Effect of chronotype on academic achievement in a sample of Italian University students: An update on sex effect

In the scientific literature, most studies suggested that the students expressing an evening chronotype (E-types) show worse academic performance than colleagues expressing a morning chronotype (M-type) (Enright & Refinetti 2017; Beşoluk et al. 2011; Gomes et al. 2011; Önder et al. 2014; Preckel et al. 2011; Taylor et al. 2011; Tonetti et al. 2015; Valladares et al. 2018). Our recent publication (Montaruli et al. 2019) confirmed the best M-types academic performance; however, N-types received the lowest grades in theoretical exams, while E-types the lowest in practical exams. Therefore, E-types seemed to perform significantly worse than M-types on practical exams alone (Montaruli et al. 2019). In the sample analysis stratified by sex, males somehow reflected the trends shown for the total sample; however, the female sample showed no statistically significant differences. This lack of statistical significance for the female group could be attributable to the lower female representation. Therefore, we hypothesised that an enlargement of the sample size could help us clarify the doubts regarding the possible chronotype differences in both males and females (Montaruli et al. 2019). In this view, we continued student enrolment with MEQ administration and exam grade recollection for students who completed their academic careers by the end of the 2018/2019 academic year. We calculated each student’s theoretical (Anatomy, Physiology, and Sport Medicine exams) and practical grades (Swimming, Volleyball, and Athletics exams). The IBM Statistical Package for Social Sciences – SPSS Statistics version 27 (IBM Corp. Released 2020. IBM SPSS Statistics for Windows, Armonk, NY: IBM Corp) was used to run the two-way ANOVA analyses testing the effects and the interactions of chronotype and sex (sex x chronotype) with Bonferroni test as a post-hoc test. Effect size (d) (Cohen calculation and interpretation) (Cohen 1977) were calculated to estimate the magnitude of the calculated effects, and interpreted as follows: . 2 = small; . 5 = medium; . 8 = big. Participants were 736 students (mean age 20.12 ± 1.63 yrs), 500 (67.9%) males and 236 (32.1%) females, with 94 (12.8%) M-types, 498 (67.7%) N-types, and 144 (19.6%) E-types. After the two-way ANOVA analysis and post-hoc tests for theoretical grades, female grade (25.2 ± 2.3) was significantly higher compared to the male one (24.5 ± 2.5; p = .015, d = .3). Furthermore, in the total sample, M-types received higher grade compared to that of N-type (p < .001, d = .5) (Table 1); while E-types showed no differences compared to the other two chronotypes, with their mean theoretical grade lying in between the other two (Table 1). In the male sample, N-types received a significantly lower theoretical grade than M-types (p < .010, d = −.4) and E-types (p < .015, d = −.3) (Table 1). Finally, in the female sample, only N-types’ theoretical grade was significantly lower than that of M-types (p < .03, d = −.4). As it is possible to see from the effect size, the magnitude of the differences in the theoretical grades range between medium (total sample) and small (male and female samples) effect size, with theoretical grades’ differences ranging between 1.1 and . 74 grades. Similarly, the Two-way ANOVA analysis and Bonferroni post-hoc tests revealed a significant higher practical grade for females (27.6 ± 1.5) than males (males: 27. ± 1.9; p = .01, d = .5). Focusing on the total sample, M-types earned a significantly higher practical grade than either N-types (p < .001, d = .5) or E-types (p < .001, d = .7) (Table 1). In the male sample, M-types reached a significantly higher grade compared to N-types (p < .001, d = .5) and E-types (p < .001, d = .6) (Table 1). Finally, only female E-types’ practical grade was significantly lower than that of M-types (p < .04, d = −.7) (Table 1).