Waking up during the night is frustrating, but it’s often completely normal—until it crosses a specific threshold that ...

Sleep Cycles: One rapid eye movement (REM) stage and three non-REM stages that altogether last about 90 to 120 minutes Benefits: Physical and mental recuperation and memory consolidation Disorders: ...

Sleep is central to the proper functioning of the immune system, which in turn has implications for mental and physical ...

A restful night alternates in cycles between non-rapid eye movement (NREM) and rapid eye movement (REM) sleep states. The study from UNIL shows that a brain region called the "locus coeruleus" (in ...

A simple guide to returning to your schedule when travel, late nights, or seasonal shifts affect your shuteye.

This article was reviewed by Felix Gussone, MD. "Stiffness" is often considered a sign of male arousal, but it’s not uncommon to experience it even when you’re not turned on. Nocturnal arousal refers ...

When a person is asleep, their core body temperature drops. Heart rate and breathing also slow down and overall metabolic activity decreases by about 10%. A sleeping body may seem inactive at first ...