The specific aims of this study are 1) to document the Dopamine Transporter (DAT) receptor occupancy of armodafinil using positron emission tomography (PET) scanning with C-11 altropane as the ligand and 2) to document the increased intrasynaptic dopamine produced by armodafinil using PET scanning with C-11 raclopride as the ligand. We hypothesize that DAT occupancy will be low with armodafinil; less than the DAT occupancy produced by therapeutic doses of methylphenidate. We also hypothesize that increases in intrasynaptic dopamine will be relatively low with armodafinil.