An Investigation of Sleep Architecture in Ziprasidone-Treated Bipolar Depression

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.