This Is Why You Jerk Awake Just As You Fall Asleep

Hypnic jerks cause you to jolt awake.

We all know the feeling. You’re starting to fall asleep, slipping in and out of consciousness. Suddenly, you’re rudely awoken by a violent jerk. You may have been dreaming of falling off a high building or cliff in the meantime. It takes you a minute to realize what’s going on, and a little longer to calm your racing heart. You just experienced a hypnic jerk. A common occurrence that’s strangely difficult to understand.

What Are Hypnic Jerks?

These unconscious spasms happen as you fall asleep.


These involuntary spasms are defined as a sudden jerky movement of the legs or the whole body right at the moment of one falling asleep. They’re more common than you think. 70% of people experience them or have experienced them at least once in their lifetime.1 These jerks may or may not be accompanied by other sensory stimuli. Some people experience a sensation of falling while others hear a loud bang and/or bright flashing lights.

Most people brush them off and fall right back into a deep sleep. Some aren’t woken up by these spasms or twitches and often wake their partners up instead. Others experience them much more frequently and intensely. So, while it isn’t a sleep disorder on its own. It can lead to sleep disruptions and insomnia out of a fear of falling asleep.


Why Does It Happen?

 It’s likely to happen if you sleep sitting up.

There are several theories for why hypnic jerks happen, but this is the most common. When you fall asleep, especially if you are tired or sleep-deprived, your systems are likely to wind down much faster than normal. If this is the case, your brain may interpret this as your body actually shutting down. In turn, it signals the muscles to tense up, often evoking a fight or flight response. Hence your heart races and your breathing quickens.


Another theory is that your muscles are toning down during the process of falling asleep, and it may just be your nervous system misfiring. The twitches happen as a result of that process. They’re likely to happen if you sleep sitting up as well (in that dull afternoon meeting perhaps). This can be tied back to an evolutionary purpose. Our primate ancestors sitting in trees would have fallen to their deaths if they fell asleep. Experts theorize that the brain signals the muscles to react quickly in this situation when it senses the body starting to relax. Unfortunately, this doesn’t bode well for you at your workplace.

Risk Factors

Caffeine can increase the frequency of hypnic jerks.


There are only theories to confirm why these hypnic jerks happen, there are certain factors that seem to increase their frequency.2

  • Changes in heart rate, inherent or caused by medication
  • Caffeine or other stimulants
  • Anti-depressants
  • Alcohol
  • Chronic Anxiety or stress
  • Heavy physical exertion.
  • Sleeping in an uncomfortable position
  • Being very tired or sleep deprived

How To Prevent Them

Create a regular sleep routine.


There a few steps that you can take to prevent them happening.

  • Stay away from caffeine, especially in the evening. Your last cup of coffee or tea should be up 4 hours before you go to bed.
  • Try to train yourself into a regular sleep routine. Go to bed at the same time every night and wake up at the same time. Time this to get at least 7 hours of sleep every night.
  • Try regular relaxation techniques to deal with stress and anxiety. Yoga, meditation, or aromatherapy can help.
  • When drinking, stick to the recommended limit of 2 standard drinks on any given day.

With this knowledge and these helpful tips and tricks, you can finally experience an undisturbed, good night’s rest.