Our research is poised to make significant contributions to the understanding of the relationship between chronotype and depression, particularly considering the dynamic nature of chronotype across different life stages. Key impacts include: 1. Exploring chronotype variability across ages: While existing literature suggests a causal relationship between chronotype and depression, we recognize that chronotype is not static throughout life. Adolescents typically experience a delay in chronotype, whereas the elderly often exhibit an advance. Our study aims to delve deeper into this relationship through a gene-environment (GE) interaction analysis. By examining effect modifications by age in various groups, including adolescents and adults, we hope to provide a more comprehensive understanding of the influential factors in this relationship. 2. Investigating the Roles of Diet: Additionally, we will investigate the potential effect modification by diet quality. This aspect of our research will particularly focus on whether diet quality modifies the relationship between chronotype and depression in adults, as opposed to adolescents. This could offer new insights into how dietary habits influence mental health and contribute to a more nuanced understanding of depression's etiology. Overall, our research aims to broaden the understanding of how chronotype, age, and diet interact to influence depression while considering other sleep and mental health influences, potentially informing more targeted and effective interventions.