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 ...

Your sleep needs vary during your lifetime and by how many sleep cycles you need to feel rested. Keeping track of your sleep schedule might not always be your top priority, but getting enough sleep is ...

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 ...