1. Department of Internal Medicine, Skaraborg Hospital, Skövde, Sweden
2. Sleep Laboratory, Department of Chest Diseases, Skaraborg Hospital, Skövde, Sweden
3. Department of Radiology, Skaraborg Hospital, Skövde, Sweden
4. Department of Clinical Chemistry, Afyon Kocatepe University Hospital, Turkey
5. Sleep Medicine Unit, Department of Neurology and Rehabilitation Medicine, Skaraborg Hospital, Skövde, Sweden