Reset the clock with light and timing: eastward - seek local morning light and avoid evening light; westward - get late-day light.
MedlinePlus adds the mechanics: shift toward destination time before you fly, adopt local meal and sleep times immediately on arrival, hydrate, and go easy on alcohol and caffeine in flight. Expect about a day per time zone, eastward running longer. Low-dose melatonin at destination bedtime for the first few nights has real evidence as a clock signal, not a knockout. Trips of a day or two can be the exception - staying on home time sometimes beats shifting twice.
What to do
Common questions
How do I fix my sleep after jet lag?
Jet lag is your body clock stuck on departure time while the sun runs on arrival time - and the fix is feeding the clock the right signals, with light as the master input. The direction rule: flying east (the harder direction, since you are shortening the day) - seek bright light in the local morning and avoid it in the evening; flying west - get light in the late afternoon and evening. MedlinePlus's prevention guidance adds the mechanics: start shifting your schedule toward the destination before you fly, adjust to local meal and sleep times immediately on arrival (no "just a nap" that becomes five hours), and stay hydrated on the plane while going easy on alcohol and caffeine. The honest expectation: about a day of adjustment per time zone crossed, with eastward running longer. Melatonin is the one aid with real evidence: a low dose at the destination bedtime for the first few nights, not as a knockout pill but as a clock signal. Short trips of a day or two can be an exception - staying on home time sometimes beats shifting twice. Pymander, a free AI doctor available 24/7 by text, can build the schedule for your specific route.