text: Sleep arousal are active brain processes medicated and associated with specific brain regions. Despite the fact that various stages of sleep are discrete and quantifiable, the exact function of sleep is unknown. Sleep is controlled both by circadian rhythms and the homeostatic drive produced by wakefulness. Circadian rhythms are produced in the suprachiasmatic nucleus by pacemaker cells which contain transcriptional regulation "clock genes" which have been highly conserved throughout evolution.
  Non-REM sleep is initiated by neurons in the preoptic and anterior hypothalamic area, whereas REM sleep is eventually elicited by the cells in the pontine tegmentum. Electroencephalography is used to analyze brain wave patterns during sleep and has the capability to differentiate between REM sleep from non-REM sleep. REM sleep cycles mimic conscious brain patterns to an extent. Night Terrors, for example, involve the partial arousal out of non-REM sleep. Similarly, REM Behavior Disorder occurs when patients have fits of violent behavior during REM sleep. Benzodiazepines are the most common treatments for sleep-related disorders.
  Dyssomnia is a class of sleep disorders which includes Primary insomnia, primary hypersomnia, narcolepsy, breathing-related sleep disorders, circadian rhythm sleep disorder, and other conditions. Primary insomnia is a disorder in which a patient has difficulty initiating and maintaining sleep. Behavior modification and a reduction in neurologically active substances such as caffeine and alcohol seem to be among the most promising treatments. Although the mechanism is unknown, brain plasticity and behavior modification are utilized to train patients to only go to bed when tired, associating the bed itself with a sleepy state.
  Narcolepsy is a condition characterized by abnormal transitions between REM and non-REM cycles during sleep and the awake cycle. Cataplexy, on the other hand, is an involuntary loss of muscle tone during wakefulness. The mechanism of narcolepsy is unknown, though recent findings suggest that orexin neurons in the lateral and posterior hypothalamus may play a critical role in reinforcing wakefulness. Narcolepsy is often treated with psychostimulants or tricyclic antidepressants in order to suppress REM sleep patterns. Sleep apnea is a common breathing disorder during sleep and is related to a disability in the central respiratory drive mechanisms. Parasomnias are a class represented by nightmares, sleep terrors, night terrors, schizophrenia, certain mood disorders, and other conditions which arise during Stage 4 of sleep.
  General anesthetics typically induce non-REM sleep characterized by amnesia, analgesia, immobility, and hypnosis by facilitating the inhibition of excitatory ion channels or the excitation of inhibitory ligand-gated channels.