Hypnic Jerks – Why We Twitch While Falling Asleep


It can be unnerving…you’re falling asleep, and then suddenly you’re wide awake, your whole body tense. Maybe you felt like you were falling or like you woke up out of a dream, even if you didn’t realize you were sleeping yet.

Up to 70% of us have this experience at one time or another, and it’s usually harmless. If it bothers you, though, or you’d like to know what’s going on with your body, here are the details.

What are these Jerks?

If you’ve had an experience like the one outlined above, you’ve experienced a hypnic jerk. These jerks happen while we’re in the hypnagogic state, which is the state between waking and sleeping, or the state of falling asleep.

These jerks are characterized by a sudden spasm or tensing of many muscle groups all at once. Some people only experience it in their muscles, while others also call out involuntarily. Many people who have hypnic jerks feel like they are falling, and some feel like they are dreaming or hallucinating, too. Others have a sudden sensation of light and sound coming from inside their own heads.

For the most part, these jerks are harmless. Sometimes, they keep people awake for a while after they occur, simply because they are so unnerving. Occasionally, the dreams or sensations that accompany them cause anxiety or fear, making it difficult to get back to sleep.

Why Do We Jerk When We’re Falling Asleep?

Researchers don’t know exactly why these jerks occur. Since they are usually harmless, there’s not a lot of research money available to study them.

There are, however, a few theories behind their existence.

When the body is falling asleep, all of the muscles slowly relax. Some theorists say that this triggers a reflex that we’ve held onto because of evolution. As we relax, the body feels like it is falling out of a tree. It sends danger signals to the entire body, causing it to tense before it hits the ground. Since primates sleep in trees and we evolved from them, this is simply something that our bodies have not yet realized we no longer need.

Other theorists have another idea. As the body relaxes into sleep, the brain waves begin to change. This triggers all sorts of other changes throughout the body. At some point, something in this process goes slightly wrong. Nerves and muscles are triggered to spasm, rather than to relax. In this theory, the hypnic jerk is basically a misfiring in the brain.

We can’t prove either of these theories in any definite way, but they give us some idea as to why we sometimes jerk when we’re trying to sleep.


What Can We Do About These Jerks?

Since we don’t know what causes hypnic jerks, it’s hard to address them directly. However, certain conditions make it more likely that they will occur. These include:

  • Anxiety
  • Stress
  • Fatigue
  • Sleep deprivation
  • Certain sleep disturbances
  • Caffeine intake
  • Exercise late at night
  • Excessive alcohol consumption

If you experience hypnic jerks and you would like to experience them less, determine which of the above conditions are relevant to your situation. Then, pick one, and eliminate it from your life.

This is easier to do with some than others. Anxiety, for instance, can be stubborn. However, you can do a lot of things to minimize yours, or at least to lower it. Take up yoga or meditation, spend some time reading before bed, or diffuse some aromatherapy oils in your room.

Once you’ve addressed a condition, track how often you have hypnic jerks. If the number is less than usual, you’ve done something to help your condition.

Over time, eliminate as many of the above conditions as you can. You should find that you experience hypnic jerks less frequently and that you’re sleeping better, overall. While you may never eliminate them completely, this should help you minimize their impact on your sleep.

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