After a long, exhausting day, you finally crawl into bed, ready to drift into a peaceful sleep. Just as you’re starting to relax, it happens—your body feels like it’s suddenly falling through space, and before you know it, you jolt awake. Your heart’s racing, and you’re wide-eyed, wondering what just happened. Sound familiar? If so, you’re definitely not alone. This strange sensation is called a hypnic jerk, also known as a sleep start, and it’s more common than you might think.

Up to 70% of people experience hypnic jerks at some point in their lives. They can feel abrupt, intense, and downright startling, and no matter how often it happens, it never seems to get less jarring. That odd sensation of falling followed by a sudden muscular twitch can shake you right out of a deepening sleep.

So what exactly causes these nighttime jolts? Scientists haven’t pinned down a single cause, but there are a couple of leading theories that offer some insight.

The first theory suggests that hypnic jerks are part of the body’s natural transition into sleep. As you start dozing off, your nervous system begins to slow down—your breathing evens out, your heart rate drops, your body temperature lowers, and your muscle tone decreases. These changes are part of the body’s way of preparing for rest. According to this theory, the sudden twitch is simply the body reacting to that physiological downshift.

The second theory takes a different angle. It proposes that as your muscles rapidly relax, your brain misinterprets this as a sign that you’re actually falling. In a split-second panic response, your brain sends signals to your muscles to tense up and “catch” yourself—much like a reflex to prevent injury. That’s why you suddenly jerk awake, even though there was no real danger.

While the exact cause remains unclear, experts do believe several outside factors can make hypnic jerks more likely or more frequent. These include stimulants like caffeine and nicotine, lack of sleep, high stress levels, and even certain medications like Adderall or Ritalin, which are known to affect the nervous system.

Now, if you find yourself experiencing hypnic jerks every night, you might wonder whether this is something to worry about. The good news? It’s totally normal. Dr. Rustgi, a sleep expert, explains that these involuntary muscle contractions are not a disorder. Instead, they’re just part of the body’s natural process of falling asleep. In his words, “It’s a kind of signal to the body that it’s going into sleep mode. It’s not dangerous or unhealthy—just part of how some people fall asleep.”

Still, just because hypnic jerks are harmless doesn’t mean they’re not annoying. For some, they can interrupt sleep regularly and lead to frustration or sleep anxiety. Fortunately, there are a few things you can do to reduce the chances of these jerks happening—or at least minimize their impact.

Here are some tips recommended by Dr. Rustgi to help reduce hypnic jerks:

1. Limit Caffeine Intake: Avoid drinking caffeinated beverages in the late afternoon or evening. Caffeine is a stimulant and can interfere with your nervous system’s ability to wind down before bed.

2. Avoid Late-Day Workouts: Exercising too close to bedtime can rev up your system and make it harder to relax. Instead, try gentle activities like stretching or yoga earlier in the day.

3. Practice Relaxation Techniques: Deep breathing exercises, meditation, or calming bedtime routines can help your body enter sleep more smoothly and prevent sudden muscle contractions.

4. Improve Sleep Hygiene: Go to bed at the same time every night, and shut off electronic devices at least an hour before you plan to sleep. Blue light from screens can disrupt your body’s natural melatonin production and interfere with your sleep cycle.

5. Manage Stress: High stress levels are a major trigger for hypnic jerks. Finding ways to unwind—whether it’s through journaling, reading, or listening to soothing music—can help your body relax.

In summary, hypnic jerks might feel scary or unpleasant, but they’re a common and natural part of the sleep process for many people. While there’s no official cure, small changes to your lifestyle and bedtime routine can make a big difference. So the next time you feel like you’re free-falling in your sleep, just remember—it’s your body’s quirky way of settling down for the night.