Deep sleep refers to slow-wave sleep — a stage in the sleep cycle when brain waves slow down. Getting enough deep sleep is crucial for numerous bodily functions. But how to increase deep sleep isn’t ...

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 ...

We’ve all been there — dragging ourselves out of bed feeling like we’ve been hit by a truck despite getting a full night’s sleep. The alarm blares, and you wonder how eight hours of rest could ...

How did you sleep last night? Your response might depend on how long you were in bed, how much of that time you spent tossing and turning or whether you feel rested. But it might also depend on ...

Even a boneless, gelatinous sack lacking a dedicated anus and brain needs its beauty sleep, a new study by researchers from Bar-Ilan University in Israel finds. Jellyfish sleep a third of every day ...