This study is a double blind, placebo controlled, 24-week crossover design. For 12 weeks subjects receive either study medication (200mg Quetiapine) or placebo, after which they will be switched to the other treatment for an additional 12 weeks. Between treatments, subjects are required to undergo a 1-week washout where no drug is given in order to clear the effects of the first treatment. At each visit subjects will complete the following assessment: Fibromyalgia Impact Questionnaire, Pittsburgh Sleep Quality Index, Beck Depression Inventory, State-Trait Anxiety Inventory, and Short Form Health Survey. Temperature, blood pressure, pulse rate, weight and waist circumference will also be recorded. Physical exams and blood tests will be performed at 1, 12, and 25 weeks