Effects of CBT and BLT in Youth With Unipolar Depression and Evening Chronotype

Inclusion Criteria: 1. Chinese aged 12-20 years old. 2. Written informed consent of participation into the study is given by the participant and his/her parent or guardian (for those aged under 18). 3. Being able to comply with the study protocol. 4. Having a DSM-5 diagnosis of depressive disorders. 5. Having a score of ≥ 40 on Children's Depression Rating Scale (CDRS-R). 6. Having a score of ≤ 41 on Horne-Östberg Morning-Eveningness Questionnaire (MEQ; classified as evening chronotype). 7. Having a sleep onset time of 11:15pm or later for 12 year olds, 11:30pm or later for 13-14 year olds, and 12:00pm or later for 15-20 years at least 3 nights per week in the past 3 months. Exclusion Criteria: 1. A current diagnosis of substance abuse or dependence; a current or past history of manic or hypomanic episode, schizophrenia spectrum disorders, neurodevelopmental disorders, organic mental disorders, or intellectual disabilities. 2. Initiation of and change of medication that may interfere with circadian rhythm within past 3 months (e.g., lithium, exogenous melatonin, melatonergic antidepressants). 3. In the opinion of the research clinician, having a clinically significant suicidality (presence of suicidal ideation with a plan or an attempt). 4. Having been enrolled in any other clinical trial investigational products within one month at the entry of the study. 5. Initiation of or change in antidepressant medication within past 3 months. 6. Having been or is currently receiving any structured psychotherapy. 7. With hearing or speech deficit. 8. Night shift worker. 9. Trans-meridian flight in the past 1 month and during intervention. 10. Presence of an eye disease (e.g., retinal blindness, severe cataract, glaucoma).