New York to Tokyo
The clock moves whether or not you are ready for it. This works out by how much, and what a bedtime walked an hour a night would look like on the way there or once you arrive.
Tokyo runs 13 hours ahead of New York. To arrive already keeping Tokyo hours, your bedtime has to move 11 hours later — from 10:00 pm to 9:00 am, on your own clock at home. That is 11 nights, so the table below starts 11 nights before you fly.
| Night | Bed | Up | Moved | Sunset there on this clock | Sunrise there on this clock |
|---|---|---|---|---|---|
| Night 1 | 11:00 pm | 7:30 am | +1h | 4:48 am | 4:25 pm |
| Night 2 | 12:00 am | 8:30 am | +2h | 4:46 am | 4:26 pm |
| Night 3 | 1:00 am | 9:30 am | +3h | 4:45 am | 4:27 pm |
| Night 4 | 2:00 am | 10:30 am | +4h | 4:43 am | 4:27 pm |
| Night 5 | 3:00 am | 11:30 am | +5h | 4:42 am | 4:28 pm |
| Night 6 | 4:00 am | 12:30 pm | +6h | 4:40 am | 4:29 pm |
| Night 7 | 5:00 am | 1:30 pm | +7h | 4:39 am | 4:30 pm |
| Night 8 | 6:00 am | 2:30 pm | +8h | 4:37 am | 4:30 pm |
| Night 9 | 7:00 am | 3:30 pm | +9h | 4:36 am | 4:31 pm |
| Night 10 | 8:00 am | 4:30 pm | +10h | 4:34 am | 4:32 pm |
| Night 11 | 9:00 am | 5:30 pm | +11h | 4:33 am | 4:33 pm |
The gap, and why it is two numbers
In January, Tokyo runs 14 hours ahead of New York. In July it runs 13 hours ahead. New York puts its clocks forward for part of the year and Tokyo does not, so a single figure would be wrong for months at a time. The planner above works from the difference on the date in its field.
What that asks of a bedtime
Taking the shorter way round the dial, the move is 10 hours later in January and 11 hours later in July. At the planner's usual step of an hour a night, that is 10 nights of shifting in January and 11 in July, either before you fly or after you land.
This is clock arithmetic and nothing else. It does not know how you sleep on aeroplanes, it makes no claim about how quickly anybody adjusts, and an hour a night is a step size rather than a finding. Shorten the step in the planner if a smaller one suits you.
New York to Tokyo through the year
New York to Tokyo is fourteen hours forward in the northern winter and thirteen in the summer, since Japan keeps one clock all year and only New York changes, on the second Sunday of March and the first Sunday of November.
At that size the planner takes the move the other way round the dial. Instead of fourteen hours earlier, it asks for ten hours later, and in summer eleven instead of thirteen. Both routes round the dial end on the same bedtime; the shorter one gets there in fewer nights.
By the sun, Tokyo is about fourteen and a quarter hours ahead of New York, since it lies 214 degrees further east, or 146 degrees further west the other way round. The two cities are about 10,850 km apart on the great circle.
A 10:00 pm bedtime in New York is noon the next day in Tokyo in winter, and 11:00 am in summer. Before you fly in January, the plan moves bedtime later each night until it reaches 8:00 am on New York's clock, which is 10:00 pm in Tokyo. After you land, the plan starts from noon local time and moves an hour later each night, until the tenth night brings it to 10:00 pm. From 10:00 am in New York in winter, and 11:00 am in summer, it is already the next day in Tokyo. Tokyo's earliest sunrise, 4:25 am in June, is 3:25 pm the day before in New York.
Japan's single clock is set nine hours ahead of Greenwich, and Tokyo lies about five degrees east of the meridian that clock is set by, so its sun runs about nineteen minutes ahead of the clock. Tokyo's earliest sunset, 4:28 pm in late November and early December, is 2:28 am the same day in New York. A New York alarm at 6:30 am is 8:30 pm in Tokyo in winter and 7:30 pm in summer. Seoul keeps the same clock as Tokyo, and Beijing one an hour behind it. On the return, the move is ten hours earlier in winter and eleven in summer, over the same number of nights.
Going back
For the return leg, or for anywhere else, the planner takes any pair of cities.
Once you are there
With the clocks settled, the ordinary question comes back: what time to go to bed for the alarm you have set. That is the wake-time pages, which count in cycles rather than in zones.