The study was longitudinal in design. A stratified random sample of adults in San Diego was used to examine risk factors in the prevalence of sleep respiratory disturbances. A structured random sample was selected by random digit telephone dialing. Subjects were studied in their homes. Some were followed yearly during the project. Each volunteer gave a brief sleep history and medical review, including blood pressure measurement, the National Interview Survey, And Quality of Well-being Scale. Blood oxygen saturation, pulse rate, snoring, and sleep duration were recorded for three nights. State-of-the-art computerized pulse oximeters and microprocessor-based activity/light monitors were used. Subjects found to have the most severe sleep respiratory disturbances underwent laboratory polysomnograms to add descriptive data and to validate the survey methodology. The prevalence of respiratory disturbances in sleep was analyzed as a function of age and sex. Associations with several aspects of morbidity were determined. The longitudinal course of respiratory disturbances in sleep were examined.