Jet Lag Planner
Build a day-by-day sleep and light schedule that shifts your body clock before and after a flight.
Your plan is rebuilt as you change any field.
- Time zone shift
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- You land
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- Recovery without a plan
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- With this plan
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Home and destination are in the same time zone, so there is no body-clock shift to make. Plan for travel fatigue (movement, water, daylight on arrival) rather than jet lag.
| Day | Bedtime | Wake | Seek bright light | Avoid bright light |
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Times before the flight are in home local time; times from Day +1 are in destination local time. A bedtime after midnight belongs to the early hours of the following morning.
These are rule-of-thumb estimates for general wellbeing, not medical advice. Everyone adapts at a different speed. Ask a doctor before using melatonin or sleep medication, especially if you are pregnant, take other medication, or have a sleep, heart or eye condition.
How it works
The planner works out the shift between your two time zones, normalised to the shortest direction (crossing 19 time zones westwards is the same body-clock job as advancing 5 hours eastwards). Travelling east you must advance your clock — go to bed and get up earlier. Travelling west you must delay it — stay up and sleep in later. It then moves your usual bedtime and wake time by the step you chose on each preparation day before departure, and finishes the remaining shift over the first nights at your destination.
Light is the strongest signal for the body clock, so every row also gives a light window. The windows are anchored to your core body temperature minimum (CBTmin), estimated the standard way as about two hours before your habitual wake time. To advance (eastward) you want bright light just after CBTmin — from two hours before to two hours after waking — and darkness in the late evening. To delay (westward) you want light in the hours before CBTmin — late evening and night — and to avoid light in the early morning. Recovery without preparation uses the classic rule of thumb: about one time zone a day going east and about 1.5 a day going west.
Time zones are listed at their fixed standard offsets — daylight saving is not applied automatically, so pick the offset your destination is actually on for your travel dates. Everything is calculated in your browser with plain JavaScript. Nothing about your trip is uploaded, stored or shared, and there are no sign-ups or ads.
Frequently asked questions
How many days does jet lag last?
The usual rule of thumb is about one time zone per day travelling east and about 1.5 time zones per day travelling west, so a six-hour eastward trip takes roughly six days to shake off and the same trip westward about four. Shifting your bedtime by an hour a day before you leave removes most of that, and the planner shows both numbers so you can compare.
Why is flying east worse than flying west?
Your body clock naturally runs slightly longer than 24 hours, so stretching the day (delaying, which is what you do flying west) is easier than compressing it (advancing, which is what you do flying east). Flying east you have to fall asleep before your body is ready, so the planner shifts you earlier in small steps and puts you in bright morning light to pull the clock forward.
When should I get bright light and when should I avoid it?
Every light window is anchored to your core body temperature minimum (CBTmin), estimated as about two hours before your habitual wake time. To advance your clock for an eastward trip, get bright light from CBTmin to four hours after it — roughly two hours either side of waking — and keep the late evening dark. To delay it for a westward trip, do the opposite: light in the late evening and night, darkness in the early morning.