The goal of this prospective randomised controlled trial is to examine the effects of cognitive behavioural therapy and bright light therapy in youths with unipolar depression and evening chronotype. The main questions it aims to answer are:

1. What is the efficacy of CBT-D and CBT-D plus bright light therapy in reducing depression severity in adolescents with depression and eveningness?
2. What are the effects of CBT-D and CBT-D plus bright light therapy on the subjective and objective sleep and circadian measures, as well as the quality of life, daytime symptoms, and functioning (e.g., sleepiness, fatigue)?