I know exactly what you are talking about....and it seems to happen when I have had an overwhelming day. I may have a grip on it by the time I go to bed, but my brain apparently has not. I fall asleep, and awake to the utmost panic, most of the time it feels like I am dying in my dream. That my mind is so far disconnected to my body...and I am startled awake from the crazy, can't go back to sleep and because of the lack of sleep...it offers me a day of more crazy...