Night Owls Breathe Easy: Sleep Timing Does Not Determine Medical School Grades

For generations of students who dread 8 a.m. lectures, the fear has been persistent and personal: night owls, the thinking goes, are doomed to underperform in an educational system built by and for early risers. A new study of preclinical medical students in Türkiye now offers those late-night learners a measure of reassurance. Researchers at Erciyes University Faculty of Medicine in Kayseri examined whether a student’s chronotype, the innate tendency toward morningness or eveningness, had any measurable effect on academic achievement, and whether attitudes toward skipping class might explain any such relationship. Their conclusion, published in BMC Medical Education, is striking in its simplicity: chronotype did not significantly distinguish high performers from low performers in this cohort.

The research team, led by Emre Yilmaz of the Department of Family Medicine together with biostatistician Mevlüde Yasemin Akşehirli Seyfeli and medical education specialist Zeynep Baykan, recruited from the full population of third-year medical students at the faculty. All 376 students in the preclinical year were invited to participate, and the response was remarkably strong: 341 students completed the face-to-face questionnaire, a participation rate of 90.7 percent. After exclusions, 319 students entered the final analyses. That near-census coverage matters, because chronotype research in medical education has often relied on small, self-selected samples in which the most sleep-deprived or disengaged students may be underrepresented.

To classify each participant, the researchers used the Morningness–Eveningness Questionnaire, or MEQ, a widely applied psychometric instrument that scores individuals along a continuum from pronounced morning preference to pronounced evening preference. The team analyzed chronotype in three categorical groups, evening, intermediate, and morning, and additionally treated the MEQ total score as a continuous variable, a dual approach that guards against the loss of statistical power and information that can occur when a continuous trait is artificially binned. Alongside the MEQ, students completed the Absenteeism Attitude Scale, a validated measure of how students think and feel about missing classes, and reported their own academic performance and attendance-related information.

The distribution of chronotypes in the cohort tells its own story about the population entering medical school. Intermediate types, those whose biological clocks fall between the extremes, dominated the sample at 72.1 percent. Evening types accounted for 17.9 percent, while confirmed morning larks made up just 10.0 percent. This skew toward the middle of the chronotype spectrum is consistent with the general adult population, in which extreme morningness and extreme eveningness are both relatively rare, and it suggests that medical students as a group are not systematically skewed toward either pole of the sleep-timing continuum.

Then came the central test. When the researchers compared grade point averages across the three chronotype groups, they found no statistically significant difference. The Kruskal–Wallis test, a non-parametric method appropriate for comparing three independent groups on a skewed outcome such as GPA, yielded H(2) = 1.750 with p = .417 and an effect size of ε² < 0.001, meaning the chronotype groups explained essentially none of the variance in academic performance. Final committee examination scores told the same story: H(2) = 0.078, p = .962, again with a negligible effect size. Whether a student was a lark, an owl, or somewhere in between, their examination results were statistically indistinguishable.

The continuous analysis reinforced the null result. Spearman correlation between the MEQ total score and GPA was ρ = 0.103 with p = .066, a weak positive trend that failed to clear the conventional significance threshold. In other words, there was at most a faint hint that slightly more morning-oriented students had slightly higher grades, but the data did not support even that modest claim with confidence. For a field in which chronotype has frequently been implicated in academic outcomes, the near-zero effect sizes here are notable, and they suggest that within a demanding, uniformly structured preclinical curriculum, individual differences in biological timing may simply be absorbed rather than amplified.

Where chronotype did show a signal was in the attitudinal domain. The MEQ total score correlated weakly but significantly with the Absenteeism Attitude Scale score (ρ = 0.152, p = .006), and the scale scores themselves differed across chronotype groups (F(2,316) = 6.997, p = .001, η² = 0.042). Intermediate-type students scored higher than evening-type students on the scale. The effect size, an eta-squared of about four percent, is small, but the pattern hints that evening-oriented students may hold somewhat more permissive or tolerant attitudes toward skipping class than their intermediate peers, a difference that could matter in attendance-structured programs.

Crucially, absenteeism attitudes were the variable most consistently tied to achievement. The Absenteeism Attitude Scale score showed a weak but significant positive association with GPA (ρ = 0.194, p < .001), a stronger and more reliable relationship than anything chronotype produced. This raises an intriguing possibility: what students believe about the acceptability of missing class may be a more meaningful psychological marker of academic engagement than when their internal clocks prefer to run. Attitudes toward attendance, unlike chronotype, are potentially modifiable, which makes them a more actionable target for educators concerned about student disengagement.

To probe whether chronotype might influence grades indirectly through attendance-related attitudes, the team turned to structural equation modeling, fitting a path model within that framework. The model confirmed the direct picture: chronotype showed no statistically significant direct association with GPA (β = 0.062, p = .256). A small total indirect association was statistically supported (β = 0.048), but when the researchers examined the specific indirect pathways, only one survived scrutiny, a serial pathway running through absenteeism tendency and then absenteeism attitude, and even that was tiny (β = 0.007). The authors are careful to note that because the design is cross-sectional, measuring all variables at a single point in time, these indirect associations must not be read as evidence of causal mediation. A snapshot cannot establish that chronotype shapes attitudes which then shape grades; the arrows in the model represent hypothesized structure, not demonstrated causation.

The study, approved by the Erciyes University Health Sciences Research Ethics Committee and conducted in accordance with the Declaration of Helsinki, carries practical implications for medical schools wrestling with scheduling and attendance policy. Its message is not that sleep timing is irrelevant to student life, but that in this large, high-response preclinical cohort, the biological clock was not the academic differentiator that folklore might predict. Instead, the psychological stance students take toward attendance showed the more consistent connection to performance. For the substantial minority of evening types, roughly one in five students in this sample, the findings offer evidence-based comfort: their grades need not be hostage to their circadian preferences. And for educators, the results suggest that interventions targeting attitudes toward absenteeism, rather than attempts to re-engineer students’ sleep schedules, may be the more promising route to supporting achievement. As with all cross-sectional work, replication in other institutions and with longitudinal designs will be needed to confirm and extend these conclusions, but for now, the night owls of the preclinical years can attend their morning lectures with somewhat less dread.

Subject of Research: Associations between chronotype, academic achievement, and absenteeism attitudes among preclinical medical students

Article Title: Chronotypic characteristics, academic achievement, and absenteeism attitudes among preclinical medical students: a cross-sectional study

Article References: Yilmaz, E., Seyfeli̇, M. Y. A., & Baykan, Z. (2026). Chronotypic characteristics, academic achievement, and absenteeism attitudes among preclinical medical students: a cross-sectional study. BMC Medical Education. https://doi.org/10.1186/s12909-026-10563-6

Image Credits: AI Generated

DOI: 10.1186/s12909-026-10563-6

Keywords: chronotype, circadian rhythm, medical students, academic achievement, absenteeism, medical education, Morningness-Eveningness Questionnaire, structural equation modeling, cross-sectional study, GPA, sleep science, Erciyes University