Why, when my leg/arm/any limb “goes to sleep” does it hurt once the feeling starts coming back to, but if I am given a numbing agent, it doesn’t hurt when the feeling comes back?

Question

So, when you fall asleep leaning on your arm and roll over, it starts to hurt as the feeling comes back. But if you go to the dentist and they numb your mouth, it doesn’t hurt once that starts coming back?

In: Biology

Answer 1

When you squish your arm it makes the little nerves go to sleep. When you stop squishing your arm the nerves wake up and tell your brain “Owie, we got squished!”

Medicine doesn’t make your nerves go to sleep, but it makes them talk quietly and your brain doesnt hear about the owies. When the medicine goes away the nerves think that your brain already heard about the owies and dont tell it again.