1. Department of Clinical Neurophysiology, Seinäjoki Central Hospital, Seinäjoki, Finland
2. Department of Technical Physics, University of Eastern Finland, Finland
3. Sleep Disorders Centre, Department of Respiratory and Sleep Medicine, Princess Alexandra Hospital, Australia
4. Diagnostic Imaging Center, Kuopio University Hospital, Finland
5. Department of Clinical Neurophysiology, Seinäjoki Central Hospital, Finland