Yesterday I was trying to go to sleep, and then I realized I hadn't moved for about 20-30 minutes because I felt SP kicking in, or at least the first stage where ur body feels really heavy. All of a sudden, I had this HUGE urge to move. My body was basically telling me to "MOVE!!! Switch positions!!!"

Is this supposed to happen? It was really strange because I never felt like that, like I was in a box constricted and I had to move. I eventually moved, but that broke SP.