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Sleep Disorders

Insomnias And Hypersomnias

Insomnias include problems with sleep onset (taking longer than 30 minutes falling asleep), sleep maintenance (waking five or more times during the night or for a total of 30 minutes or more), early arousal (less than 6.5 hours of sleep over a typical night), light sleep, and conditioning (learning not to sleep by associating certain bedtime cues with the inability to sleep). Insomnias may be transient (lasting no longer than three weeks) or persistent. Most people experience transient insomnias, perhaps due to stress, excitement, illness, or even a sudden change to high altitude. These are treatable by short-term prescription drugs and, sometimes, relaxation techniques. When insomnia becomes persistent, it is usually classed as a disorder. Persistent insomnias may result from medical and/or psychiatric disorders, prescription drug use, and substance abuse, and often result in chronic fatigue, impaired daytime functioning, and hypersomnia.

Hypersomnias manifest as excessive daytime sleepiness, uncontrollable sleep attacks, and, in the extreme, causes people to fall asleep at highly inappropriate times, such as driving a car or when holding a conversation. Most hypersomnias, like narcolepsy and those associated with apnea (breathing cessation), are caused by some other disorder and are therefore symptomatic. Some, however, like idiopathic central nervous system (CNS) hypersomnia and Kleine-Levin syndrome, are termed "idiopathic" for their unknown origin. CNS hypersomnia causes a continuous state of sleepiness from which long naps and nighttime sleep provides no relief. This is usually a life-long disorder and treatment is still somewhat experimental and relatively ineffective. Kleine-Levin syndrome is a rare disorder seen three times as often in males as females, beginning in the late teens or twenties. Symptoms are periods of excessive sleepiness, excessive overeating, abnormal behavior, irritability, loss of sexual inhibition, and sometimes hallucinations. These periods may last days or weeks, occur one or more times a year, and disappear about the age of 40. Behavior between attacks is normal, and the sufferer often has little recall of the attack. Stimulant drugs may reduce sleepiness for brief periods, and lithium meets with some success in preventing recurrence.

A patient with acute sleep apnea is monitored during a night's sleep at a Stanford University Lab. Photograph by Russell D. Curtis. National Audubon Society Collection/Photo Researchers, Inc. Reproduced by permission.

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Science EncyclopediaScience & Philosophy: Semiotics to SmeltingSleep Disorders - Insomnias And Hypersomnias, Observation And Classification Of Sleep Disorders, Dyssomnias, Parasomnias, Diagnosis Of Sleep Disorders