Participants will be randomly assigned to receive either armodafinil or a placebo daily for 4 weeks. Participants randomized to active medication and who show improvements in symptoms will be offered armodafinil for an additional 12 weeks. For them, the study duration is 16 weeks. Participants who did not receive armodafinil will be offered armodafinil for 16 weeks. For these participants, the study duration is 20 weeks. Participants who did not benefit from armodafinil will receive alternate treatment options. All participants will have weekly study visits for the first 4 weeks of the study and biweekly visits for the remainder of the study. At each visit, participants will complete various tasks to determine cognitive function, and self-report scales will be used to determine symptoms of depression and fatigue. After completion of 16 weeks, participants responding to armodafinil will be transitioned to the publicly available modafinil over the course of 2 weeks.