JET LAG SLEEP
Pick origin and destination, your usual bedtime, and how many nights you have before the flight. The planner steps bedtime and light toward the destination clock.
Move bedtime, wake time and light toward the destination clock.
Pick an arrival time to sketch the nights.
Planning aid, not medical advice. About one day per time zone is a clinic rule of thumb.
READ BEFORE YOU GO
How it works, examples, limits and sources behind the tool.
The planner reads the IANA offset of both cities on your arrival date, so daylight saving is included. A positive gap means the destination clock is ahead (usually an eastbound body-clock advance); a negative gap means it is behind (a delay). The number of zones is the rounded absolute gap, not the hours in the air.
Each scheduled night moves bedtime and wake time one hour toward the destination. Nights before departure are shown in origin time; arrival night and the next local day are shown in destination time. Eastbound plans point you at morning light; westbound plans at afternoon and evening light. If you nap after landing, keep it under about 30 minutes.
London to Tokyo in July is about eight zones east. If you usually sleep at 23:00, two prep nights move that to 22:00 then 21:00 London time. Arrival night is shown on the Tokyo clock, still a few hours short of a full 23:00 local bedtime — the remaining days are the “one day per zone” tail, not a one-night fix.
Shanghai to Los Angeles is a long westbound hop (about 15 zones in summer). Prep nights delay bedtime in Shanghai; the first Los Angeles night still sits earlier than a local 23:00. New York to Paris is a shorter eastbound case, often about six zones in summer. Change the arrival date around March or November if either city uses daylight saving.
Use it when the trip crosses about three time zones or more, and you can move sleep a little in the two or three nights before departure. It is most useful next to a flight that lands in the destination morning or evening, when the first light and the first night decide how ugly day two feels.
Skip a full shift for a weekend two zones away. Use the timezone tool if you only need to know what time it is there; use this page when you need a bedtime sequence. The jet-lag guide on this site covers meals, caffeine and why east is usually harder.
Sleeping the whole flight, then taking a four-hour nap after an eastbound morning landing, is the usual way to lock the origin clock in place. Pulling the hotel curtains at 09:00 destination time does the same. Alcohol as a sleeping pill fragments the first night.
Another is reversing the light: eastbound trips want morning outdoor light and a dim evening; westbound trips want afternoon and evening light and not a long dark lie-in. A 15-zone westbound plan will not finish in two prep nights — the summary’s “days to adapt” is the remaining work, not a failure of the tool.
The one-day-per-zone sketch follows public explanations from the U.S. CDC, Cleveland Clinic and the NHS. Eastbound travel is often harder than the same number of zones westbound; this page does not try to model age, sleep debt or melatonin. Light windows are planning labels, not a prescription for lux or sunglasses.
The city list is the same planning set as the timezone tool, not every IANA zone. Half-hour offsets would round. The tool does not read airline schedules, cabin light or a wearable. People with a sleep disorder, night-shift work or a medical condition should ask a clinician; this page is not treatment.
A common clinic sketch is about one day per time zone crossed. Eastbound is often slower. The planner’s “days to adapt” is that integer, not a promise that one night will fix it.
When the destination clock is ahead you are usually going east: sleep earlier and use morning light. When it is behind you are usually going west: delay sleep and use afternoon and evening light.
Follow the destination day-night, not a goal of sleeping the whole flight. A long nap after landing locks the origin clock; if you nap, keep it to about 30 minutes.
No. This page only sketches a sleep sequence from the arrival-date timezone gap. Ask a clinician if you have a sleep disorder, work nights, or take related medicine.