Of course my mind is pretty mixed up during sleep, but it seemed to feel somewhat the same. It was as if a 220 volt surged against my head while holding it in its grip, and sort of hurt and made me dizzy (while lying in bed) although it was too scary and quick to really figure it out. As far as I can tell I shook it off all within what seemed to be about a second. This happened a few times last month too. I will ask my doctor as soon as I can see him, but is it something to forget about and/or can it become chronic?