A sleeping foot can be considered a temporary neuropathy. The foot falls asleep when pressure is put on the nerve that supplies it. (The affected nerve is usually the peroneal nerve or the sciatic nerve.)
Pressure interferes with the blood supply to the nerve, making the nerve give off abnormal signals (a pins-and-needles sensation), called paresthesias.
Relieving the pressure, for example, by moving around, restores the nerve’s blood supply. As a result, the nerve can function normally, and the pins-and-needles sensation stops.