Jet lag calculator
Enter how many time zones you're crossing and your usual sleep times. You'll get a day-by-day plan — when to sleep, when to seek bright light and when to avoid it — to move your body clock to local time faster.
Your trip
Loading time zones…
+5 h · flying east (clock must advance)
Estimated adjustment
5 days
Shifting about 1 hour per day. All times below are in home time on pre-departure days and destination local time after arrival.
Arrival day (local time)
Sleep 3:00 am – 11:00 am
Seek light 8:30 am – 11:30 am
Avoid light 4:30 am – 8:30 am
Day 1 after arrival (local time)
Sleep 2:00 am – 10:00 am
Seek light 7:30 am – 10:30 am
Avoid light 3:30 am – 7:30 am
Day 2 after arrival (local time)
Sleep 1:00 am – 9:00 am
Seek light 6:30 am – 9:30 am
Avoid light 2:30 am – 6:30 am
Day 3 after arrival (local time)
Sleep 12:00 am – 8:00 am
Seek light 5:30 am – 8:30 am
Avoid light 1:30 am – 5:30 am
Day 4 after arrival (local time)
Sleep 11:00 pm – 7:00 am
Seek light 4:30 am – 7:30 am
Avoid light 12:30 am – 4:30 am
How to get over jet lag
Jet lag happens because your internal clock — steered by the suprachiasmatic nucleus in the brain — stays on home time while the sun switches to local time. It shifts only about an hour a day on its own, usually faster going west than east. The CDC Yellow Book's rule of thumb is roughly one day of recovery per time zone crossed.
Light is the main lever. Bright light in the hours after your body temperature low point (roughly 2–3 hours before your usual wake time) moves your clock earlier; light in the hours before that low point moves it later. The plan above times light and darkness around that point, following the approach described by Eastman and Burgess in their jet-lag research.
Practical tips
- Going east (e.g. New York → London) is harder: you have to fall asleep earlier than your body wants. Morning light helps; avoid bright light in the evening before your new bedtime.
- Going west is easier: stay up later and get evening light.
- Short trips of 2–3 days: consider staying on home time instead.
- On the plane, sleep only if it's night at your destination. Stay hydrated; go easy on alcohol.
- Melatonin is used for jet lag and discussed in the CDC Yellow Book, but dosing and timing matter and it isn't right for everyone — ask a pharmacist or doctor.
Questions people ask
How long does jet lag last?
Roughly a day per time zone crossed without any intervention, per the CDC Yellow Book. Timing light and sleep deliberately can shorten that, and westward trips usually adjust faster than eastward ones.
Is jet lag worse flying east or west?
East for most people. Your body clock naturally runs slightly longer than 24 hours, so staying up later (westward) is easier than falling asleep earlier (eastward).
Should I sleep on the plane?
Sleep if it is night-time at your destination; try to stay awake if it is daytime there. Eye mask, earplugs and limiting alcohol help.
Does light really fix jet lag?
Light is the strongest signal your body clock responds to. The timing matters: the same light can move your clock earlier or later depending on when you see it, which is why the plan gives specific windows.