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 and …

Sleep is a body process that allows your body to rest, repair and restore itself. You need sleep to function properly. Lack of sleep has links to many health issues.

May 15, 2024 · Quality sleep means you are getting uninterrupted and refreshing sleep. Getting quality sleep is not just about how many hours you sleep, but how well you sleep.

Jul 10, 2025 · 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 matters, how it …

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 is regulated and …

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 more.

1 day ago · The sleep cycle starts with three non-REM stages and one REM stage. Ideally, you repeatedly cycle through each stage. Learn how long each stage lasts.

Nov 5, 2025 · A succinctly defined specific purpose of sleep remains unclear, but that is partly because sleep is a dynamic state that influences all physiology, rather than an individual organ or other …

6 days ago · Sleep is critical to your health and well-being. Learn about why you need sleep, how much you need, and how you can get better sleep.

Sleep is largely driven by the body’s internal clock, which takes cues from external elements such as sunlight and temperature. The body’s natural sleep-and-wake cycle is reasonably attuned to...