What is sleep?

  • (noun): A natural and periodic state of rest during which consciousness of the world is suspended.
    Example: "He didn't get enough sleep last night"
    Synonyms: slumber
    See also — Additional definitions below


Sleep is a naturally recurring state characterized by reduced or absent consciousness, relatively suspended sensory activity, and inactivity of nearly all voluntary muscles. It is distinguished from quiet wakefulness by a decreased ability to react to stimuli, and is more easily reversible than being in hibernation or a coma. Sleep is a heightened anabolic state, accentuating the growth and rejuvenation of the immune, nervous, skeletal and muscular systems. It is observed in all mammals, all birds, and many reptiles, amphibians, and fish.

Read more about Sleep.

Some articles on sleep:

May 2005 In Science - May 1, 2005
... brain functions in order to wake up its owner only when he has emerged from deep sleep ... The clock, called SleepSmart, measures the sleep cycle and waits until its owner is in his lightest phase of sleep before rousing him ...
Go To Sleep (disambiguation)
... "Go to Sleep" is a song by Radiohead ... Go to Sleep or Go 2 Sleep may also refer to "Go to Sleep" (Lupe Fiasco song) "Go to Sleep", a song by Barbra Streisand from the film On a Clear Day You Can See Forever "Go to Sleep", a song by Eminem, DMX ...
Sleep in Non-humans
... Neurological sleep states can be difficult to detect in some animals ... In these cases, sleep may be defined using behavioral characteristics such as minimal movement, postures typical for the species, and reduced responsiveness to ... Sleep is quickly reversible, as opposed to hibernation or coma, and sleep deprivation is followed by longer or deeper rebound sleep ...
Fiction (The Comsat Angels Album)
... Fiction was less gloomy than the Comsats' previous album, Sleep No More ... Fellows said of the change "I certainly didn't want to make another record as intense as Sleep No More — at least not immediately ... Sleep No More was so dark that I felt it skewed things a bit — possibly even mentally for me ...
Dorsal Raphe Nucleus - Role in Narcolepsy
... to narcolepsy, this is logical, as the raphe nuclei have been known to play a role in the sleep/wake cycle ... This has thought to be a dissociation of what normally happens during REM sleep, when all muscle tone is lost except for the eyes ... waking hours, partially active during non-REM sleep, and have almost ceased during REM sleep ...

More definitions of "sleep":

  • (noun): A period of time spent sleeping.
    Example: "He felt better after a little sleep"
    Synonyms: nap
  • (noun): Euphemisms for death (based on an analogy between lying in a bed and in a tomb).
    Example: "They had to put their family pet to sleep"
    Synonyms: rest, eternal rest, eternal sleep, quietus
  • (verb): Be able to accommodate for sleeping.
    Example: "This tent sleeps six people"
  • (noun): A torpid state resembling sleep.

Famous quotes containing the word sleep:

    That a famous library has been cursed by a woman is a matter of complete indifference to a famous library. Venerable and calm, with all its treasures safe locked within its breast, it sleeps complacently and will, so far as I am concerned, so sleep forever. Never will I wake these echoes, never will I ask for that hospitality again ...
    Virginia Woolf (1882–1941)

    I shall die as my fathers died, and sleep as they sleep; even so.
    For the glass of the years is brittle wherein we gaze for a span;
    A little soul for a little bears up this corpse which is man.
    So long I endure, no longer; and laugh not again, neither weep.
    For there is no God found stronger than death; and death is a sleep.
    —A.C. (Algernon Charles)

    Sweet is the sleep of laborers, whether they eat little or much; but the surfeit of the rich will not let them sleep.
    Bible: Hebrew, Ecclesiastes 5:12.