Happened to me again on Monday. For me, when it occurs it seems to have something to do with stress and/or lack of sleep. I had been up for a very long time and was very tired, so tired that I had trouble falling asleep! I was sleeping in a strange place (on the sofa). I woke up and was terrified, flat on my back and could not move. Fell back asleep after what seemed like an eternity of hell, and again it was non-specific but very frightening at the time. Scared the shit out of me!!!
