(HealthDay News) -- A disorder called deep vein thrombosis (DVT) occurs when a blood clot forms in the body's deep veins, most often in the legs.

Your risk increases when you're confined to sitting for a long period without the benefit of exercise, such as on a long plane flight.

The American Council on Exercise offers these suggestions to help reduce the risk of DVT while you're on a long flight:

• If your flight takes three hours or longer, get up and walk around at least once every 30 minutes.
• While you're sitting, perform some simple leg, foot and ankle stretches and exercises.
• Don't wear constricting clothing.
• Nap in short bursts of no more than 30 minutes at a time.
• Drink plenty of water, and limit alcohol and caffeine.
• Take a brisk walk around the airport terminal if you have a layover.