Abstract
Sleep apnea, which is characterized by frequent episodes of apnea or hypopnea during sleep, is among the most common chronic disorders in adults. Sleep apnea associated with hypersomnolence is conservatively estimated to affect 2 to 4 percent of the middle-aged population of the United States, but the proportion of this population in whom polysomnography would provide evidence of sleep apnea, defined as an apnea–hypopnea index of five or more episodes per hour of sleep, is approximately five times as great.1 Although the clinical importance of sleep apnea that is not overtly symptomatic remains controversial, there is evidence that it is . . .