Why Do We Jolt When Falling Asleep?

You’re lying comfortably in bed, you’re eyelids getting heavier when suddenly you jolt awake with muscles tensed and you’re gasping for air.  Have you ever experienced that involuntary jolt when falling asleep? Those jolts are called hypnagogic jolts and  also referred to as ‘hypnic jerks’ or ‘sleep starts’. The name comes from the hypnagogic state, the transitional period between wakefulness and sleep.

This sensation of falling whilst you drift  asleep is a common occurrence, with up to 70% of people experiencing the jolts. Unfortunately, the cause is unknown. Naturally, there are a number of theories on the internet as to why we experience those sudden jolts.

The involuntary muscle spasms can occur spontaneously, however, may also be induced by sound, light or other external stimulations. Some people have reported hypnic jerks to be accompanied by hallucinations, the sensation of falling, or loud noises from within the head.

One of the more popular theories is that the falling sensation is the result of the natural downshifting of our nervous system which occurs as we’re falling asleep.

Naturally, there are numerous theories as to why we suffer these nighttime jerks. One theory suggests that as you’re drifting off to sleep, the brain misinterprets the relaxing of your muscles as a sign that you’re falling, therefore triggering signals for your muscles to tense up, in order to protect you. Others believe that as our breathing and heart rate slow down and the body temperature drops, the muscle tone shifts, which causes an involuntary twitch of the muscles.

There’s also the theory of evolution and that these hypnic jerks are the result of an ancient primate reflex. Those who hold a belief in this theory believe that the hypnic jerks allow us to wake one last time before we fall asleep, therefore allowing a final period to check for danger.

More often than not, hypnic jerks are nothing to worry about, with up to 70% of people experiencing the jolts at some point in their life. However, if you experience the jerks and jolts on a regular basis, you should go and speak to your doctor.


Written by: Downland Bedding Posted on: 27th July 2016