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The bimodal preference is a fourth diurnal preference proposed by re-scoring the Morningness-Eveningness Questionnaire. The present work aimed to describe the prevalence of the bimodal preference in a sample of undergraduate students and to characterize the bimodal type in terms of their health and sleep-related outcomes. A web-based cross-sectional study conducted between September 2018 and March 2021 (convenience sampling method). The sample was composed of undergraduate students who completed an electronic form that included the Morningness and Eveningness Questionnaire, the Pittsburgh Sleep Quality Index, the Self-Compassion Scale, the Epworth Sleepiness Scale, the Hospital Anxiety and Depression Scale, and the World Health Organization Subjective Well-Being Index. The final sample consisted of 615 students (82% female, mean age: 23.4 ± 6.5 years), of whom 108 (18%) had positive bimodality indexes. Bimodal subjects comprised 48 students, 8% of the total sample. Bimodal subjects had poorer subjective sleep quality, more daytime sleepiness, lower subjective well-being, greater anxiety and depression symptoms, and lower self-compassion than morning and/or intermediate types; they did not differ from evening types. The description of bimodal diurnal preference in this population may be of interest for the design of academic policies more in line with the circadian reality of students.

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Introduction: Adolescence is marked by physiological and social changes, such as puberty, increased responsibilities and earlier school start times. This often leads to insufficient sleep on school nights and the need to compensate for lost sleep on weekends, causing a misalignment between biological and social times, which has been termed social jetlag (SJL). SJL triggers stress responses and is associated with several negative health outcomes, including higher cardiometabolic risk in adults. In adolescence, however, SJL has only been consistently related to increases in adiposity but its association with other cardiometabolic indicators are unclear. Method: In a sample of 278 healthy early adolescents (9-15 years of age; 168 girls) we investigated: 1) whether self-reported SJL is associated (using path analyses) with a cardiometabolic status latent factor obtained by testing the best fitting model via confirmatory factor analyses from an initial set of eight indicators [body mass index (BMI), waist/height ratio, triglyceride concentration, diastolic and systolic blood pressure, glycated hemoglobin, total cholesterol/high-density lipoprotein ratio (chol/HDL), and % body fat]; and 2) whether age and/or pubertal status influence the association between SJL and cardiometabolic status. Result: We found that, for girls, higher SJL was associated with more adverse cardiometabolic latent scores (the shared variance of BMI, waist/height ratio, chol/HDL and systolic blood pressure, which had acceptable model fit indices). However, the role of age and pubertal status in this association was unclear for both sexes. Discussion: SJL was associated with adverse cardiometabolic latent traits beyond increases in adiposity in this observational study in early female adolescents. Because disruptions of circadian rhythms are believed to lead to dysregulated energy homeostasis and not vice-versa, our findings highlight the need for sleep interventions in adolescence to help reduce the global burden of cardiometabolic ill health, especially in girls.

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Circadian hygiene, a concept not to be confused with the notion of public or social hygiene, should be discussed among experts and society. Light-dark cycles and other possible synchronizers of the human circadian timing system affect ways of life, including sleeping, eating, working and physical activity. Some of these behaviors have also been investigated individually as synchronizers (e.g., eating times). Therefore, the knowledge held today about circadian rhythms, and their implications for health, allows future perspectives in this field to be mapped. The present article summarizes the latest knowledge on factors influencing circadian rhythms to discuss a perspective for the future of health promotion based on circadian hygiene. However, it is important to highlight that circadian hygiene is the product of an imbrication of individual and societal involvement. First, it is important to adopt practices and devise public health policies in line with circadian hygiene. Second, individual healthy habits require internal rhythms to be examined. Last, the research agenda on circadian hygiene can be developed on a public as well as individual level, raising the question as to how much society is willing to embrace this change.

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Introdução: na Introdução: Na saúde infantil, o sono desempenha um papel significativo, especialmente na maturação física e cognitiva e nas capacidades de lidar com estresse, regular emoções e socializar.Objetivo: analisar hábitos do sono infantil ao longo do primeiro ano de vida e fatores associados aos despertares noturnos segundo percepções maternas.Método: estudo longitudinal, prospectivo, com acompanhamento de 144 mães e crianças no primeiro mês, terceiro/quarto mês e 12º/13º mês de idade, de um município de médio porte do interior paulista, Brasil. Hábitos de sono foram analisados com medidas de tendência central e dispersão e testes de associação válido Qui-quadrado e Exato de Fisher, nível de significância α=0,05.Resultados: o local predominante onde as crianças dormem é o mesmo quarto e mesma cama dos cuidadores parentais. A maior parte das crianças dorme em decúbito lateral e dorsal. Tempo médio de sono foi 12,5h no primeiro mês, 11,5h no terceiro/quarto mês e 11,5h no 12º/13º mês. Tempo médio do sono noturno aumentou e sono diurno diminuiu. Do primeiro mês para o 12° mês de vida, não houve mudanças nos despertares noturnos. Percepção do sono como problema aumentou de 4% para 9% entre as participantes.Conclusão: três momentos no primeiro ano de vida trazem características dos hábitos do sono infantil, sobre local onde as crianças dormem, posição de dormir, tempo médio de sono e despertares noturnos, sugerindo a importância de informações obtidas longitudinalmente. Despertares noturnos mostraram-se associados à ocorrência do desmame e à percepção materna de considerar o sono da criança um problema.

Introduction: in children's health, sleep plays a significant role, especially in physical and cognitive maturation and in the abilities to deal with stress, regulate emotions and socialize.Objective: to analyze children's sleep habits during the first year of life and factors associated with nighttime awakenings according to maternal perceptions.Methods: a longitudinal, prospective study, with follow-up of 144 mothers and their children in the first month, third/fourth month and 12th/13th month of age, in a medium-sized city in the interior of São Paulo, Brazil. Sleep habits were analyzed using measures of central tendency and dispersion and valid association tests Chi-square and Fisher's exact, significance level α=0.05.Results: the predominant place where children sleep is the same room and bed as the parental caregivers. Most children sleep in the lateral and dorsal decubitus position. Mean sleep time was 12:30h in the first month, 11:30h in the third/fourth month and 11:24h in the 12th month. Mean nighttime sleep time increased and daytime sleep decreased. From the first month to the 12th month of life, there were no changes in nocturnal awakenings. Perception of sleep as a problem increased from 4% to 9% among participants.Conclusion: three moments in the first year of life show characteristics of children's sleep habits, about where children sleep, sleeping position, average sleep time and nocturnal awakenings, suggesting the importance of information obtained longitudinally. Nocturnal awakenings were associated with the occurrence of weaning and the maternal perception about child sleep as a problem.

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Introduction: the great increase in childhood obesity rates is well documented in the scientific literature. However, the influence of diet on sleep quality in children and adolescents still needs further research in order to be better understood. The objective of this study was to evaluate the association between diet and sleep characteristics and in children and adolescents with obesity. Methods: observational analytical cross-sectional study with prospective data collection. Forty-three children and adolescents aged between 6 and 13 years diagnosed with obesity and treated at a public tertiary care institution participated in the study. The 6-day Food Intake Registry was used to evaluate the intake of energy and macronutrients. To investigate the risk of sleep disturbances and to know the routine and characteristics of sleeping habits, the Sleep Disturbance Scale for Children (SDSC) questionnaire was used. Results: and discussion: Food intake showed association with Sleep Breathing Disorders (SBD) and Sleep Wake Transition Disorders (SWTD). The sum of all SDSC factors demonstrated the presence of pathological sleep in most patients (n = 25).

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This study aims to describe the athletes' sleep regularity using the Sleep Regularity Index (SRI) and determine whether factors, such as sex, competitive level and sport type, could affect the sleep/wake rhythm. It is a descriptive, cross-sectional study consisting of 172 athletes (25 ± 7 y old; 45 women). Seventy-three competed in team sports and 99 in individual sports. Furthermore, 56 competed in the international level, 95 in the national and 21 in the regional. We recorded the SRI values for at least 5 d via continuous actigraphy. We recorded a mean SRI value of 73 ± 12. We found no significant differences between athletes' sleep parameters in relation to sleep regularity. Furthermore, SRI data showed no correlations (Spearman's ρ) with sleep parameters, bed time and wake time. Female athletes (p = 0.001) and individual sport athletes (p = 0.001) reported better sleep regularity than their counterparts. International-level athletes reported better sleep regularity than those in other competitive levels (national: p = 0.001; regional: p = 0.024). Our study showed that international level athletes, female athletes and individual sport athletes reported better sleep regularity. Additionally, SRI data showed no correlation with athletes' sleep parameters, bed and wake time.

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OBJECTIVE: We tested the effect of later school start time (LSST) by 1 hour during 1 week on sleep, sleepiness, and mood profile using within-subject design. DESIGN: A within-subject 3-weeks-long interventional study. A baseline week with school starting at 7:30 AM (week A), followed by an intervention week with school starting at 8:30 AM (week B), and a recovery week with school start time back to 7:30 AM (week C). Mixed model for repeated measures analysis was applied to test for the LSST effect between weeks. SETTING: A private high school with high level of socioeconomic status. PARTICIPANTS: Forty-eight adolescents from 3 different high school years. MEASUREMENTS: Participants were invited to wear actigraphs continuously during the 3 experimental weeks. Somnolence was obtained every school day twice, at arrival and before departure of school. Sleep quality and mood profile were evaluated by standard measures by the end of each school week, resulting in 3 repeated measures for each variable. RESULTS: Thirty-eight adolescents completed the study. Adolescents woke up later during week B (7:42 ± 00:30) in comparison to weeks A (6:54 ± 00:12) and C (6:46 ± 00:15) (p < .001), with no significant change on sleep onset between weeks (p = .657), resulting in a longer sleep duration in week B (p < .001). Significant improvements on sleepiness and mood profile were also reported during week B. CONCLUSIONS: Starting school later was effective in improving multiple aspects from sleep patterns, subjective sleepiness, and mood profile.

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OBJECTIVE: To investigate the occurrence of daytime sleepiness and associated sleep factors in a sample of elementary school students who attended school in the afternoon schedule. METHODS: Sleep data from 363 Brazilian public school students (12.78 ± 1.36 years, 206 girls) were obtained by applying questionnaires in classrooms. All subjects attended school in the afternoon schedule, with classes starting between 1:00 and 1:20 p.m. Daytime sleepiness was assessed by the pediatric daytime sleepiness scale; sleep quality, by the mini-sleep questionnaire; and sleep patterns and chronotypes, by the Munich chronotype questionnaire. Scores equal to or greater than 15 pediatric daytime sleepiness scale points were considered as excessive daytime sleepiness. The predictive power of sleep variables on daytime sleepiness was evaluated by a multiple linear regression. RESULTS: The subjects in the sample had an average time in bed greater than nine hours both on school days and on weekends. Nevertheless, 52.1% had an average pediatric daytime sleepiness scale score equal to or greater than 15 points, indicative of excessive daytime sleepiness. As for their quality of sleep, 41.1% had a very altered sleep. We observed, by a multiple linear regression, that quality of sleep (ß = 0.417), chronotype (ß = 0.174), mid-sleep on school days (ß = 0.138), and time in bed (ß = - 0.091) were all significant in predicting daytime sleepiness. CONCLUSION: This study showed the occurrence of excessive daytime sleepiness in non-sleep deprived students who attended school in the afternoon. The worst quality of sleep and eveningness had a greater predictive power on daytime sleepiness than time in bed. Therefore, we must consider other factors in addition to sleep duration when planning interventions for daytime sleepiness.

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ABSTRACT OBJECTIVE To investigate the occurrence of daytime sleepiness and associated sleep factors in a sample of elementary school students who attended school in the afternoon schedule. METHODS Sleep data from 363 Brazilian public school students (12.78 ± 1.36 years, 206 girls) were obtained by applying questionnaires in classrooms. All subjects attended school in the afternoon schedule, with classes starting between 1:00 and 1:20 p.m. Daytime sleepiness was assessed by the pediatric daytime sleepiness scale; sleep quality, by the mini-sleep questionnaire; and sleep patterns and chronotypes, by the Munich chronotype questionnaire. Scores equal to or greater than 15 pediatric daytime sleepiness scale points were considered as excessive daytime sleepiness. The predictive power of sleep variables on daytime sleepiness was evaluated by a multiple linear regression. RESULTS The subjects in the sample had an average time in bed greater than nine hours both on school days and on weekends. Nevertheless, 52.1% had an average pediatric daytime sleepiness scale score equal to or greater than 15 points, indicative of excessive daytime sleepiness. As for their quality of sleep, 41.1% had a very altered sleep. We observed, by a multiple linear regression, that quality of sleep (β = 0.417), chronotype (β = 0.174), mid-sleep on school days (β = 0.138), and time in bed (β = - 0.091) were all significant in predicting daytime sleepiness. CONCLUSION This study showed the occurrence of excessive daytime sleepiness in non-sleep deprived students who attended school in the afternoon. The worst quality of sleep and eveningness had a greater predictive power on daytime sleepiness than time in bed. Therefore, we must consider other factors in addition to sleep duration when planning interventions for daytime sleepiness.

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BACKGROUND: The prevalence of chronic sleep restriction during adolescence is a major public health issue. Napping has been adopted to alleviate sleep pressure complaints. However, it also has the potential to amplify sleep restriction due to a vicious cycle triggered by delayed sleep times. The aim of this study was to investigate sleep and napping habits in a sample of Brazilian adolescents. METHODS: This study enrolled 1554 high school students and included the evaluation of sleep times, daytime sleepiness, sleep quality, and circadian preference. The students were asked about their napping routine, ie its frequency and duration per week. RESULTS: The adolescent sleep recommendation was achieved by only 27.6% of the sample. Napping habit was reported by 58.1%, with 36.2% of nappers informing naps in 1-2 times per week. Prolonged naps were reported by 44.9% of nappers. Nappers had later median bedtime (23:30) and reduced time in bed (TIB) (median = 07:00 h) compared to non-nappers. The frequency of nappers who did not achieve satisfactory TIB was higher than non-nappers. In addition, nappers reported increased daytime sleepiness and poor sleep quality. Later bedtimes and reduced TIB were associated with longer nap duration. Increased sleepiness and poor sleep quality were linked to a higher nap frequency. CONCLUSIONS: This exploratory survey demonstrated a severe sleep restriction faced by Brazilian adolescents. Napping can be an efficient strategy to counteract sleep restriction, but it needs to be adopted with caution due to the detrimental effects of frequent and prolonged naps on nocturnal sleep.

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Social jetlag (SJL) causes impairment of academic achievement; on the other hand, the personality factor of conscientiousness is related to better grades. We evaluated the impact of conscientiousness on the academic consequences of social jetlag. Undergraduate students (n = 556) were evaluated throughout their first 3 years of university education. Conscientiousness, as a mediating factor in the structural equation modeling, explained 20% of the effect of SJL on academic achievement. This is the first cohort study to evaluate the mediating effect of personality on the consequences of SJL.

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Parkinson's disease (PD) is a progressive neurodegenerative disease, with a worldwide incidence of 1% in individuals >60 years of age. Its primary characteristics include postural impairments and changes in circadian rhythms. The authors investigated the association between postural impairment and changes in circadian rhythms in 24 PD subjects diagnosed with stages 1 to 3 on the Hoehn-Yard (HY) scale and regularly used dopaminergic medication for at least 1 year (experimental group - EG) and 24 healthy elderly individuals without a history of neurological impairment as the control group (CG). Static balance tests using a force plate were performed, and activity/rest rhythm, according to the relative amplitude of L5 and M10 values, was monitored for seven consecutive days using actimetry. The results indicated differences in posturographic indicators of mediolateral displacement (ML) [EG, 4.71 ± 0.85 mm; CG, 2.79 ± 0.53 mm (p < .0001)] and anteroposterior displacement of the center of pressure (COP) [EG, 5.61 ± 2.43 mm; CG, 8.23 ± 1.72 mm (< 0.0001)], ML velocity of the COP [EG, 2.39 ± 0.83 mm/s; CG, 1.40 ± 0.18 mm/s (p < .0001)], and total distance of the COP in the tandem stance condition [EG, 227.6 ± 75 mm; CG, 53.4 ± 6.1 mm (p < .0001)] between the EG and CG. There was no correlation between relative amplitude and posturographic data for the EG. Postural impairments were verified in comparing the EG and CG; however, there was no association between posturographic indicators and activity/rest rhythm.

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Studies focusing on human rhythmicity show that human circadian rhythm suffers constant changes across lifespan. Changes in rest-activity patterns can be studied through nonparametric variables of actigraphy: L5 (an individual's least active 5 h), M10 (an individual's most active 10 h) and RA (relative amplitude of the rest-activity rhythm). The variable RA is the normalized difference between L5 and M10 - the higher the RA, the greater the difference between these two variables. This study used the data bank of the Human Chronobiology Laboratory of Federal University of Paraná (Brazil). It analyzed actimetric data of 93 children between 4 and 11 years of age in their naturalistic context in order to describe the development of nonparametric variables. Correlation between age and L5 was significantly negative (rho = - 0.29, p = 0.004), while correlation between age and RA was significantly positive (rho = 0.31, p = 0.003). The variables M10, sL5 (start of L5) and sM10 (start of M10) did not show significant correlation to age. Furthermore, there were no statistical differences between genders. The population of this study, healthy children, has been poorly assessed by similar literature. Through our results, we have demonstrated that, as children age, L5 significantly decreases, which reflects a smaller fragmentation of circadian rhythm. As an expected consequence, RA significantly increases. In other words, these nonparametric variables of actimetry successfully demonstrate that children tend to reduce nocturnal activity as they age, a phenomenon that reflects the ongoing consolidation of circadian rhythm.

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Parkinson's disease (PD) is a chronic disorder that presents a range of premotor signs, such as sleep disturbances and cognitive decline, which are key non-motor features of the disease. Increasing evidence of a possible association between sleep disruption and the neurodegenerative process suggests that sleep impairment could produce a detectable metabolic signature on the disease. In order to integrate neurocognitive and metabolic parameters, we performed untargeted and targeted metabolic profiling of the rotenone PD model in a chronic sleep restriction (SR) (6 h/day for 21 days) condition. We found that SR combined with PD altered several behavioural (reversal of locomotor activity impairment; cognitive impairment; delay of rest-activity rhythm) and metabolic parameters (branched-chain amino acids, tryptophan pathway, phenylalanine, and lipoproteins, pointing to mitochondrial impairment). If combined, our results bring a plethora of parameters that represents reliable early-phase PD biomarkers which can easily be measured and could be translated to human studies.

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There is still insufficient data about the characteristics and clinical significance of the bimodal chronotype. We evaluated more than 1000 students with Morningness-Eveningness Questionnaire, Munich Chronotype Questionnaire (MCTQ), Pittsburgh Sleep Quality Index and 36-item Short Form Health Survey. Twelve percent of the sample was bimodal and they showed similar results to intermediate chronotype in MCTQ-chronotype and social jetlag, both different from morning and evening chronotypes. However, their quality of life and sleep quality were similar to evening types, both different from morning and intermediate types. We discuss if being bimodal would be a maladaptive aspect of circadian preference.

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To characterize circadian rest-activity rhythm in COPD, 26 cases (66.9 ± 8.5y) and 15 controls (63.0 ± 10.7y) were assessed by actimetry. Rhythm fragmentation was measured by intradaily variability (IV), while synchronization to the 24-h light-dark cycle was measured by interdaily stability (IS). The average activity during the least active 5-h period (L5) and the average activity during the most active 10-h period (M10) were used to calculate the relative amplitude mean [RAm = (M10-L5)/(M10+L5)]. COPD patients presented higher IVm (0.242 ± 0.097 vs 0.182 ± 0.063) and L5 (36.849 ± 18.239 vs 19.888 ± 12.268) and lower RAm (0.696 ± 0.134 vs 0.833 ± 0.093) than controls. Future studies on the effects of chronotherapy measures in COPD are warranted.

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BACKGROUND: Daylight Saving Time (DST) annually moves clocks 1 hour forward, when daytime is longer than night. Previous studies from medium and high latitude locations have pointed to a disruptive effect of DST on human circadian rhythms. Since Brazil is an equatorial country implementing DST, a different relationship between photic and social synchronisers may interfere with DST effects. AIM: To explore the prevalence and duration of self-reported discomfort related to DST among Brazilian residents (latitude 12-33° S, longditude 39-57° W). It was hypothesised that an elevated prevalence of self-reported discomfort would be found in Brazil, due to the pronounced uncoupling between social and geophysical synchronisers. SUBJECTS AND METHODS: In total, 12 467 volunteers completed a web-based, Brazilian version of Horne-Östberg Morningness-Eveningness Questionnaire, provided demographic information, and answered questions related to DST complaints (discomfort, duration of discomfort). RESULTS: Of the total sample, 45.43% reported no discomfort related to DST, with meaningful proportions for all chronotypes. However, eveningness was most associated with discomfort. About one fourth of the total sample reported discomfort over the whole DST period. Gender interaction is largely supported by these results. CONCLUSIONS: DST at low latitude locations may be disruptive for circadian rhythms, since seasonality of sunrise near the equator is negligible or very mild.

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The rotation of the Earth around its own axis and around the sun determines the characteristics of the light/dark cycle, the most stable and ancient 24 h temporal cue for all organisms. Due to the tilt in the earth's axis in relation to the plane of the earth's orbit around the sun, sunlight reaches the Earth differentially depending on the latitude. The timing of circadian rhythms varies among individuals of a given population and biological and environmental factors underlie this variability. In the present study, we tested the hypothesis that latitude is associated to the regulation of circadian rhythm in humans. We have studied chronotype profiles across latitudinal cline from around 0° to 32° South in Brazil in a sample of 12,884 volunteers living in the same time zone. The analysis of the results revealed that humans are sensitive to the different sunlight signals tied to differences in latitude, resulting in a morning to evening latitudinal cline of chronotypes towards higher latitudes.

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Abstract Objective: The aim of this study was to translate and validate the Pediatric Daytime Sleepiness Scale (PDSS) into Brazilian Portuguese. Methods: The translation/validation process was carried out through translation, back translation, technical review, assessment of verbal comprehension/clarity of the scale by experts and a focus group, test–retest, and application of the tool. The reproducibility analysis was performed by applying the PDSS in test–retest; internal consistency was verified by applying the scale in 90 children and adolescents. Results: The mean score of the sum of PDSS questions was 15.6 (SD = 5.0) points. The PDSS showed appropriate indicators of content validation and clarity for the Brazilian Portuguese version. The internal consistency analysis showed a Cronbach's alpha of 0.784. The PDSS showed adequate reproducibility. The PDSS scores showed a significant and negative correlation with time spent in bed (r = −0.214; p = 0.023). Conclusion: The Brazilian Portuguese version of the PDSS shows satisfactory indicators of validity and can be applied in clinical practice and scientific research.

Resumo Objetivo: Traduzir e validar o Pediatric Daytime Sleepiness Scale (PDSS) para o português (Brasil). Método: O processo da tradução/validação deu-se por meio da tradução, retrotradução, revisão técnica, avaliação da compreensão verbal/clareza do questionário por especialistas e por grupo focal, teste-reteste e aplicação do instrumento. A análise de reprodutibilidade fez-se por meio da aplicação da PDSS em teste-reteste e a consistência interna pela aplicação da escala em 90 crianças e adolescentes. Resultados: A pontuação média verificada no somatório das questões da PDSS foi 15,6 (5) pontos. A PDSS apresentou adequados indicadores de validade de conteúdo e clareza de linguagem em português do Brasil. A análise da consistência interna identificou alfa de Cronbach de 0,784. A PDSS apresentou adequada reprodutibilidade. Os escores da PDSS apresentaram correlação negativa e significativa com o tempo na cama (r = -0,214; p = 0,023). Conclusões: A versão em português da PDSS apresenta satisfatórios indicadores de validade e pode ser aplicada na prática clínica e em pesquisas científicas.

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This study aimed to investigate the prevalence and factors associated with short sleep duration in adolescents from Maravilha – Santa Catarina (SC), southern Brazil. Methods: The sample consisted of 516 adolescents aged 10–19 years of both genders. Issues associated with short sleep duration and difficulty falling asleep, chronotype, daytime sleepiness, physical activity, sedentary behavior and weight status were investigated. Results: The prevalence of short sleep duration (<8h on school days) was 53.6%. Adolescents aged 17–19 years showed a 2.05-fold (95%CI: 1.20–3.50) greater prevalence of short sleep duration than those aged 10–12 years. The ones studying in morning and evening shifts had a higher prevalence of short sleep duration compared to those in the afternoon shift. Older age and school shift were the main factors associated with short sleep duration. Conclusions: Adolescents from Maravilha showed high prevalence of short sleep duration, and older adolescents that studied in the morning and evening shifts showed reduced sleep.

Investigar a prevalência e os fatores associados à baixa duração do sono de adolescentes do município de Maravilha (SC), Brasil. Métodos: A amostra foi formada por 516 adolescentes, de 10 a 19 anos, de ambos os sexos. Foram investigadas questões associadas à baixa duração do sono, como dificuldade de pegar no sono, cronotipo, sonolência diurna, atividade física, comportamento sedentário e status de peso. Resultados: A prevalência de baixa duração do sono (<8h nos dias com aula) foi de 53,6%. Os adolescentes com 17-19 anos tiveram 2,05 (IC95% 1,20-3,50) vezes mais chances de apresentar baixa duração do sono do que os com 10-12 anos. Aqueles que estudavam nos turnos manhã e noite apresentaram maior prevalência de baixa duração de sono, com relação aos do turno da tarde. Idade mais avançada e turno escolar foram os principais fatores associados à baixa duração do sono. Conclusões: Os adolescentes de Maravilha apresentaram alta prevalência de baixa duração do sono. Os mais velhos, que estudam de manhã e à noite, apresentaram sono reduzido.

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