1. Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Maryland
2. Sleep Disorders Center, Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
3. Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland
4. Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
5. Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, Georgia