In a subcohort of 3,000 MrOS participants, comprehensive and accurate assessments of sleep will be added using in-home polysomnography, wrist actigraphy, questionnaires and other measures; and prospective adjudication of cardiovascular disease (CVD) events, to the extensive measures that have already been performed or planned in the MrOS cohort study. These new measures will enable testing of several important hypotheses: 1) to characterize the associations between sleep disruption and subsequent CVD events during 3.5 years of follow-up, 2) to determine if sleep disturbances are associated with an increased risk of total and cause-specific mortality in older men, 3) to test whether sleep disturbances are associated with increased risk of falls and decreased physical function, 4) to test whether sleep disturbances are associated with impaired cognitive function in older men, and 5) to test whether sleep disorders are associated with bone density and fracture risk in older men. The bank of MrOS specimens will be supplemented to allow for testing of future hypotheses concerning the role of sleep in the development of age-related diseases and conditions.