Few things may spoil a night’s sleep more than the agonizing sensation of springing awake in panic. Perhaps you’ve had it on occasion – most of our readers will at some point – and if you haven’t, consider yourself fortunate. Many people find it distressing to be woken up from a deep sleep, which is typically followed by the sense of falling.

It’s similar to having a dream where you’re falling and then waking up right before landing. Unfortunately, you never get used to it, and it can be tough to fall asleep peacefully again thereafter. But what exactly does this jerking sensation indicate? Why does it appear to be a completely natural and widespread occurrence among most humans? Is there anything you can do to avoid this from happening?

We did some research on the subject, and while many aspects of this creepy phenomenon remain unknown, we do have a few answers that may be of interest to anyone who has ever woken up in the middle of the night with their heart pounding out of their chest. First and foremost, let us refer to the feelings by their proper name: hypnic jerks. Also known as sleep beginnings, these are the abrupt, often overwhelming muscle spasms that occur as you fall asleep.

What we know: According to the Sleep Foundation, hypnic jerks often affect one side of your body, such as your left arm or right leg, and their source is mostly unknown to researchers. In truth, all we have to rely on are speculations supported by a few facts, such as the fact that hypnic jerks (hypnic being short for hypnagogic) originate in the same area of your brain that regulates your startle response. Figures, right?

It’s possible that as your muscles begin to relax entirely, which is an obvious and unavoidable component of falling asleep, your brain believes you’re actually falling and reacts by effectively jump-starting your muscles into action. Another idea holds that hypnic jerks are linked to the dream-like visuals that may accompany them. In other words, your brain is blurring the barrier between the dream world and reality, causing your muscles to activate in order to provide a physical reaction to whatever you are experiencing in your head while sleeping.

Why is this happening? Unfortunately, determining why you are experiencing hypnic jerks is not an exact science, but there are a few suggestions as to what may enhance the likelihood of them occurring. According to the Sleep Foundation, risk factors include excessive caffeine or stimulant usage, vigorous exercise before bedtime, emotional stress, and sleep loss.

Caffeine and nicotine, for example, can have an important role since they stay in the body for hours after use. Such products prevent weariness and make falling asleep more difficult, so it’s not surprising that they can cause hypnic jerks. Similarly, intense exercise late at night is not necessarily correlated with drowsily collapsing into one’s bed and drifting off to sleep. On the contrary, exercise is an energizing activity that causes the body to feel alert rather than exhausted.

It’s crucial to remember that hypnic jerks can occur at any age, in a variety of forms, and appear to be extremely prevalent. According to the Sleep Foundation, up to 70% of people experience hynpic jerks, which can be uncomfortable but are not hazardous. What can be done? So, all of this prompts the obvious question: how can we avoid or better control the symptoms of irritating hypnic jerks?

There are actually a few things you can do to give yourself the best chance of eliminating them, such as improving your sleeping habits (going to bed and waking up at the same times each evening and morning, for example), attempting to reduce stress in your life, exercising every day (but not too late in the day), limiting your caffeine consumption, and reducing or eliminating nicotine and alcohol.