The primary objective of this study is to elucidate the underlying mechanisms of youth depression and eveningness chronotype, with a particular focus on investigating whether eveningness contributes to deficits in reward processing among adolescents. The research will primarily employ polysomnography (PSG) and electroencephalography (EEG) techniques to examine sleep patterns and neural activity associated with reward processing in adolescents exhibiting an evening chronotype. Moreover, this study adopts a longitudinal design to investigate the temporal dynamics of these factors and their potential changes over time.