Therefore, we propose to study the efficacy and safety of light therapy for the treatment of bipolar type II patients relapsing into a depressive phase during the period of September to mid-March. This will be a double-blind randomized placebo-controlled study. Bipolar II out-patients will be recruited from our bipolar disorders program and from our 5 general psychiatry out-patient clinics. We will recruit bipolar type II patients facing a depressive phase and after they give their informed consent and we had verified they meet all inclusion and exclusion criteria, they will be randomized blindly to Bright-light (10 000 lux) vs Dim-light placebo (100 lux) therapies. Both, patient and investigator/rater will be blind to the type of light treatment assigned to the patient. The light therapy will take place during 30 minutes daily in the morning AFTER the usual awakening time of the patient in order to avoid even partial sleep deprivation which would confound the results if we were to observe a greater switch rate into mania or hypomania.