1. Section of Clinical Neurology and Center for Multiple Sclerosis, Department of Medical and Surgical Sciences of Communication and Behaviour, University of Ferrara, Italy,
2. Department of Public Health and Primary Health Care, University of Bergen, Norway
3. Department of Health and Social Research, Bergen University College, Bergen, Norway
4. Sleep Research Unit, Psychiatric Clinic, University of Athens, Greece
5. Section of Clinical Neurology and Center for Multiple Sclerosis, Department of Medical and Surgical Sciences of Communication and Behaviour, University of Ferrara, Italy