Goodwall Health's post on Goodwall - The startling spasm is often described as a falling sensation or an electric shock. It tends to happen more often when a person hasn't had enough sleep or is trying to not fall asleep. They're also common when in motion - such as sitting in a moving car or airplane - when your body may react to the sensation when entering the lighter stages of sleep. Other factors that can instigate a hypnic jerk include: stress, caffeine, and alcohol. #health