Hypnic Jerk: Ever Woken up with a Jolt?

    When you wake up with a jolt, it's called a Hypnic Jerk. This usually happens during the lightest stages of sleep, and can happen as a natural reaction when you fall asleep in a car or airplane.

    Have you ever fallen asleep, only to suddenly wake up with a jolt? It's actually called a hypnic jerk.

    The startling spasm is often described as a falling sensation or an electric shock. It tends to happen more often when a person hasn't had enough sleep or is trying to not fall asleep.

    They're also common when in motion - such as sitting in a moving car or airplane - when your body may react to the sensation when entering the lighter stages of sleep.

    Other factors that can instigate a hypnic jerk include: stress, caffeine, and alcohol.

    There's also a theory that suggests hypnic jerks are the body's reaction to falling asleep much in the way that a person may twitch when dying, and the hypnic jerk is a reflex used to keep the body functioning.

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