Why Your Body Sometimes Jerks As You Fall Asleep

A closer look at hypnic jerks

Images by the author (CC BY-SA 4.0)

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.

Why Do We Sleep?

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…