That moment when, just before falling asleep, you jump as if you had missed a step or fallen into the void for no apparent reason… Sound familiar? This strange phenomenon has a name, it’s more common than you think, and it hides fascinating secrets about how our brains work. Ready to lift the veil on this nocturnal mystery?
Hypnic shake: what exactly is it?
You’re about to fall asleep. Your body relaxes, your breathing slows down… and suddenly, your legs or arms suddenly contract. This reflex movement, called a “hypnic jerk” (or “sleep startle”), is a sudden muscle contraction that occurs at the very beginning of sleep.
About 60-70% of people experience it at one time or another, often without knowing that it is a perfectly normal phenomenon. If this wakes you up with a start, it’s only because the brain is sending a signal… a little too intense!