This study uses polysomnographs(PSG) to investigate sleep patterns in patients with bipolar depression. This is a double-blind, placebo-controlled, study of ziprasidone that is added to patients current medications. The objective is to relate changes in slow wave and rapid eye movement sleep to changes in mood and overall illness severity. Participants will be randomly assigned to add either placebo or ziprasidone to their current treatment regimen. Participants make 3 to 4 study visits, over a 1 month period, at which they will be asked about their history, mood and sleep quality. Participants will also have three in-home overnight polysomnographs.

Inclusion Criteria:

• A diagnosis of Bipolar Disorder Type 1,2 or NOS by Diagnostic and Statistical Manual of Mental Disorders- Fourth Edition (DSM-IV).
• Current depressive episode with a HAMD-17 of >16.
• Males or Females over age 18yrs.
• Inpatients or outpatients.
• Female patients of childbearing potential must be using a reliable method of contraception and have a negative urine human chorionic gonadotropin (HCG) test at enrolment.
• Able to understand and comply with the requirements of the study.
• Provision of written informed consent.

Exclusion Criteria:

• Current Manic, Hypomanic or Mixed episode, with YMRS > 12.
• Current or past diagnosis of Schizophrenia and Dementia.
• Pregnant women, or women in childbearing age, not willing to use appropriate contraception or women currently nursing.
• Patient on any other antipsychotic medication.
• Patients who, in the opinion of the investigator, pose an imminent risk of suicide or a danger to self or others.
• Known intolerance or lack of response to Ziprasidone, as judged by the investigator.
• Benzodiazepines and all other sleep-aids must be discontinued prior to participation in the study if they have not been at a stable dosage for the 4 weeks previous to entry into the study.
• No change to the current medication regime (excluding discontinuation of sleep aids and antipsychotic medications) is allowed 4 weeks prior to the first PSG reading.
• Administration of a depot antipsychotic injection within two dosing interval (for the depot) before randomization.
• Substance or alcohol dependence at enrolment or in the last three months (except for caffeine or nicotine dependence), as defined by DSM-IV criteria.
• Serious, unstable or inadequately treated medical illness as judged by the investigator.
• History of epilepsy or uncontrolled seizures.
• Involvement in the planning and conduct of the study.
• Previous enrolment in the present study.
• Participation in another drug trial within 4 weeks prior enrolment into this study or longer in accordance with local requirements.
• Patients with serum potassium, magnesium and/or calcium levels outside the normal range at baseline.
• Patients with marked liver function abnormalities at baseline, demonstrated by laboratory values, by judgment of the investigator.
• Known serological evidence of HIV, or acute or chronic hepatitis; donation of blood or blood products for transfusion prior to initiation of the treatment with study drug, during the study and for 30 days after the study has ended.
• Known history of QT prolongation (including congenital long QT syndrome).
• Recent acute myocardial infarction or uncompensated heart failure.
• Currently taking other drugs that are known to prolong the QT interval.