• Avoid concurrent use with fluvoxamine, which markedly inhibits CYP1A2 (the primary melatonin metabolic pathway) and can cause excessive melatonin accumulation. 1
• Limit alcohol and CNS depressants (benzodiazepines, sedative-hypnotics) when using melatonin due to additive sedation and impaired psychomotor performance. 1

Duration Errors

• Do not use melatonin as a long-term solution for chronic insomnia beyond 3–4 months; the American Academy of Sleep Medicine explicitly states that efficacy and safety data are limited to short-term studies. 1, 5
• Attempt periodic dose reduction or discontinuation every 3–6 months to determine the lowest effective dose or whether continued therapy is necessary. 1

When Melatonin Is Not Appropriate

• Primary insomnia without circadian component: The American Academy of Sleep Medicine recommends against melatonin as first-line therapy; consider cognitive-behavioral therapy for insomnia (CBT-I) or FDA-approved hypnotics (eszopiclone, zolpidem, ramelteon, doxepin 3–6 mg for sleep maintenance). 1
• Irregular sleep-wake rhythm disorder in elderly with dementia: Strong recommendation against use due to lack of benefit and potential harm. 8, 1