I love window seats on a long flight. There’s nothing like getting a big-picture perspective on planet Earth when you’re looking out at big, billowing clouds and the tiny ground below from 30,000 feet. But it turns out, sitting next to the window could actually be bad for your health.

That’s because people who sit next to the window tend to get up less often during a flight. You can’t blame them. After all, who wants to climb over two strangers in the middle and aisle seats, especially if they’re sound asleep or have their seat-back trays piled high with food or a laptop?

And the risk isn’t due entirely to shrinking leg room; this isn’t just a problem for people traveling in coach. Even those in business and first class tend to avoid getting up if they’re by the window.

These clots can develop when parts of your body, most typically your legs, are dependent, or lower, than the rest of you, and not moving much. Blood clots can cause swelling and pain locally, and if they travel through your veins to your lungs, they can cause a pulmonary embolism, which can be life threatening.

The American College of Chest Physicians has  published guidelines about the risks of getting blood clots in your legs, also called deep venous thrombosis (DVT), published in the journal Chest.

What Puts You at Risk

Those who are flying long distance who have the greatest risk are sitting in a window seat, on birth control pills or supplementary estrogen, have had a previous clot, have a disability that restricts their mobility, have problems with blood coagulation, are obese, have recently had surgery or trauma, or have cancer. Others at risk include people who are are pregnant and seniors. The longer the trip, the greater your risk. If you’re healthy, your risk is still relatively low.

You may be pleased to hear that the guidelines suggest there is no definitive evidence to support that dehydration, alcohol intake, or sitting in economy class increases a patient’s risk for developing blood clot resulting from long-distance flights.

Things You Can Do to Prevent DVT

There are some things you can do to reduce your risk of DVT:

• Walk up and down the aisle every hour or two.
• Wear below-the-knee graduated compression socks.
• Don’t take a sleeping pill. You’ll find you sit virtually immobilized when you’re snoozing.
• Don’t take aspirin or anticoagulants with the intention of cutting your risk of DVT.  If you’re at high risk for DVT, talk with your healthcare provider before your trip.
• If you’re in a bus or a train for more than an hour or two, these tips also apply. If you’re in a car, pull over and get out to stretch and walk around a bit every couple of hours, too.
• While you’re seated, do occasional leg exercises (to the extent there’s room), flexing your feet (lifting them up) and stretching.

Learn more from the Centers for Disease Control and Prevention (CDC).