What causes my foot falls asleep while driving?

Position: The position that you sit in may be compressing the sciatic nerve and causing your foot to go numb.

Might be your back: Check your driver's seat the next time, the position may be contributing the problem. The nerves to the lower extremity stem from the lower back and positional changes can disrupt the nerve signal. This can sometime cause numbness. You need to have this checked. See a podiatrist to rule out any local problem in the foot first. An addt'l referral to a back specialist may follow.