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This preprint tests whether sleep (both sleep quality and sleep hygiene combined in a so-called sleep latent variable), chronotype, and perceived stress are associated with academic achievement in university students. The question studied is relevant because academic achievement can affect students’ future opportunities and sleep habits are potentially changeable. A cross-sectional online survey (N = 393) has done, measures included the MEQ, SHI, PSQI, PSS, and a self-reported average percentage grade. The model showed the modest grades (R² = .047). Chronotype (morningness; β = .15, p = .003) and perceived stress (β = -.12, p = .017) predicted achievement, with higher morningness and lower stress associated with higher grades, while the sleep latent variable did not (p = .156). Exploratory analyses have shown that, stress did not account for the relation between sleep latent variable and achievement, and that sleep hygiene, but not sleep quality, accounted for the association between chronotype and academic achievement.

The study has some strong points:

• Aims and hypotheses are clearly stated, and the topic is relevant to university students wellbeing and academic performance

• Sleep hygiene, chronotype, and perceived stress are considered together, and thus study goes beyond measuring sleep duration and quality

• The authors report an a priori power analysis with validated measures and reliability estimates are shown for the study’s own sample

• Attention checks and exclusion criteria strengthen data quality. The non-significant sleep finding and exploratory mediation analyses are reviewed transparently

• The manuscript is clearly written and easy to follow

Major Comments

• Academic achievement is given to participants’ self-reported average percentage grade, calculated from assessment feedback received over the previous six months (pp. 10, 11). It would be helpful to provide more detail on how participants calculated this average, whether it came to university records, regarding to different grading systems, degree programmes, and study year levels. The time frames of the measures also differ. Grades shows a six-month period and the PSQI and PSS refer to the previous month, while all data were collected in a single survey between 5 February and 17 March 2024.

• The Discussion does not appear to include a dedicated limitations section, so readers cannot easily judge how far the findings apply. Such a section could cover the cross-sectional design, self-report measures and different time periods of the measures.

Suggestions: Please consider adding a brief explanation of how participants calculated their average grade and acknowledging the different time measures. The authors could also discuss these issues in a limitations section and suggest that future research use officially recorded grades or a longitudinal design.

Overall:

This preprint addresses a relevant and practically important question about the relationships among sleep behaviours, chronotype, perceived stress, and academic achievement in university students. This research includes clearly stated aim, a reasonably large sample, validated measures, an a priori power analysis, attention checks, and clear reports of both non-significant and exploratory findings.

Competing interests

The author declares that they have no competing interests.

Use of Artificial Intelligence (AI)

The author declares that they used generative AI to come up with new ideas for their review.