Question: what does it mean when somebody jumps in their sleep?
Answer: A hypnic jerk is an involuntary twitch of one or more muscles that occurs as a person is falling asleep. It tends to happen just as the person is transitioning from a wakeful state to a sleeping state. Hypnic jerks are a type of involuntary muscle movement called myoclonus. Hiccups are another common form of myoclonus.