Day 1Bed ~1h earlier
- Seek bright light in the morning (first few hours after waking) to advance your clock.
- Dim lights and avoid screens in the late evening.
- A morning coffee is fine; stop caffeine by early afternoon so it does not delay sleep.
Free tool
Choose where you are flying from and to. We count the timezones you cross, estimate how many days your body clock needs to catch up, and lay out a day-by-day light and sleep plan you can start before you even board.
For 3 nights before you fly, try going to bed about 1 hour earlier each night to pre-adapt toward your destination.
Flying east means advancing your clock — landing somewhere where it is already later than your body expects. The human circadian rhythm runs a touch longer than 24 hours, so it stretches (delays) more easily than it shrinks (advances). Going west, you stay up later and sleep in, which feels natural. Going east, you have to fall asleep and wake earlier than your body wants, which is why we weight an eastward trip as slower to recover from than the same distance west.
A widely cited heuristic is that the body clock shifts roughly one hour per day, so it takes about one day to recover for every timezone crossed. It is a rough guide, not a promise: age, sleep quality, daylight exposure, and how strictly you follow a schedule all move the number. Use the estimate to set expectations and plan buffer days around important meetings or events, not as a medical timeline.
Of everything that shifts your body clock, timed light is the most powerful. Morning light advances your clock (good for eastward trips); evening light delays it (good for westward). The plan above tells you when to seek bright light and when to avoid it for each day of recovery. Pair it with a consistent wake time and you will adjust faster than light or schedule alone. If you are coordinating across zones once you land, the time zone converter keeps your calls in everyone's waking hours.