What Is Melatonin?
Melatonin is a hormone produced by the pineal gland that signals your body it's time to sleep. Production rises in darkness and falls with light exposure. As a supplement, melatonin is widely available over the counter in many countries and is one of the most studied interventions for jet lag.
The Evidence: What Studies Show
A 2002 Cochrane Review — and subsequent updates — found that melatonin is effective at reducing jet lag when crossing 5 or more time zones, particularly for eastward travel. Key findings:
- Reduces jet lag severity scores by approximately 50% in controlled trials
- Most effective when crossing 5+ time zones eastward
- Works primarily by shifting the timing of circadian rhythms, not by directly inducing sedation
- Less evidence for westward travel effectiveness
When and How Much to Take
The timing of melatonin matters more than the dose. Guidelines from circadian researchers:
- Dose: 0.5 mg to 1 mg is as effective as 5 mg for circadian shifting, with fewer side effects. Most commercial tablets are 5–10 mg — far more than needed.
- Eastward travel: Take 0.5 mg at the target bedtime of your destination for the first 3–4 nights after arrival.
- Pre-travel use: For eastward trips, 0.5 mg taken 5 hours before new target bedtime in the days before departure can pre-shift your clock.
Important Caveats
- Melatonin at the wrong time can delay adaptation rather than accelerate it — timing is critical.
- Avoid taking melatonin in the morning at the destination, as this can anchor your circadian clock to your departure time zone.
- Consult a doctor before use if you take blood thinners, immunosuppressants, or diabetes medications, as melatonin can interact with these.
- Melatonin is a prescription drug in some countries (UK, Australia) — check local regulations.
Alternatives and Complements
Melatonin works best as part of a comprehensive approach, not as a standalone fix:
- Combine with strategic light exposure for synergistic effect
- Use sleep-promoting practices (cool room, dark environment, no screens) alongside melatonin
- Consider prescription sleep aids for very short high-stakes trips — discuss with a travel medicine physician
Bottom Line
Yes, melatonin works for jet lag when used correctly — but "correctly" is the operative word. Low doses, proper timing relative to destination clock, and eastward travel are the conditions where evidence is strongest. It's not a magic pill, but it's a useful, low-risk tool in the traveler's toolkit.