What are the recommended melatonin doses for adults with insomnia, elderly patients, pediatric patients, jet lag, and shift‑work sleep disorder, and what safety precautions should be considered?

Melatonin Dosing Recommendations

For circadian rhythm disorders like delayed sleep-wake phase disorder, use 3-5 mg of immediate-release melatonin taken between 19:00-21:00 for adults, or 0.15 mg/kg taken 1.5-2 hours before bedtime for children; however, melatonin should NOT be used for chronic insomnia as first-line therapy due to minimal efficacy. 1, 2

Primary Insomnia: Not Recommended

• The American Academy of Sleep Medicine explicitly recommends AGAINST using melatonin for chronic insomnia in adults due to minimal efficacy—only a 9-minute reduction in sleep latency compared to placebo. 2
• Melatonin performs poorly for sleep onset or maintenance insomnia, with very low quality evidence supporting its use. 2, 3
• If treating primary insomnia, use FDA-approved hypnotics (zolpidem, eszopiclone) instead of melatonin. 2

Delayed Sleep-Wake Phase Disorder (DSWPD)

Adults with DSWPD

• Start with 3-5 mg immediate-release melatonin taken between 19:00-21:00 for at least 28 days. 1, 2, 3
• This regimen increased total sleep time by 56 minutes and decreased sleep latency by 37.7 minutes in non-depressed adults. 1, 3
• The timing window of 19:00-21:00 is critical—taking melatonin at the wrong time (morning/afternoon) worsens circadian misalignment. 2, 4

Children with DSWPD (No Comorbidities)

• Use weight-based dosing: 0.15 mg/kg taken 1.5-2.0 hours before habitual bedtime for at least 6 nights. 1, 2, 3
• This dose showed optimal results in children aged 6-12 years with moderate quality evidence. 1
• For a 30 kg child, this equals approximately 4.5 mg. 1

Children with DSWPD and Psychiatric Comorbidities

• Give 3 mg if <40 kg or 5 mg if ≥40 kg, administered at 18:00-19:00 for 4 weeks. 2, 3
• This applies to children with autism spectrum disorders or other psychiatric conditions. 3

Elderly Patients

• Prolonged-release melatonin 2 mg taken 1-2 hours before bedtime may provide modest benefit for elderly insomniacs (≥55 years), though evidence quality is low. 1, 3, 5
• The American Academy of Sleep Medicine's recommendation against melatonin for primary insomnia still applies to elderly patients. 2, 3
• Elderly patients with documented low melatonin levels or those chronically using benzodiazepines may respond better. 6
• Treatment duration of 3-12 weeks is recommended for elderly patients. 5

Jet Lag

• Take 0.5-5 mg melatonin close to target bedtime (22:00-midnight) at the destination for flights crossing 5 or more time zones. 7
• Daily doses between 0.5-5 mg are similarly effective, though 5 mg helps people fall asleep faster than 0.5 mg. 7
• The number needed to treat is 2, making this remarkably effective. 7
• Benefit is greater for eastward flights and when crossing more time zones. 7
• Timing is critical: taking melatonin early in the day causes sleepiness and delays adaptation to local time. 7

Shift-Work Sleep Disorder

• No high-quality guideline evidence was provided for shift-work disorder dosing.
• Based on circadian principles, 3-5 mg taken before the desired sleep period would be reasonable, though this extrapolates from DSWPD data. 2

Dose Escalation and Maximum Dosing

• If 3 mg is ineffective after 1-2 weeks, increase by 3 mg increments up to a maximum of 10-15 mg. 2, 4
• The typical effective range is 3-5 mg for most adults. 2, 3
• Doses above 10 mg risk receptor desensitization with no additional benefit. 2, 3
• Lower doses (0.5-3 mg) can paradoxically be more effective than higher doses due to receptor physiology. 4

Formulation Selection

• Immediate-release formulations are more effective than slow-release for sleep onset. 3, 4, 7
• Slow-release 2 mg melatonin showed relative ineffectiveness compared to immediate-release in DSWPD trials. 1
• Choose United States Pharmacopeial Convention (USP) Verified formulations when possible for reliable dosing and purity. 4

Safety Precautions and Contraindications

• Use extreme caution in patients taking warfarin—documented case reports show potential interactions. 4, 7
• Exercise caution in patients with epilepsy based on case reports. 1, 4, 7
• Monitor for impaired glucose tolerance in patients with diabetes risk factors. 4
• Common mild side effects include morning headache, morning sleepiness, and gastrointestinal upset. 2, 3
• No serious adverse reactions have been documented across age groups in short-term use. 1, 2, 3
• Avoid long-term use beyond 3-4 months for chronic insomnia due to insufficient safety data. 4

Critical Pitfalls to Avoid

• Do not use melatonin as first-line treatment for chronic insomnia—the evidence is weak and FDA-approved hypnotics are superior. 2, 4
• Do not take melatonin in the morning or afternoon except for specific circadian disorders—this worsens circadian misalignment. 4, 7
• Avoid alcohol consumption and excessive caffeine after 14:00 as these interact with melatonin. 4
• Do not use in elderly patients with dementia and irregular sleep-wake rhythm disorder—evidence shows potential harm. 1
• Medications like tricyclic antidepressants, MAOIs, and SSRIs can induce or exacerbate REM sleep behavior disorder when combined with melatonin. 1

Special Populations

Non-24-Hour Sleep-Wake Rhythm Disorder (Blind Adults)

• Use 0.5-10 mg melatonin taken either 1 hour before preferred bedtime or at a fixed time (21:00) for 26-81 days. 2
• This shows an odds ratio for entrainment of 21.18 (95% CI: 3.22-39.17). 2

REM Sleep Behavior Disorder

• Doses of 3-12 mg at bedtime are used, though clonazepam remains first-line. 1, 3
• Melatonin has good efficacy on clinical symptoms and is well tolerated. 5

Alzheimer's Disease and Mild Cognitive Impairment

• Use 2-5 mg or up to 10 mg as add-on treatment for sleep disorders, prescribed as early as possible for long periods. 5
• Light therapy used 12 hours before melatonin has positive synergistic effects. 5
• May have beneficial effects on cognitive function in MCI but shows no effect in moderate to severe Alzheimer's disease. 5