Jet Lag Planner

Your body clock runs on roughly a 24-hour cycle set mainly by daylight. When you cross time zones, it is still on home time and takes a few days to catch up. On average it shifts about an hour a day when you fly east and a little faster when you fly west, which is why flying east usually feels worse.

What helps most

• Light at the right time. Light is the strongest signal to your body clock. Morning light moves it earlier (good after flying east), and evening light moves it later (good after flying west).
• Shift your sleep before you go. Moving your bedtime an hour a day for a few days before departure gives you a head start.
• Live on local time from arrival. Eat meals at local times, and keep any daytime nap under 30 minutes.
• Drink water, go easy on alcohol and caffeine, especially in the second half of the day.

Very large time changes

For shifts of 9 hours or more flying east, some people find it easier to adjust the other way, staying up later each day, because the body clock moves later more easily than earlier.

The formula

flying east: days to adjust ≈ hours of time change
flying west: days to adjust ≈ hours ÷ 1.5 (rounded up)

Worked example

Flying from Doha (UTC+3) to New York while it is on daylight saving time (UTC−4) is a 7-hour change flying west. At about 1.5 hours a day westward, 7 ÷ 1.5 ≈ 4.7, so allow about 5 days. Before you fly, move a 23:00 bedtime an hour later each day for three days (00:00, 01:00, then 02:00). From arrival, sleep at 23:00 local time and get afternoon light.

General guidance only, not medical advice. If you take medication on a schedule, or have a sleep or health condition, ask your doctor how to adjust it for the time change.