Nocturnal Flinching

When someone is sleeping and they have a dream or thought of themselves getting hurt or falling, and their body physically reacts, and causes them to jerk or flinch rather spasmodically.

Guy: What the fuck tracy, you kicked me in the balls last night in bed???

Tracy: sorry, i had a bad dream and probably got a nocturnal flinching.

Guy: go fuck yourself, we're done.