1. Faculty of Medicine, University of Iceland, Reykjavík, Iceland
2. Department of Respiratory Medicine and Sleep, Landspitali - The National University Hospital of Iceland
3. Department of Medical Sciences: Respiratory Medicine and Allergology, Uppsala University, Sweden
4. Mental Health Services, Landspitali - The National University Hospital of Iceland
5. Center for Sleep and Circadian Neurobiology and Division of Sleep Medicine/Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
6. Department of Psychiatry, University of Pennsylvania School of Medicine, Philadelphia, PA
7. Department of Otolaryngology, Landspitali - The National University Hospital of Iceland, Reykjavik, Iceland
8. Philadelphia Veterans Affairs Medical Center, Philadelphia, PA