1. From the Central Satakunta Health Federation of Municipalities (P.K.), Harjavalta, Finland; Departments of Surgery (P.A.) and Family Medicine (P.J.), Satakunta Hospital District, Pori, Finland; Departments of Pulmonary Diseases (T.S.) and Medicine (I.K.), Turku University Hospital, Turku, Finland; Sleep Research Unit (T.S.), Department of Physiology, University of Turku, Turku, Finland.