You know the startling way your body will sometimes jerk, twitch, or jump right as you're getting all comfortable and drifting off to sleep? You probably do — roughly 70 percent of the global population experiences this random, frustrating physical quirk. Thanks to a recent, digestable YouTube video, we now have a better way of understanding why.
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YouTube channel SciShow recently tackled this familiar feeling — oftentimes referred to as a hypnic jerk or sleep start — and they deciphered two likely explanations.
The first one involves neuroscience. Host Michael Aranda says, "As you fall asleep, there are two different systems in your brain that are basically battling each other." The first system, the reticular activating system, deals with alertness. The second system, the ventrolateral preoptic nucleus, is referred to as a sleep switch. As you fall asleep, there's a figurative hand-off from one system to the other; however, sometimes the alert part of your brain wants to maintain control of your body — resulting in an involuntary movement or twitch.
Another theory involves evolution, and while it is less common, it's still pretty interesting! "Some scientists think that the ancient primate brain associated relaxation, or the beginning stages of sleep, with falling out of a tree," says Aranda. Therefore, these hypnic jerks were a way of waking up the primate before their possible fall.
While it is extremely common, the video also confers ways to prevent it from happening, like limiting your caffeine intake, working out in the morning, and reducing your overall stress levels.