Descriptionary

nocturnal sleep-related eating disorder a disorder suffered by sleepwalkers, who get up and not only walk around during sleep but also eat and then don't remember doing so.

non-24-hour sleep-wake syndrome a disorder in which one may sleep at different times, with drowsi­ness coming in unpredictable fashion day by day, seen most often in blind people.

NREM non-REM sleep. Sleep without dreams or the rapid eye movement that accompanies dream sleep.

obstructive sleep apnea a cessation of breathing during sleep, caused by the closing off of part or all of the airway, triggering awakenings.

parasomnia any disorder that occurs during sleep and disturbs it.

periodic limb movement disorder also known as nocturnal myoclonus, the involuntary movement of one or more of the limbs while sleeping.

phase advance getting out of bed earlier in the morning in order to feel drowsy and fall asleep earlier in the evening.

phase delay sleeping later in the morning and con­sequently feeling drowsy later in the evening than normal.

Pickwickian syndrome obstructive sleep apnea that results in deficient air intake throughout the day and night, seen in obese patients. Also known as obesity- hypoventilation syndrome.

polysomnogram a physiological recording of a sleeper's breathing, brain waves, muscle movements, etc., to measure for disturbances and overall sleep quality.

rebound insomnia after cessation of sleep medica­tions, a return or worsening of insomnia.

REM sleep a cycle of sleep that recurs throughout the night and is characterized by dreaming and by rapid eye movement under the eyelids.

REM sleep behavior disorder a disorder in which one gets out of bed, experiences hallucinations, and may physically act out a dream as it is happening, often seen as evidence of brain damage or brain tumors.

restless legs syndrome

a sleep disorder character­ized by involuntary jerking of the legs or a sensation of bugs crawling underneath the skin of one's legs, requiring movement of the legs for relief.

serotonin a neurotransmitter involved in moods, memory, and sleep. A shortage may cause problems with insomnia.

sexsomnia related to sleepwalking, the performing of sexual acts during sleep.

sleep apnea cessation of breathing during sleep by all causes, including obstructions in the airway and by brain abnormalities that allow the sleeper to sim­ply stop taking breaths.

sleep architecture the cycles of sleep and their dura­tions as they occur throughout the night and as they change over time with age, and also as graphed out on a chart.

sleep cycle any distinct stage of sleep, such as REM sleep, or light, stage 1 sleep.

sleep debt the long-term loss of sufficient sleep, resulting in daytime fatigue, loss of memory, and other deficiencies.

sleep disorder any abnormality occurring during or around sleep, including insomnia, restless legs syn­drome, sleep apnea, etc.

sleep fragmentation interrupted sleep.

sleep hygiene habits and techniques used to assure a good night's sleep, such as avoiding caffeine, going to bed at the same time every night, keeping the bed­room cool and dark, etc.

sleep hyperhidrosis extreme sweating during sleep.

sleep paralysis the inability to move the body dur­ing REM sleep, to prevent the sleeper from acting out his dreams.

sleep talking talking during sleep, usually occurring during dream sleep. Also known as somniloquy.

sleep walking getting up during the deepest stages of sleep and walking around, common among chil­dren ages four to 12. Also known as somnambulism.

somnambulism see sleep walking.

somniloquy

see sleep talking.

somniphobia fear of falling asleep, which can occur with an anxiety disorder or as a result of sleep apnea.

Somnus in Roman mythology, the personification of sleep.

snoring the noise made by vibrations of the soft palate when inhaling during sleep.

suprachiasmatic nucleus a part of the brain that regulates the biological clock and the sleep-wake cycle.

unihemispheric sleep seen in dolphins and some birds, a form of sleep in which only one-half of the brain slumbers while the other half remains awake.

sociology and culture

affirmative action a controversial government pro­gram or policy aimed at providing increased educa­tional and employment opportunities for minorities or women through such means as hiring quotas, legal incentives, or easing of qualifying standards.

ageism prejudice and discrimination against the elderly.