You've had your foot bent in an awkward position for a long time, and now it feels kind of numb, making it difficult to stand up. When this happens, we often say our foot is asleep.

That loss of feeling, also common in the legs and arms, is caused by the "temporary compression of nerves," says Rebecca Traub, an assistant professor of neurology at Columbia University. When the nerve is pinched, it doesn't communicate signals to the spine and brain correctly.