1. Division of Sleep Medicine, Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
2. Division of Pulmonary, Critical Care and Sleep Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
3. West Australian Sleep Disorders Research Institute, Department of Pulmonary Physiology and Sleep Medicine, Sir Charles Gairdner Hospital, Nedlands, WA, Australia
4. Sleep Medicine Section, Corporal Michael J. Crescenz Veterans Affairs Medical Center, Philadelphia, PA, USA
5. Biostatistics Core, Division of Sleep Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA