Carpal tunnel syndrome is a condition that can cause numbness and tingling in the hands and arms. According to the Mayo Clinic, it's typically caused by a compressed nerve that runs through the wrist. There are several different things that can cause carpal tunnel such as repetitive use of the same hand and wrist movements, injury, genetics, and the positioning of your hand and wrist. A 2011 study published in the journal Hand found a link between sleeping on the side and carpal tunnel syndrome.Your arms going numb while sleeping is pretty normal, especially if you sleep in a certain position. If you experience numbness that's not related to the way you're sleeping, it's not a bad idea to talk to your doctor.