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 ...

Your sleep cycle includes light, slow-wave, deep, and REM sleep, which repeat throughout the night. To get restful sleep, you need to spend the right amount of time in each stage of the sleep cycle.

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 ...