Why Does Your Body Jerk When Falling Asleep?

The Science Behind Hypnic Jerks
If you’ve ever experienced a sudden body jerk as you’re drifting off to sleep, you’re not alone. These unexpected movements, known as hypnic jerks or sleep starts, occur during the transition from wakefulness to the first stage of sleep. Despite feeling startling, they’re common—studies show that up to 70% of people experience them at some point.

What Are Hypnic Jerks?
A hypnic jerk is an involuntary muscle contraction that typically happens when your body begins to relax as you fall asleep. It’s thought to occur because parts of your nervous system are still active while others are already slipping into a sleep state. This can cause your brain to send mixed signals to your body, resulting in a sudden twitch or jerk.

Sleep experts explain that these jerks are more likely to happen when you’re overtired or not getting enough rest. When you’re severely sleep-deprived, your body can skip some of the usual stages of sleep, going directly from light sleep into rapid eye movement (REM) sleep. This abrupt shift may increase the likelihood of a hypnic jerk.

Are Hypnic Jerks Harmful?
The good news is that hypnic jerks are benign. They’re not linked to any serious health conditions and typically don’t require treatment. However, they can be alarming—particularly if they wake you up or make it harder to fall back asleep.

If you find hypnic jerks occurring frequently, consider looking at your sleep schedule. Consistently getting seven to nine hours of quality sleep each night can help reduce their occurrence. It’s also a good idea to develop a relaxing bedtime routine to signal to your body that it’s time to wind down.

Coping with Hypnic Jerks
For many, hypnic jerks are a simple sign that your body is overtired and craving rest. By making small adjustments to your daily habits—like avoiding caffeine late in the day, maintaining a consistent bedtime, and managing stress—you can help reduce the frequency of these nighttime twitches.

If a hypnic jerk startles you awake, remind yourself that it’s not harmful. Relax, take a few deep breaths, and focus on easing back into sleep. With a balanced sleep routine and healthy habits, hypnic jerks can become less frequent, allowing you to enjoy a more restful night’s sleep.