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Updated: Jul 27, 2025

Human Circadian Phenotyping and Diurnal Performance Testing in the Real World
Published on: April 7, 2020
Chronotype as a predictor of scholar performance in a full-time middle school
R R Cezário1, D Freitas2, S Chahad-Ehlers3
1Universidade de São Paulo - USP, Department of Biology, Graduate Program in Entomology, Ribeirão Preto, SP, Brasil.
Abstract:
The performance of day-to-day tasks, whether satisfactory or unsatisfactory, varies due to several environmental synchronizers, including the 24-hour light-dark cycle. For instance, human performance on physical and/or cognitive demanding activities reaches its peak during the day when the body temperature is at its circadian peak. Individual differences in the circadian peaks in temperature along with individuals' timing of sleep is referred to as chronotype. Here, we aimed to answer if (a) chronotypes affect the performance of students in a Brazilian full-time school with an early start time and if (b) there are differences in performance based on chronotype. We expected to find (a) a positive effect of the morning chronotype on the students' performance, particularly in subjects that take place in early morning; (b) while a negative effect of the evening chronotype in that same period. To address the effect of the chronotype on the students' scholar performance we build a Generalized Linear Mixed Model (GLMM). Results support the hypothesis that the students' performance is partially attributed to their chronotype. In particular, our findings shows that evening-type students are expected to have an increase of 0.038 (p ≤0.05) log counts on their performance in Portuguese classes compared to other chronotypes. Here we add evidence for the effect that individual chronotypes have on the students' performance in a Brazilian full-time middle school. Distinctive features of the studied Brazilian full-time middle school related to chronotypes are discussed.
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