Have you ever felt yourself twitch while falling asleep? If you have, you know just how weird it feels. You're all settled in for the night, and as you feel yourself drifting off to sleep you suddenly SNAP out of it with a jerk of your muscles. Some people report feeling a sensation of falling, or even a loud noise and bright flash of light, which triggers them to jerk awake. Others, however, don't remember the jumps and twitches that preface their sleep.
The science behind what we do while we sleep is something that still puzzles scientists to this day. Did you know that we still don't know why we need sleep? I mean, no one is arguing that we need it, considering every single person eventually falls asleep if they stay awake long enough, but the actual biology behind it is unclear. The prevailing theory is that sleep allows our bodies and brains to recover, with the brain strengthening the knowledge and skills that we use and trimming away those that we don't.
So, what's the reason for this strange twitching many of us experience before sleep? Is it something that can be prevented? A relic of our primate ancestors, perhaps? Scroll through the images below to learn more about why scientists say our bodies get a little jittery when we cross over into sleep.
The twitch that you experience before falling asleep is called a hypnagogic jerk.
In case you ever thought you were the only one who felt these, you should know that 60 - 70 percent of people report having hypnagogic jerks.
You may even experience them without realizing it. Since they take place in that space between consciousness and unconsciousness, hypnagogic jerks typically aren't remembered unless they cause you to wake up.
Right now, there are two major theories as to why they occur:
1. Hypnagogic jerks are a natural part of falling asleep.
As we transition, the nerves in our brain will sometimes misfire and cause a muscle spasm. As Trace Dominguez from DNews puts it: " ... like a shift change at a factory, the handoff has lots of little things that have to go right for the brain to allow sleep to set in." So, if the different parts of our brain in charge of sleep and consciousness are two employees in the middle of a shift change, a hypnagogic jerk is one of them forgetting to clock in.
2. Hypnagogic jerks are a leftover self-defense mechanism from our primate ancestors.
Predators aren't a big concern of ours these days, but our evolutionary ancestors were putting themselves in a pretty vulnerable position when they fell asleep. Since they often slept in trees, these jerks would wake them up if they were about to fall.
For more info on hypnagogic jerks, check out this clip:
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