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School start time influences sleep parameters. Differences between circadian sleep parameters on weekends and weekdays have been associated with obesity, sleep, and psychiatric disorders. Moreover, circadian rhythm dysregulation affects the secretion of some hormones, such as melatonin and cortisol. In the current study, we investigate the effect of school start time on cortisol and melatonin levels in a community sample of Brazilian children and adolescents. This was a cross-sectional study of 454 students (mean age, 12.81 ± 2.56 years; 58.6% female). From this sample, 80 participants were randomly selected for saliva collection to measure melatonin and cortisol levels. Circadian sleep parameters were assessed by self-reported sleep and wake up schedules and the Morningness-Eveningness Questionnaire. The outcomes, salivary melatonin and cortisol levels, were measured in morning, afternoon and night saliva samples, and behavior problems were assessed using the Child Behavior Checklist (CBCL). The main results revealed that morning school start time decreased the secretion of melatonin. Morning melatonin levels were significantly positively correlated with the sleep midpoint on weekdays and on weekends. Afternoon melatonin levels were positively correlated with the sleep midpoint on weekends in the morning school students. Conversely, in the afternoon school students, night melatonin levels were negatively correlated with the sleep midpoint on weekdays. Cortisol secretion did not correlate with circadian sleep parameters in any of the school time groups. In conclusion, school start time influences melatonin secretion, which correlated with circadian sleep parameters. This correlation depends on the presence of psychiatric symptoms. Our findings emphasize the importance of drawing attention to the influence of school start time on the circadian rhythm of children and adolescents.

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Introdução: O diabetes tipo 2 cresce alarmantemente, e os fitoterápicos estão sendo indicados para utilização como hipoglicemiantes. Objetivos: Relacionar os índices antropométricos com o uso do fitoterápico Bauhinia forficata em pacientes portadores de diabetes mellitus tipo 2. Métodos: Selecionaram-se 37 indivíduos que foram divididos em dois grupos: grupo 1 – intervenção, e 2 – controle, e acompanhados por oito meses. Foram realizadas três verificações antropométricas. Resultados: No grupo 1, as medidas de prega cutânea triciptal (PCT) e compleição altura/punho tiveram diferença significativa, já a média da PCT aumentou de 21,42 mm para 22,67 (t= -2,702; p=0,0205), visto que houve também aumento de peso e IMC, e a compleição altura/punho aumentou de 9,35 cm para 9,62 cm (t = -2,289; p=0,0428). Conclusão: A avaliação antropométrica, quando comparadas as três medições, mostrou uma variação significativa na PCT e na altura/punho dos participantes do grupo 1, porém, quando avaliados os dois grupos, essa diferença não foi estatisticamente significativa.