Sleep
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.
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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)