What Jet Lag Actually Does to Your Body, and What Helps
Jet lag happens when your internal body clock is still running on your home time zone while the sun, meals, and everyone around you run on a new one. Knowing what causes jet lag, which is a mismatch rather than simple tiredness, is the key to easing it, and the most effective steps start before you board.
Your body runs on a roughly 24-hour cycle called a circadian rhythm. A small cluster of cells in the brain acts as a master clock, and it uses light as its main signal for what time it is. That clock shapes when you feel sleepy, when you’re hungry, how alert you are, and even when your digestion is most active. Cross several time zones quickly and the clock can’t keep up. It shifts gradually, so for a few days your body is sending signals meant for a place you’ve left.
That’s why the symptoms go beyond feeling tired. You might lie awake at midnight and crash at 3 p.m., lose your appetite at dinner, feel foggy or irritable, or notice an upset stomach. The more time zones you cross, the longer it tends to last, and flying east is usually harder than flying west because most people find it easier to stay up later than to fall asleep earlier. The NHS guide to jet lag gives a clear overview of symptoms and how long they typically last.
What causes jet lag to hit harder, and how to get ahead of it
Because the clock moves slowly, you can give it a head start. In the few days before a long trip, shift your bedtime and wake time by an hour or so each day toward the new time zone. Heading east, go to bed and get up a little earlier; heading west, a little later. Even a partial shift means fewer hours to make up on arrival.
On the plane, set your watch or phone to the destination time and start living on it. Sleep if it’s night where you’re going, and try to stay awake if it’s daytime. Choosing a seat that suits your plan helps, which is part of the thinking in aisle vs window seat for a long flight. Drink water steadily, and go easy on alcohol, which fragments sleep, and on caffeine late in your new day.
After you land
Light is the strongest tool you have. Get outside in daylight at the right time: morning light generally helps after flying east, and late-afternoon light after flying west. Eat meals on local time, even if you’re not very hungry, since mealtimes also nudge the clock.
If you need a nap, keep it short and early in the afternoon so it doesn’t steal from your first real night. Resist the urge to sleep the moment you check in at 10 a.m.
Plan your first day lightly if you can. Scheduling an important meeting or a long drive on arrival day is asking a lot from a brain still set to another continent. Building a buffer day into your week-before international trip checklist can make the rest of the trip easier.
If you take medication on a strict schedule or have a health condition affected by sleep, talk to your doctor or pharmacist before you travel about how to handle the time change.
