Jet Lag Planner
Enter your route and dates, and get a practical schedule for adjusting before, during, and after a time-zone change.
The method is published. The tool is not built yet.
A calculator that will not show its arithmetic is not evidence-first. The assumptions behind an estimate are the part you most need in order to judge whether the estimate is worth anything, so on Restadian they are published first and separately.
That is what this page is. It sets out what the tool will measure, what it will ask you for, what it will assume, and where the method is still being specified. When the tool ships it will do what is described here — and if the method changes while it is being built, this page changes with it.
There is nothing to run on this page. Nothing written below depends on the tool existing yet.
The method
What it will estimate
How far your internal clock needs to move, in which direction, and a plausible pace for moving it — then a day-by-day arrangement of light and sleep timing that works with that direction rather than against it.
What it will ask you for
- Where you are flying from and to.
- Your departure and arrival times.
- Your usual sleep window at home.
- How long you are staying.
That last one matters more than people expect. A two-day trip and a two-week trip call for different strategies, and for a short enough stay the sensible plan may be not to adjust at all — which the planner will say when it applies.
What it will give back
A schedule covering the days before you fly, the flight itself, and the days after you land: when to seek light, when to avoid it, when to aim for sleep, and how far to move each day.
Eastward and westward travel will be handled as the different problems they are. Moving your clock later is generally easier than moving it earlier, and a plan that ignores direction is not much of a plan.
The assumptions it will rest on
- Direction of travel changes the difficulty. Advancing your clock and delaying it are not symmetrical tasks, and the plan is built around that asymmetry.
- Light timing is the primary lever available to a traveller. It is the one intervention that is free, available everywhere, and supported by a well-described mechanism.
- Partial adjustment is often the right goal. For short trips, fully shifting and then shifting back costs more than it returns.
- Your home sleep window approximates your starting phase. As with the Circadian Planner, this is a planning assumption rather than a measurement.
Where the method is still being specified
The pace of adjustment per day, and the exact boundaries of the light-seeking and light-avoidance windows relative to your estimated clock, are not settled. These depend on direction and on individual variation, and the figures will not be published here before their sources are attached.
What it will not do
- It will not recommend melatonin or any other supplement, and it will not calculate a dose or a timing for one. There will be no automated dosing of anything, at any point, for any route.
- It will not recommend prescription sleep medication or advise on using one you already take.
- It will not advise on alcohol or caffeine as travel sleep aids.
- It will not assess your fitness to work or to drive on arrival.
Limitations
It cannot know your individual rate of adjustment. People differ, and the same person can differ between trips.
It cannot see conditions at your destination — whether your mornings there will actually contain light, whether your schedule lets you be outside at the hour the plan asks for, or whether a seven o’clock meeting makes the whole thing moot.