In high school athletes, body composition plays a crucial role in both physical development and athletic performance. However, there is a lack of studies demonstrating a connection between sleep and body composition in high school athletes. The aim of this study was to assess the quantity and quality of sleep in high school athletes and explore its relationship with body composition. A cross-sectional analysis confirmed a correlation between sleep quality and body composition, but no such relationship was identified longitudinally. The findings suggest that sleep in high school athletes is partially linked to body composition, emphasizing the significance of adequate sleep.