Jet Lag Recovery: How Many Days per Time Zone, and How to Shift Your Clock
October 29, 2026
Jet lag occurs when your internal body clock is out of step with local time after crossing time zones. The body clock adjusts slowly, about 1 to 1.5 hours per day, and adjusts more easily when you delay it (stay up later, flying west) than when you advance it (sleep earlier, flying east). A common rule of thumb is that recovery takes about one day per time zone crossed when traveling east, and about two thirds of a day per zone when traveling west.
These are rough estimates; people vary with age, sleep habits, and how well they use light exposure. Still, the formula helps you plan important meetings, athletic events, or activities after a long flight.
Skip the math and get your answer instantly:
Open the Time Calculator →Estimated Recovery Times
The table applies the rule of thumb. For trips beyond 12 time zones the body adapts in the direction that is shortest: a 13-hour eastward trip is treated as an 11-hour westward shift. Many people report that crossing 3 or fewer zones causes little trouble, while 8 or more zones can take a week or longer to fully adjust. Symptoms include poor sleep, fatigue, digestive problems, and reduced concentration, and are usually worse after eastward flights.
| Time zones crossed | Direction | Estimated days to adjust |
|---|---|---|
| 3 | East | 3.0 |
| 3 | West | 2.0 |
| 6 | East | 6.0 |
| 6 | West | 4.0 |
| 9 | West | 6.0 |
| 8 | East | 8.0 |
Shifting Before You Go
Start 3 to 4 days before departure. For an eastward trip, go to bed and wake about 1 hour earlier each day. For a 5-hour shift, this gets you 3 to 4 hours of the way before leaving. For a westward trip, go to bed and wake 1 hour later each day. Move meals in the same direction. Shifting by 1 hour per day is realistic for most people, while 30 minutes is easier on a busy schedule. If you can't shift beforehand, set your watch to the destination time at boarding and try to sleep or stay awake according to local night and day on the plane.
Light and Timing
Light is the strongest signal for the body clock. After an eastward flight, get bright light in the morning at the destination and avoid bright light late in the evening; after a westward flight, seek light in the late afternoon and evening. Avoid morning light on arrival if you crossed more than 8 time zones east, as it may shift your clock the wrong way. Short naps of 20 to 30 minutes help, but long naps may hamper night sleep. Caffeine can help in the morning but should stop at least 8 hours before bedtime, and alcohol worsens sleep quality.
Trip Planning Tips
Arrive a day or two early for an important event. If a trip is shorter than 3 days, it may be easier to stay on home time and schedule meetings during hours that work. Stay hydrated and move around during the flight. Fixed schedules help: eat and sleep at local times from the first day. Melatonin is sometimes used at a low dose near the target bedtime; discuss it with a healthcare professional, especially if you take other medications.
Frequently Asked Questions
How long does jet lag last?
About one day per time zone eastward and about two thirds of a day per zone westward, as a rough guide.
Is it worse flying east or west?
Usually east, because advancing the body clock is harder than delaying it.
When should I start adjusting my schedule?
3 to 4 days before departure, shifting by about 1 hour a day.
What is the most powerful tool against jet lag?
Well-timed exposure to bright light.
Should I nap after landing?
Only short naps of 20 to 30 minutes.