system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When I sleep on my arm then wake up with my arm so numb that I can't even move it, exactly what is going on inside my arm?
gpt
when you sleep on it you interrupt blood flow in that area because you compress the arteries; this causes a failure in the nerves of the arm to function properly, so they can't send any signal to the brain (that's why you lose your sensations and the ability to move the limb and the hand). Only when the circulation improves (when you wake up and you free the arm) the nerves start to function again and you gradually get back to normality.