The general term dyssomnia includes a variety of possible disorders that result in excessive sleepiness or difficulty in beginning or maintaining sleep. Simple causes for such disorders include schedule changes or travel to different time zones (jet lag). Insomnia refers to insufficient or nonrestorative sleep despite ample opportunity to sleep. There may be physical causes for insomnia, but often it is related to emotional upset caused by stressful events. Narcolepsy is characterized by brief, uncontrollable attacks of sleep during the day. The disorder is treated with stimulants, regulation of sleep habits, and short daytime naps.
Sleep apnea refers to failure to breathe for brief periods during sleep. It usually results from upper airway obstruction, as is seen in obesity, alcohol consumption, or weakened throat muscles, and is usually accompanied by loud snoring with brief periods of silence. Dental appliances that move the tongue and jaw forward may help to prevent sleep apnea. Other options are surgery to correct obstruction or positive air pressure delivered through a mask.
Sleep disorders are diagnosed by physical examination, a sleep history, and a log of sleep habits, including details of the sleep environment and note of any substances consumed that may interfere with sleep. Study in a sleep laboratory with a variety of electric and other studies, composing a polysomnography, may also be needed.
Sleep studies characterize two components of normal sleep, each of which shows a specific EEG pattern. Non-rapid eye movement (NREM) sleep has four stages, which take a person progressively into the deepest level of sleep. If sleepwalking (somnambulism) occurs, it occurs during this stage. NREM sleep is interrupted about every 1.5 hours by episodes of rapid eye movement (REM) sleep, during which the eyes move rapidly, although they are closed. Dreaming occurs during REM sleep and muscles lose tone, while heart rate, blood pressure, and brain activity increase.
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