Why do we sometimes feel like we fall when we fall asleep?

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!

Why do we have this feeling of falling?

The answer lies in the gradual transition between wakefulness and sleep. When the body relaxes quickly, the brain can misinterpret this sudden release. He believes, wrongly, that we are falling... and reacts by causing a muscle jolt.

This little glitch in internal communication between the brain and the body is actually a protective reflex, a kind of emergency reminder in case you are... installed at height. Yes, you read that right!

A surprising explanation: our distant origins

According to some researchers, hypnic tremors may be a legacy of our distant ancestors. At a time when sleeping in trees was synonymous with survival, a sudden loss of muscle tone could indicate a risk of falling.

The startle would then serve as a safety mechanism to adjust posture while sleeping. An intriguing theory that gives a completely different perspective to this moment when you think you are falling... in his bed.