I'm energized after 7.5 or 9 hours sleep, but groggy after 8. A sleep expert tells me why.

Sleep is one of medicine's underused data streams. Clinically, disturbed sleep has often been treated as a symptom of a disorder, but sleep is also a physiological state in which brain, cardiac, ...

With so much to do heading into the busy holiday season, is anyone getting enough sleep? Most sleep experts advise that adults get seven to nine hours of sleep per night for good health and emotional ...