This is normal if you have been sleeping in a way to put pressure on a nerve or ganglia in your leg or back.
The pressure temporarily cuts off blood supply the ganglia or nerve, causing it to have a temporarily compromised function.
The nerve impulses are not getting through. It is a temporary form of paralysis, and goes away as soon as blood and circulation are restored.
Your leg does not work well when its nerves are "asleep" as you call it.
Your reply has information to suggest that something else could be going on besides a simple issue of your leg falling asleep. Since you report that you did not have a tingling sensation, I would have to expand the potentiality of other causes.
However, assuming it is a nerve compression or ganglionic compression caused by the way you were sleeping; compression on the spine may not necessarily cause a tingling sensation in the legs.
Your foot can still move, because your leg is operating it. It is kind of like, your knew gets its strength form the quadriceps muscles. The foot gets its strength from the gastrocnemius muscles (calf).
So even though you may feel tingling in your feet, as long as the calf and quads are working, you can still be mobile, with just a little bit of concentration.
If the symptoms you described were caused by, say a lumbar compression, you may not have felt a tingling sensation in your legs, depending on which nerves and ganglia were compressed from your sleeping posture.
However, this also introduces other considerations, which would require a differential diagnosis based on a physical examination of your spine and hips, and testing of reflexes by a physician.
Your differential now generally would include: