How to use the jet lag sleep shift planner
- Enter the time zone difference in whole hours and choose whether you travel east or west.
- Enter your usual bedtime and wake time, the minutes you plan to shift each day, and the days before leaving you can start.
- Read the day by day table. Before departure the times are on your home clock; after arrival they are on the destination clock.
- The last row shows your usual times on local time, which is when the shift is finished.
Formula
total shift = time zone difference x 60 minutes
shift after day d = min(total shift, d x minutes per day)
east: bedtime and wake time move earlier; west: they move later
destination clock time = usual time + (total shift - shift so far) for east, minus it for west
The plan moves your schedule toward the destination clock by a fixed amount each day until it matches. The travel day keeps the shift from the day before.
Six hours east with three days to prepare
Your usual times are bed at 11:00 pm and up at 7:00 am, you plan to shift 60 minutes a day, and you start three days before leaving. Three days before: bed 10:00 pm, up 6:00 am. Two days before: 9:00 pm and 5:00 am. One day before and on the travel day: 8:00 pm and 4:00 am, a shift of 3 hours.
At the destination, 3 hours remain. Day 1 shows bed at 1:00 am and up at 9:00 am on local time. Day 2 shows 12:00 am and 8:00 am, and day 3 shows 11:00 pm and 7:00 am, the same as at home. Six hours at 60 minutes a day takes 6 days in all.
Why the clock changes at arrival
Before you leave, bedtimes are on your home clock. After you land, everything is on local time, and each day's sleep time is closer to your usual local bedtime. The plan keeps the same total shift, so the table connects the two clocks without a jump. If you have fewer days before leaving than you need, the rest of the shift continues at the destination.
What this is not
This is arithmetic for a plan you choose. It does not give medical advice or say how fast a person adapts, and it says nothing about light exposure, meals, caffeine or medicine. People differ, so ask a health professional about your own situation. To compare time zones, use the Time Zone Converter, and to average your sleep times, the Average Bedtime Calculator.
Assumptions and limits
- The shift per day is a number you choose. The default of 60 minutes is an example.
- The time zone difference is entered in whole hours, up to 12.
- Daylight saving changes and half-hour zones are not modeled.
- The plan does not account for flight time or the length of the trip.
Frequently asked questions
Why does east mean earlier?
The destination clock is ahead of home when you go east, so local bedtime arrives sooner by your body's clock. Moving your sleep earlier before and after the trip brings the two closer together.
What if I have no days before leaving?
Enter 0. The plan then starts at the destination, and the table shows the days after arrival until your times match local time.
Can I choose a larger daily shift?
Yes, from 10 to 240 minutes. A larger shift finishes sooner but is a bigger change each day. The page does not say which is right for you.
Does the table end when the shift is complete?
Yes. The last row is the first day on which the schedule matches your usual times on local time. Any later days would be identical.