sleep, resting state in which an individual becomes relatively quiescent and relatively unaware of the environment. During sleep, which is in part a period of rest and relaxation, most physiological functions such as body temperature, blood pressure, and rate of breathing and heartbeat decrease. However, sleep is also a time of repair and growth, and some tissues, e.g., epithelium, proliferate more rapidly during sleep.

In humans, sleep occurs in cyclical patterns; in each cycle of 1 1-2 to 2 hr, the sleeper moves through four stages of sleep, from Stage 1 to Stage 4, and back again to Stage 1. In the first stage, low-frequency, low-amplitude theta waves characterize brain activity. The stage usually lasts only several minutes, before the individual drifts into Stage 2 sleep, and the brain moves into low-frequency, high-amplitude waves. Stage 3 signals an increase of low-frequency, high-amplitude delta waves, and at Stage 4 sleep these delta waves account for more than half of all brain wave activity (see electroencephalography electroencephalography (əlĕk'trōĕnsĕf'əlŏg`rafē)
..... Click the link for more information. ). Rapid-eye-movement (REM) sleep occurs during Stage 1 sleep at the end of each cycle, and people woken up at this time usually report that they have been dreaming. Dream deprivation or sleep deprivation results in detrimental changes in personality, perceptual processes, and intellectual functioning. There is some evidence that emotional and environmental deprivation disrupts the sleep patterns of young children, which in turn inhibits the secretion of growth hormone, normally secreted maximally during sleep.

The amount of sleep needed depends on both the individual and the environment: For instance, worrying, critical individuals tend to need both more sleep and more dream sleep than easygoing ones, and stress and worry during the day result in an increase in REM sleep. It has been hypothesized that while deeper stages of sleep are physically restorative, REM sleep is psychically restorative. REM sleep is also believed to integrate new information in the brain and to reactivate the sleeping brain without waking the sleeper. There is evidence that the hypothalamus and thalamus of the brain initiate sleep and that part of the midbrain acts as an arousal system. See also dream dream, mental activity associated with the rapid-eye-movement (REM) period of sleep. It is commonly made up of a number of visual images, scenes or thoughts expressed in terms of seeing rather than in those of the other senses or in words.
..... Click the link for more information. ; insomnia insomnia, abnormal wakefulness or inability to sleep . The condition may result from illness or physical discomfort, or it may be caused by stimulants such as coffee or drugs. However, frequently some psychological factor, such as worry or tension, is the cause.
..... Click the link for more information. ; narcolepsy narcolepsy, a sleep disorder characterized by excessive daytime sleepiness and recurring unwanted episodes of sleep ("sleep attacks"). People with narcolepsy may abruptly fall asleep at almost any time, including while talking, eating, or even walking.
..... Click the link for more information. ; sleep apnea sleep apnea, episodes of interrupted breathing during sleep. Obstructive sleep apnea is a common disorder in which relaxation of muscles in the throat repeatedly close off the airway during sleep; the person wakes just enough to take a gasping breath.
..... Click the link for more information. .

sleep

Natural periodic suspension of consciousness during which the powers of the body are restored. Humans normally sleep at night, whereas nocturnal species sleep during the day. The average human sleep requirement is about 7.5 hours. Sleep is divided into two main types, REM (rapid-eye-movement) and NREM (non-REM); each recurs cyclically several times during a normal period of sleep. REM sleep is characterized by increased neuronal activity of the forebrain and midbrain, by depressed muscle tone, and by dreaming (see dream), rapid eye movements, and vascular congestion of the sex organs. NREM sleep is divided into four stages, the last of which is the deep, restorative, quiet sleep commonly associated with “a good night's rest.” See also insomnia, narcolepsy.

(1) In programming, an inactive state due to an endless loop or programmed delay. A sleep statement in a programming language creates a delay for some specified amount of time.

(2) The inactive status of a program. It begins processing after receiving a signal.

(3) The inactive status of a terminal, computer or other device that is awakened by sending it a code or pressing the on button. See standby mode.

Sleep

Amina

in her sleep, walks on a dangerous bridge, complaining of her unhappiness. [Ital. Opera: La Sonnambula in Osborne Opera]

Cupid

while sleeping, revealed by Psyche’s lamp as her lover. [Gk. Myth.: Benét, 822]

Deiphobus

while sleeping, he is betrayed by Helen and slain by Menelaus. [Rom. Lit.: Aeneid VI]

dormouse

snoozes all through the mad tea-party. [Br. Lit.: Alice’s Adventures in Wonderland]

Endymion

man kept immortally youthful through eternal sleep. [Gk. Myth.: Howe, 91]

Epimenides

philosopher nods off for 57 years in cave. [Gk. Legend: LLEI, I: 283]

hypnale asp

which kills by inducing sleep. [Medieval Animal Symbolism: White, 174]

Hypnos

god of slumber. [Gk. Myth.: Hall, 250]

Joe (Fat Boy)

“Damn that boy, he’s gone to sleep again.” [Br. Lit.: Dickens Pickwick Papers]

Lady Macbeth

while sleepwalking, discloses her terrible deeds. [Br. Drama: Shakespeare Macbeth]

land of Nod

mythical land of sleep; humorous reference to biblical land in Genesis. [Am. and Br. Usage; O.T.: Genesis 4:16]

Morpheus Hypno’s

son and god of dreams. [Gk. Myth.: Howe, 172]

poppy

attribute of Hypnos, Greek god of sleep. [Art: Hall, 250]

Sandman

induces sleep by sprinkling sand in children’s eyes. [Folklore: Brewer Dictionary, 966]

Seven Sleepers

youths who fled Decian persecution; slept for more than 200 years. [Christian and Muslim Tradition: Benét, 918]

Sleeping Beauty

enchanted heroine awakened from century of slumber by prince’s kiss. [Fairy Tale: Brewer Dictionary, 1011]

Snow White

poisoned apple induces her sleep; prince awakens her. [Children’s Lit.: Bettelheim, 213]

Somnus

god of sleep; son of Nox. [Rom. Myth.: Wheeler, 349]

Van Winkle, Rip

slept for 20 years, thereby missing war. [Am. Lit.: “Rip Van Winkle” in Hart, 714]

Winkie, Wee Willie

made sure all the children were asleep. [Nurs. Rhyme: Opie, 424]

1.	(operating system, multitasking)	sleep - (Or "block") When a process on a multitasking system asks the scheduler to deactivate it until some given external event (e.g. an interrupt or a specified time delay) occurs. The alternative is to poll or "busy wait" for the event but this uses processing power. Also used in the phrase "sleep on" (or "block on") some external event, meaning to wait for it. E.g. the Unix command of the same name which pauses the current process for a given number of seconds.
2.	(hardware)	sleep - To go into partial deactivation to save power.

Sleep (redirected from quietus)

sleep

Sleep
(redirected from quietus)