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.