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 ...

Learn facts about sleep, during which the body rests, recuperates and performs essential repairs. When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works.

The sleep cycle has three NREM stages and one REM stage. Deep sleep occurs in stage 3 and is crucial for feeling refreshed. REM sleep helps in processing and storing memories. As we sleep, our brain ...

REM stands for Rapid Eye Movement and it’s seen as the deepest stage of the sleep cycle. As the name states, REM sleep is ...