1 Department of Medicine, Division of Allergy, Pulmonary, and Critical Care, Vanderbilt University Medical Center, Nashville, TN, and Division of Sleep Disorders, Vanderbilt University Medical Center, Nashville, TN; Division of Sleep Disorders, Vanderbilt University Medical Center, Nashville, TN, and Department of Neurology, Vanderbilt University Medical Center, Nashville, TN; Department of Medicine, Division of Allergy, Pulmonary, and Critical Care, Vanderbilt University Medical Center, Nashville, TN, Center for Health Services Research, Vanderbilt University Medical Center, Nashville, TN, and VA Tennessee Health Care System, Geriatric Research Education and Clinical Center.