Digital leisure activities—online games, short videos, and extracurricular reading—are popular among elementary school students. These activities can extend learning beyond the classroom but may also compete for time and energy, potentially impacting academic performance, especially for students with less self-control. This study investigates the relationship between these activities and exam scores, using advanced analytical methods. The findings reveal a significant correlation between learning outcomes and the frequency, duration, and fatigue associated with these leisure activities. Specifically, the frequency of extracurricular reading negatively correlates with science performance (effect coefficient -0.242), while the duration positively correlates (effect coefficient 0.440). An intriguing ”hourglass effect” was observed, where exam scores are heavily influenced by the time and energy students with low self-control spend on recreational activities. These results provide valuable insights into balancing digital leisure with academic responsibilities, offering practical guidance for educators in planning school content and developing educational strategies. By understanding the impact of digital leisure on learning, this research supports the development of more effective learning technologies to enhance academic outcomes in elementary education.