Well, that doesn't happen. But when (this doesn't happen that often at all) I'm sleeping, and I have a nightmare, I know it.
First, my vision is cut to a very low portion, meaning a lot of my vision blurred in my dreams.
Sometimes, I'm running to my (this may sound silly) parents bedroom saying I heard a noise or something, and for some reason I look into another room.
It's dark, I can't see anything. As I walk away I see a slight hand, creeping from the corner of my eye. RIGHT WHEN THIS HAPPENS, A HUGE SOUND THAT SOUNDS LIKE A MOTEM OR LOUD BUZZING COMES OUT OF NOWHERE...I startles the hell out of me all the time.
Does that happen to anyone?