1. Department of Physical and Rehabilitation Medicine, Päijät-Häme Central Hospital, Lahti, Finland
2. Faculty of Medicine, Helsinki University, Helsinki, Finland
3. Helsinki Sleep Clinic, Vitalmed Research Center, Helsinki, Finland
4. Department of Clinical Neurosciences, University of Helsinki, Helsinki, Finland
5. Primary Health Care Unit, Kuopio University Hospital, Finland
6. Folkhälsan Research Center, Helsinki, Finland
7. Department of Rheumatology, Päijät-Häme Central Hospital, Lahti, Finland