Sleep - Wikipedia
Sleep is a state of reduced mental and physical activity in which consciousness is altered and certain sensory activity is inhibited. During sleep, there is a marked decrease in muscle activity …
Sleep: How Much You Need and Its 4 Stages - Cleveland Clinic …
Dec 3, 2021 · When you sleep, your body rests, recovers and rebuilds itself through four stages. Here’s how much sleep you need to feel rested.
Why Do We Need Sleep? - Sleep Foundation
Apr 5, 2024 · Everyone needs sleep, but about one in three American adults don’t get enough of it. The consequences of sleep deprivation are serious, so it’s worth learning why sleep …
Brain Basics: Understanding Sleep | National Institute of …
Feb 25, 2025 · Sleep is a complex and dynamic process that affects how you function in ways scientists are now beginning to understand. This webpage describes how your need for sleep …
Science of Sleep: What is Sleep? | Sleep Medicine - Harvard …
Oct 1, 2021 · From observations of behavioral changes that accompany sleep and simultaneous physiological changes, scientists now define sleep in humans based on brain wave activity …
Stages of Sleep: What Happens in a Sleep Cycle
Dec 8, 2023 · There are four sleep stages, including one for rapid eye movement (REM) sleep and three that form non-REM (NREM) sleep. These stages are determined based on an …
The Science of Sleep: Understanding What Happens When You Sleep
What exactly does sleep do for your body and mind? Here’s what researchers know about the science of sleep—including the stages of sleep, your biological clock, health connections and …
Sleep Physiology - Sleep Disorders and Sleep Deprivation - NCBI Bookshelf
Humans spend about one-third of their lives asleep. There are two types of sleep, non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. NREM sleep is divided into …
Physiology, Sleep Stages - StatPearls - NCBI Bookshelf
Jan 26, 2024 · The human body cycles through 2 phases of sleep, (1) rapid eye movement (REM) and (2) nonrapid eye movement (NREM) sleep, which is further divided into 3 stages—N1 to …
How Sleep Works: Understanding the Science of Sleep
Oct 23, 2020 · Sleep is a complex and dynamic biological process that still isn’t fully understood. Learn about how sleep works and why it’s vital for overall health.