31st Jan 2024

Introduction: This study analysed the associations between sleep duration, sedentary behaviour (SB), and physical activity (PA) in children and adolescents. Understanding these associations is crucial due to their impact on overall health and well-being and the potential to develop interventions that promote healthier habits. Methods: Participants were 1231 subjects aged 10 to 18 years. Sleep was measured with the Pittsburgh Sleep Quality Index (PSQI), PA was measured with the International Physical Activity Questionnaire (IPAQ), and SB was estimated through a questionnaire assessing daily time (h) spent on personal computers for study (PCS) and leisure (PCL), tablets, smartphones (SPH), social networks (SN), watching television (TV), total screen time (TST), and sitting (ST). Participants were categorized into two groups based on sleep duration: “less than 8 hours” and “more than 8 hours” per day. Mann-Whitney U test was used to compare differences between two independent groups and Logistic Regression was employed to predict the probability of an event occurring. SB (+2h, -2h) and PA (active, inactive) variables were recoded into binary variables. All statistical analyses were performed in SPSS with a significance level set at 5% (P<0.05). Results: Participants with less than 8h of sleep per day spent less time watching TV (p=0.034) but more time on PCL (p=0.02), smartphones (p<0.001), social networks (p<0.001), and higher TST (p<0.001). For logistic regression, the overall model was statistically significant when compared to the null model, X2(8)=40.792, p<0.001. Those spending more than 2h using PCL (OR=1.429, p=0.004), SPH (OR=1.427, p=0.024), and SN (OR=1.349, p=0.035) are more likely to sleep less than 8h. No associations were found for PA. Conclusions: These findings suggest that SB are associated with sleep hours. Recommendations for improving sleep habits might involve moderating these behaviours. The Portuguese Foundation for Science and Technology (FCT) supported this work under the project UIDB04045/2020.