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Jet Lag Adjustment Planner
Jet Lag Adjustment Planner tells you when light helps and when it hurts; the direction of travel is what flips the answer.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Health & Fitness
Jet Lag Adjustment Planner
Frontend preview — no upload or external service.
Adjustment plan
A 10.5 hour westward shift: seek evening light on arrival, avoid morning light for the first two days, and expect roughly one day of adjustment per time zone.
How the Jet Lag Adjustment Planner works
- Enter both time zones and your normal wake time, which anchors the estimate of your temperature minimum.
- Follow the light plan — seeking light at the wrong time shifts your clock the wrong way, which is worse than doing nothing.
- Expect adjustment to take roughly a day per time zone, and longer eastward than westward.
The method
Light shifts the body clock in a direction that depends on when it arrives relative to your core temperature minimum, roughly two hours before habitual wake time.
light after the temperature minimum advances the clock; light before it delays
This is why the same morning walk helps after an eastward flight and hinders after a westward one.
FAQ
Why is eastward harder?
Because it requires advancing the body clock, and the human circadian rhythm runs slightly longer than 24 hours, making it easier to delay than to advance. Westward travel works with that tendency.
When should I get light?
It depends on direction and on your temperature minimum, roughly two hours before your usual wake time. Light after that point advances your clock; light before it delays. Getting this backwards makes jet lag worse.
Do melatonin or sleep aids help?
Timing and dose matter and the evidence varies by preparation and jurisdiction. That is a question for a pharmacist or doctor, particularly alongside other medication.
How we compare
| Feature | Online Tool Store | A paper log | A subscription health app |
|---|---|---|---|
| Direction-aware light timing | ✓ | ✗ | Generic |
| Day-by-day plan | ✓ | ✗ | ✓ |
| No account needed | ✓ | ✓ | ✗ |
| Nothing uploaded | ✓ | ✗ | ✗ |
Jet Lag Adjustment Planner tells you when light helps and when it hurts; the direction of travel is what flips the answer.