Background
Depression remains the leading cause of disability worldwide, imposing substantial burdens on mental and physical health. Increasing physical activity has been consistently linked to reduced depression risk, yet the 24-hour day imposes constraints, meaning time allocated to physical activity must come at the expense of other behaviors such as sedentary activities or sleep. Among sedentary behaviors, TV-watching stands out due to its association with increased depressive symptoms, likely driven by biological and psychosocial mechanisms including dopamine dysregulation and social isolation. However, it is unclear how reallocating time from TV-watching to other activities such as physical exercise or sleep impacts major depressive disorder (MD) incidence across different age groups.
