How to Beat Jet Lag: A Traveler's Time Zone Guide

Jet lag happens because your body's internal clock — the circadian rhythm — adjusts to a new time zone far more slowly than a plane crosses it. The bigger the time difference and the more zones you cross, the worse the mismatch.

Eastward Is Harder Than Westward

Flying east (say, Seattle to London) generally causes worse jet lag than flying the same number of zones west, because it requires your body to shorten its day, and the human circadian rhythm naturally runs slightly longer than 24 hours, making it easier to stay up later than to fall asleep earlier.

Before You Fly

Adjust gradually rather than all at once — a sudden four-hour shift the night before a flight is far less effective than a gentler multi-day ramp.

During the Flight

• Set your watch to the destination time zone as soon as you board.
• Seek light exposure (window shade up) if it's daytime at your destination; avoid it (shade down, eye mask) if it's nighttime there.
• Stay hydrated and limit alcohol and caffeine, both of which worsen sleep disruption at altitude.

After You Land

Get outside in daylight as soon as possible if you arrived in the morning or early afternoon local time — sunlight is the strongest signal for resetting your circadian clock. If you land at night, keep lights dim and head toward sleep on the new local schedule immediately, resisting the urge to nap for more than 20–30 minutes.

A Rough Rule of Thumb

Most people need roughly one day of adjustment per time zone crossed, though eastward travel and older age both tend to slow that down. A trip crossing five zones might mean four to five days before you're fully adjusted.

Frequently Asked Questions

Generally worse flying east, since it requires shortening your body's natural day rather than lengthening it.

Roughly one day of adjustment per time zone crossed is a reasonable estimate, though this varies by individual and direction of travel.