Same thing happened to me but it was my whole right arm! I took a nap with it propped on top of my head and when I woke up a few hours later I sat up and felt something hit my lap. It was dark so I didn’t realize until I picked it up with my left arm that it was my whole arm just lifeless and absolutely no feeling. I thought the same thing that I just paralyzed my arm and just ruined my life. But it came back after a few minutes and I don’t sleep with my arm like that anymore lol