Influence of Hydration on Mood and Cognition: A Cross-Sectional Study in MBBS Students and Interns

Introduction: Adequate hydration is essential for optimal brain function and emotional regulation. In medical education, where sustained attention, decision-making, and emotional resilience are critical, the impact of hydration on cognitive performance and mood remains underexplored. This study aimed to evaluate the relationship between hydration status, cognitive performance, and mood among MBBS students and medical interns. 
Methods: A cross-sectional study was conducted among 320 participants (MBBS students and medical interns). Hydration was assessed using self-reported daily water intake and biochemical markers—serum urea and blood urea nitrogen (BUN). Mood was evaluated using the Hamilton Depression Rating Scale (HDRS), and cognitive flexibility was measured with the Stroop Colour and Word Test. Data were analysed using ANOVA for group comparisons and Pearson’s correlation for associations between hydration, mood, and cognition. 
Results: Interns, particularly those in intensive care unit (ICU) postings, recorded significantly higher HDRS scores (mean: 15.3±3.2) compared to MBBS students (mean: 9.1±2.8; p=0.0051). ICU interns also made more Stroop errors (mean: 7.4±1.9), although the difference across groups was not statistically significant (p=0.6062). Serum urea and BUN levels were higher in interns but not significantly different between groups. Among interns, BUN was moderately correlated with HDRS (r=–0.452, p=0.0027) and Stroop errors (r=0.358, p=0.0200), indicating that hydration status was linked to both mood disturbance and cognitive errors. 
Conclusion: Dehydration may contribute to poorer mood and increased cognitive errors, especially among medical interns in high-stress clinical settings. Interventions promoting adequate hydration, alongside broader wellness strategies, could support cognitive efficiency and emotional well-being.