This morning I woke up and couldn't feel my right arm from the shoulder down. I'd had similar happen before but not the whole arm and to a much lessor degree. I quickly got up and out of bed to start shaking the arm, changing its elevation to the rest of my body, and getting the fingers to tighten and release. Within a minute or two I managed to get feeling back in my arm and it appears to be mostly okay now. It still feels like there is a little deadness feeling to the arm, though.
I am never sleeping in that position again. Ever. Bleh.