What is it? Fitness

Do you get hypnic jerks while sleeping?

It happens when you’re waddling at the brink of awake and asleep. When your heart rate slows down, your muscles are relaxing, you are taking deeper breaths, and letting yourself fall asleep. And then, out of nowhere, one of your limbs twitches, not enough to pull you out of your slumber, but enough for you to take notice and subconsciously assume that you’ve been dreaming about falling.

This is the phenomenon called hypnic (or hypnagogic) jerks: slight involuntary movements of the arms and/or legs during the early stages of sleep.

“Hypnic jerks typically occur when there is a shift from Stage 1 of Non Rapid Eye Movement sleep to Stage 2,” explains Dr Senthil Nathan, neurologist at Fortis Malar Hospital, Chennai.

Your sleep cycle is divided into Non Rapid Eye Movement (NREM) and Rapid Eye Movement (REM). When you lie down to sleep, you start with the NREM cycle, which again, has three stages. The first 10 minutes when your eyes are closed, but you haven’t really slept. The second when you’re in light sleep, and the third, when you are in a deep sleep.

About 90 minutes after you’ve slept, the REM cycle begins, in which your eyes move under the lids. Those that have intense dreams, are likely to have a longer REM cycle. Then the NREM cycle takes over again.

The phenomenon of hypnic jerks is as natural as it is common, serving as a signal for the body that it’s switching to sleep mode. There are many theories behind this physiological process.

“It has been postulated that it is a vestige from our primate ancestors. Primates would sleep on trees or unsafe places, where when their muscles started relaxing, they could fall down. That’s why they experience an involuntary contraction of the muscles like a protective reflex to maintain posture,” says Dr Senthil Nathan.

Overall, hypnic jerks are benign and aren’t a cause for worry, he says. However, “they can get more aggressive, and cause movement of the entire body when there’s excessive caffeine intake, or excessive workload and stress,” he adds.

It’s only in case of extreme cases, when the jerks are violent and wake you up from sleep that it may be a sign of a sleep disorder, and you need to see a doctor.

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Printable version | Jul 20, 2021 6:00:30 PM | https://www.thehindu.com/life-and-style/fitness/what-is-it-hypnic-jerks/article26565572.ece

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