Eli5: What is really happening when body parts “fall asleep” & why does the sensation feel that way?

Question

I undeestand it has to do with blood flow and such… but I’m curious why it feels tingly or even painful sometimes?

In: Biology

Answer 1

Blood supply to a nerve is insufficient to keep nerve functional is “falling asleep”. When thisnhappens there is no sensation. You just lose function of that part of the body. The pins and needles sensation is what nerves do when they begin to wake up after blood flow is restored. Essentially the nerve is in a temporary state of chaos and is firing off erratic impulses and the brain interprets it as that pins and needles sensation.

btw, the same thing happens when damages nerves heal and restore the connection. You will get something similar to that sam pins and needles sensation when the damaged nerve regains function.