Excessive daytime sleepiness (hypersomnolence) is a classic symptom of inadequate nocturnal sleep, which manifests itself pathologically in various ways. Typically, much of the daytime sleepiness in today's society is a result of irregular sleep patterns and times (e.g., shift work), lack of adequate sleep, poor nutrition, and certain medications. Sleep disorders are grouped into eight major categories:
Insomnias, including psychophysiologic insomnia and inadequate sleep hygiene
Sleep-related breathing disorders, including central or obstructive sleep apnea (OSA)
Hypersomnias, including narcolepsy and recurrent hypersomnia
Circadian rhythm sleep disorders, including jet lag disorder and shift work disorder
Parasomnias, including sleep terrors, sleep walking, and nightmare disorder
Sleep-related movement disorders, including restless legs syndrome and sleep-related bruxism
Apparently normal variations, including long or short sleeper and sleep talking
Other sleep disorders, including physiologic sleep disorder and environmental sleep disorder
The insomnias are sleep disorders characterized by difficulty initiating or maintaining sleep or problems with sleep duration, consolidation, or quality. Sleep-related breathing disorders are characterized by problems associated with ventilation, such as partial (hypopnea) or complete (apnea) cessation of airflow during sleep, or alveolar hypoventilation. The hypersomnias include those disorders in which the primary complaint is excessive daytime sleepiness; however, it is not due to nocturnal disturbed sleep or a circadian rhythm disorder. The circadian rhythm disorders result from a misalignment of the endogenous rhythm and the exogenous factors that affect the timing of sleep. The parasomnias are a group of disorders that occur during initiation or within sleep as a result of some undesirable experience or physical event. Movements that disturb the normal sleep architecture fall into the category of sleep-related movement disorders. These disorders are marked by relatively simple, stereotyped body movements that range from leg jerks to teeth grinding. The "short" and "long" sleepers are classified under the category of apparently normal variants. A short sleeper, also referred to as a healthy hyposomniac, sleeps substantially less in a 24-hour period than is expected (sleep duration <5 hours in a 24-hour period before age 60 years). A longer sleeper, also referred to as a healthy hypersomniac, consistently sleeps more in a 24-hour period than is expected (sleep duration >10 hours in a 24-hour period). Finally, there are those sleep disorders that fall into a category, other sleep disorders, for lack of a clear underlying cause or insufficient background to make a diagnosis. There are other disorders, such as fibromyalgia or gastroesophageal reflux, that may affect sleep or may be affected by sleep but do not fall into any of the categories as listed in The International Classification of Sleep Disorders, Third Edition, published in 2014 by the American Academy of Sleep Medicine. This group of disorders, nonetheless, should be considered in the differential diagnosis.
Subtopic(s):