Sleep disorders

Antonio Culebras MD (Dr. Culebras of SUNY Upstate Medical University has no relevant financial relationships to disclose.)
Originally released January 19, 1994; last updated October 20, 2016; expires October 20, 2019

This article includes discussion of sleep disorders, circadian rhythm sleep disorders, insomnia associated with intrinsic sleep disorders, sleep disorders presenting with altered breathing during sleep, sleep disorders presenting with altered sensation during arousals, sleep disorders presenting with complex movements during sleep, sleep disorders presenting with excessive sleepiness, sleep disorders presenting with insomnia, and sleep disorders presenting with simple movements during sleep. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

The author offers an overview of the sleep disorders. This area of medicine has experienced a quasi-explosive expansion since the early development of clinical sleep laboratories in the 1970s. Sleep medicine oversees conditions as common as insomnia, restless legs syndrome, and sleep apnea, which have emerged as important risk factors for vascular disease and other ailments such as diabetes. New information points to moderate to severe sleep apnea as a factor in cognitive decline. Sleep neurology also covers less common but equally socially destructive disorders such as narcolepsy and the circadian dysrhythmias. Many neurologic disorders have associated sleep dysfunctions. The study of sleep physiology and pathophysiology is a window to the function of the brain. Overall successful clinical management of sleep disorders, whether insomnias or hypersomnias, improves the quality of life. This article discusses the most salient innovations and discoveries in sleep medicine that have occurred during the preceding year.

Key points

 

• Sleep medicine oversees conditions as common as insomnia, restless legs syndrome, and sleep apnea that reduce the quality of life and diminish the health of the individual.

 

• Some of these conditions have emerged as important risk factors for vascular disease, diabetes, and cognitive decline.

 

• It also covers less common but equally socially destructive disorders such as narcolepsy and the circadian dysrhythmias.

 

• Many neurologic disorders have associated sleep dysfunctions.

 

• The study of sleep physiology and pathophysiology is a window to the function of the brain.

 

• Successful clinical management of sleep disorders, whether insomnias, hypersomnias, parasomnias, or breathing disorders, improves the quality of life and ameliorates the health of the individual.

Historical note and terminology

Although sleep is a universal experience, it was not studied systematically by scientists and physicians until the 20th century. Prior to the discovery of brain electrical activity, sleep was often assumed to be a passive response to reduced cerebral stimulation associated with mental and cerebral inactivity. Aristotle believed that the condition of sleep was initiated by warm vapors from the stomach (Horne 1988). Others attributed sleep to the effects of vascular congestion or anemia or to the buildup of "hypnotoxins."

Berger's demonstration of changes in the electroencephalogram (EEG) during sleep followed by the sleep-EEG studies of Loomis and colleagues provided the first definite evidence that the brain is not passive during sleep (Berger 1930; Loomis et al 1937). Studies of encephalitis lethargica by von Economo, of hypothalamic and thalamic stimulation by Hess, and of the reticular activating system by Moruzzi and Magoun provided major advances in the understanding of the neuroanatomical substrate of sleep and wakefulness (von Economo 1930; Hess 1944; Moruzzi and Magoun 1949). The discoveries of rapid eye movement (REM) sleep (Aserinsky and Kleitman 1953) and repetitive cycles of REM and NREM sleep throughout the night (Dement and Kleitman 1957) led to a new view of sleep as an active process with distinctive neurophysiological substrates underlying the 2 major sleep states.

Physicians have known for centuries that sleep disturbance is often a sign of disease, but the recognition that primary sleep disorders are common, serious, and often treatable has occurred mainly in the second half of the 20th century. Narcolepsy, recognized in the 19th century, was often considered a form of epilepsy or a psychiatric disturbance until the discovery of its association with abnormal REM sleep (Rechtschaffen et al 1963; Takahashi and Jimbo 1963). This discovery made narcolepsy the first identified primary sleep disorder; that is, a disorder associated with abnormalities of the sleep process and associated primarily with sleep-related symptoms.

In the mid-1960s, 2 other discoveries led to the recognition that sleep could facilitate the appearance of specific disorders. The first was the identification of abnormal breathing patterns during sleep in association with obesity (Pickwickian syndrome) (Gastaut et al 1965; Jung and Kuhlo 1965); the second was the discovery of regular recurring patterns of leg movements during sleep (Lugaresi et al 1966), now called periodic limb movements of sleep. Further study of breathing during sleep led to the recognition of the importance of upper airway occlusion as a primary cause of sleep-related breathing disturbance (Sadoul and Lugaresi 1972).

In the 1970s, the first sleep clinics appeared devoted specifically to diagnosis and treatment of a broad range of sleep disorders. The Association of Sleep Disorders Centers, organized in 1975, provided a focus for development of the field of sleep disorders medicine. Subsequent major events included the publication of Sleep, the first journal devoted specifically to sleep disorders medicine. As the breadth of the field emerged, it became apparent that a nosology devoted to sleep disorders was required. The Association of Sleep Disorders Centers published the first classification of sleep disorders in 1979 (Association of Sleep Disorders Centers 1979). A more comprehensive classification was published by the American Sleep Disorders Association in 1990 as the International Classification of Sleep Disorders, and revised in 2000 (American Sleep Disorders Association 2000). It was updated in 2005 by the American Academy of Sleep Medicine and again in 2014 (American Academy of Sleep Medicine 2014) (Table 1). The first board certification exam on sleep medicine offered by authorized member boards of the American Board of Medical Specialties (American Board of Psychiatry and Neurology, American Board of Family Medicine, American Board of Internal Medicine, American Board of Otolaryngology and American Board of Pediatrics).took place in November 2007 and will be given every 2 years. Waivers of formal fellowship training to apply for the new exam expired in 2011.

Table 1. International Classification of Sleep Disorders

 

1. Insomnia
2. Sleep-related breathing disorders
3. Central disorders of hypersomnolence
4. Circadian rhythm sleep-wake disorders
5. Parasomnias
Sleep-related movement disorders
7. Other sleep disorders

Appendix A: Sleep related medical and neurologic disorders
Appendix B: ICD-10-CM coding for substance-induced sleep disorders

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