This Is Your Body on Jet Lag

You can’t avoid it, according to science. But you can make it less of a drag.

Nina Bahadur


Illustration: Mark Wang

JJet lag is pretty much inevitable during long-distance travel. Wherever you go, whatever you do, you are at the mercy of your very powerful, very stubborn body clock.

“Our body clock has a strong effect on when we feel alert and when we feel sleepy across a 24-hour period,” says Leon Lack, PhD, a clinical psychologist at the Adelaide Institute for Sleep Health at Flinders University in South Australia.

Lack says the best way to understand jet lag is to think of a body clock as having a pendulum that swings back and forth between “feeling awake” and “feeling tired.” Most people feel awake when it’s light out and sleepy when it’s dark out, and they get used to falling asleep and waking up around the same time. But the pendulum swing can be interrupted when people are traveling, or if people keep inconsistent sleep schedules (like in the case of night shift workers).

“If you take that pendulum and fly it 10 time zones across the world, you’re faced with a different light and dark schedule, but your pendulum keeps going on your home time,” Lack says. “It starts producing sleepiness during an inappropriate time during the day in your current location. That oscillation between alertness and…