Cognitive Behavioral Therapy, Modafinil, or Both for Multiple Sclerosis Fatigue

This clinical trial will compare the effectiveness of 3 treatments for fatigue in Multiple Sclerosis: 1) a commonly used behavioral treatment strategy (telephone-based cognitive behavioral therapy), 2) a commonly used medication (modafinil), and 3) a combination of both therapies. Each participant will receive one of these 3 treatments for a total of 12 weeks. Hypotheses are that, at 12 weeks, treatment with combination therapy will overall lead to greater reductions in fatigue impact, fatigue severity, and fatigability compared to monotherapy, and that comorbid depression, sleep disturbances, and baseline disability level will be important effect modifiers that influence treatment effect and adherence.