Work out circadian rhythm shift instantly with clear inputs, formula shown and shareable results.
Estimates jet lag adaptation time from the number of time zones crossed, allowing for the faster phase delay achieved when travelling westward.
Circadian adaptation
Days to adapt = time zones crossed / achievable shift per day, with westward delays typically achieved about 1.5 times faster than eastward advances
Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
The free-running human circadian period is slightly longer than 24 hours, so delaying the clock is easier than advancing it.
Timed light exposure, meal timing and melatonin can speed realignment, though the direction of the shift still matters.