Jet lag happens when your internal body clock has not yet caught up with the local time at your destination. A common rule of thumb is that your circadian rhythm resets at roughly one hour per day, and eastbound travel (losing hours) tends to feel harder than westbound travel (gaining hours).
This guide walks through what you can do before you leave, and four habits that help your body clock catch up after you arrive.
Why jet lag happens
Your body clock runs on a cycle close to 24 hours. It uses cues like morning light, meal timing, and activity to stay aligned with the outside world. When you fly across several time zones, your clock is still running on your home schedule while the world around you is on local time. That mismatch shows up as poor sleep, daytime sleepiness, appetite changes, and reduced focus.
To close the gap, you need to give your body new cues — light, food, and sleep — on the new schedule.
What you can do before the trip
Starting a few days before departure, shift your bedtime and wake time gradually toward your destination. A common recommendation is about 15 to 30 minutes per day.
- For eastbound travel (destination time is earlier than home), move bedtime and wake time slightly earlier each day.
- For westbound travel (destination time is later than home), move bedtime and wake time slightly later each day.
- Avoid big swings like pulling an all-nighter the night before; that tends to make the first days worse.
To plan each night's target, the Bedtime Calculator can estimate a bedtime from your goal wake time and the sleep you want to get. It is a useful way to sketch out the first night at your destination.
Four habits that speed up recovery after arrival
Once you land, these four habits help your body clock align with local time faster.
1. Get morning light outdoors
Morning outdoor light is the strongest cue your body clock uses. A 15 to 30 minute walk outside in the local morning teaches your body that it is daytime here. Even on cloudy days, outdoor light is much brighter than typical indoor lighting, so stepping outside is still worth it.
2. Eat on local time
Shifting breakfast, lunch, and dinner to the local schedule helps anchor your body clock through the digestive system. Even if you are not very hungry, a light breakfast at the local time is often better than skipping it.
3. Keep naps short
If you feel sleepy during the day, a short nap of about 20 to 30 minutes is usually enough to take the edge off. Longer naps can make it harder to fall asleep at night and stretch the recovery out. Try to finish any nap by early afternoon.
4. Use caffeine and alcohol carefully
Caffeine in the morning and early afternoon can help with daytime alertness. Caffeine within roughly six hours of bedtime often interferes with falling asleep, so it is safer to avoid it late in the day. Alcohol can feel like it helps you sleep, but it tends to reduce sleep quality later in the night, so go easy on the first days.
Direction-specific tips
Eastbound (losing hours)
Eastbound trips ask you to fall asleep earlier than your body expects, which is the harder direction for most people. Shifting earlier for a few days before the flight helps. On arrival day, get morning light, and dim bright light (including bright screens) in the evening so your body can wind down on local time.
Westbound (gaining hours)
Westbound trips ask you to stay awake longer than usual. On arrival day, try to stay active until the local bedtime. Late-afternoon outdoor light signals to your body that it is still daytime, which makes it easier to hold on until local night. Keep any naps short.
Plan your first bedtime with the Bedtime Calculator
Picking a wake time first and working backward is an easy way to plan the first night. The Bedtime Calculator takes your wake time, target sleep duration, and the time you need to fall asleep, and returns three bedtime options (minimum, recommended, and extended).
For example:
- Target wake time: 7:00 local
- Sleep target: 7 hours
- Time to fall asleep: 15 minutes
From that, you get a practical bedtime estimate for your first local night. You can also use the same approach while shifting before the trip.
Related tools
- Sleep Calculator: If you want to see when to wake up based on a bedtime you already have in mind.
- Evening Routine Builder: If you want a calmer wind-down on arrival night to help sleep come more easily.
A note on medical advice
This article is general guidance and is not medical advice. If you have long-lasting insomnia, severe daytime sleepiness, or other symptoms that do not improve, please talk to a qualified healthcare professional.
Sources
- Harvard Health Publishing, "Resetting your circadian clock to minimize jet lag" — https://www.health.harvard.edu/blog/resetting-your-circadian-clock-to-minimize-jet-lag-2016090810279
- Sleep Foundation, "How to Get Over Jet Lag" — https://www.sleepfoundation.org/travel-and-sleep/how-to-get-over-jet-lag
- Centers for Disease Control and Prevention (CDC), Travelers' Health — https://wwwnc.cdc.gov/travel/
- Mayo Clinic, "Jet lag disorder" — https://www.mayoclinic.org/diseases-conditions/jet-lag/symptoms-causes/syc-20374027