Time of day and cognitive performance in university students: implications for learning and higher education

Abstract

Background and Study Aim. Cognitive performance shows variation across the day and may differ between cognitive domains. The extent to which these differences are observed under standardized living conditions remains of practical interest because environmental and lifestyle factors may influence cognitive outcomes. The aim of this study was to examine the influence of the time of day on selected cognitive functions in healthy university students. Materials and Methods. Sixty healthy male university students (mean age: 20.68 ± 0.97 years) were randomly assigned to morning (8:00–11:00 a.m.), afternoon (1:00–3:00 p.m.), or evening (5:00–7:00 p.m.) testing sessions. Cognitive performance was assessed using the Face/Name Association Test, the Stroop Color-Word Test, and the Trail Making Test (TMT A and B). Testing procedures were standardized across all groups. Statistical analyses included simple linear regression and one-way ANOVA. Tukey's HSD test was used for post hoc multiple comparisons. Additionally, planned pairwise comparisons between testing periods were evaluated using independent-samples t-tests. Results. Students tested in the morning demonstrated significantly better performance than those tested in the afternoon in both TMT A and TMT B, and on the Stroop Test (p < 0.01). No significant differences were observed between the morning and evening groups or between the afternoon and evening groups. Face/Name Association Test accuracy and retrieval time did not differ significantly across testing periods. Linear regression analyses indicated only weak associations between clock time and cognitive outcomes, suggesting that cognitive performance was more strongly associated with the testing period than with the exact clock time. Conclusions. These findings indicate that selected measures of executive function, particularly cognitive flexibility, attention, and inhibitory control, are sensitive to the time of day even under carefully controlled environmental conditions. These results highlight the educational relevance of considering circadian timing when scheduling cognitively demanding academic activities, examinations, and intensive learning sessions in higher education. The study also highlighted the value of conducting chronobiological research under standardized residential conditions, which help minimize the influence of common environmental confounders.