Where does this come from, and can I check it?

Hypnic jerks are brief muscle jolts that often arrive with a sensation of falling. The figure is taken from Sleep Foundation, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a human body fact?

Yes. It sits on the Human Body shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

What else can I read about it?

The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

A sudden twitch can strike just as sleep begins

Hypnic jerks are brief muscle jolts that often arrive with a sensation of falling As muscles relax at sleep onset, a sudden involuntary contraction can fire in the arms or legs. It is sometimes paired with a dreamlike sense of stepping off a ledge. The jerk is harmless and becomes less frequent with age, though the reason it happens is still debated. It sits in Mondo's human body collection, one of 200 facts that each trace back to the reference below.

Where this comes from

Sleep Foundation

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

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Science trivia

More facts like this

The brain paralyzes major muscles during REM dream sleepMotor neuron inhibition prevents acting out vivid dream sequences physically The hippocampus replays the day to build memoriesDuring sleep, it reactivates recent patterns and passes them to the cortex The pineal gland regulates daily sleep rhythms with melatoninLight exposure signals the brain to adjust hormone production for sleep The brain flushes metabolic waste products while you sleepCerebrospinal fluid sweeps through tissue spaces to remove toxic proteins Core body temperature drops naturally during night sleepThermoregulatory cooling lowers metabolic rate to conserve resting energy Sleep runs in cycles of roughly ninety minutesA night typically contains four to six cycles that move through light sleep, deep sleep and REM

Tags: sleep, twitch, muscles

A sudden twitch can strike just as sleep begins: the short answers

Where does this come from, and can I check it?: Hypnic jerks are brief muscle jolts that often arrive with a sensation of falling. The figure is taken from Sleep Foundation, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a human body fact?: Yes. It sits on the Human Body shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.