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Why Your Body Sometimes Jerks As You Fall Asleep
A closer look at hypnic jerks
Ahh… sleep. How nice. You turn off the lights. You close your weary eyes. You sigh. You relax. Your breathing slows down. Your mind begins to wander off, fading into the nightly oblivion.
Then…
You stumble, trip, fall. Your body jolts. Your leg kicks. Your heart pounds. Huh? What happened? Did you mistakenly fall asleep on a trapdoor?
Nope. You simply experienced a hypnic jerk.
What’s a hypnic jerk?
A hypnic jerk, or sleep start, is a phenomenon that occurs when your body transitions from wakefulness to sleep. It involves a sudden involuntary muscle twitch and is frequently accompanied by a falling or tripping sensation. It’s that strange muscle spasm that happens when you’re lying in bed, trying to sleep, and are suddenly jolted awake because you feel like you stumbled over something.
Hypnic jerks are common and benign.
But what causes them? Well, no one really knows. It’s still a mystery. However, researchers have come up with several hypotheses that may explain them, with the following two being the most popular.
Hypothesis 1: Your body twitches as daytime motor control is overridden by sleep paralysis
How is it that a bedfellow of yours doesn’t wake up pummeled and bruised if you have a dream about a boxing match? Is it because they’re having a complementary dream where they’re blocking all your jabs, hooks, and other punches?
