A Clinical Study of Light Therapy on Depressive Episodes of Bipolar Disorder

Inclusion Criteria: * ages 18 to 65 years * comply with the DSM-IV diagnosis of Bipolar I or II Disorder and a current depressive episode * HAMD score ≥17 points * intake of just one particular psychotropic drug(a mood stabilizer or an atypical antipsychotic drug) except of antidepressants and lasted 2 weeks. Exclusion Criteria: * inability to provide informed consent; * previous treatment with BLT * presence of another major psychiatric illness such as schizophrenia, schizoaffective disorder, lifetime alcohol or substance dependence * diagnosed with a rapid-cycling bipolar disorder or currently in the mixed state or YMRS score\>12 points * use of antidepressants medications * significant medical illness such as diabetes mellitus,heart failure, renal failure, severe liver function abnormalities,hyperthyroidism or hypothyroidism * pregnancy; * received magnified electroconvulsive therapy orRepetitive Transcranial Magnetic Stimulation in the past 3 months * an eye condition that could be negatively affected by bright light * suicidal risk or other factor making trial participation clinically inappropriate.