The National Health and Nutrition Examination Survey (NHANES) is a national health survey that combines interviews and physical examinations to collect data on the prevalence of diseases, chronic conditions, and risk factors in the population. The survey examines a nationally representative sample of about 5,000 persons each year, located in counties across the country. The Physical Activity/Sleep component will involve providing an accelerometer-based monitor to survey participants ages 3 years and older and request that the monitor be worn around the clock on the wrist for seven days. The device will collect movement data that will provide information about physical activity as well as the duration and efficiency of sleep. The Strength component will take place in the mobile examination center. Participants ages 6 years and older will be asked to squeeze a hand-grip dynamometer with each hand and the strength of the squeeze will be recorded.