A couple times in the past month or so, i'll wake up in the middle of the night and my left arm will be completely un-responsive. There' no tingling, I can't move it, in fact there's no feeling at all. I can pick it up with my right hand, but it feels like a foreign object. It goes away after a minute or two.
This wouldn't bother me if I slept on my side, but I sleep on my back I'm not sure what the cause it.