05/23/2012 09:21 am ET

Why Do We Twitch As We're Falling Asleep?

You're drifting off to sleep, when suddenly you feel like you're plunging off a cliff -- and you jerk awake. The jolt is disorienting, and you must try again to fall asleep.

As many as 70 percent of people experience sleep starts or hypnic jerks while falling asleep, says Dr. William Kohler, medical director of the Florida Sleep Institute and director of the pediatric sleep services at Florida Hospital, Tampa.

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