Falling off a cliff or drowning are classic dream scenarios scary enough to make anyone instantly wake up, but the muscle-tensing jerk that some people experience while lying in bed trying to fall asleep is next-level terrifying.
Much like a bizarre dream, the incident will leave you up at night wondering what just happened and what it all means. The jerk now has an official name: hypnic jerk or sleep start. According to Carl Bazil, M.D. Ph.D., director of the Sleep Disorders Center at New York–Presbyterian/Columbia University Medical Center, the phenomenon is caused by a sudden increase in muscle activity. While it happens to just about everybody, the intensity of the jerk varies from person to person. For some people, this means twitching without waking up, while others literally scream out in fear (and scarethe sleep out of their partners).
Experts haven't pinpointed the exact cause of sleep starts, but they have narrowed it down to what seems to be a neurological battle between the brain systems that keep you awake and those that help you sleep. "One of the things that happens as you fall asleep is your muscles relax, but the awake part may still be stimulating enough that it will temporarily overreact and you get this jerk of muscle activity," Dr. Bazil told The Cut.
They may be harmless, but if you're looking to get a good night's sleep without any hiccups, you may want to reconsider your afternoon coffee. Doctors do know that caffeine is the most common sleep start insigator, along with tobacco and stimulant medications like Adderall.
As for those startling jerks that you sometimes experience as you nod off during a boring class or day at work? They're not the same, but a protective process to keep you from falling asleep standing up.
The best solution to prevent any type of sleep-related jerk? A good night's rest.
(via The Cut)