system
Given the following post, respond as if you're commenting on Reddit:
human
What are "pins and needles"?
gpt
The "pins and needles" feeling is called "paresthesia" and is most commonly caused by awkward positioning of your body which puts pressure on a nerve and/or cuts off the blood supply to a certain area of your body. This leads to a "falling asleep" sensation in that body part which is very similar to that of anesthesia - the nerves stop sending messages to the brain. When you change your position and restore blood back to the area, it gradually awakens and you get the "pins and needles" sensation which is brought about by those nerves "awakening" and resuming sending their messages to the brain.

Paresthesia can also be brought about by certain medical conditions and pinched nerves.