Plan recovery from crossing time zones.
The body clock does not jump to a new time zone; it drifts, and it drifts at a rate that depends on direction. Because the free-running human circadian period is slightly longer than 24 hours, delaying the clock is easier than advancing it: westward travel resynchronises at roughly 1.5 hours per day while eastward travel manages about 1 hour per day. Crossing seven zones eastward therefore takes about a week, whereas the same seven westward takes under five days. Shifting your sleep schedule for a few days before departure banks part of that adjustment while you are still at home, reducing what is left to absorb on arrival. Light is the strongest tool for steering the drift, and the timing is direction-dependent — morning light advances the clock, evening light delays it.
Adjustment rate
Eastward about 1 h per day; westward about 1.5 h per day
Pre-travel credit
Hours banked = min(zones crossed, pre-shift days x rate)
Recovery time
Days = (zones crossed - hours banked) / rate per day
General wellbeing guidance for recreational planning, not medical advice. Individual needs vary with health conditions, medication and injury history. Consult a qualified health professional — a doctor, physiotherapist or accredited practitioner — before starting, changing or relying on any recovery, therapy or training protocol.
The unforced human circadian rhythm runs slightly longer than 24 hours, so the clock naturally prefers to drift later. Westward travel asks it to do exactly that. Eastward travel asks it to run short, which it resists — hence the roughly 50 percent slower adjustment rate.
After eastward travel, get bright light in the destination morning and keep evenings dim, which advances your clock. After westward travel, do the opposite: late-afternoon and evening light with dim mornings, to delay it. Getting the timing backwards actively pushes your clock the wrong way.
For trips crossing more than about four zones with a fixed commitment soon after arrival, yes. Moving bedtime and wake time 60 to 90 minutes per day for two or three days can remove a third of the adjustment burden. For short trips of a day or two, many travellers do better staying on home time entirely.