For melatonin for jet lag after an eastward flight, timing matters as much as whether you use it. Your body clock needs to shift earlier to match the destination, so carefully timed light and melatonin may help. A pill taken at the wrong time, or bright light at the wrong point in your body clock’s cycle, can work against that shift.
Think in destination time, but don’t assume every destination morning is the right moment for bright light. How many time zones you cross, your arrival time and your existing sleep schedule all affect the plan.
Why Eastward Jet Lag Needs a Different Clock Shift
Flying east moves the local clock ahead. Your body, still following home time, needs to advance—move its sleep and wake rhythms earlier—to catch up. The CDC’s 2026 Yellow Book chapter on jet lag says eastward adjustment is generally slower than westward adjustment: average adaptation is about one hour a day eastward, compared with 1.5 hours westward. Those are averages, not a timetable for any one traveler.
That’s why advice for a westbound trip may not suit an eastbound one. The CDC suggests that shifting sleep earlier by about an hour a day for two or three days before eastward travel may reduce the adjustment needed after arrival. Even a partial shift can be useful; avoid cutting sleep short to force it.
Use Light to Support the Advance
Light is a powerful cue for your internal clock. For an eastward shift, bright light in the morning and less light in the evening can support moving your rhythm earlier. The CDC’s example itinerary for travel from Washington, DC, to London advises getting bright light early and avoiding light in the evening; it also recommends daylight after arrival.
But light’s effect depends on when it reaches you in your body-clock cycle—not just the hour on the destination clock. With a large time difference or an awkward arrival, the right window may not match an ordinary local morning. Use a schedule tailored to your route if you need precise timing, rather than treating “get morning sun” as a universal rule. In the evening, dim indoor lighting and limiting bright screens may help; see this guide to how screen light can affect sleep.
What the Research Says About Melatonin for Jet Lag
A Cochrane review by Andrew Herxheimer and Keith Petrie assessed 10 randomized trials in airline passengers, airline staff and military personnel. Eight trials found that melatonin taken close to destination bedtime—around 10 p.m. to midnight—reduced jet-lag symptoms after flights crossing five or more time zones. The review found less reason to expect benefit after westward travel, which fits the different direction of the body-clock shift.
The review reported similar effectiveness across doses of 0.5–5 mg, with doses above 5 mg showing no added effectiveness. These are findings from trials, not a personal dosing recommendation. Timing is critical: taking melatonin at the wrong time, particularly early in the day, may cause sleepiness and delay adjustment. A separate controlled study of 31 people flying from London to eastern Australia across 10 time zones found no clear benefit from 5 mg a day. The researchers noted that participants had busy schedules and frequent, erratic daylight exposure. Together, the findings suggest melatonin can help, but do not guarantee it will, especially when light and sleep timing are inconsistent.
Check Local Rules and Your Own Safety
Melatonin is regulated differently around the world. In the United States it is generally sold as a dietary supplement, while in the United Kingdom it is prescription-only. Rules and approved uses vary among European Union countries; in Australia, access depends on the product and its conditions of supply. A product’s availability does not mean it is approved for jet lag or that products are regulated identically. Check your country’s medicines regulator or ask a pharmacist, and check destination rules before carrying it across borders.
Quality control is another consideration: the Cochrane review called for routine pharmaceutical quality control of melatonin products. The CDC also notes limited information about interactions with other medicines. Case reports have raised concerns for people with epilepsy and for those taking warfarin. If either applies to you—or you take other regular medication—ask a clinician or pharmacist before using melatonin. Seek medical advice for a plan suited to your health and route rather than relying on a generic flight-time dose.
