If your body suddenly jerks while you’re falling asleep, here’s what it means

Exhausted and worn out, you’re finally in bed and sinking into what will be a deep sleep, when your body begins to “fall” and suddenly jolts to stop that “fall.” Naturally, you’ll wake up immediately and wonder where it came from.

And no matter how many times it happens, you never get used to it, it never seems less abrupt, and it never gets better. The sensation of falling can be downright terrifying, and ends with an involuntary, sudden, and shocking leap.

If this has happened to you at least once, you’re not alone. In fact, up to 70% of people experience this phenomenon, also known as hypnic jerks (or sleep attacks). No one knows for sure what causes these sudden jolts.

The Science Behind Hypnic Jerkys

The Science Behind Hypnic Jerkys

Although there’s no complete explanation for how and why hypnic jerks occur, two theories suggest some causes. One holds that hypnic jerks are the result of the nervous system’s natural slowing down during sleep.

The explanation lies in the changes in muscle tone that occur as a result of slowing breathing and heart rate, and the natural drop in body temperature. In this transition, theory suggests that contractions are a response to this drop.

The other theory suggests that this happens because of the rapid relaxation of the muscles, which the brain interprets as if you were actually falling. In response, it signals the muscles to contract, so you can protect yourself.