Uncle Jetlag didn't get the name for nothing. Jet lag happens when you cross time zones faster than your internal clock can adjust. You can't eliminate it — but you can shorten it a lot.
Why it happens
Your body runs on a roughly 24-hour circadian rhythm, set mainly by light. Cross several time zones and your clock is suddenly out of sync with local daylight, meals and sleep. Result: wide awake at 3am, foggy at 3pm.
Before you fly
- Shift gradually. For 2–3 days before departure, move bedtime an hour earlier each day if flying east, or an hour later if flying west (CDC).
- Arrive rested. Starting a long-haul trip already sleep-deprived makes everything worse.
- Plan your arrival day. Avoid scheduling important meetings or long drives immediately after landing.
On the plane
- Set your watch to destination time as soon as you board, and try to sleep when it's night there.
- Hydrate. Cabin air is dry.
- Go easy on alcohol, and avoid caffeine close to when you want to sleep.
- Move — walk the aisle and stretch periodically.
After you land
- Get daylight at the right time. Light is the strongest signal to reset your clock.
- After flying east: get morning light. It moves your clock earlier.
- After flying west: get evening light. It moves your clock later.
- After crossing many time zones, light at the wrong time of your body clock can push it the wrong way. Jet-lag planning apps can work out your personal light windows.
- Use caffeine strategically. The CDC suggests modest caffeine during local daytime, stopping about 6 hours before bedtime.
- Eat on local time.
- If you must nap, keep it short — and not late in the afternoon.
- Stay up until a reasonable local bedtime on day one.
Worked example: Johannesburg → Tbilisi → London
- Johannesburg to Tbilisi is about 2 hours east. You'll feel mild effects for a day or two. Get morning light and go to bed a little earlier.
- Tbilisi to London is 3–4 hours west, depending on the season, and usually easier. Stay up until local bedtime and get evening light.
- Harare to Toronto is about 6 hours west in summer. Expect around four days to fully adjust.
Short trips
For a two- or three-day trip, it can make sense to stay closer to home time rather than fully adjusting — schedule important commitments when you'd naturally be alert.