During sleep, the body goes through multiple sleep cycles. Each cycle consists of four stages: three stages of non-rapid eye movement (non-REM) sleep and one stage of rapid eye movement (REM) sleep. A ...

Ever wonder why some mornings you wake up ready to go, and others you feel like a zombie? The difference often comes down to when you wake up during your sleep cycle, and that’s exactly what a sleep ...

During sleep, your body cycles through 4 stages and 2 phases, all of which contribute to your overall health. Quality sleep is important for your memory, immune system, muscles, and more. Sleep is one ...

The internet claims waking at the end of a sleep cycle will leave you refreshed, but experts aren’t convinced. By Clarissa Brincat Published Sep 9, 2025 9:00 AM EDT Image: DepositPhotos Get the ...

Sleeping for 7 to 9 hours at night isn't the only way to catch some z's. Here are four alternative sleep cycles -- and they're pretty obscure. Annie Miller Medical Reviewer Annie Miller is a licensed ...

You can monitor several key health metrics over time right from your wrist. Here's how to interpret data on a fitness tracker ...