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Chronotype as a predictor of scholar performance in a full-time middle school

Cronotipo como preditor de desempenho em uma escola de ensino médio de tempo integral

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.

Keywords:
chronobiology; circadian system; sleep; matutine; vespertine

Resumo

O desempenho em tarefas no dia a dia, seja satisfatório ou insatisfatório, varia devido a diversos sincronizadores ambientais, incluindo o ciclo claro-escuro de 24 horas. Por exemplo, o desempenho humano em atividades físicas e/ou cognitivamente exigentes atinge seu pico durante o dia, quando a temperatura corporal está no pico circadiano. Diferenças individuais nos picos circadianos de temperatura, juntamente com o horário de sono dos indivíduos, são referidas como cronotipo. Neste trabalho o objetivo foi responder se a) os cronotipos afetam o desempenho dos estudantes em uma escola brasileira de período integral e se b) há diferenças no desempenho com base no cronotipo. Esperamos encontrar a) um efeito positivo do cronotipo matutino no desempenho dos estudantes, especialmente em disciplinas que ocorrem no período da manhã; b) enquanto um efeito negativo do cronotipo vespertino nesse mesmo período. Para endereçar o efeito do cronotipo no desempenho acadêmico dos estudantes, construímos um Modelo Linear Generalizado Misto (GLMM). Os resultados corroboraram a hipótese de que o desempenho dos estudantes é parcialmente atribuído ao seu cronotipo. Em particular, nossos resultados mostram que é esperado que os estudantes vespertinos tenham um aumento de 0,038 (p ≤ 0,05) pontos logarítmicos em seu desempenho em aulas de Língua Portuguesa em comparação com outros cronotipos. Assim, adicionamos evidências para o efeito que o cronotipo têm no desempenho dos estudantes em uma escola de ensino médio integral no Brasil. As características particulares da escola estudada e suas relações com os cronotipos foram discutidas.

Palavras-chave:
cronobiologia; sistema circadiano; sono; matutinos; vespertinos

1. Introduction

The human circadian rhythmicity, a special type of biological rhythm, plays a crucial role in various day-to-day activities, whether exercising, during a nap or performing cognitive demanding tasks (Koukkari and Sothern, 2007KOUKKARI, W.L. and SOTHERN, R.B., 2007. Introducing biological rhythms: a primer on the temporal organization of life, with implications for Health, Society, Reproduction and the Natural Environment. New York: Springer Science & Business Media, Inc.). This rhythm describes biological variations, including changes in core body temperature and plasma melatonin, which follow a roughly 24-hour cycle (± 4 hours) (Halberg et al., 1977HALBERG, F., CARANDENTE, F., CORNELISSEN, G. and KATINAS, G.S., 1977. Glossary of chronobiology. Chronobiologia, vol. 4, suppl. 1, pp. 1-189. PMid:352650.). By comparing an individual’s body temperature to specific environmental cues, known as zeitgebers or "time-givers", such as the 24-hour day, researchers can assess the individual’s phase of entrainment, a measure of their alignment with the external environment (Roenneberg, 2012ROENNEBERG, T., 2012. What is chronotype? Sleep and Biological Rhythms, vol. 10, no. 2, pp. 75-76. http://dx.doi.org/10.1111/j.1479-8425.2012.00541.x.
http://dx.doi.org/10.1111/j.1479-8425.20...
; Koukkari and Sothern, 2007KOUKKARI, W.L. and SOTHERN, R.B., 2007. Introducing biological rhythms: a primer on the temporal organization of life, with implications for Health, Society, Reproduction and the Natural Environment. New York: Springer Science & Business Media, Inc.). In other words, researchers concerned in the study of biological rhythms can determine the specific times when an individual’s body temperature reaches a circadian peak or trough during a 24-hour period, thereby identifying the optimal times for physical exercise or cognitive tasks. For instance, the individuals’ performance on such physical and cognitive activities typically peaks during the day, when their body temperature reaches its highest point, and decline during the night when body temperature is at its lowest (Koukkari and Sothern, 2007KOUKKARI, W.L. and SOTHERN, R.B., 2007. Introducing biological rhythms: a primer on the temporal organization of life, with implications for Health, Society, Reproduction and the Natural Environment. New York: Springer Science & Business Media, Inc.; Wright Junior et al., 2002). Overall, understanding the role of the circadian rhythm in regulating various physiological processes and its influence on daily activities has important implications for human health and performance.

Furthermore, individual differences in the timing of sleep relative to local time, in conjunction with the circadian peak in body temperature, are collectively referred to as chronotype (Stampi, 1992STAMPI, C., 1992. Why we nap: evolution, chronobiology, and functions of polyphasic and ultrashort sleep. Boston, MA: Birkhäuser Boston. http://dx.doi.org/10.1007/978-1-4757-2210-9.
http://dx.doi.org/10.1007/978-1-4757-221...
; Roenneberg, 2012ROENNEBERG, T., 2012. What is chronotype? Sleep and Biological Rhythms, vol. 10, no. 2, pp. 75-76. http://dx.doi.org/10.1111/j.1479-8425.2012.00541.x.
http://dx.doi.org/10.1111/j.1479-8425.20...
; Foster and Kreitzman, 2004FOSTER, R.G. and KREITZMAN, L., 2004. Rhythms of life: the biological clocks that control the daily lives of every living thing. Great Britain: Profile books.; Kerkhof and van Dongen, 1996KERKHOF, G.A. and VAN DONGEN, H.P.A., 1996. Morning-type and evening-type individuals differ in the phase position of their endogenous circadian oscillator. Neuroscience Letters, vol. 218, no. 3, pp. 153-156. http://dx.doi.org/10.1016/S0304-3940(96)13140-2. PMid:8945751.
http://dx.doi.org/10.1016/S0304-3940(96)...
). The Morningness-Eveningness Questionnaire (MEQ) provides a subjective measure of an individual’s chronotype, as defined by Horne and Östberg (Horne, Östberg 1976HORNE, J.A. and ÖSTBERG, O., 1976. A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms. International Journal of Chronobiology, vol. 4, no. 2, pp. 97-110. PMid:1027738.). The MEQ scores individuals based on five chronotypes, including definitely morning (MA), moderately morning (MM), indifferent (IN), moderately evening (MV), and definitely evening (VE). Typically, MA individuals display an earlier oral temperature peak compared to VE individuals, in addition to higher daytime temperature and lower post-peak temperature (Horne and Östberg, 1976HORNE, J.A. and ÖSTBERG, O., 1976. A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms. International Journal of Chronobiology, vol. 4, no. 2, pp. 97-110. PMid:1027738.; Kerkhof and van Dongen, 1996KERKHOF, G.A. and VAN DONGEN, H.P.A., 1996. Morning-type and evening-type individuals differ in the phase position of their endogenous circadian oscillator. Neuroscience Letters, vol. 218, no. 3, pp. 153-156. http://dx.doi.org/10.1016/S0304-3940(96)13140-2. PMid:8945751.
http://dx.doi.org/10.1016/S0304-3940(96)...
; Adan et al., 2012ADAN, A., ARCHER, S.N., HIDALGO, M.P., DI MILIA, L., NATALE, V. and RANDLER, C., 2012. Circadian typology: a comprehensive review. Chronobiology International, vol. 29, no. 9, pp. 1153-1175. http://dx.doi.org/10.3109/07420528.2012.719971. PMid:23004349.
http://dx.doi.org/10.3109/07420528.2012....
). Indifferent individuals have temperatures that fall between those of the other chronotypes (Horne and Östberg, 1976HORNE, J.A. and ÖSTBERG, O., 1976. A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms. International Journal of Chronobiology, vol. 4, no. 2, pp. 97-110. PMid:1027738.; Adan et al., 2012ADAN, A., ARCHER, S.N., HIDALGO, M.P., DI MILIA, L., NATALE, V. and RANDLER, C., 2012. Circadian typology: a comprehensive review. Chronobiology International, vol. 29, no. 9, pp. 1153-1175. http://dx.doi.org/10.3109/07420528.2012.719971. PMid:23004349.
http://dx.doi.org/10.3109/07420528.2012....
).

In addition, the Horne-Östberg morningness-eveningness questionnaire (MEQ) is a validated measure of an individual’s chronotype, based on their sleep-wake cycle (Horne, Östberg, 1976HORNE, J.A. and ÖSTBERG, O., 1976. A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms. International Journal of Chronobiology, vol. 4, no. 2, pp. 97-110. PMid:1027738.; Valdez et al., 2012VALDEZ, P., RAMÍREZ. and GARCÍA, A., 2012. Circadian rhythms in cognitive performance: implications for neuropsychological assessment. ChronoPhysiology and Therapy, pp. 81. http://dx.doi.org/10.2147/CPT.S32586.
http://dx.doi.org/10.2147/CPT.S32586...
; Roenneberg, 2012ROENNEBERG, T., 2012. What is chronotype? Sleep and Biological Rhythms, vol. 10, no. 2, pp. 75-76. http://dx.doi.org/10.1111/j.1479-8425.2012.00541.x.
http://dx.doi.org/10.1111/j.1479-8425.20...
; Koukkari and Sothern, 2007KOUKKARI, W.L. and SOTHERN, R.B., 2007. Introducing biological rhythms: a primer on the temporal organization of life, with implications for Health, Society, Reproduction and the Natural Environment. New York: Springer Science & Business Media, Inc.). The use of the MEQ in controlled populations has enabled researchers to investigate how environmental synchronizers, such as school schedules, impact an individual’s internal phase and subsequent performance (Horne and Östberg, 1976HORNE, J.A. and ÖSTBERG, O., 1976. A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms. International Journal of Chronobiology, vol. 4, no. 2, pp. 97-110. PMid:1027738.; Valdez et al., 2012VALDEZ, P., RAMÍREZ. and GARCÍA, A., 2012. Circadian rhythms in cognitive performance: implications for neuropsychological assessment. ChronoPhysiology and Therapy, pp. 81. http://dx.doi.org/10.2147/CPT.S32586.
http://dx.doi.org/10.2147/CPT.S32586...
; Roenneberg, 2012ROENNEBERG, T., 2012. What is chronotype? Sleep and Biological Rhythms, vol. 10, no. 2, pp. 75-76. http://dx.doi.org/10.1111/j.1479-8425.2012.00541.x.
http://dx.doi.org/10.1111/j.1479-8425.20...
; Koukkari and Sothern, 2007KOUKKARI, W.L. and SOTHERN, R.B., 2007. Introducing biological rhythms: a primer on the temporal organization of life, with implications for Health, Society, Reproduction and the Natural Environment. New York: Springer Science & Business Media, Inc.). Through its application, the MEQ has yielded valuable insights into the influence of chronotype on performance in various settings, including organizational environments (Barber et al., 2013BARBER, L., GRAWITCH, M.J. and MUNZ, D.C., 2013. Are better sleepers more engaged workers? A self-regulatory approach to sleep hygiene and work engagement. Stress and Health, vol. 29, no. 4, pp. 307-316. http://dx.doi.org/10.1002/smi.2468. PMid:23086901.
http://dx.doi.org/10.1002/smi.2468...
), physical activities (Rossi et al. 2015ROSSI, A., FORMENTI, D., VITALE, J.A., CALOGIURI, G. and WEYDAHL, A., 2015. The effect of chronotype on psychophysiological responses during aerobic self-paced exercises. Perceptual and Motor Skills, vol. 121, no. 3, pp. 840-855. http://dx.doi.org/10.2466/27.29.PMS.121c28x1. PMid:26682609.
http://dx.doi.org/10.2466/27.29.PMS.121c...
), and educational institutions (Lund et al., 2010LUND, H.G., REIDER, B.D., WHITING, A.B. and PRICHARD, J.R., 2010. Sleep patterns and predictors of disturbed sleep in a large population of college students. The Journal of Adolescent Health, vol. 46, no. 2, pp. 124-132. http://dx.doi.org/10.1016/j.jadohealth.2009.06.016. PMid:20113918.
http://dx.doi.org/10.1016/j.jadohealth.2...
; Díaz-Morales and Escribano, 2013DÍAZ-MORALES, J.F. and ESCRIBANO, C., 2013. Circadian preference and thinking styles: implications for school achievement. Chronobiology International, vol. 30, no. 10, pp. 1231-1239. http://dx.doi.org/10.3109/07420528.2013.813854. PMid:24024592.
http://dx.doi.org/10.3109/07420528.2013....
; Rique et al., 2014RIQUE, G.L.N., FERNANDES FILHO, G.M.C., FERREIRA, A.D.C. and DE SOUSA-MUÑOZ, R.L., 2014. Relationship between chronotype and quality of sleep in medical students at the Federal University of Paraiba, Brazil. Sleep Science, vol. 7, no. 2, pp. 96-102. http://dx.doi.org/10.1016/j.slsci.2014.09.004. PMid:26483910.
http://dx.doi.org/10.1016/j.slsci.2014.0...
; Arrona-Palacios et al., 2015ARRONA-PALACIOS, A., GARCÍA, A. and VALDEZ, P., 2015. Sleep–wake habits and circadian preference in Mexican secondary school. Sleep Medicine, vol. 16, no. 10, pp. 1259-1264. http://dx.doi.org/10.1016/j.sleep.2015.05.026. PMid:26429755.
http://dx.doi.org/10.1016/j.sleep.2015.0...
; Randler and Frech, 2006RANDLER, C. and FRECH, D., 2006. Correlation between morningness – eveningness and final school leaving exams. Biological Rhythm Research, vol. 37, no. 3, pp. 233-239. http://dx.doi.org/10.1080/09291010600645780.
http://dx.doi.org/10.1080/09291010600645...
; Beşoluk et al., 2011BEŞOLUK, S., ÖNDER, İ. and DEVECI, İ., 2011. Morningness-eveningness preferences and academic achievement of university students. Chronobiology International, vol. 28, no. 2, pp. 118-125. http://dx.doi.org/10.3109/07420528.2010.540729. PMid:21231873.
http://dx.doi.org/10.3109/07420528.2010....
). The understanding of chronotypes is essential in determining the optimal time for individuals to perform physical and cognitive activities, which can ultimately enhance their performance and well-being.

In educational settings, there is a clear relationship between students’ cognitive performance, both subjectively and academically, and their chronotype (Lund et al., 2010LUND, H.G., REIDER, B.D., WHITING, A.B. and PRICHARD, J.R., 2010. Sleep patterns and predictors of disturbed sleep in a large population of college students. The Journal of Adolescent Health, vol. 46, no. 2, pp. 124-132. http://dx.doi.org/10.1016/j.jadohealth.2009.06.016. PMid:20113918.
http://dx.doi.org/10.1016/j.jadohealth.2...
; Díaz-Morales and Escribano, 2013DÍAZ-MORALES, J.F. and ESCRIBANO, C., 2013. Circadian preference and thinking styles: implications for school achievement. Chronobiology International, vol. 30, no. 10, pp. 1231-1239. http://dx.doi.org/10.3109/07420528.2013.813854. PMid:24024592.
http://dx.doi.org/10.3109/07420528.2013....
; Rique et al., 2014RIQUE, G.L.N., FERNANDES FILHO, G.M.C., FERREIRA, A.D.C. and DE SOUSA-MUÑOZ, R.L., 2014. Relationship between chronotype and quality of sleep in medical students at the Federal University of Paraiba, Brazil. Sleep Science, vol. 7, no. 2, pp. 96-102. http://dx.doi.org/10.1016/j.slsci.2014.09.004. PMid:26483910.
http://dx.doi.org/10.1016/j.slsci.2014.0...
; Arrona-Palacios et al., 2015ARRONA-PALACIOS, A., GARCÍA, A. and VALDEZ, P., 2015. Sleep–wake habits and circadian preference in Mexican secondary school. Sleep Medicine, vol. 16, no. 10, pp. 1259-1264. http://dx.doi.org/10.1016/j.sleep.2015.05.026. PMid:26429755.
http://dx.doi.org/10.1016/j.sleep.2015.0...
; Randler and Frech, 2006RANDLER, C. and FRECH, D., 2006. Correlation between morningness – eveningness and final school leaving exams. Biological Rhythm Research, vol. 37, no. 3, pp. 233-239. http://dx.doi.org/10.1080/09291010600645780.
http://dx.doi.org/10.1080/09291010600645...
; Beşoluk et al., 2011BEŞOLUK, S., ÖNDER, İ. and DEVECI, İ., 2011. Morningness-eveningness preferences and academic achievement of university students. Chronobiology International, vol. 28, no. 2, pp. 118-125. http://dx.doi.org/10.3109/07420528.2010.540729. PMid:21231873.
http://dx.doi.org/10.3109/07420528.2010....
). Research has shown that middle and high school students with a moderately evening (MV) or definitely evening (VE) chronotype may struggle with early school start times (e.g., between 7h and 8h am in Brazilian schools), resulting in shorter sleep durations during weekdays (Carissimi et al., 2016CARISSIMI, A., DRESCH, F., MARTINS, A.C., LEVANDOVSKI, R.M., ADAN, A., NATALE, V., MARTONI, M. and HIDALGO, M.P., 2016. The influence of school time on sleep patterns of children and adolescents. Sleep Medicine, vol. 19, pp. 33-39. http://dx.doi.org/10.1016/j.sleep.2015.09.024. PMid:27198945.
http://dx.doi.org/10.1016/j.sleep.2015.0...
; Sousa et al., 2007SOUSA, I.C., ARAUJO, J.F. and DE AZEVEDO, C.V.M., 2007. The effect of a sleep hygiene education program on the sleep-wake cycle of Brazilian adolescent students. Sleep and Biological Rhythms, vol. 5, no. 4, pp. 251-258. http://dx.doi.org/10.1111/j.1479-8425.2007.00318.x.
http://dx.doi.org/10.1111/j.1479-8425.20...
, 2009SOUSA, I. C., LOUZADA, F. M. and AZEVEDO, C. V. M., 2009. Sleep-wake cycle irregularity and daytime sleepiness in adolescents on schooldays and on vacation days. Sleep Science, vol. 2, no. 1, pp. 30-35.). These students may attempt to compensate for this sleep deficit by sleeping up to 2 hours more on weekends (Sousa et al., 2007SOUSA, I.C., ARAUJO, J.F. and DE AZEVEDO, C.V.M., 2007. The effect of a sleep hygiene education program on the sleep-wake cycle of Brazilian adolescent students. Sleep and Biological Rhythms, vol. 5, no. 4, pp. 251-258. http://dx.doi.org/10.1111/j.1479-8425.2007.00318.x.
http://dx.doi.org/10.1111/j.1479-8425.20...
). Besides that, the effect of early school start times can be especially detrimental for evening-type students, leading to significant disadvantages compared to their morning-type peers, even in important exams such as those used for university entrance decision (Randler and Frech, 2006RANDLER, C. and FRECH, D., 2006. Correlation between morningness – eveningness and final school leaving exams. Biological Rhythm Research, vol. 37, no. 3, pp. 233-239. http://dx.doi.org/10.1080/09291010600645780.
http://dx.doi.org/10.1080/09291010600645...
). Moreover, research has also shown that early school start times can negatively impact the scholar performance of middle school students with an evening chronotype, further highlighting the importance of considering individual differences in sleep-wake patterns in educational settings (Arrona-Palacios et al., 2015ARRONA-PALACIOS, A., GARCÍA, A. and VALDEZ, P., 2015. Sleep–wake habits and circadian preference in Mexican secondary school. Sleep Medicine, vol. 16, no. 10, pp. 1259-1264. http://dx.doi.org/10.1016/j.sleep.2015.05.026. PMid:26429755.
http://dx.doi.org/10.1016/j.sleep.2015.0...
; Rique et al., 2014RIQUE, G.L.N., FERNANDES FILHO, G.M.C., FERREIRA, A.D.C. and DE SOUSA-MUÑOZ, R.L., 2014. Relationship between chronotype and quality of sleep in medical students at the Federal University of Paraiba, Brazil. Sleep Science, vol. 7, no. 2, pp. 96-102. http://dx.doi.org/10.1016/j.slsci.2014.09.004. PMid:26483910.
http://dx.doi.org/10.1016/j.slsci.2014.0...
; Fallone et al., 2002FALLONE, G., OWENS, J.A. and DEANE, J., 2002. Sleepiness in children and adolescents: clinical implications. Sleep Medicine Reviews, vol. 6, no. 4, pp. 287-306. http://dx.doi.org/10.1053/smrv.2001.0192. PMid:12531133.
http://dx.doi.org/10.1053/smrv.2001.0192...
; Shochat et al., 2014SHOCHAT, T., COHEN-ZION, M. and TZISCHINSKY, O., 2014. Functional consequences of inadequate sleep in adolescents: a systematic review. Sleep Medicine Reviews, vol. 18, no. 1, pp. 75-87. http://dx.doi.org/10.1016/j.smrv.2013.03.005. PMid:23806891.
http://dx.doi.org/10.1016/j.smrv.2013.03...
).

Therefore, we conducted a study to analyze the impact of chronotype on the subjective and school-declared performance of Brazilian full-time school students. Our goal was to answer if (a) the chronotypes affect the students’ school-declared performance, and (b) if there are performance differences between chronotypes. Based on previous research (Lund et al., 2010LUND, H.G., REIDER, B.D., WHITING, A.B. and PRICHARD, J.R., 2010. Sleep patterns and predictors of disturbed sleep in a large population of college students. The Journal of Adolescent Health, vol. 46, no. 2, pp. 124-132. http://dx.doi.org/10.1016/j.jadohealth.2009.06.016. PMid:20113918.
http://dx.doi.org/10.1016/j.jadohealth.2...
; Díaz-Morales and Escribano, 2013DÍAZ-MORALES, J.F. and ESCRIBANO, C., 2013. Circadian preference and thinking styles: implications for school achievement. Chronobiology International, vol. 30, no. 10, pp. 1231-1239. http://dx.doi.org/10.3109/07420528.2013.813854. PMid:24024592.
http://dx.doi.org/10.3109/07420528.2013....
; Rique et al., 2014RIQUE, G.L.N., FERNANDES FILHO, G.M.C., FERREIRA, A.D.C. and DE SOUSA-MUÑOZ, R.L., 2014. Relationship between chronotype and quality of sleep in medical students at the Federal University of Paraiba, Brazil. Sleep Science, vol. 7, no. 2, pp. 96-102. http://dx.doi.org/10.1016/j.slsci.2014.09.004. PMid:26483910.
http://dx.doi.org/10.1016/j.slsci.2014.0...
; Arrona-Palacios et al., 2015ARRONA-PALACIOS, A., GARCÍA, A. and VALDEZ, P., 2015. Sleep–wake habits and circadian preference in Mexican secondary school. Sleep Medicine, vol. 16, no. 10, pp. 1259-1264. http://dx.doi.org/10.1016/j.sleep.2015.05.026. PMid:26429755.
http://dx.doi.org/10.1016/j.sleep.2015.0...
; Fallone et al., 2002FALLONE, G., OWENS, J.A. and DEANE, J., 2002. Sleepiness in children and adolescents: clinical implications. Sleep Medicine Reviews, vol. 6, no. 4, pp. 287-306. http://dx.doi.org/10.1053/smrv.2001.0192. PMid:12531133.
http://dx.doi.org/10.1053/smrv.2001.0192...
; Randler and Frech, 2006RANDLER, C. and FRECH, D., 2006. Correlation between morningness – eveningness and final school leaving exams. Biological Rhythm Research, vol. 37, no. 3, pp. 233-239. http://dx.doi.org/10.1080/09291010600645780.
http://dx.doi.org/10.1080/09291010600645...
; Shochat et al., 2014SHOCHAT, T., COHEN-ZION, M. and TZISCHINSKY, O., 2014. Functional consequences of inadequate sleep in adolescents: a systematic review. Sleep Medicine Reviews, vol. 18, no. 1, pp. 75-87. http://dx.doi.org/10.1016/j.smrv.2013.03.005. PMid:23806891.
http://dx.doi.org/10.1016/j.smrv.2013.03...
; Beşoluk et al., 2011BEŞOLUK, S., ÖNDER, İ. and DEVECI, İ., 2011. Morningness-eveningness preferences and academic achievement of university students. Chronobiology International, vol. 28, no. 2, pp. 118-125. http://dx.doi.org/10.3109/07420528.2010.540729. PMid:21231873.
http://dx.doi.org/10.3109/07420528.2010....
) that has examined the effect of chronotype on scholar performance, we hypothesized that (a) morning chronotypes would have a positive effect on scholar performance, particularly in morning classes, and (b) evening chronotypes would have a negative effect during the same period. This study is, to our knowledge, the first to investigate the influence of chronotype on adolescent students’ performance in a full-time school.

2. Materials and Methods

2.1. Data availability statement

The datasets generated and analyzed during the current study are available in the Zenodo repository (see Cezário et al., 2022CEZÁRIO, R.R., FREITAS, D. and CHAHAD-EHLERS, S., 2022. Students' chronotype predicts performance in a Brazilian full-time middle school. Zenodo. Dataset. https://doi.org/10.5281/zenodo.7044899.
https://doi.org/10.5281/zenodo.7044899...
).

2.2. Written informed consent form

The coordinator of the Brazilian full-time middle school signed a Written Informed Consent Form prior to data collection on behalf of the students. Participation was voluntary. Data collection have been performed in accordance with the ethical principles of the Declaration of Helsinki (WMA, 2013WORLD MEDICAL ASSOCIATION - WMA, 2013. Declaration of Helsink - ethical principles for medical research involving human subjects. In: Proceedings of the 64th WMA General Assembly, 2013, Fortaleza. Ferney-Voltaire, França: WMA, pp. 1-4.). The data collection procedure was conducted in 2019 by RRC as part of his undergraduate thesis.

2.3. Research subjects

Fifty-five (n = 55) students (35 male and 20 female) aged 14 to 15 years participated in data collection. The students were from three different classrooms (A = 14, B = 20, and C = 21) of the 8th grade (i.e., middle school) of a full-time school from 7:30 a.m. to 4:30 p.m.). Only students with a minimum attendance of 75% were eligible to participate in data collection. The students’ performance was assessed based on their school-declared grade in three cognitive demanding subjects (Portuguese, Science, and Math) (see, Valdez et al., 2012VALDEZ, P., RAMÍREZ. and GARCÍA, A., 2012. Circadian rhythms in cognitive performance: implications for neuropsychological assessment. ChronoPhysiology and Therapy, pp. 81. http://dx.doi.org/10.2147/CPT.S32586.
http://dx.doi.org/10.2147/CPT.S32586...
; Zerbini et al., 2017ZERBINI, G., VAN DER VINNE, V., OTTO, L.K.M., KANTERMANN, T., KRIJNEN, W.P., ROENNEBERG, T. and MERROW, M., 2017. Lower school performance in late chronotypes: underlying factors and mechanisms. Scientific Reports, vol. 7, no. 1, pp. 4385. http://dx.doi.org/10.1038/s41598-017-04076-y. PMid:28663569.
http://dx.doi.org/10.1038/s41598-017-040...
) during the year 2019, which served as a proxy for their cognitive performance. These subjects were selected based on their relevance and frequency in the school curriculum as well as on the fact that they rely on different mental abilities, fluid (Science and Math subjects) and crystallized intelligence (Portuguese language subject) (Zerbini et al., 2017ZERBINI, G., VAN DER VINNE, V., OTTO, L.K.M., KANTERMANN, T., KRIJNEN, W.P., ROENNEBERG, T. and MERROW, M., 2017. Lower school performance in late chronotypes: underlying factors and mechanisms. Scientific Reports, vol. 7, no. 1, pp. 4385. http://dx.doi.org/10.1038/s41598-017-04076-y. PMid:28663569.
http://dx.doi.org/10.1038/s41598-017-040...
).

2.4. Assessing the students’ chronotype

To assess the students’ chronotype, we used the Morningness-Eveningness Questionnaire (MEQ) adapted for the Brazilian population (Benedito-Silva et al., 1990BENEDITO-SILVA, A.A., MENNA-BARRETO, L., MARQUES, N. and TENREIRO, S., 1990. A self-assessment questionnaire for the determination of morningness-eveningness types in Brazil. Progress in Clinical and Biological Research, vol. 341B, pp. 89-98. PMid:2217379.), which assigns a chronotype based on the individual’s circadian peaks in temperature (Horne and Östberg, 1976HORNE, J.A. and ÖSTBERG, O., 1976. A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms. International Journal of Chronobiology, vol. 4, no. 2, pp. 97-110. PMid:1027738.). The Brazilian MEQ contains 19 questions, each with a unique score ranging from 1 to 5. The total score is used to determine the individual’s chronotype, with scores of 70-86 indicating a definitely morning (MA) type, 59-69 indicating a moderately morning (MM) type, 42-58 indicating an indifferent (IN) type, 31-41 indicating a moderately evening (MV) type, and 16-30 indicating a definitely evening (VE) type (Benedito-Silva et al., 1990BENEDITO-SILVA, A.A., MENNA-BARRETO, L., MARQUES, N. and TENREIRO, S., 1990. A self-assessment questionnaire for the determination of morningness-eveningness types in Brazil. Progress in Clinical and Biological Research, vol. 341B, pp. 89-98. PMid:2217379.).

2.5. Assessing the students’ subjective performance

To further understand the correspondence between school-declared performance and subjective perception, we conducted a qualitative assessment of the students’ self-reported performance. Using a Likert scale ranging from 1 (very bad performance) to 5 (very good performance), we asked the students to rate their own performance, providing insights into their impressions and perspectives regarding their scholar achievement.

2.6. Statistical analysis

To address the effect of the chronotype on the students’ scholar performance we built a Generalized Linear Mixed Model (GLMM) by using ‘lme4’ package for R environment (Bates et al., 2015BATES, D., MÄCHLER, M., BOLKER, B. and WALKER, S., 2015. Fitting linear mixed-effects models using lme4. Journal of Statistical Software, vol. 67, no. 1, pp. 1-48. http://dx.doi.org/10.18637/jss.v067.i01.
http://dx.doi.org/10.18637/jss.v067.i01...
). We used the students’ school-declared performance as dependent variables, while the students’ chronotype, the school subjects and students’ classes were considered our independent variables. The distribution frequency of the students’ scholar performance was considered Gamma with a canonical inverse function for the mean values, and a Laplace integral approximation. The model optimizer used for the GLMM was “bobyqa” from ‘minqa’ package (Bates et al., 2014BATES, D., MULLEN, K.M., NASH, J.C. and VARADHAN, R., 2014 [viewed 15 February 2023]. minqa: Derivative-free optimization algorithms by quadratic approximation [online]. CRAN. Available from: http://optimizer.r-forge.r-project.org.1.2.4
http://optimizer.r-forge.r-project.org.1...
). The students were considered our variable of random effect.

Then, because our data was not normally distributed, we performed a non-parametric Kruskal-Wallis’ test to access the differences between students’ subjective and school-declared performance attributed to their chronotypes. Kruskal-Wallis’ test allow the comparison between three or more groups (i.e., independent variables) against a continuous variable (i.e., dependent or response variable) (Kruskal and Wallis, 1952KRUSKAL, W.H. and WALLIS, W.A., 1952. Use of ranks in one-criterion variance analysis. Journal of the American Statistical Association, vol. 47, no. 260, pp. 583-621. http://dx.doi.org/10.1080/01621459.1952.10483441.
http://dx.doi.org/10.1080/01621459.1952....
). Epsilon Squared (ɛ2) effect size is reported. Epsilon Squared assumes the value from 0 (indicating no relationship) to 1 (indicating a perfect relationship) between the variables (Cohen, 1992COHEN, J., 1992. A power primer. Psychological Bulletin, vol. 112, no. 1, pp. 155-159. http://dx.doi.org/10.1037/0033-2909.112.1.155. PMid:19565683.
http://dx.doi.org/10.1037/0033-2909.112....
). All statistical analysis were performed in R environment (R Core Team, 2022R CORE TEAM, 2022 [viewed 15 February 2023]. R: A language and environment for statistical computing [online]. Austria: R Foundation for Statistical Computing. Available from: https://www.R-project.org/
https://www.R-project.org/...
). The Kruskal-Wallis test was performed using the ‘jmv’ package for R environment (The Jamovi Project, 2022THE JAMOVI PROJECT, 2022. [viewed 15 February 2023]. jamovi (Version 2.3.0) [online]. Available from: https://www.jamovi.org
https://www.jamovi.org...
).

3. Results

3.1. Morningness-eveningness assessment and students’ school grade

The results of the MEQ showed that out of 55 students: none exhibited the definitely morning (MA) chronotype, 3 were moderately morning (MM), 39 were indifferent (IN), 7 were moderately evening (MV), and 6 were definitely evening (VE). The school schedule is reported (Table S1).

3.2. The effect of chronotype on students’ performance

Math is the only subject that shows a correlation between subjective and school-declared performance (p = 0.034) (Figure 1). There is little agreement between students’ perception and teachers’ evaluation of performance in Portuguese (p = 0.919) and Science (p = 0.929) (Figure 1). The Generalized Linear Mixed Model (GLMM) considering the students’ performance as dependent variable and the interaction between chronotype and school subjects as independent variable had the lowest Akaike Information Criterion (AIC) value (i.e., criteria for model selection) (Table 1). The model indicates that moderately evening (MV) chronotype is positively associated with performance in Portuguese classes (estimate = 0.038, p < 0.05) (Table 2; Figure 2), suggesting that performance is affected by the individuals’ chronotype. Despite the majority of Portuguese classes occurring before the students’ lunchtime (i.e., 11h55 to 12h55) during late morning (Table S1), they were not considered early. Additionally, the Kruskal-Wallis’ test indicated significant differences in the students’ school-declared performance across different school subjects that may be attributed to their chronotypes (Table 3). Notably, among the school subjects, the study of the Portuguese language was more impacted by the chronotype (Table 3).

Figure 1
Scatterplot of subjective-declared against school-declared performance for Portuguese (A), Science (B) and Math (C) subjects. The measures were found to be significantly correlated for Math (p = 0.034). There was little agreement between students' perception and teachers' evaluation of performance in Portuguese (p = 0.919) and Science (p = 0.929). To reduce data point superposition, subjective-declared performance was jittered.
Table 1
Generalized Linear Mixed Models (GLMM) showing Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC), log-Likelihood (logLik), Deviance, chi-square difference test (χ2), and probability value (P). The GLMM was built to unravel the relationship between students’ chronotype and performance. The students were treated as a random effect. Significant results are highlighted in bold (α = 0.05).
Table 2
Fixed effects for the Generalized Linear Mixed Model (GLMM) showing Estimate, Standard Error (SE), and t-value for each predictor. The GLMM examines the effect of students’ chronotype and school subjects (independent variables) on scholar performance (dependent variable), while considering the students as a random effect.
Figure 2
Scatterplot showing the impact of chronotype (MM, IN, MV, and VE) on school-declared performance for Portuguese (A), Science (B) and Math (C) subjects. The plot shows that moderately evening chronotypes demonstrate lower school-declared performance in Portuguese classes. MM = moderately morning; IN = indifferent; MV = moderately evening; VE = definitely evening chronotypes.
Table 3
Kruskal-Wallis’ tests showing chi-square difference test (χ2), Degree of Freedom (DF) and epsilon-squared (ɛ2) effect size considering the differences between students’ subjective and school-declared performance for Science, Portuguese, and Math, with students’ chronotype as the grouping variable. The tests showed a medium effect of chronotype on school-declared performance for Portuguese (ɛ2 = 0.14), and no significant effects for Science and Math.

4. Discussion

By using a morningness-eveningness questionnaire (MEQ) adapted for the Brazilian population, we were able to characterize the subjective sleep-wake cycle preferences (chronotype) of middle school students attending an early start time full-time school (from 7:30 a.m. to 4:30 p.m.). Our results showed that the students’ chronotype affects their school-declared performance, indicating a positive effect on Portuguese classes. Notably, although we expected moderately evening students to perform poorly, this was not the case, possibly due to the fact that most Portuguese classes were held during the late morning (between 9:25 a.m. and 12:55 p.m.) after the mid-morning break, which provided enough time for these students to become alert. Other studies showed similar patterns regarding language school subject, though their results were from schools of either morning, afternoon, or evening start times (Goldin et al., 2020GOLDIN, A.P., SIGMAN, M., BRAIER, G., GOLOMBEK, D.A. and LEONE, M.J., 2020. Interplay of chronotype and school timing predicts school performance. Nature Human Behaviour, vol. 4, no. 4, pp. 387-396. http://dx.doi.org/10.1038/s41562-020-0820-2. PMid:32042108.
http://dx.doi.org/10.1038/s41562-020-082...
; Zerbini et al., 2017ZERBINI, G., VAN DER VINNE, V., OTTO, L.K.M., KANTERMANN, T., KRIJNEN, W.P., ROENNEBERG, T. and MERROW, M., 2017. Lower school performance in late chronotypes: underlying factors and mechanisms. Scientific Reports, vol. 7, no. 1, pp. 4385. http://dx.doi.org/10.1038/s41598-017-04076-y. PMid:28663569.
http://dx.doi.org/10.1038/s41598-017-040...
). Indeed, evening-type students exhibit slightly higher grades in language subjects in evening school timing compared to out-of-phase, morning students. Even in schools of early start time the effect of chronotype on language grade is very low or almost absent (Goldin et al., 2020GOLDIN, A.P., SIGMAN, M., BRAIER, G., GOLOMBEK, D.A. and LEONE, M.J., 2020. Interplay of chronotype and school timing predicts school performance. Nature Human Behaviour, vol. 4, no. 4, pp. 387-396. http://dx.doi.org/10.1038/s41562-020-0820-2. PMid:32042108.
http://dx.doi.org/10.1038/s41562-020-082...
; Zerbini et al., 2017ZERBINI, G., VAN DER VINNE, V., OTTO, L.K.M., KANTERMANN, T., KRIJNEN, W.P., ROENNEBERG, T. and MERROW, M., 2017. Lower school performance in late chronotypes: underlying factors and mechanisms. Scientific Reports, vol. 7, no. 1, pp. 4385. http://dx.doi.org/10.1038/s41598-017-04076-y. PMid:28663569.
http://dx.doi.org/10.1038/s41598-017-040...
). These results highlight the importance of considering students’ chronotype when scheduling classes.

Chronotype is a crucial aspect of students’ lives from a (chrono)biological but also from a decision- and policy-making standpoint (Lund et al., 2010LUND, H.G., REIDER, B.D., WHITING, A.B. and PRICHARD, J.R., 2010. Sleep patterns and predictors of disturbed sleep in a large population of college students. The Journal of Adolescent Health, vol. 46, no. 2, pp. 124-132. http://dx.doi.org/10.1016/j.jadohealth.2009.06.016. PMid:20113918.
http://dx.doi.org/10.1016/j.jadohealth.2...
; Díaz-Morales and Escribano, 2013DÍAZ-MORALES, J.F. and ESCRIBANO, C., 2013. Circadian preference and thinking styles: implications for school achievement. Chronobiology International, vol. 30, no. 10, pp. 1231-1239. http://dx.doi.org/10.3109/07420528.2013.813854. PMid:24024592.
http://dx.doi.org/10.3109/07420528.2013....
; Rique et al., 2014RIQUE, G.L.N., FERNANDES FILHO, G.M.C., FERREIRA, A.D.C. and DE SOUSA-MUÑOZ, R.L., 2014. Relationship between chronotype and quality of sleep in medical students at the Federal University of Paraiba, Brazil. Sleep Science, vol. 7, no. 2, pp. 96-102. http://dx.doi.org/10.1016/j.slsci.2014.09.004. PMid:26483910.
http://dx.doi.org/10.1016/j.slsci.2014.0...
; Arrona-Palacios et al., 2015ARRONA-PALACIOS, A., GARCÍA, A. and VALDEZ, P., 2015. Sleep–wake habits and circadian preference in Mexican secondary school. Sleep Medicine, vol. 16, no. 10, pp. 1259-1264. http://dx.doi.org/10.1016/j.sleep.2015.05.026. PMid:26429755.
http://dx.doi.org/10.1016/j.sleep.2015.0...
; Fallone et al., 2002FALLONE, G., OWENS, J.A. and DEANE, J., 2002. Sleepiness in children and adolescents: clinical implications. Sleep Medicine Reviews, vol. 6, no. 4, pp. 287-306. http://dx.doi.org/10.1053/smrv.2001.0192. PMid:12531133.
http://dx.doi.org/10.1053/smrv.2001.0192...
; Randler and Frech, 2006RANDLER, C. and FRECH, D., 2006. Correlation between morningness – eveningness and final school leaving exams. Biological Rhythm Research, vol. 37, no. 3, pp. 233-239. http://dx.doi.org/10.1080/09291010600645780.
http://dx.doi.org/10.1080/09291010600645...
). For instance, students who are out of phase tend to experience lower subjective and school-declared performance due to their poorer sleep quality, in contrast to their entrained counterpart (Lund et al., 2010LUND, H.G., REIDER, B.D., WHITING, A.B. and PRICHARD, J.R., 2010. Sleep patterns and predictors of disturbed sleep in a large population of college students. The Journal of Adolescent Health, vol. 46, no. 2, pp. 124-132. http://dx.doi.org/10.1016/j.jadohealth.2009.06.016. PMid:20113918.
http://dx.doi.org/10.1016/j.jadohealth.2...
; Díaz-Morales and Escribano, 2013DÍAZ-MORALES, J.F. and ESCRIBANO, C., 2013. Circadian preference and thinking styles: implications for school achievement. Chronobiology International, vol. 30, no. 10, pp. 1231-1239. http://dx.doi.org/10.3109/07420528.2013.813854. PMid:24024592.
http://dx.doi.org/10.3109/07420528.2013....
; Rique et al., 2014RIQUE, G.L.N., FERNANDES FILHO, G.M.C., FERREIRA, A.D.C. and DE SOUSA-MUÑOZ, R.L., 2014. Relationship between chronotype and quality of sleep in medical students at the Federal University of Paraiba, Brazil. Sleep Science, vol. 7, no. 2, pp. 96-102. http://dx.doi.org/10.1016/j.slsci.2014.09.004. PMid:26483910.
http://dx.doi.org/10.1016/j.slsci.2014.0...
; Arrona-Palacios et al., 2015ARRONA-PALACIOS, A., GARCÍA, A. and VALDEZ, P., 2015. Sleep–wake habits and circadian preference in Mexican secondary school. Sleep Medicine, vol. 16, no. 10, pp. 1259-1264. http://dx.doi.org/10.1016/j.sleep.2015.05.026. PMid:26429755.
http://dx.doi.org/10.1016/j.sleep.2015.0...
; Fallone et al., 2002FALLONE, G., OWENS, J.A. and DEANE, J., 2002. Sleepiness in children and adolescents: clinical implications. Sleep Medicine Reviews, vol. 6, no. 4, pp. 287-306. http://dx.doi.org/10.1053/smrv.2001.0192. PMid:12531133.
http://dx.doi.org/10.1053/smrv.2001.0192...
; Randler and Frech, 2006RANDLER, C. and FRECH, D., 2006. Correlation between morningness – eveningness and final school leaving exams. Biological Rhythm Research, vol. 37, no. 3, pp. 233-239. http://dx.doi.org/10.1080/09291010600645780.
http://dx.doi.org/10.1080/09291010600645...
). In middle and high schools, poor sleep quality has been associated with a decline in quality of life, which manifests in various psychosocial disorders such as increased drug use and risk-taking behaviors, depressed mood, motor and cognitive deficits, and a decrease in academic performance (Wolfson and Carskadon, 1998WOLFSON, A.R. and CARSKADON, M.A., 1998. Sleep schedules and daytime functioning in adolescents. Child Development, vol. 69, no. 4, pp. 875-887. http://dx.doi.org/10.1111/j.1467-8624.1998.tb06149.x. PMid:9768476.
http://dx.doi.org/10.1111/j.1467-8624.19...
; Shochat et al., 2014SHOCHAT, T., COHEN-ZION, M. and TZISCHINSKY, O., 2014. Functional consequences of inadequate sleep in adolescents: a systematic review. Sleep Medicine Reviews, vol. 18, no. 1, pp. 75-87. http://dx.doi.org/10.1016/j.smrv.2013.03.005. PMid:23806891.
http://dx.doi.org/10.1016/j.smrv.2013.03...
; Wolfson and Carskadon, 2003WOLFSON, A.R. and CARSKADON, M.A., 2003. Understanding adolescent’s sleep patterns and school performance: a critical appraisal. Sleep Medicine Reviews, vol. 7, no. 6, pp. 491-506. http://dx.doi.org/10.1016/S1087-0792(03)90003-7. PMid:15018092.
http://dx.doi.org/10.1016/S1087-0792(03)...
; Fallone et al., 2002FALLONE, G., OWENS, J.A. and DEANE, J., 2002. Sleepiness in children and adolescents: clinical implications. Sleep Medicine Reviews, vol. 6, no. 4, pp. 287-306. http://dx.doi.org/10.1053/smrv.2001.0192. PMid:12531133.
http://dx.doi.org/10.1053/smrv.2001.0192...
; Randler and Frech, 2006RANDLER, C. and FRECH, D., 2006. Correlation between morningness – eveningness and final school leaving exams. Biological Rhythm Research, vol. 37, no. 3, pp. 233-239. http://dx.doi.org/10.1080/09291010600645780.
http://dx.doi.org/10.1080/09291010600645...
; Lund et al., 2010LUND, H.G., REIDER, B.D., WHITING, A.B. and PRICHARD, J.R., 2010. Sleep patterns and predictors of disturbed sleep in a large population of college students. The Journal of Adolescent Health, vol. 46, no. 2, pp. 124-132. http://dx.doi.org/10.1016/j.jadohealth.2009.06.016. PMid:20113918.
http://dx.doi.org/10.1016/j.jadohealth.2...
; Díaz-Morales, Escribano 2013DÍAZ-MORALES, J.F. and ESCRIBANO, C., 2013. Circadian preference and thinking styles: implications for school achievement. Chronobiology International, vol. 30, no. 10, pp. 1231-1239. http://dx.doi.org/10.3109/07420528.2013.813854. PMid:24024592.
http://dx.doi.org/10.3109/07420528.2013....
; Rique et al. 2014RIQUE, G.L.N., FERNANDES FILHO, G.M.C., FERREIRA, A.D.C. and DE SOUSA-MUÑOZ, R.L., 2014. Relationship between chronotype and quality of sleep in medical students at the Federal University of Paraiba, Brazil. Sleep Science, vol. 7, no. 2, pp. 96-102. http://dx.doi.org/10.1016/j.slsci.2014.09.004. PMid:26483910.
http://dx.doi.org/10.1016/j.slsci.2014.0...
; Arrona-Palacios et al. 2015ARRONA-PALACIOS, A., GARCÍA, A. and VALDEZ, P., 2015. Sleep–wake habits and circadian preference in Mexican secondary school. Sleep Medicine, vol. 16, no. 10, pp. 1259-1264. http://dx.doi.org/10.1016/j.sleep.2015.05.026. PMid:26429755.
http://dx.doi.org/10.1016/j.sleep.2015.0...
). These findings suggest that sleep quality is an essential component of overall health and that addressing sleep-related issues in students may improve their scholar performance and overall well-being.

Results show that moderately morning chronotypes tended to have a positive effect in students’ performance. Morning individuals exhibit a circadian temperature peak earlier than evening individuals as well as higher daytime temperature and lower post peak temperature (Horne and Östberg, 1976HORNE, J.A. and ÖSTBERG, O., 1976. A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms. International Journal of Chronobiology, vol. 4, no. 2, pp. 97-110. PMid:1027738.; Kerkhof and van Dongen, 1996KERKHOF, G.A. and VAN DONGEN, H.P.A., 1996. Morning-type and evening-type individuals differ in the phase position of their endogenous circadian oscillator. Neuroscience Letters, vol. 218, no. 3, pp. 153-156. http://dx.doi.org/10.1016/S0304-3940(96)13140-2. PMid:8945751.
http://dx.doi.org/10.1016/S0304-3940(96)...
; Adan et al., 2012ADAN, A., ARCHER, S.N., HIDALGO, M.P., DI MILIA, L., NATALE, V. and RANDLER, C., 2012. Circadian typology: a comprehensive review. Chronobiology International, vol. 29, no. 9, pp. 1153-1175. http://dx.doi.org/10.3109/07420528.2012.719971. PMid:23004349.
http://dx.doi.org/10.3109/07420528.2012....
). Moreover, the performance of moderately morning students increases during the day, whilst decreases during the night (Koukkari and Sothern, 2007KOUKKARI, W.L. and SOTHERN, R.B., 2007. Introducing biological rhythms: a primer on the temporal organization of life, with implications for Health, Society, Reproduction and the Natural Environment. New York: Springer Science & Business Media, Inc.; Wright Junior et al., 2002WRIGHT JUNIOR, K.P., HULL, J.T. and CZEISLER, C.A., 2002. Relationship between alertness, performance, and body temperature in humans. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology, vol. 283, no. 6, pp. R1370-R1377. http://dx.doi.org/10.1152/ajpregu.00205.2002. PMid:12388468.
http://dx.doi.org/10.1152/ajpregu.00205....
). Hence, morning-type students may not have the same difficulties as evening-type students when it comes to wake up early because of the school start time. Indeed, morning-type students usually have higher school-declared performance compared to evening students in schools which have early start time. For instance, morning-type students from an early start time Spanish middle school (aged between 10 and 14) declare higher subjective performance than evening students (Díaz-Morales and Escribano, 2013DÍAZ-MORALES, J.F. and ESCRIBANO, C., 2013. Circadian preference and thinking styles: implications for school achievement. Chronobiology International, vol. 30, no. 10, pp. 1231-1239. http://dx.doi.org/10.3109/07420528.2013.813854. PMid:24024592.
http://dx.doi.org/10.3109/07420528.2013....
) (see also Fallone et al., 2002FALLONE, G., OWENS, J.A. and DEANE, J., 2002. Sleepiness in children and adolescents: clinical implications. Sleep Medicine Reviews, vol. 6, no. 4, pp. 287-306. http://dx.doi.org/10.1053/smrv.2001.0192. PMid:12531133.
http://dx.doi.org/10.1053/smrv.2001.0192...
; Wolfson and Carskadon 2003WOLFSON, A.R. and CARSKADON, M.A., 2003. Understanding adolescent’s sleep patterns and school performance: a critical appraisal. Sleep Medicine Reviews, vol. 7, no. 6, pp. 491-506. http://dx.doi.org/10.1016/S1087-0792(03)90003-7. PMid:15018092.
http://dx.doi.org/10.1016/S1087-0792(03)...
, 1998WOLFSON, A.R. and CARSKADON, M.A., 1998. Sleep schedules and daytime functioning in adolescents. Child Development, vol. 69, no. 4, pp. 875-887. http://dx.doi.org/10.1111/j.1467-8624.1998.tb06149.x. PMid:9768476.
http://dx.doi.org/10.1111/j.1467-8624.19...
; Shochat et al., 2014SHOCHAT, T., COHEN-ZION, M. and TZISCHINSKY, O., 2014. Functional consequences of inadequate sleep in adolescents: a systematic review. Sleep Medicine Reviews, vol. 18, no. 1, pp. 75-87. http://dx.doi.org/10.1016/j.smrv.2013.03.005. PMid:23806891.
http://dx.doi.org/10.1016/j.smrv.2013.03...
). Nonetheless, the positive effect of the evening chronotype on the students’ performance may be an artifact caused by the subjective character of the MEQ as the students’ subjective performance did not correlate with their school-declared performance (i.e., the performance obtained in the school tests and schoolwork); or yet, as our study suggest, the full-time school may be the cause of this effect of the chronotype on the students’ performance.

Meanwhile, the definitely-evening chronotype tended to have a negative effect on the students’ performance. Perhaps a larger sample size would enable us to better understand the chronotype effects on definitely-evening individuals, who are known to be even more affected by early start times in schools. In Brazilian schools, which typically start between 7 and 8 am, evening-type students may struggle to wake up early and experience significant performance disparities compared to morning-type students. This finding is consistent with results from German high schools, where evening-type students have been found to perform worse on school exams than morning-type students (Randler and Frech, 2006RANDLER, C. and FRECH, D., 2006. Correlation between morningness – eveningness and final school leaving exams. Biological Rhythm Research, vol. 37, no. 3, pp. 233-239. http://dx.doi.org/10.1080/09291010600645780.
http://dx.doi.org/10.1080/09291010600645...
). In their final year in high school, the final exams of these students are used for university entrance decisions, so a poor school performance may negatively affect their future life choices (Randler and Frech, 2006RANDLER, C. and FRECH, D., 2006. Correlation between morningness – eveningness and final school leaving exams. Biological Rhythm Research, vol. 37, no. 3, pp. 233-239. http://dx.doi.org/10.1080/09291010600645780.
http://dx.doi.org/10.1080/09291010600645...
). Once in university, because of the early university start time out of phase students (i.e., evening-type students) also suffer from sleep deprivation and in consequence achieve lower academic performance (Beşoluk et al., 2011BEŞOLUK, S., ÖNDER, İ. and DEVECI, İ., 2011. Morningness-eveningness preferences and academic achievement of university students. Chronobiology International, vol. 28, no. 2, pp. 118-125. http://dx.doi.org/10.3109/07420528.2010.540729. PMid:21231873.
http://dx.doi.org/10.3109/07420528.2010....
; Rique et al., 2014RIQUE, G.L.N., FERNANDES FILHO, G.M.C., FERREIRA, A.D.C. and DE SOUSA-MUÑOZ, R.L., 2014. Relationship between chronotype and quality of sleep in medical students at the Federal University of Paraiba, Brazil. Sleep Science, vol. 7, no. 2, pp. 96-102. http://dx.doi.org/10.1016/j.slsci.2014.09.004. PMid:26483910.
http://dx.doi.org/10.1016/j.slsci.2014.0...
; Medeiros et al., 2001MEDEIROS, A.L.D., MENDES, D.B.F., LIMA, P.F. and ARAUJO, J.F., 2001. The relationships between sleep-wake cycle and academic performance in medical students. Biological Rhythm Research, vol. 32, no. 2, pp. 263-270. http://dx.doi.org/10.1076/brhm.32.2.263.1359.
http://dx.doi.org/10.1076/brhm.32.2.263....
). As sleep deprivation have chronic effects on the students’ life quality and had become a serious public health issue, schools and universities should adopt measures to circumvent this problem. The partnership between sleep scientists and educators should allow a better understanding of how sleep patterns impact scholar performance (Wolfson and Carskadon, 1998WOLFSON, A.R. and CARSKADON, M.A., 1998. Sleep schedules and daytime functioning in adolescents. Child Development, vol. 69, no. 4, pp. 875-887. http://dx.doi.org/10.1111/j.1467-8624.1998.tb06149.x. PMid:9768476.
http://dx.doi.org/10.1111/j.1467-8624.19...
; Shochat et al., 2014SHOCHAT, T., COHEN-ZION, M. and TZISCHINSKY, O., 2014. Functional consequences of inadequate sleep in adolescents: a systematic review. Sleep Medicine Reviews, vol. 18, no. 1, pp. 75-87. http://dx.doi.org/10.1016/j.smrv.2013.03.005. PMid:23806891.
http://dx.doi.org/10.1016/j.smrv.2013.03...
; Wolfson and Carskadon, 2003WOLFSON, A.R. and CARSKADON, M.A., 2003. Understanding adolescent’s sleep patterns and school performance: a critical appraisal. Sleep Medicine Reviews, vol. 7, no. 6, pp. 491-506. http://dx.doi.org/10.1016/S1087-0792(03)90003-7. PMid:15018092.
http://dx.doi.org/10.1016/S1087-0792(03)...
; Mazzilli Louzada and Pereira, 2019MAZZILLI LOUZADA, F. and PEREIRA, S.I.R., 2019. Adolescents’ sleep/wake patterns and school schedules: towards flexibility. Biological Rhythm Research, vol. 50, no. 1, pp. 78-84. http://dx.doi.org/10.1080/09291016.2018.1491263.
http://dx.doi.org/10.1080/09291016.2018....
). Policymakers and researchers should develop targeted interventions to increase students’ sleep hygiene, prevent the negative effects of an out-of-phase chronotype on performance, and promote better scholar outcomes (Wolfson and Carskadon, 1998WOLFSON, A.R. and CARSKADON, M.A., 1998. Sleep schedules and daytime functioning in adolescents. Child Development, vol. 69, no. 4, pp. 875-887. http://dx.doi.org/10.1111/j.1467-8624.1998.tb06149.x. PMid:9768476.
http://dx.doi.org/10.1111/j.1467-8624.19...
; Shochat et al., 2014SHOCHAT, T., COHEN-ZION, M. and TZISCHINSKY, O., 2014. Functional consequences of inadequate sleep in adolescents: a systematic review. Sleep Medicine Reviews, vol. 18, no. 1, pp. 75-87. http://dx.doi.org/10.1016/j.smrv.2013.03.005. PMid:23806891.
http://dx.doi.org/10.1016/j.smrv.2013.03...
; Wolfson and Carskadon, 2003WOLFSON, A.R. and CARSKADON, M.A., 2003. Understanding adolescent’s sleep patterns and school performance: a critical appraisal. Sleep Medicine Reviews, vol. 7, no. 6, pp. 491-506. http://dx.doi.org/10.1016/S1087-0792(03)90003-7. PMid:15018092.
http://dx.doi.org/10.1016/S1087-0792(03)...
).

Additionally, several unique factors of the Brazilian full-time middle school that was studied may have contributed to the observed effects of chronotypes on school-declared performance, especially the positive response of moderately evening students in language subjects. First, the school schedule has its start time at 7h30 in the morning, which is 30 minutes later than many other Brazilian schools. This small delay led to a shift in students’ bedtimes and have a substantial positive impact on their mood (Owens et al., 2017OWENS, J.A., DEARTH-WESLEY, T., HERMAN, A.N., OAKES, J.M. and WHITAKER, R.C., 2017. A quasi-experimental study of the impact of school start time changes on adolescent sleep. Sleep Health, vol. 3, no. 6, pp. 437-443. http://dx.doi.org/10.1016/j.sleh.2017.09.001. PMid:29157637.
http://dx.doi.org/10.1016/j.sleh.2017.09...
). Second, along with the traditional school subjects (see Brasil, 1996BRASIL, 1996 [viewed 15 February 2023]. Lei nº 9.394, de 20 de Dezembro de 1996. Estabelece as diretrizes e bases da educação nacional [online]. Diário Oficial da República Federativa do Brasil, Brasilia, 23 dezembro. Available from: http://www.planalto.gov.br/ccivil_03/leis/l9394.htm
http://www.planalto.gov.br/ccivil_03/lei...
) the full time-school studied here offers subjects such as (i) “life project”, where students discuss their aspirations; (ii) “elective courses”, which allow students to diversify their learning; and (iii) “guidance”, which provides students with an opportunity to resolve any doubts they may have about their coursework. Third, the larger number of breaks between the classes in the full-time school, such as 9:10 to 9:25 am and 11:55 am to 12:55 pm, compared to non-full-time schools, could provide students with an opportunity to interact with each other, eat their snacks, and recharge their energy. Future studies should explore these factors further to determine their specific contributions to the observed effects of chronotype on scholar performance.

In sum, the present study add evidence demonstrating the impact of individual chronotypes on the scholar performance of middle school students attending to full-time schools. Our results support the hypothesis that evening-type students tended to have worse performance than morning-type students in early start time schools. Additionally, the results suggest that chronotype is a significant predictor of scholar performance and that scholar performance are partially because of chronotype. We conclude that future studies should address the relative effects that sleep deprivation have on the students’ school and academic performance along with their socioeconomic and cultural context. A larger sample of male and female subjects of different age (Duarte et al., 2014DUARTE, L.L., MENNA-BARRETO, L., MIGUEL, M.A.L., LOUZADA, F., ARAÚJO, J., ALAM, M., AREAS, R. and PEDRAZZOLI, M., 2014. Chronotype ontogeny related to gender. Brazilian Journal of Medical and Biological Research, vol. 47, no. 4, pp. 316-320. http://dx.doi.org/10.1590/1414-431X20143001. PMid:24714814.
http://dx.doi.org/10.1590/1414-431X20143...
; Koukkari and Sothern, 2007KOUKKARI, W.L. and SOTHERN, R.B., 2007. Introducing biological rhythms: a primer on the temporal organization of life, with implications for Health, Society, Reproduction and the Natural Environment. New York: Springer Science & Business Media, Inc.) and from different locations (Leocadio-Miguel et al., 2017LEOCADIO-MIGUEL, M.A., LOUZADA, F.M., DUARTE, L.L., AREAS, R.P., ALAM, M., FREIRE, M.V., FONTENELE-ARAUJO, J., MENNA-BARRETO, L. and PEDRAZZOLI, M., 2017. Latitudinal cline of chronotype. Scientific Reports, vol. 7, no. 1, pp. 5437. http://dx.doi.org/10.1038/s41598-017-05797-w. PMid:28710358.
http://dx.doi.org/10.1038/s41598-017-057...
; Koukkari and Sothern, 2007KOUKKARI, W.L. and SOTHERN, R.B., 2007. Introducing biological rhythms: a primer on the temporal organization of life, with implications for Health, Society, Reproduction and the Natural Environment. New York: Springer Science & Business Media, Inc.) may provide greater support to our results. As previously (Shochat et al., 2014SHOCHAT, T., COHEN-ZION, M. and TZISCHINSKY, O., 2014. Functional consequences of inadequate sleep in adolescents: a systematic review. Sleep Medicine Reviews, vol. 18, no. 1, pp. 75-87. http://dx.doi.org/10.1016/j.smrv.2013.03.005. PMid:23806891.
http://dx.doi.org/10.1016/j.smrv.2013.03...
) suggested, interventions designed to promote healthy sleep practices in school and university students are needed.

Acknowledgements

This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001. DF thanks to Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq - Pq - 1C). Authors thank Mr. Sergio Ricardo Pizano Rodrigues, Sebastião de Oliveira Rocha State School, São Carlos, SP, for his assistance.

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Publication Dates

  • Publication in this collection
    02 June 2023
  • Date of issue
    2023

History

  • Received
    15 Feb 2023
  • Accepted
    28 Apr 2023
Instituto Internacional de Ecologia R. Bento Carlos, 750, 13560-660 São Carlos SP - Brasil, Tel. e Fax: (55 16) 3362-5400 - São Carlos - SP - Brazil
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