Most people know the moment. You finally begin to relax after a long day, your eyes close, and sleep slowly starts to take over.
Then suddenly your body jerks. For a split second it can feel like you are slipping, falling or missing a step in the dark.
The strange sensation can be surprising, but sleep experts say it happens to millions of people and is usually completely harmless.
A strange sleep reflex
Doctors call the sudden movement a hypnic jerk. It normally appears right as the body shifts from being awake to entering the first stage of sleep.
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During this transition, the muscles naturally begin to relax. Some sleep researchers believe the brain occasionally misreads that relaxation as a signal that the body is losing balance or falling.
In response, the nervous system quickly sends a signal through the muscles. That signal creates the sudden twitch that wakes someone up.
According to sleep research summarized by Medical News Today, these jolts most commonly occur in the earliest sleep stages when the body is still adjusting.
A possible survival instinct
Some scientists believe the reaction could be linked to early human survival.
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One theory suggests the reflex may date back to prehistoric times when humans often slept in trees or unstable places. A quick muscle contraction might have helped prevent someone from falling during sleep.
While that explanation is still debated, experts agree the sensation itself is not dangerous.
What can trigger it
Certain daily habits appear to increase the chances of experiencing these sleep jolts. Sleep specialists often highlight several common triggers:
- caffeine or nicotine later in the day
- high stress levels
- irregular sleep routines
- intense exercise shortly before bedtime
Creating a consistent sleep schedule and limiting stimulants in the evening may help reduce how often it happens.
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Sources: Unilad
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