Identification of Chronotypes of Students From Undergraduate Courses of Biological Sciences and Geography at the Universidade Do Estado Do Rio Grande Do Norte, Brazil

*Corresponding author e-mail: abfragoso@gmail.com Introduction: The synchronization between the environment and the individuals internal body clock is required for the normal function of any organism. Many of the learning difficulties and adaptation problems to school activities or work can be a consequence of existing differences in the chronobiological characteristics among individuals. We analyzed the circadian typology of students from undergraduate courses of Biological Sciences (diurnal) and Geography (nocturnal) at the Universidade do Estado do Rio Grande do Norte, northeastern Brazil. Methods: We submit a specific questionnaire with the aim of identifying the students’ chronotype. Central and dispersion tendencies measures were calculated according to undergraduate course and gender (Student t). Ninety five university student volunteers (33% men; 67% women) of Biological Sciences (47) and Geography (48) filled the Brazilian version of the Chronotype Questionnaire (CQ), the Portuguese translation of the Horne and Östberg’s Morningness-Eveningness Questionnaire (MEQ). CQ score distribution was correlated to the normal curve (range=27- 74; mean=51.0; s.d.= 10.0). Results: It was verified a heterogeneity of chronotypes in university students (n=95) with individuals moderately matutine (21.0%), intermediate (61.0%) and moderately vespertine (18.0%) being found. There was no gender-by-chronotype association (p=0.233). CQ means were significatively different (p=0.004) when undergraduate Biology students (54.0±8.7) were compared to Geography students (48,2±10.4). We verified that 25.5% students in the Biological Sciences course were moderately matutine, 68.1% were intermediate and 6.4% were moderately vespertine (n=47). By the other hand, Geography students were 16.6% moderately matutine, 54.2% intermediate and 29.2% moderately vespertine (n=48). Conclusion: Based on these results, we conclude that there was a predominance of the intermediate chronotype, there were differences between the students’ chronotypes of Biology (diurnal) and Geography (nocturnal) courses and that most volunteers study in a schedule suitable for their chronotype. Our results reinforce the value of knowing biological rithms and chronotypes for the planning of work and study activities. Support: CNPq/ FAPERN/ UERN Publication History Article published online: 16 June 2026 © 2009. Brazilian Sleep Academy. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/) Thieme Revinter Publicações Ltda. Rua Rego Freitas, 175, loja 1, República, São Paulo, SP, CEP 01220-010, Brazil