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