Effect of Dehydration on Cognitive Performance and Reaction Time Among Athletes at the University of Ibadan

Even mild dehydration has been documented to impair cognitive function and motor performance, which are critical for competitive athletic success. This study investigated the effect of dehydration on cognitive performance and reaction time among athletes at the University of Ibadan, Oyo State, South West Nigeria. Forty registered university athletes were enrolled in a within-subject experimental design. Participants were assessed under three hydration conditions: euhydrated, mildly dehydrated (approximately 2 percent body mass loss), and ad libitum rehydrated. Cognitive performance was evaluated using the trail-making test and digit span task, while simple and choice reaction times were measured with a validated computer-based platform. Urine specific gravity confirmed hydration status. Repeated-measures ANOVA and post-hoc tests were used. Results showed significant deterioration in cognitive performance scores and increased reaction times under mildly dehydrated conditions compared to euhydrated. Rehydration restored performance close to baseline levels. Reaction time impairment was more pronounced in choice reaction tasks, suggesting dehydration preferentially affects attentional processing. The study concludes that even modest dehydration negatively impacts athletic cognitive function at the University of Ibadan. Coaches and sports physicians are advised to prioritise hydration monitoring and enforce structured fluid intake protocols during training and competition. Keywords: dehydration, cognitive performance, reaction time, athletes, University of Ibadan.