From The Art and Popular Culture Encyclopedia
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.
Dreaming is the perceived experience of sensory images and sounds during sleep, in a sequence which the dreamer usually perceives more as an apparent participant than as an observer. Dreaming is stimulated by the pons and mostly occurs during the REM phase of sleep.
People have proposed many hypotheses about the functions of dreaming. Sigmund Freud postulated that dreams are the symbolic expression of frustrated desires that have been relegated to the unconscious mind, and he used dream interpretation in the form of psychoanalysis to uncover these desires. See Freud: The Interpretation of Dreams.
While penile erections are commonly believed to indicate dreams with sexual content, they are not more frequent during sexual dreams than they are during nonsexual dreams. The parasympathetic nervous system experiences increased activity during REM sleep which may cause erection of the penis or clitoris. In males, 80% to 95% of erection accompanies REM sleep while only about 12% of men's dreams contain sexual content.
Freud's work concerns the psychological role of dreams, which does not exclude any physiological role they may have. Recent research claims that sleep has the overall role of consolidation and organization of synaptic connections formed during learning and experience. As such, Freud's work is not ruled out. Nevertheless, Freud's research has been expanded on, especially with regard to the organization and consolidation of recent memory.
- Cortisol awakening response
- Morvan's syndrome
- Polyphasic sleep
- Power nap
- Segmented sleep
- Sleep architecture
- Sleep deprivation
- Sleep medicine
- Sleep paralysis
- Sudden infant death syndrome
- Sudden unexpected death syndrome
- Ultradian and circadian rhythms.
- To "sleep with someone" implies having sexual relations with that person.
- The substance found in the corner of one's eye upon waking, which is a normal buildup of tears, mucus, and dirt that appears at the edge of the eyelids after sleep, otherwise known as rheum and sometimes inaccurately called mucopurulent discharge.
- Transient paresthesia, the sensation produced by an extremity which has "fallen asleep".
- Sleep (painting), a painting by Salvador Dali
- Sleep (film), a 1963 film by Andy Warhol
- The Big Sleep, a 1939 novel by Raymond Chandler, which was later made into two films
- Le Sommeil by Courbet