Shift toward the destination's clock before you fly, get daylight at the right time on arrival, stay awake until a normal local bedtime, use caffeine only in the morning, and go easy on alcohol on the plane. Expect about one day of recovery per 1–2 time zones.
Jet lag is your body clock being out of sync with local time; light is the main lever.
Eastbound (Europe, Asia from the Americas): harder. Start going to bed earlier a few days before, take the overnight flight, sleep on board if you can, and get morning light on arrival. Avoid a long nap; if you must, cap it at 30 minutes.
Westbound (Americas from Europe/Asia): easier. Stay up until local bedtime; evening light helps.
On the plane: hydrate, skip alcohol, move every couple of hours, set your watch to destination time at takeoff.
Melatonin: low doses at destination bedtime help some people eastbound; check legality (it’s prescription-only in some countries).
Big shifts (LA–Singapore, London–Sydney) take most people three to five days regardless.
Related questions
How do I sleep on a plane in economy?
Pick a window seat away from galleys and lavatories, board rested not exhausted, use a neck pillow that supports the chin, an eye mask and earplugs, skip alcohol and heavy meals, and sleep on the destination's schedule. Full answer →
How do I survive a long-haul flight?
Choose your seat deliberately, dress in layers, drink water and skip alcohol, walk every two hours, download entertainment in advance, bring your own snacks, and plan sleep around the destination's clock. Compression socks help on flights over eight hours. Full answer →
Airline, airport and government rules change without notice. Treat this as a starting point and confirm with the airline or authority for your specific trip. Request a correction if something is out of date.