The SHHS adds in-home polysomnography to the data collected in each of the cohorts under study. Using the Compumedics SleepWatch polysomnograph, a single over-night polysomnogram is obtained at home for the subjects; the montage includes oximetry, heart rate, chest wall and abdominal movement, nasal/oral airflow, body position, EEG, ECG, and chin EMG. In-home monitoring provides data on the occurrence of sleep-disordered breathing and on arousals.