Additive Effect of High Sugar Intake and Prolonged Screen Exposure on Cognitive Performance in Young Adults

This study examined the combined effects of sugar intake and screen exposure on concentration and fatigue among medical students. A cross‑sectional survey of 133 participants assessed dietary habits, daily screen use, and cognitive outcomes. Analysis revealed that students with daily sugar consumption had the highest percentage of low concentration (45.1%), whereas those who rarely or never consumed sugar demonstrated the strongest concentration outcomes (55.6% high concentration). The association between sugar intake frequency and concentration levels was statistically significant (χ² = 12.15, df = 4, p = 0.016). Similarly, prolonged screen exposure (>7 hours/day) was linked to elevated moderate (n = 28) and low concentration (n = 17) levels, together with reduced fatigue resistance (n = 11). In contrast, students limiting screen use to less than two hours per day exhibited the lowest incidence of low concentration (n = 3) and greater resilience to fatigue. Combined analysis suggested an additive effect, with high sugar intake and prolonged screen exposure jointly predicting poorer concentration and higher fatigue complaints, although this association was not statistically significant (χ² = 19.43, df = 16, p = 0.247). These findings highlight the importance of reducing free sugar intake and moderating screen time to preserve cognitive performance and support long‑term brain health in student populations.