That hasn't happened to me in a long time, but I do remember it happening. The scary ones are when I know I'm dreaming and I try to wake up, think I am, and try to wake up again, and again, and each time I think I AM awake, but find myself waking up again. EEEKKKK. Talk about alternate realities!! Makes you start to wonder if you ever DID really wake up, or you start to wonder/dream if you CAN wake up; what are you going to do if you can't!?!