ABSTRACT OBJECTIVE The COVID-19 pandemic has raised numerous concerns regarding its effects on individuals’ health and lifestyle. We aim to analyze potential changes in adolescent sleep patterns from before and during the pandemic and identify specific predictors of changes. METHODS A subgroup of adolescents from a population-based birth cohort from Pelotas, Brazil, was assessed pre-pandemic (T1, November-2019 to March-2020) and peri-pandemic (T2, August-2021 to December-2021) in in-person interviews (n = 1,949). Sleep parameters, including sleep duration and latency time on workdays and free days, as well as social jetlag (SJL), were assessed using the Munich ChronoType Questionnaire (MCTQ). Socio-demographic, pre-pandemic, and pandemic-related predictors were analyzed. Changes in sleep parameters from T1 to T2 were estimated by multivariate latent change score modeling. RESULTS The latent change factor shows a significant mean increase in workday sleep duration (M = 0.334, p < 0.001), workday sleep latency (M = 0.029, p = 0.002), and free day sleep latency (M = 0.021, p = 0.034), and a decreased in SJL (M = −0.758, p < 0.001) during the pandemic. Female adolescents presented higher increases in workday sleep duration. Adolescents who adopted a stricter social distancing level during the pandemic presented greater increases in workday sleep duration and smaller reductions in SJL. Self-evaluated insomnia during the pandemic predicted lower increases in workday and free day sleep duration and higher increases in workday and free day sleep latency. CONCLUSION The COVID-19 outbreak brought certain advantages regarding increased sleep duration and reduced SJL. However, the observed increase in sleep latency and the influence of self-reported insomnia could be related to psychological distress inherent to the pandemic. COVID19 COVID 19 COVID-1 individuals lifestyle populationbased population based Pelotas Brazil prepandemic pre T1, T (T1 November2019 November 2019 November-201 March2020 March 2020 March-2020 peripandemic peri T2, (T2 August2021 August 2021 August-202 December2021 December December-2021 inperson person n 1,949. 1949 1,949 . 1 949 1,949) days SJL, , (SJL) MCTQ. MCTQ (MCTQ) Sociodemographic, Sociodemographic Socio demographic, demographic Socio-demographic prepandemic, pandemic, pandemicrelated analyzed modeling M 0334 0 334 0.334 0.001, 0001 0.001 001 0029 029 0.029 0.002, 0002 0.002 002 0.002) 0021 021 0.021 0.034, 0034 0.034 034 0.034) 0758 758 −0.758 Selfevaluated Self evaluated However selfreported self reported COVID1 COVID- (T November201 201 November-20 March202 202 March-202 August202 August-20 December202 December-202 194 1,94 94 (SJL (MCTQ 033 33 0.33 000 0.00 00 02 0.02 003 0.03 03 075 75 −0.75 November20 20 November-2 March20 March-20 August20 August-2 December20 December-20 1,9 9 3 0.3 0.0 07 7 −0.7 November2 2 November- March2 March-2 August2 August- December2 December-2 1, 0. −0. March- December- −0 −

ABSTRACT OBJECTIVE The COVID-19 pandemic has raised numerous concerns regarding its effects on individuals’ health and lifestyle. We aim to analyze potential changes in adolescent sleep patterns from before and during the pandemic and identify specific predictors of changes. METHODS A subgroup of adolescents from a population-based birth cohort from Pelotas, Brazil, was assessed pre-pandemic (T1, November-2019 to March-2020) and peri-pandemic (T2, August-2021 to December-2021) in in-person interviews (n = 1,949). Sleep parameters, including sleep duration and latency time on workdays and free days, as well as social jetlag (SJL), were assessed using the Munich ChronoType Questionnaire (MCTQ). Socio-demographic, pre-pandemic, and pandemic-related predictors were analyzed. Changes in sleep parameters from T1 to T2 were estimated by multivariate latent change score modeling. RESULTS The latent change factor shows a significant mean increase in workday sleep duration (M = 0.334, p < 0.001), workday sleep latency (M = 0.029, p = 0.002), and free day sleep latency (M = 0.021, p = 0.034), and a decreased in SJL (M = −0.758, p < 0.001) during the pandemic. Female adolescents presented higher increases in workday sleep duration. Adolescents who adopted a stricter social distancing level during the pandemic presented greater increases in workday sleep duration and smaller reductions in SJL. Self-evaluated insomnia during the pandemic predicted lower increases in workday and free day sleep duration and higher increases in workday and free day sleep latency. CONCLUSION The COVID-19 outbreak brought certain advantages regarding increased sleep duration and reduced SJL. However, the observed increase in sleep latency and the influence of self-reported insomnia could be related to psychological distress inherent to the pandemic.

Objectives: There is growing interest in examining the impacts of the coronavirus disease 2019 (COVID-19) pandemic on adolescent socioemotional development. This study aimed to examine changes in adolescent emotion regulation (ER), self-esteem (SE), and locus of control (LoC) from before to during the pandemic in a Brazilian birth cohort, and to investigate the variables associated with changes in those socioemotional competences. Methods: 1,949 adolescents from the 2004 Pelotas Birth Cohort were assessed before (T1, November 2019 to March 2020) and during (T2, August to December 2021) the COVID-19 pandemic (mean ages [SD] = 15.69 [0.19] and 17.41 [0.26], respectively). Adolescents’ socioemotional competences were assessed, including ER, SE, and LoC. Sociodemographic, pre-pandemic, and pandemic-related correlates were examined as predictors of change. Multivariate latent change score models were used in the analyses. Results: There were significant mean increases in adolescents’ ER and SE (mean ER = 1.918, p < 0.001; mean SE = 1.561, p = 0.001) and a significant mean decrease (towards internalization) in LoC levels (MLoC = -0.497, p < 0.01) during the pandemic. Factors that predicted a lower competency increase included family conflicts, harsh parenting, and maternal depressive symptoms during the pandemic. Conclusion: Despite the stress imposed by the COVID-19 pandemic, the adolescents of this cohort showed positive development in their socioemotional competences. Family-related factors emerged as important predictors of adolescent socioemotional adjustment during the study period. Objectives 201 COVID19 COVID 19 (COVID-19 , (ER) selfesteem self esteem (SE) (LoC Methods 1949 1 949 1,94 200 T1, T1 T (T1 2020 T2, T2 (T2 2021 COVID-1 SD [SD 1569 15 69 15.6 0.19 019 0 [0.19 1741 17 41 17.4 0.26, 026 0.26 26 [0.26] respectively. respectively . respectively) Adolescents Sociodemographic prepandemic, prepandemic pre pre-pandemic pandemicrelated related analyses Results 1918 918 1.918 0.001 0001 001 1561 561 1.561 towards internalization MLoC 0.497, 0497 497 -0.497 0.01 01 conflicts parenting Conclusion Familyrelated Family period 20 COVID1 (COVID-1 (ER (SE 194 94 1,9 (T 202 COVID- 156 6 15. 0.1 [0.1 174 4 17. 02 0.2 2 [0.26 191 91 1.91 0.00 000 00 56 1.56 0.497 049 49 -0.49 0.0 (COVID- 9 1, 0. [0. [0.2 1.9 5 1.5 0.49 04 -0.4 (COVID [0 1. 0.4 -0. [ -0 -

Objectives: The objective of this study was to investigate the prevalence of the following risk behaviors: experimentation with cigarettes, electronic cigarettes, alcohol, substances, delinquent behavior, and sex at age 15, stratified by sex and socioeconomic position. We also investigated the prevalence of cigarette and alcohol experimentation at age 11 and the persistence and cumulative incidence of these behaviors between 11 and 15 years of age. Methods: In this cohort study, we included 3,491 11-year-olds and 1,949 15-year-olds from the 2004 Pelotas Birth Cohort. All outcomes were identified via confidential questionnaires and were analyzed as binary variables. Results: At age 11, there was a higher prevalence of cigarette experimentation among boys. At age 15, there was a higher prevalence of experimentation with alcohol, cigarettes, and substances among girls; experimentation with cigarettes and sex were more prevalent among those in a low socioeconomic position. We found a high cumulative incidence of alcohol experimentation, as well as persistent alcohol experimentation, in both boys and girls. Conclusions: Further research should clarify causal paths of the high prevalence of risk behaviors during adolescence and its increase among girls. Objectives behavior position 1 Methods 3491 3 491 3,49 11yearolds yearolds year olds 1949 949 1,94 15yearolds 200 Cohort variables Results girls Conclusions 349 49 3,4 194 94 1,9 20 34 4 3, 19 9 1, 2