Why does my body jerk when I fall asleep?

Reviewed by Yoshinori Abe, MD

Internal Medicine

Hypnic jerks are sudden, involuntary muscle twitches that happen as you fall asleep. Also known as sleep starts, they are extremely common—affecting up to 70% of people—and are typically harmless. These jerks may be triggered by stress, caffeine, intense exercise before bed, or sleep deprivation. Most people experience them occasionally with no cause for concern.

However, if muscle jerks are frequent, disrupt your sleep, or occur alongside other symptoms, they could point to an underlying issue worth exploring. Understanding your symptoms is the first step toward better sleep and peace of mind. Take a free, instant, online symptom check to get personalized insights into what may be causing your nighttime jerks and clear guidance on your next steps.

Reviewed for medical accuracy: 07/20/2026

Important Next Steps

Learn why body jerks happen as you fall asleep Discover if your sleep twitches need care today Find out what causes sudden sleep jerks See OTC options for sleep-related twitching relief Find a doctor for sleep movement disorders Understand home remedies for falling-asleep jerks Discover likely causes of sleep jerks and twitches

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Explanation

When you are just starting to fall asleep, you may feel a sudden jerk in your body. These are called hypnic jerks, and they are quite common. A hypnic jerk is a quick, involuntary muscle movement that happens when you are transitioning from being awake to sleeping.

What causes hypnic jerks?

They can happen when you are very tired or stressed.
Drinking caffeine or exercising too close to bedtime may make them more likely.

Are they harmful?

Hypnic jerks are usually harmless and don't mean anything is wrong.
If they happen a lot and bother you, it may help to relax before bed.

It's important to remember that these jerks are a normal part of falling asleep for many people. If you have concerns about your sleep or experience other unusual symptoms, take our free AI symptom checker to better understand what might be happening with your health.

(References)

Chiaro G, Calandra-Buonaura G, Sambati L, Cecere A, Ferri C, Caletti MT, et al. (2016). Hypnic jerks are an underestimated sleep motor .... Sleep medicine, 28007358.
Torio M, Sanefuji M, & Hara T. (2013). [A one-year-old male infant with sleep-associated febrile .... No to hattatsu = Brain and development, 23951945.

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