Objectives: 1- to provide a detailed characterization of fatigue in a cohort of selected MS patients, including a definition of the boundaries and the overlaps between fatigue, somnolence, mood disorders and attention dysfunction; 2- to see how the prevalence and the overlaps between fatigue, somnolence, depression and attention dysfunction are influenced by the method of assessment. 3-To better characterize the sleep structure in MS patients with fatigue under both the macro- and microstructural point of view.
