1. Department of Medicine Perelman School of Medicine University of Pennsylvania Philadelphia PA USA
2. Center for Sleep and Circadian Neurobiology University of Pennsylvania Philadelphia PA USA
3. Sleep Medicine Section Crescenz Veterans Affairs Medical Center Philadelphia PA USA
4. Sleep Department Landspitali – The National University Hospital of Iceland Reykjavik Iceland
5. Faculty of Medicine University of Iceland Reykjavik Iceland
6. School of Science and Engineering Reykjavik University Reykjavik Iceland
7. Internal Medicine Services Landspitali – The National University Hospital of Iceland Reykjavik Iceland
8. Biomedical Statistical Consulting Wynnewood PA USA
9. Cardiovascular Division Department of Medicine Perelman School of Medicine University of Pennsylvania Philadelphia PA USA