We’ve all stepped off the jet bridge feeling tired, groggy, or ready to practically drop on the floor and take a nap in the middle of a terminal. At least, most of us have.

Traveling can make anyone tired, though it affects some people more than others. This phenomenon is known as jet lag and it’s actually a real, temporary disorder rather than just a traveler’s myth.

What is jet lag? 

The Mayo Clinic defines jet lag as “a temporary sleep problem that can affect anyone who quickly travels across multiple time zones.” Our body’s internal clock, our circadian rhythms, stay in one time zone while we physically travel to another, which means our bodies and our body clocks are out of sync. Contrary to popular belief, it’s not actually caused by a lack of sleep.

You may not experience as much jet lag flying domestically from New York to New Orleans, unless you’re particularly sensitive. But flying from New York to Los Angeles and vice versa can cause the fatigue to really set in. International travel, of course, can be especially brutal for this very reason.

There are many reasons why jet lag occurs, and it really has to do with our physiology and what happens to our bodies while in flight. While there’s little you can do to control the plane’s environment, there are ways to prepare your body and take care of yourself after a trip.

What causes jet lag? 

You’re Dehydrated

It’s no secret that the atmosphere in the plane’s cabin is incredibly dry. This is mostly due to the high altitude, according to The Points Guy, but also because plane air filtration systems often don’t allow for as much humidity as we’re used to on the ground. Combine the air with drinks containing alcohol or caffeine, which are also notorious dehydrators, and people can often experience dry skin and eyes, or even headaches, fatigue, and dizziness.

The Plane’s Elevation and Pressure

The body has to adjust fairly quickly to being at 36,000 feet. Of course, this is why cabins are pressurized – to minimize the effects of being at such a high elevation – but this can also take a toll on the body. According to the Points Guy, cabin pressure isn’t exactly calibrated to what you would feel at sea level. Instead, it’s more like how you’d feel in the Rocky Mountains or Machu Picchu, between 6,000 and 8,000 feet elevation. It should also be noted that at these elevations, the air is much thinner, so there is less oxygen than you would have on the ground. It’s a great improvement compared to cabins that are not pressurized at all, but this can still lead to swelling, ear pressure, and symptoms similar to altitude sickness. You may notice that you feel a bit bloated too, according to the Cleveland Clinic, because “pressure changes cause the gas inside your stomach and intestines to expand.”

You’re Stressed Out

Let’s all take a deep breath and remind ourselves that travel is especially stressful, even if it may not seem like it. After all, we just have to sit in our tiny seats and wait for the plane to touch down again, right? Well, according to the Cleveland Clinic, that’s  leaving out several stress factors like getting to the airport on time, fighting your way through the security line, finding your gate, getting your bags situated, dealing with the overstimulation of being around thousands of people at once, and then finally sitting in a chair that is most likely less comfortable than you would like for a long haul flight.

You’re Exposed to Germs

Plane’s air filtration systems are quite advanced these days and can help filter out germs and viruses, which is why it’s actually recommended to open your air vents when you travel. Still, you can be exposed to germs and viruses from the people around you or from things you touch around the airport. “We can catch something from other passengers who are coughing, sneezing, or even just breathing nearby,” said Dr. Matthew Goldman from the Cleveland Clinic.

What can you do to prevent jet lag? 

Drink Water and Avoid Alcohol and Caffeine

Reaching for coffee or soda may be our first instinct when we’re tired, but it’s not the best thing to do for our bodies. Similarly, it’s a myth that a cocktail, wine, or beer will help you sleep on a flight to combat jet lag. Sorry to be a buzzkill, but the number one thing anyone can do to avoid or cure their jet lag is to hydrate. The most efficient way of doing this is to, of course, drink water, as recommended by the Cleveland Clinic. Avoiding dehydrating beverages like alcohol or caffeine can also help the hydration process. Ordering a cocktail can be one way to relax and make your flight experience a little more luxurious, but try to drink a bottle of water as well to avoid getting too dehydrated.

Get Moving

Moving around the cabin, according to The Points Guy, is a great way to keep your blood flowing and get oxygen to your brain so you can fight fatigue and swelling. It can also reduce your risk of serious health concerns that come with sitting for too long on flights, such as dangerous blood clots known as deep vein thrombosis. Getting up and moving a little bit every 30 minutes should be sufficient – and shouldn’t disturb your fellow passengers too much.

Avoid Fatty Foods

Increased gas and belly bloating can make any flight excruciatingly uncomfortable, so it’s important to avoid greasy foods or anything that might make your gas worse, according to the Cleveland Clinic. Bring healthy plane snacks like gluten-free nut blends, energy bites, fruit, or vegetables to help your body stay energized, hydrated, and less bloated.

Relieve Pressure

Have you ever tried to pop your ears during take off or landing? It’s actually a great way to relieve pressure, according to the Cleveland Clinic. Yawning, swallowing, chewing gum, and sucking on a piece of hard candy can help open your inner ears. Not only does this relieve headache-inducing pressure, it can also stave off motion sickness and altitude sickness symptoms too, since it helps your body equalize and restore balance. It’s also important to remember to relieve emotional or mental pressure too. Noise canceling headphones and a good travel pillow can be ways to make your flight more comfortable, or you can even practice meditating while in flight to relieve stress and help yourself feel rested.

Take Your Vitamins

Vitamins C and B, to be precise, are the best supplements to take while flying. B12 helps boost your mood, increases red blood cell formation, and gives you energy, according to Healthline. Vitamin C, of course, can help boost your immune system and fight sickness caused by viruses and bacteria. Drinking some all natural juice is a good way to get your vitamins and hydrate at the same time.

Trick Your Circadian Rhythm

The Mayo Clinic suggests a few ways to help your body get back in sync with its internal clock. One way is to regulate your exposure to bright light. If you’re traveling westward, exposing yourself to light in the evening helps you adjust to a later time zone. If you’re traveling eastward, exposing yourself to morning light is better to adapt to earlier time zones. One exception to this is if you’ve traveled more than eight time zones away from your point of departure. If that’s the case, wear sunglasses and avoid bright light in the morning and soak in the rays in the afternoon if you’re traveling east, and if you’re going west, avoid sunlight for a few hours before dark for a few days.

Another way to get your body clock up to speed is to take melatonin, a hormone our body produces naturally to help us sleep. Take a supplement a half hour before you want to go to bed so you can adjust to your destination’s time zone.

The Mayo Clinic suggests sleeping on your flight only if it is night time where you’re traveling. Think about it this way: if you’re not planning to sleep during the day where you’re going, try not to sleep on your flight (even if it was night time when you took off). This may be challenging, but it’s one way to reset your clock.

Take Your Time

Going slow and taking your time, when you can, will help you avoid unnecessary stress and adjust to your new schedule. Plan your meal times around your current time zone, enjoy getting from point A to point B, arrive to anywhere you can early so you don’t feel rushed, and schedule some time to recover from your flight before you are on the go again. It’s guaranteed to make your trip more enjoyable if your body is also in peak condition.