What makes our arms, legs fall asleep......!!

This is definitely a strange sensation -- we get up out of seat, and all you feel from one foot is an uncomfortable tingling. Or we wake up in the middle of the night, and we can't move arm at all. And then, as body part "wakes up," the strange tingling intensifies.
 Just what is going on here?


Usually, we feel this familiar sensation after we've been putting pressure on part of body -- sitting on a foot, sleeping on an arm, etc. When we apply this pressure for a prolonged period of time, actually cut off communication from brain to parts of body. The pressure squeezes nerve pathways so that the nerves can't transmit electrochemical impulses properly. 

                                                 Nerve impulses carry sensation information from nerve endings in the body to the brain, as well as instructions from the brain to the parts of the body. When interfering with this transfer by squeezing the nerve pathways, we don't have full feeling in that body part, and brain has trouble telling the body part what to do.

This pressure can also squeeze arteries, stopping them from carrying nutrients to body cells. Without these nutrients, the nerve cells may behave abnormally, which can further interfere with communicating bodily sensations.

 Once do move your foot, stretch legs, or roll over off arm, the nerve impulses begin to flow properly again. But we don't regain feeling right away, however. 
There is a certain amount of re-adjustment time before the nerves transmit impulses correctly again. This increases the intensity of the tingling, causing the familiar "pins and needles" sensation.

The tingling may be followed by a more uncomfortable burning sensation, before our body part finally returns to normal. This happens because the nerves in our body are made up of separate long nerve cells that carry different sorts of impulses. These nerve fibers have different surrounding structures. Some nerve fibers have thicker "insulation" around them and so take longer to begin transmitting impulses properly after they've been squeezed. The fibers that transmit pain and temperature information are relatively thin, so we feel the tingling situations pretty quickly.