Bright Light Therapy in the Treatment of Non-seasonal Bipolar Depression

Inclusion Criteria: * Patients must be aged from 18 to 55 year-old. * Patients must read and understand French language, and must provide written informed consent. * Patients must be inpatients or outpatients followed in psychiatry for a major depressive episodes. * Patients must have a diagnosis of bipolar disorder, type I or II, according to the DSM-5 and determined by a SCID. * Patients must have a major depressive episode, at least of moderate intensity, according to the DSM-5, with a MADRS total score ≥20 and determined by a SCID. * Patients must have a mood stabilizer since at least 4 weeks at standard dosage (lithium, or sodium valproate, or second generation antipsychotics such as quetiapine, aripiprazole, olanzapine). * Female patients must be using a medically accepted means of contraception. * Patients must be affiliated to the social security scheme. Exclusion Criteria: * Patients under guardianship or deprivation of liberty by administrative or judicial decision * Seasonal pattern of major depressive episode according to DSM-5 criteria. * Psychotic, mixed, or catatonic characteristics according to DSM-5 criteria * High suicidal risk assessed by the Columbia Scale of Suicide Risk Severity (C-SSRS) * Not stabilized comorbidities (addictive disorders according to the DSM-5 criteria or other decompensated general medical cause). * Ophthalmic pathology (cataract, macular degeneration, glaucoma, retinitis pigmentosa) and diseases affecting the retina (retinopathy, diabetes, herpes, etc.). * Photosensitive treatment, including the following treatments: * Cyclins (Vibramycin®, Doxycycline®) * Amiodarone (Cordarone®, Amiodarone®) * Phenothiazines (Largactil®, Modecate®, Nozinan®, Melleril®, Trilafon®) * Methotrexate (Methotrexate®) * Sulfamides (antibiotics, diuretics or hypoglycemic agents) * Chloroquine (Nivaquine®) * Some anti-inflammatories (Apranax®, Indocid®) * Psoralens used in puvatherapy * Isotretinoin (Roaccutane® and generics) * Verteporfin (Visudyne®). * Lactating or pregnant women (pregnancy urine positive test). * Subjects who have already used light therapy in the last 6 months. * Therapeutic resistance of the current major depressive episode (≥2 traditional antidepressants such as SSRI, IRSNA, MAOI or tricyclic, at effective therapeutic dosage for more than 6 weeks) * Use of another antidepressant strategy than the mood stabilizer, including antidepressants of all classes (which will have to be stopped before the initiation of light therapy) and psychotherapy with onset \<1 month.