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Jet lag planner

Enter where you are flying and when. You get a day-by-day plan for when to sleep, when to get bright light, and when to keep it low, in local time. No signup needed.

Where are you flying?

NY, United States

United Kingdom

When do you fly?

Leave New York City

New York City local time

Land in London

London local time

At home I usually wake up at

Drag or scroll to adjust. Tap the time to type.

At home I usually go to sleep at

Drag or scroll to adjust. Tap the time to type.

Days to prepare before you fly

Each prep day moves your sleep about an hour toward London while you are still at home, so there is less to do after you land. Zero is fine if your schedule is fixed.

Enter the date and time you leave and land.

Back home, keep the rhythm

Jet lag fades in days. The everyday version, waking tired and wired at night, is what Calibrate plans for. Answer a few questions and get a daily plan around your real schedule.

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Related reads: How much morning sunlight you need, How to fix your sleep schedule with light timing and How to dim your lights in the evening.

Jet lag calculator: how the plan works

Body clock low point

About 2.5 hours before your usual wake time

Flying east

Light after that point, about 1 hour earlier a day 1

Flying west

Light before that point, about 1.5 hours later a day 1,2

Learn more

Your body clock runs on its own schedule and resets mostly through light reaching your eyes. When you land in a new time zone it is still set to home, so you feel awake at the wrong times and sleepy at the wrong times. Light shifts the clock in a direction that depends on when you see it: light after the low point of your body clock moves it earlier, and light before the low point moves it later 3.

The planner estimates that low point from your usual wake time, then gives each day a window of bright light to seek and, where it falls while you are awake, a window to avoid. It moves the low point a step each day until your body clock matches local time. The same timing is used for days you prepare at home before you fly 1,2.

Why this is an estimate

Body clocks differ. Early risers and night owls start from different places, and sleep on the plane, daylight at your destination, and how much light you actually get all change how fast you adjust 1. Treat the windows as a strong starting point, not a schedule you have to hit to the minute.

Learn more

If a window lands at an awkward time, part of it is better than none, and getting light at the wrong time is the thing to avoid most. Trips of a day or two are often easier to ride out on home time than to adjust for. Ask a clinician before using melatonin.

Jet lag calculator: when to sleep

Learn more

Sleep on local time from the first night, at the clock times you keep at home: if you sleep 11:00 PM to 7:00 AM in New York, sleep 11:00 PM to 7:00 AM in London too. The plan does not move your bedtime after you land. It moves your body clock toward that bedtime with light, so falling asleep gets easier each night. On preparation days at home, the plan does move your sleep, about an hour a day toward your destination.

Jet lag FAQ

How does this jet lag calculator work?

It reads the clock difference between your two cities on the day you land, then works out whether moving your body clock earlier or later is the shorter trip. It estimates the low point of your body clock at about two and a half hours before your usual wake time and places light around it: light in the hours after that point tends to move your clock earlier, and light in the hours before it tends to move it later. The plan moves about 1 hour a day when you need to go earlier and about 1.5 hours a day when you need to go later.

When should I sleep after a long flight?

Go to bed and get up on local time from the first night, at the same clock times you keep at home. The light windows do the work of moving your body clock toward local time. If you are exhausted on arrival day, a short nap early in the afternoon is usually easier to recover from than a long one.

Is jet lag worse flying east or west?

Flying east is usually harder. Going east asks your body clock to move earlier, and most people find it easier to stay up later than to fall asleep earlier. That is why the planner allows a little more movement per day for westward trips than for eastward ones.

How many days does jet lag last?

A common rule of thumb is about a day for each time zone crossed, and it varies from person to person. The plan length shown here comes from the same pacing: roughly one hour a day for an eastward shift and one and a half hours a day for a westward shift. Preparing a few days before you fly takes some of those days off the far end.

What if I cannot get outside during the light window?

Get the brightest light you can. A seat by a large window helps, and a bright light lamp at the table is a reasonable stand-in on a dark morning. For the low light windows, dim the room, turn screens down, and wear sunglasses if you have to go out. This is wellness education, not medical advice.

References

  1. Eastman CI, Burgess HJ (2009). How to travel the world without jet lag. Sleep Medicine Clinics, 4(2), 241-255. doi.org/10.1016/j.jsmc.2009.02.006
  2. Revell VL, Eastman CI (2005). How to trick mother nature into letting you fly around or stay up all night. Journal of Biological Rhythms, 20(4), 353-365. doi.org/10.1177/0748730405277233
  3. Khalsa SBS, Jewett ME, Cajochen C, Czeisler CA (2003). A phase response curve to single bright light pulses in human subjects. The Journal of Physiology, 549(3), 945-952. doi.org/10.1113/jphysiol.2003.040477

This planner is for wellness education and gives estimates, not medical advice. It does not diagnose or treat any condition. If you have a sleep disorder, are pregnant, or take medication that affects sleep, talk with your health care provider before changing your sleep schedule.

Jet Lag Planner: When to Sleep and Seek Light | Calibrate