Inclusion Criteria: - 18 years of age or older - Histologically confirmed malignant glioma including anaplastic astrocytoma, anaplastic oligodendroglioma, anaplastic oligoastrocytoma (WHO grade III/IV), glioblastoma multiforme (WHO grade IV) or gliosarcoma. Patients with a grade II astrocytoma, mixed oligo-astrocytoma or oligodendroglioma who are being treated with irradiation are also eligible - Scheduled to receive irradiation to a total dose of 50-60 Gy. Patients receiving hyperfractionated radiotherapy are also eligible - KPS of 70% or greater - Electrolytes within normal institutional limits: BUN and Creatinine < 2.5 x ULN: AST, ALT, Bilirubin < 2.5 x ULN - Life expectancy of six months or greater - Able to swallow medication Exclusion Criteria: - History of cardiac arrhythmia or unstable angina - Has taken armodafinil or modafinil - Has taken a psychostimulant or a monoamine oxidase inhibitor on a regular basis within the past 30 days - A history of clinically significant cardiac disease, including a history of recent myocardial infarction, history of unstable angina, history of left ventricular hypertrophy, or a history of ischemic ECG changes, chest pain, arrhythmia, or other clinically significant manifestations of mitral valve prolapse in association with use of CNS stimulants, uncontrolled hypertension, alcohol or drug abuse, severe headaches, glaucoma, narcolepsy, a psychotic disorder or Tourette's syndrome - Patients taking warfarin for anticoagulation are eligible, but monitoring of prothrombin times is suggested as a precaution - Hemoglobin level of less then 12 g/dl - Laboratory evidence of hypothyroidism with an elevated TSH concentration in the blood greater than 5.0 mlU/L - Current treatment or history of psychotic disorder, bipolar disorder, or anxiety disorder - Patients with a score of > 31 on the Beck depression inventory consistent with severe depression - Known hypersensitivity to armodafinil or related compounds - Patients who have been receiving MAO inhibitors during the past 14 days