This is an open label 8-week trial of modafinil up to 400 mg daily added to a stable antipsychotic regimen to evaluate the effect modafinil on cognition, sedation, and weight in patients with chronic schizophrenia. We hypothesize that modafinil, a wake-promoting agent, will lead to improved cognition, increased wakefulness, and decreased weight in patients with schizophrenia who are on stable antipsychotic regimens