So THAT'S Why Jet Lag Feels Worse When You Fly East

You can thank your body's natural clock.

Jet lag is a drag no matter which direction you fly. But did you know the experience is usually worse after you’ve traveled east than after you’ve gone west?

Frequent travelers have recognized this effect for quite some time. Your body’s internal clock naturally follows a cycle that’s slightly longer than 24 hours, at about 24.5 hours long. Traveling west across time zones gives your body the extra time it naturally wants in a day, while flying east shortens the day and makes it harder to adjust, as the Washington Post explained in 2012. Whoa.

And now, we have even more insight on the science behind jet lag recovery, thanks to new research in the scientific journal Chaos.

Scientists from the University of Maryland set out to understand how the cells in your brain’s Suprachiasmatic Nucleus respond to travel, as they’re responsible for controlling your circadian rhythm.

In a new time zone, “the brain’s... pacemaker cells cannot instantly establish a rhythm appropriate to the new time-zone,” the researchers explain. They created a mathematical model to better understand how quickly these cells can adjust.

After much modeling (AKA lots of complicated math), the scientists confirmed what travelers have known for years as mathematically true: Your brain cells should indeed take longer to adjust after flying east because they naturally tend to follow a cycle that’s about 30 minutes more than 24 hours long, and that 30-minute difference provides an advantage for cell recovery if you’re traveling west.

Researchers also estimated that it would take about six days to recover from a westbound trip across six time zones, but about eight days to recover from an eastbound trip across the same number of time zones. This means you’ll likely spend about two more days feeling dazed, confused and sleepy after traveling from NYC to Rome than after making your return trip. Yikes.

Keep in mind these are simply the scientists’ calculations, and they haven’t been tested in experiments yet. But the information is all the more reason to stay hydrated, bring snacks and squeeze in a workout to reduce the jet lag struggle on your next trip.

Happy travels!

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