Circadian Jet Lag Adjustment Calculator
How many days to adjust, and when to seek light.
Enter your values
ⓘ Live results
Results
- Days to fully adjust
- 9.1 days
- Adjustment speed
- 40 min per day
- Seek bright light
- Early morning at your destination
- Avoid light
- Late evening
Quick answer
The body clock shifts about one hour per day westward and 40 minutes per day eastward, so eastward travel takes longer to adjust to.
How to use the Circadian Jet Lag Adjustment Calculator
- 1Enter how many time zones you are crossing.
- 2Choose the direction of travel.
- 3Follow the light exposure guidance.
Worked example
Using the values the calculator loads with:
Inputs
- Time zones crossed6
- DirectionEastward (Europe/Asia)
Results
- Days to fully adjust9.1 days
- Adjustment speed40 min per day
- Seek bright lightEarly morning at your destination
- Avoid lightLate evening
Frequently asked questions
Why is eastward harder?
The natural human circadian period is slightly longer than 24 hours, so delaying (westward) is easier than advancing (eastward).
Does melatonin help?
Low doses timed to the destination evening can speed eastward adjustment; discuss timing with a clinician.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.