RESUMO
Background: Time spent on screen devices affects sleep quality and duration leading to several health impairments in youth. Although physical activity (PA) benefits sleep patterns and decreases screen time in adolescents, it is unclear whether the relationship between sleep quality/duration and screen time could be influenced by PA levels. Objective: To analyze the association between sleep quality and duration with screen time in Brazilian adolescents according PA levels. Methods: The sample included 1010 adolescents aged 13.2 ± 2.4 years (n = 556 females - 55 % of the sample). Sleep quality and sleep duration, and PA were assessed by Mini Sleep and Baecke questionnaires, respectively. Participants in the highest quartile were classified as physically active. Screen time was analyzed by the self-reported number of hours spent on different screen devices (i.e., television, computer, videogame, and cellphone/tablet). Participants in the highest tertile were classified as having high screen time. Sex, age, and body mass index were considered covariates in binary logistic regression models. Results: Poor sleep quality was observed in 52.3 % of the sample, whereas 46.6 % reported sleeping less than eight hours/day. High screen time was associated with poor sleep quality (OR = 1.45; 95 %CI = 1.01-2.12) and insufficient sleep duration (OR = 1.52; 95 %CI = 1.01-2.03) in adolescents insufficiently active. There were no associations between screen time and sleep parameters in active adolescents. Conclusion: High screen time was associated with poor sleep quality and insufficient sleep duration only in insufficiently active adolescents. These results suggest that high PA levels may contribute to improving sleep patterns in pediatric population.
RESUMO
This study aimed to analyze the relationship of physical activity in different domains with cardiac autonomic modulation in adults. A sample of 252 adults was randomly selected, with mean age of 42.1 (± 16.5) years, being 58% of women. Cardiac autonomic modulation was assessed through indexes of heart rate variability in time (SDNN, RMSSD) and frequency (LF, HF) domains for linear method, and by Poincaré plot for non-linear method (SD1, SD2 components). Domains of PA (occupation, sport, leisure time/commuting, and total) were assessed by Baecke's questionnaire. Variables of age, gender, socioeconomic status (questionnaire) and body mass index (objectively measures) were covariates. Occupational PA was positively related to LF (ß = 2.39, 95% CI 0.24; 4.54), sports PA was positively related to SDNN (ß = 3.26, 95% CI 0.18; 7.05), RMSSD (ß = 4.07, 95% CI 0.31; 7.85), and SD1 (ß = 2.85, 95% CI 0.11; 5.81), and leisure time/commuting PA was positively related to SDNN (ß = 3.36, 95% CI 0.28; 6.70) and RMSSD (ß = 3.53, 95% CI 0.46; 7.52) indexes. Total PA was related to RMSSD (ß = 1.70, 95% CI 0.04; 3.72). Sports, leisure time/commuting, and total PA were related to higher parasympathetic modulation, while occupational PA was related to higher sympathetic modulation to the heart in adults.