Mondo Knows Facts
Sleep runs in cycles of roughly ninety minutes
A night typically contains four to six cycles that move through light sleep, deep sleep and REM Each cycle begins with light N1 and N2 sleep, descends into slow-wave N3 sleep, then rises into REM. Early cycles hold more deep sleep, while later ones stretch the REM periods. Waking briefly between cycles is common and usually forgotten. It sits in Mondo's human body collection, one of 200 facts that each trace back to the reference below.
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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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Tags: sleep, cycles, rem
Sleep runs in cycles of roughly ninety minutes: the short answers
- Where does this come from, and can I check it?
- A night typically contains four to six cycles that move through light sleep, deep sleep and REM. 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.