We report the results of a study of the effects of sleep-disordered breathing in a cohort of healthy elderly subjects followed longitudinally for 3 years. In a comprehensive evaluation of daytime functioning, including medical history and physical examination, pulmonary function testing and neuropsychiatric testing, we found very little difference in the neuropsychiatric or medical sequelae between those subjects with moderate [apnea+hypopnea index (AHI) > or = 5] and low (AHI < 5) levels of sleep-disordered breathing at baseline. Although there were no differences in the electrocardiogram, pulse rate or cardiac history data, a mild association was found between indices of sleep-disordered breathing and pulmonary function. We conclude that moderate levels of sleep-disordered breathing in an otherwise asymptomatic healthy geriatric patient should probably not be considered pathologic in the short term.