You know the feeling: One moment you're about to doze off, the next you're jerking awake in a puddle of sweat. Not too pleasant, huh? That feeling has an actual scientific name, and there are ways to experience it less frequently.
Whether you have the full-on falling sensation or just experience involuntary muscle twitches as you fall asleep, hypnic jerks are actually really common. According to SciShow's video, 70 percent of the population experiences them. But we think we speak for everyone when we ask: Why?
The show's host, Michael Aranda, says the most common theory behind the cause of hypnic jerks is that the brain has a sort of "sleeping-waking war." It involves the reticular activating system (RAS) of your brain, which is responsible for the sleep-wake cycle and controls how alert you are, and the ventrolateral preoptic nucleus (VLPO), which helps you fall asleep and is often called the "sleep switch."
One silly way we like to think about these two parts of the brain: The RAS is a control freak, and the VLPO is totally laid-back. As you shift from being alert to being asleep, the RAS can still cause twitching as it attempts to maintain control before the VLPO takes over. When you jerk and suddenly wake up, the RAS basically won the battle against the VLPO.
But a less common theory centers on evolution: Some scientists believe what's left of our ancient primate ancestors' brain associates the beginning stages of sleep — right when the body is starting to relax — with falling out of a tree. Obviously we don't hang out in trees anymore, but back when our ancestors did, the hypnic jerk helped them wake up quickly so they wouldn't fall and hurt themselves. Or at least have time to brace themselves if they did.
Although hypnic jerks aren't dangerous, there are some ways you can limit them from scaring the beejeebers out of you when all you want is a good night's rest:
- Cut down on caffeine
- Stop working out at night and try mornings instead
- Cut down your stress level with a little meditation or yoga
- Get the recommended amount of sleep each night
Happy snoozing! And if you do happen to experience the falling-off-a-cliff sensation, don't worry — just tell your RAS and VLPO to give peace a chance.