This Is Your Body on Jet Lag

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

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 sleepiness, driven by our body clock, continues to take place.”

Global data indicates more people are traveling abroad than ever before, which means more jet lag. Earlier this year, the World Tourism Organization, a United Nations agency, reported that the number of people traveling overseas reached 1.4 billion in 2018, marking a 6% increase from the year prior. The group says it expects this figure to continue to grow.

If you’re one of the billions of people planning faraway travel, here’s what you should know.

“Exposure to bright light gently nudges the body clock so that our sleep period is pushed back into the nighttime.”

The symptoms, and how to lessen them

The main affliction of jet lag, as anyone who has ever experienced it can attest, is an intense desire to sleep during the daytime or stay awake at night. Jet lag can also contribute to moodiness, digestive distress, trouble concentrating, and generally feeling subpar — likely all the result of a lack of sleep as well as uncomfortable sitting positions, air quality, and pressure. According to the American Academy of Sleep Medicine, these symptoms tend to feel worse as people get older.

Those side effects can be lessened if people can quickly match their internal clock to their destination’s clock. There are a few ways to do this, according to experts. For example, the Mayo Clinic says exposure to bright daylight during the morning hours of your current location will help signal to your body that it’s time to be awake. And keeping yourself in a dark, cool room when you should be sleeping will help introduce nighttime cues.

“Exposure to bright light gently nudges the body clock so that our sleep period is pushed back into the nighttime,” Lack says. “Outside sunshine is the best thing that helps.”

Bright light exposure (ideally from the sun) combats jet lag by stimulating cells in the eye that connect to a part of the brain called the hypothalamus, which helps control circadian rhythms. Activating that part of the brain each morning is important for maintaining a normal circadian rhythm, experts say.

Another jet lag remedy to try is melatonin — a hormone the body uses to regulate its internal clock. During the day, the body suppresses melatonin to help you feel alert. At nighttime, the release of melatonin helps cue the body that it’s time to sleep. The theory is that taking a melatonin supplement before bed can help you fall asleep at an appropriate time for the time zone you’re currently in. The CDC points out that research backing up these claims is pretty limited, but melatonin supplements are generally safe for short-term use.

Some researchers, Lack included, are developing more intensive solutions. Lack has been working on a pair of funky-looking light therapy glasses called Re-Timer ($149), which shine specially formulated LEDs into the eyes and could help mitigate jet lag among travelers. The idea is that the lights “trick” the body into thinking it’s early in the day. Wearing the glasses for short sessions before a trip or during the journey may help align the body’s clock with a traveler’s destination. He says his glasses are particularly helpful if there’s no direct sunlight available.

While research is still very early, there are also some proof-of-concept studies that suggest there are some drug compounds that could help. Drugs that suppress vasopressin, a hormone regulating water storage, may help reset body clocks to avoid the symptoms of jet lag, as early mice studies have suggested.

Two things you should try to avoid if at all possible? Relying on prescription sleeping pills and using booze to help you fall asleep. Sleeping pills come with side effects that could hinder travel, like dizziness or impairments the following day. And even though a gin and tonic on the plane might leave you feeling drowsy, your sleep won’t last.

Ultimately, as uncomfortable as jet lag can be, it’s temporary (though people with regular inconsistent sleep schedules could experience longer-term issues). After travel, sleep patterns will return to normal, with no lasting impact on health. And making that trip overseas may be worth a couple days of unpleasantness.

Writer and editor in New York City.

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