This term covers several conditions, including insomnia, narcolepsy, sleep apnea, nocturnal cramps, and restless legs syndrome. Insomnia is commonly caused by anxiety, depression, or physical conditions, such as urinary frequency. Sleep apnea has several causes, including flabby muscles in the upper airway (floppy uvula) and defective brainstem regulation of respiratory rhythm. Narcolepsy is an uncommon condition in which an overwhelming desire to sleep occurs during what are otherwise normal waking hours.
Subjects: Public Health and Epidemiology.