How to Use the Post-Flight Sleep Plan Calculator
The hardest part of jet lag isn't the flight itself — it's that your body clock keeps running on your old time zone regardless of what the local clock says. This calculator uses your departure and arrival UTC offsets plus flight duration to work out your exact local arrival time, then suggests the bedtime that will reset your circadian rhythm fastest.
The logic is simple. If you land during local nighttime (9pm to 3am), try to get to bed as soon as you can settle in. If you land during the day or evening, push through and stay awake until around 10pm local time — that's what helps your body clock reset. The calculator shows both the recommended bedtime and how many hours you'll need to stay awake to reach it.
Recovery difficulty is based on the shorter direction of the time difference, not the raw offset gap. A 20-hour difference is really just a 4-hour difference the other way around, so the calculator always uses the smaller number. As a rule of thumb, expect roughly one day of adjustment per hour of time difference — getting plenty of daylight after landing and limiting caffeine and naps can speed that up.
Frequently Asked Questions
Your body clock is most sensitive to light exposure and sleep timing. Sleeping during local nighttime resets your circadian rhythm fastest, while sleeping at the wrong local hour can actually delay adjustment.
Flying east (which shortens your day, e.g. Asia to the US West Coast) is generally harder than flying west. The human body clock adjusts more easily to a lengthened day than a shortened one.