Jet Lag Survival Guide: East Is Hard, West Is Easy

3 a.m. in a Tokyo hotel room, and you’re staring at the ceiling. By every local rule it’s the middle of the night, but your body insists it’s mid-afternoon back home—not sleepy, wide awake, even a little hungry.

Congratulations: your body hasn’t gotten off the plane yet.

You travel with two clocks. The one on your phone has already switched to Tokyo time; the one inside you is still faithfully keeping the home clock. That mismatch is jet lag: the body clock says sleep, but locally it’s afternoon; the sleepless small hours you’re lying through are actually your body’s early evening.

Why is east hard and west easy? Because the body’s clock is naturally a late homeward kind of clock: its own day runs a bit over 24 hours, so drifting backward suits it—swimming with the current—while pushing forward is swimming upstream. Fly west (clock back, later nights and later mornings) and things usually smooth out in days. Fly east (clock forward, earlier everything) and it’s a much harder pull. And the clock resets at a limited pace—the rule of thumb from research and travel medicine is about one hour per day—so crossing several time zones means several days of catching up.

The good news: you can help the clock save effort. It doesn’t read passports; it reads light and routine—and both can be deployed in advance:

2–3 days before departure

• Flying east: move bedtime and wake time 30–60 minutes earlier each day; more light in the morning, dim things down in the evening.
• Flying west: the reverse—slightly later nights and mornings, more light in the evening.
• On the plane, switch your watch to destination time and follow the new schedule from there.

After landing

1. Daytime: get outside. Live by local time—15–30 minutes outdoors when the local day is bright, and let the local sun do the resetting. On eastbound trips, that morning dose matters most.
2. When it’s sleep time: full blackout. Dim the lights after sundown, put the phone away. Waking in the small hours is normal—that’s your body’s “afternoon.” No clock-checking, lie still, roll over, drift back.
3. Eat on local time. Meals are a secondary clock cue. Eat breakfast, and don’t live on instant noodles.
4. Caffeine for emergencies, not for surplus: cut it off after 3 p.m. local time (we covered this in “The Half-Life of Caffeine”)—don’t stack a caffeine bill on top of the jet lag.
5. Short trips: consider not adjusting at all. Gone two or three days? Keeping home hours is cheaper—you skip the second adjustment on the way back.

A rough first night is close to guaranteed. Survive first, optimize later—most people suddenly find they’ve “synced” somewhere in days three to five.

And if these days only have room for one thing: get outside in the daytime sun. It’s the cheapest and the strongest move in the entire jet lag playbook.

I’ve run this play two hundred times. The body isn’t a machine—you can’t reboot it with a button. But it’s very reasonable: line up the light and the schedule, and it follows, one hour a day.

—By Zhou Xing-Yuan · Former International Flight Crew

A small reminder: Sleep Academy articles offer science explainers and everyday lifestyle suggestions—they are not a substitute for medical diagnosis or treatment. If you’ve been sleeping poorly for a long time, or your sleep problems come with other physical or emotional symptoms, please talk to a doctor or a sleep professional.