What is the recommended dose of melatonin (melatonin) for an adult patient with insomnia?

Melatonin Dosing for Insomnia in Adults

Melatonin is not recommended for chronic insomnia in adults, as the American Academy of Sleep Medicine explicitly advises against its use based on evidence showing no clinically significant benefit at the studied 2 mg dose. 1, 2, 3

Why Melatonin Fails for Chronic Insomnia

The 2017 American Academy of Sleep Medicine guideline evaluated trials using 2 mg doses and found only a 9-minute reduction in sleep latency compared to placebo—well below the threshold for clinical significance. 1, 3 The evidence quality was very low due to publication bias, heterogeneity, and imprecision, with benefits approximately equal to harms. 2, 3

For chronic insomnia, consider FDA-approved hypnotics (such as eszopiclone, zolpidem, or suvorexant) or cognitive behavioral therapy for insomnia (CBT-I) instead. 2

When Melatonin IS Appropriate: Circadian Rhythm Disorders

Delayed Sleep-Wake Phase Disorder (DSWPD)

Use 5 mg of melatonin administered between 19:00-21:00 (7-9 PM), which is 1.5-2 hours before desired sleep onset, for a minimum of 28 days. 2, 3

• This timing is critical—administering at bedtime rather than 1-2 hours before is a common error that reduces efficacy. 3
• This dose showed reduction in sleep latency by 38-44 minutes and increased total sleep time by 41-56 minutes in DSWPD patients. 2, 3
• This represents a weak recommendation based on low-quality evidence but is the only context where melatonin demonstrates meaningful benefit. 2

Formulation Considerations

Prolonged-release (sustained-release) formulations are preferred over immediate-release for maintaining sleep throughout the night and mimicking normal physiological circadian rhythm. 3

• The 2 mg prolonged-release formulation showed approximately 19 minutes reduction in sleep latency in elderly patients (≥55 years) compared to placebo. 3
• In older adults with insomnia, 2 mg prolonged-release melatonin produced clinically meaningful improvements in sleep quality, morning alertness, and sleep onset latency (24.3 minutes vs 12.9 minutes for placebo). 4

Critical Dosing Pitfalls to Avoid

• Do not increase dose beyond 5 mg—escalation provides no definitive additional benefits. 3
• Timing matters more than dose: administration at bedtime rather than 1-2 hours before desired sleep is the most common error. 3
• Do not use for chronic insomnia: this is an ineffective indication where other therapies are superior. 1, 2, 3

Practical Dosing Algorithm

Step 1: Identify the Sleep Disorder Type

• Chronic insomnia (difficulty falling or staying asleep without circadian component): Do not use melatonin; proceed to FDA-approved hypnotics or CBT-I. 2, 3
• Delayed sleep-wake phase disorder or circadian rhythm disorder: Proceed to Step 2. 2

Step 2: For DSWPD/Circadian Disorders

• Dose: 5 mg melatonin. 2, 3
• Timing: Between 19:00-21:00 (or 1.5-2 hours before desired sleep time, NOT at bedtime). 2, 3
• Duration: Minimum 28 days to assess efficacy before considering adjustment. 2, 3
• Formulation: Preferably prolonged-release if available. 3

Special Population Considerations

Elderly Patients (≥55 Years)

• The 2 mg prolonged-release dose may provide modest benefit in this specific age group for insomnia, though still not formally recommended by guidelines. 3, 4
• Melatonin is not listed on the American Geriatrics Society Beers Criteria, representing a safer option than many alternatives in elderly patients. 3

Safety Profile

• Side effects are mild when taking usual doses (up to 6 mg), with no evidence of toxicity, severe side effects, or dependence even at high doses. 5
• Monitor for additive sedation if patients are on multiple CNS-active medications. 3
• No specific dose adjustments needed for renal or hepatic impairment. 3