Inclusion Criteria:

• Age ≥ 6 years and ≤ 18 years 10 months at the time of study entry (so that participants will be < 19 at the 6 week evaluation, which is the upper age limit for which the included instruments are valid).
• Diagnosis of a primary brain tumor treated with at least one of the following:
  1. neurosurgical resection of the brain tumor;
  2. cranial irradiation; or
  3. any chemotherapy to treat the brain tumor.
• Off-treatment and progression-free for at least 12 months and ≤ 14 years. Treatment cessation is defined as the final dose of chemotherapy, the last dose (fraction) of radiation or date of surgery, whichever occurred last.
• Parent/Legal Guardian and child able to read English or Spanish.
• Vision and hearing (eyeglasses and/or hearing aid permissible) sufficient for valid test administration and cooperation with examinations.
• Availability of a reliable parent or legal guardian who is willing and able to complete all of the outcome measures and fulfill the requirements of the study, including administration of medications and accompanying the participant to all study visits.
• Females of childbearing potential must have a negative pregnancy test result and must agree to use a medically acceptable method of contraception throughout the entire study period and for 30 days after the last dose of study drug.
• Childbearing potential is defined as girls who are >Tanner stage 2, except for those who have documented pan pituitary insufficiency or other hormonal state incompatible with pregnancy.
• Urine pregnancy tests are acceptable.

Exclusion Criteria:

• Off treatment > 14 years
• Inability to perform the testing procedure (for example, because of aphasia, motor deficits affecting the dominant hand, or IQ < 70)
• Known cardiac disorders including arrhythmias, hypertension requiring treatment or structural heart disease
• Diagnosis of narcolepsy, sick sinus syndrome, arrhythmia or prolonged QTc
• History of stroke or head injury associated with loss of consciousness within 12 months of registration
• History of grade 2 depression or anxiety or treatment with antidepressants, antipsychotics or MAO inhibitors within 30 days of registration
• Concurrent treatment with any medications or substances that are potent inhibitors or inducers of CYP3A4, hepatic enzyme inducing antiepileptic drugs (EIAEDs),or other drugs known to affect the metabolism of modafinil. Examples include but are not limited to itraconazole, ketoconazole, doxycycline, rifampin, St. John's wort, phenytoin, phenobarbital, diazepam, tricyclic antidepressants.
• If patients were previously taking, EIAEDs, they must be off for > 2 weeks prior to study enrollment.
• Treatment with other stimulant medications within 14 days of registration; however, a diagnosis of ADHD does NOT exclude a child from participation
• Participants with known hypersensitivity to modafinil, armodafinil or any of its components