Discover how aligning your wake-up time with the 90-minute sleep cycle can help you wake up refreshed and improve your ... This 90-minute pattern isn’t just some random quirk of human biology.

Whether polyphasic sleep exists among modern humans is also up for debate. While some argue for a stricter definition of the phenomenon, others include naps, siestas, and brief nighttime forays as ...

Human sleep cycles have varied across time. At one time, people woke up for an hour or more in the middle of the night. Evelyn Hyder on Wednesday, Sept. 6, 2023, in Rochester.

In general, setting aside enough time to sleep is the best way to ensure your brain reaches deeper stages — and depending on deficits, it may spend more time in REM or deep sleep as it cycles ...