Circadian Fluctuations of Cognitive and Psychomotor Performance in Medical Students: The Role of Daytime and Chronotype Patterns

Objective: Our research aimed to explore the impact of chronotype and time of day on the cognitive and psychomotor performance of medical students around 25 years old. The study provides evidence that an individual’s circadian rhythm affects their daily performance and cognitive processes.Methods: To measure selective attention and inhibition, we utilized the Stroop test, while three subtests from the fourth edition of Wechsler Adult Intelligence Scale (WAIS-IV) were employed to measure simple attention and working memory. In addition, the Leed psychomotor tester was utilized to measure perception and motor reaction time, and the morningness-eveningness questionnaire was administered to investigate students’ chronotype. Statistical analysis were based on many tests depending on the correlation types. We mainly used ANOVA repeated measures, Bonferroni post-hoc test, ANOVA I, chi-square, and Pearson correlation tests.Results: Our findings suggest that students exhibit decreased selective attention (F=128.842b, p<0.01, η²=0.868, 95% CI=2.744–16.998) and weakened inhibition during the late afternoon (6 p.m.) when the largest margin of error was committed (1.56±2.90) compared to 10 a.m. (0.82±1.72), leading to increased difficulty resisting interference; except that the size effect was small (η²>0.13). Simple attention reaches its peak in the morning around 10 a.m., while memory performance and auditory modality of working memory reach their peaks at 10 a.m. and the end of the afternoon (6 p.m.), respectively.Conclusion: Our study underscores the importance of taking wake time and body temperature into account when examining task performance. Overall, the study highlights the importance of considering circadian rhythm and chronotype when designing academic and athletic schedules.