1. Department of Neurology, Division of Multiple Sclerosis and Neuroimmunology, University of Michigan, Ann Arbor, MI, USA
2. Department of Neurology, Division of Sleep Medicine, University of Michigan, Ann Arbor, MI, USA
3. Department of Physical Medicine and Rehabilitation, University of Michigan, Ann Arbor, MI, USA
4. Epidemiology Group, School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Scotland, UK
5. Department of Anesthesiology, Chronic Pain & Fatigue Research Center, University of Michigan, Ann Arbor, MI, USA
6. Department of Rehabilitation Medicine, University of Washington, Seattle, WA, USA