Here's the lowdown on jet lag, from how you get it to how you get over it.
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Returning from a dream vacation is already sad enough, but when you add jet lag to the mix, it can turn into a real nightmare.

As any frequent flyer will tell you, the effects of jet lag–ranging from headaches to depression–are no joke. But, there are ways to stave off this nasty byproduct of traveling to far away places. Here’s everything you need to know about jet lag and how to stop it in its tracks.

What Is Jet Lag Exactly?

The Mayo Clinic defines jet lag as a “temporary sleep problem that can affect anyone who quickly travels across multiple time zones.” It is also often referred to as "jet lag disorder."

What Causes Jet Lag?

How do you get jet lag?
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Jet lag is typically the result of traveling across multiple time zones in a single flight. When people travel far distances, their natural sleep cycle—known as circadian rhythm—is thrown out of whack. According to the National Sleep Foundation, a human’s circadian rhythm is measured by the “distinct rise and fall of body temperature, plasma levels of certain hormones and other biological conditions.” These natural changes are heavily influenced by a human’s exposure to sunlight, which helps our biological clock determine when we should be awake or asleep.

When a person travels through a different morning and night (say, on a trip from New York to London, which comes with a five-hour time difference), his or her brain can no longer process the time in the same way, which is how you get jet lag.

Is Jet Lag Worse Going East or West?

Why Is Jet Lag Worse From West to East?
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According to a 2016 study published in Chaos, jet lag is indeed worse for those traveling east. This happens because when you travel east, you're shortening you day–meaning your circadian rhythm has to work harder to catch up.

“Basically, what we show is this eastward-westward asymmetry ... comes from the fact that your [circadian rhythms] have a natural period that is a little longer than 24 hours,” Associate Professor Michelle Girvan told Travel + Leisure. “You expect to advance your internal clock if you travel east and backward if you travel west,” Girvan explained. "However, if you travel a large number of time zones eastward, your internal clock doesn’t phase advance like you would expect. Instead, it phases delays.”

How Long Does It Take to Recover From Jet Lag?

Symptoms of jet lag are compounded the farther you travel, the Mayo Clinic reports, adding that it typically takes one day to recover from jet lag for each time zone crossed. So, if you traveled that New York-to-London flight path with a five-hour time difference, you can expect the consequences of jet lag to last for about five days.

Can You Get Sick From Jet Lag?

Can You Get Sick From Jet Lag?
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Jet lag can indeed cause some rather severe physical symptoms. According to the Mayo Clinic, symptoms can include disturbed sleep—like insomnia, early waking, or excessive sleepiness—daytime fatigue, difficulty functioning during the day, upset stomach, and mood changes.

If your symptoms continue, or if you're a frequent traveler, the Mayo Clinic suggests you could benefit from meeting with a sleep specialist.

How Can I Treat Jet Lag Symptoms?

People Sleeping on a Plane to Prevent Jet Lag Symptoms
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The best thing you can do to get over jet lag is to stave off the effects before they ever begin. To do so, the Sleep Foundation suggests you first attempt to book a flight in the early morning so you can arrive by evening. Upon arrival, try to stay awake until 10 p.m. local time to reset your body's clock. You can also try resetting your body's clock before you depart by getting up and going to bed earlier several days prior to an eastward trip.

If it’s nighttime at your destination when you depart, try your best to sleep on the plane to help yourself get on the new time zone. Make sure to bring an eye mask, earplugs and a pillow for maximum comfort.

How Can I Get Over Jet Lag?

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If you need more assistance, try this no-fail technique to sleeping comfortably on any flight.

Lastly, avoid consuming any alcohol or caffeine while flying, which will dehydrate you and further exacerbate jet lag symptoms. Stop drinking these things at least three to four hours before bedtime in your new destination, too. If you're unable to prevent the symptoms, try these five scientifically-proven tips to overcome jet lag during your trip.

While experiencing jet lag is almost guaranteed in specific situations, at least you get to travel to a new and thrilling destination, which makes being a little sleepy worth it.