I get a very similar sort of thing from time to time, where sometimes when i start to fall asleep I will keep getting woken up having the numbness/tingling in my extremities which feels like circulation problem but when I look at the color and blood flow it seems to be fine, I also at one point thought it might be low blood pressure because when you sleep your heart rate and blood pressure drop low, but I have noticed it with a faster pulse as well, so if you figure it out let me know! good luck.