has this ever happened to you?
you’re drifting off to sleep — warm and cosy under the covers. maybe you’re starting to dream about your next vacation, plans for the weekend, or maybe your morning coffee, when suddenly, your entire body jerks violently, waking you up — just as you were about to settle into dreamland.
what is a hypnic jerk?
a hypnic jerk, sometimes called a sleep start, myoclonic jerk or night start is an involuntary muscle contraction that is named for the hypnagogic state — the period of transition between wakefulness and sleep.
according to the
sleep foundation
, hypnic jerks occur at random, usually affect one side of your body and can happen just once or multiple times in a row.
hypnic jerks are a type of myoclonus — or quick — involuntary muscle jerk. hiccups, and spasms relating to anxiety or exercise are other common forms of myoclonus.
why do hypnic jerks happen?
while we don’t know for sure why hypnic jerks occur, there are a couple theories.
according to
bbc future
, hypnic jerks may indicate that the motor system has control over the body, even as sleep sets in. “rather than having a single ‘sleep-wake’ switch in the brain for controlling our sleep … we have two opposing systems balanced against each other that go through a daily dance, where each has to wrest control from the other,” wrote author tom stafford.