How should melatonin be dosed and timed to prevent or treat jet lag?

How to Take Melatonin for Jet Lag

For jet lag prevention and treatment, take 0.5–5 mg of immediate-release melatonin close to the target bedtime at your destination (10 PM to midnight local time), starting on the day of arrival and continuing for 2–4 days after crossing five or more time zones. 1, 2

Dosing Strategy by Time Zones Crossed

For Flights Crossing 5+ Time Zones (Especially Eastward)

• Take 0.5–5 mg of immediate-release melatonin at the destination bedtime (10 PM–midnight local time) starting on arrival day 1, 2
• Continue for 2–4 nights after arrival until your sleep-wake cycle normalizes 1, 2
• The 5 mg dose helps you fall asleep faster and sleep better compared to 0.5 mg, though both doses are similarly effective for reducing jet lag symptoms 1, 2
• Eastward flights produce more severe jet lag and benefit most from melatonin 1, 2

For Flights Crossing 2–4 Time Zones

• Melatonin can still be used if needed, though the benefit is less pronounced 1, 2
• Use the same dosing strategy: 0.5–5 mg at destination bedtime 1, 2

For Very Long Flights (7–8+ Time Zones)

• Consider starting melatonin 2–3 days before departure to begin circadian adjustment 3
• However, this pre-departure approach carries risk: taking melatonin during the day at your departure location will cause unwanted sleepiness and may worsen circadian misalignment 3
• The safer approach for most travelers is to start melatonin only after arrival at destination bedtime 1, 2

Critical Timing Considerations

Timing is everything with melatonin for jet lag—taking it at the wrong time will worsen your symptoms rather than help. 1, 2

• Never take melatonin early in the day at your destination, as this causes daytime sleepiness and delays adaptation to local time 1, 2
• The optimal window is close to target bedtime (10 PM–midnight) at your destination 1, 2
• Melatonin works by providing a "dark pulse" signal to reset your circadian clock to match the new time zone 4

Formulation Matters

• Use immediate-release melatonin, not slow-release formulations 1, 2
• Slow-release 2 mg melatonin is relatively ineffective for jet lag because a short-lived higher peak concentration works better for circadian resynchronization 1, 2
• Choose United States Pharmacopeial Convention (USP) Verified products when possible for reliable dosing, as melatonin is regulated as a dietary supplement with variable quality control 5

Dose Selection

• Doses between 0.5 mg and 5 mg are similarly effective for reducing jet lag 1, 2
• The 5 mg dose produces faster sleep onset and better sleep quality compared to 0.5 mg 1, 2
• Doses above 5 mg provide no additional benefit and may increase side effects 1, 2
• A practical starting dose is 3–5 mg for most adults 5, 6

Expected Benefits

• The number needed to treat (NNT) is 2, meaning for every two people who use melatonin for jet lag, one will experience significant benefit 1, 2
• Melatonin accelerates circadian re-entrainment by approximately 15 minutes per day 7
• Benefits include reduced fatigue, improved nighttime sleep, better daytime alertness, and faster return to normal functioning 1, 2

Safety and Contraindications

Avoid Melatonin If You Have:

• Epilepsy: Case reports suggest potential harm, though systematic data are lacking 1, 2
• Warfarin use: Possible drug interaction reported to WHO adverse event databases 1, 2, 5

Common Mild Side Effects:

• Morning headache, morning sleepiness, and gastrointestinal upset may occur, particularly at higher doses 5
• The incidence of side effects is low with short-term use for jet lag 1, 2

Practical Algorithm

1. Determine your time zone change: Count the number of time zones crossed
2. If crossing 5+ zones (especially eastward): Plan to take melatonin at destination
3. On arrival day: Take 3–5 mg immediate-release melatonin at 10 PM–midnight local time
4. Continue for 2–4 nights until sleep normalizes
5. If crossing 2–4 zones: Use the same approach if you experience jet lag symptoms
6. Avoid daytime dosing at your destination to prevent worsening circadian misalignment

Important Caveats

• Do not use melatonin for chronic insomnia—the American Academy of Sleep Medicine recommends against this due to minimal efficacy 5
• Jet lag is a distinct circadian rhythm disorder where melatonin's chronobiotic (time-shifting) properties are highly effective, unlike primary insomnia 1, 2
• Occasional short-term use for jet lag appears safe, but long-term daily use beyond 3–4 months lacks sufficient safety data 5
• Combine melatonin with strategic bright light exposure during daytime hours at your destination to enhance circadian adaptation 4