nojetlagMelatonin for Jet Lag: What the Evidence Actually Says About Dosage and Timing
A research-based look at melatonin for jet lag — how it works, what dose the studies used, and when to take it.
Melatonin is the hormone your pineal gland releases when darkness falls, signaling to the rest of your body that it's time to prepare for sleep. It doesn't knock you out the way a sedative does — it's better understood as a timing signal than a sleep aid. That distinction matters, because it explains both why melatonin can help with jet lag and why taking it incorrectly can make things worse.
What the research shows
A well-known Cochrane systematic review (Herxheimer & Petrie) looked at multiple randomized controlled trials and found that melatonin taken close to the target bedtime at the destination reduced jet lag symptoms in travelers crossing five or more time zones, particularly on eastward flights. The effect was consistent across doses ranging from 0.5 mg to 5 mg, with higher doses producing more reliable sleep onset but not necessarily better overall recovery.
Timing matters more than dose
The most common mistake is timing. Melatonin taken at the wrong point in your circadian cycle can actually shift your clock in the wrong direction — delaying rather than advancing it. The general guidance drawn from the research:
- Eastward travel (e.g., Rome to Tokyo): take melatonin close to the destination's bedtime, starting on the day of travel or the evening you arrive.
- Westward travel (e.g., Rome to New York): melatonin is generally less necessary; if used, it's typically taken later in the new local evening.
Taking melatonin in the morning at your destination, when your body is biologically still in its evening phase back home, is a common error that can worsen grogginess.
Dose and duration
Lower doses (0.5–1 mg) appear sufficient to shift the clock's timing signal, while higher doses (3–5 mg) are more likely to induce drowsiness — useful if sleep onset itself is the problem. Most study protocols used melatonin for three to five days after arrival, not as an ongoing supplement.
Safety notes
Melatonin is available over the counter in many countries but is regulated as a prescription drug in others (including parts of the EU). It can interact with blood thinners, immunosuppressants, and diabetes medications, and isn't well studied in pregnant or breastfeeding people. Checking with a pharmacist or doctor before your trip — especially if you take other medication — is worth the five minutes it takes.
Melatonin is one tool among several. Combined with correctly timed light exposure, which remains the strongest lever for circadian adjustment, it tends to perform better than as a standalone strategy.
This article summarizes published research for general education. It is not a substitute for personalized medical advice.
Read how we select and verify our sources: Editorial Methodology