Adequate Hydration and Sleep Support Pre‐Test Cognitive Performance in College Students
Authors: Beezhold Bonnie , Radnitz Cynthia , Dalrymple Jessica , Feldman Arielle , Todd Lauren , Fatima Faoqiya , Filbin Christine , Fritz Rebecca , Gerlach Emily , Gulling Phoebe , Walker Emily 
Published: November 2023

Cognitive performance is impacted by lifestyle factors including diet. Although this relationship is extensively studied in aging adults, there is little research in college students. Academic success is dependent on an ability to attend, process, and recall information, but lifestyle profile of the average college student is characterized by factors such as high intake of convenience foods and caffeine, lack of sleep and exercise, and stress with class loads. We investigated the associations between lifestyle factors and cognitive performance in college students in a cross‐sectional study that consisted of cognitive testing (“brain games”) and completion of a survey of personal factors related to cognition. A convenience sample of 75 undergraduate and graduate students (13 m/62 f), aged 18–24 years, was recruited on two regional college campuses. Participation incentives included class extra credit, gift card drawings, and satisfaction of course research requirement. Participants took an online test battery provided by Cogstate which measured cognitive performance in the general domains of attention, processing speed, executive function, and memory. They also completed an online survey that contained demographic questions, lifestyle questions about factors such as sleep, relaxation methods, exercise, and meal patterns, and diet questions that included pre‐test intakes and typical food intakes. Total study time was about 45 minutes. Several pre‐test factors surveyed were significantly associated with individual test score means. Pre‐test water/other fluid intake was associated with visual memory scores, r = −0.256, n = 69, p = 0.034. Students who reported drinking <8 oz versus ≥8 oz of water or other liquids before testing had a 6.85 higher mean visual memory test score (p = 0.003, eta squared = .13; poorer visual memory function). Pre‐test sleep hours were associated with verbal learning scores, r = 0.304, n = 74, p = 0.008. Students who reported sleeping <7 hours versus ≥7 hours the night before testing had a 4.0 lower mean verbal learning score (p < 0.01, eta squared = .21; poorer verbal learning function). Results for pre‐test intake of sugary foods within 2 hrs of testing (N/Y) were conflicting; intake was associated with higher visual memory scores, r = 0.278, n = 74, p = 0.016 (poorer function), and with lower psychomotor function scores, r = −0.252, n = 72, p = 0.033 (improved psychomotor function). Students who consumed sugary foods before testing had a 5.91 higher mean visual memory score (p = 0.116; poorer function) and a 0.05 lower mean psychomotor function score (p = 0.033, eta squared = .06; improved function) than those who did not consume sugar. Adequate hydration and sleep before a challenging academic task appear to be important for optimal visual memory and verbal learning function, both of which are involved in the ability to recall information. Sugar intake, which supplies brain glucose quickly, may actually improve psychomotor function depending on the timing of the tasks and/or whether concomitant nutrients help prevent the subsequent drop in glucose.

Support or Funding Information

This project had no funding.