Dead limbs, not s good sign?

My limbs fall asleep at night when I am sleeping, becoming numb and unresponsive, and causing me to wake up many times during the night to change positions so that they will "wake up". I assume the blood flow to my arms/hands is being cut off, but I remember hearing that pinched nerves can make a limb fall asleep. This happens to my arms, hands or just my fingers, nearly every night. Lately it has gotten worse, and I woke up with both arms dead at the same time despite not being in any strange positions that you would think would cut off blood flow. Could this be a nerve problem or is it likely a blood problem?