Question: What is happening inside you when you sleep on your arm and goes numb and you cant feel it?

Keywords: , , , , , , ,

  1. What has happened is the nerves have stopped working temporarily.

    Nerves are long tubes that carry an electrical signals from one end to the other, but if you squash them flat they will slowly stop working. This is called a ‘pressure block’ and usually takes about 30-40 minutes to be complete in the arm, but the arm will start to feel strange after about 10-15 minutes.

    If you can’t feel you arm after sleeping on it that means you have blocked the sensory nerves that carry messages about touch, hot, cold, pain and other things up to the brain. If you also can’t move you arm, then you have blocked the motor nerves that take messages from the brain down to you muscles.

    Surgeons sometimes use these blocks as a form of anaesthesia and I use these blocks to do experiments. Being able to temporarily anaesthetise an arm (so you can’t feel it) and temporarily paralyse an arm (so you can’t move it) is very useful when investigating how the brain and the muscle communicate.