How Long Is a Sleep Cycle? The 4 Stages of Sleep, Explained
A sleep cycle lasts about 90 minutes in adults, but anywhere from 70 to 110. Here is what happens in each stage, and why the timing matters when you wake up.
A sleep cycle lasts about 90 minutes in adults, but anywhere from 70 to 110. Here is what happens in each stage, and why the timing matters when you wake up.