Electronic device and social network use and sleep outcomes among adolescents: the EHDLA study.

BACKGROUND: Considering the evident risk in the literature between the use of screen devices and sleep, there are still few studies on the relationship between each electronic screen device, media programs and sleep duration and sleep-related problems among adolescents and which variables interfere in these relationships. Therefore, this study has the following objectives: (1) to determine which are the most common electronic display devices related to sleep time and outcomes and (2) to determine which are the most common social network applications, such as Instagram and WhatsApp, associated with sleep outcomes. METHODS: This was a cross-sectional study with 1101 Spanish adolescents between 12 and 17 years old. Age, sex, sleep, psychosocial health, adherence to the Mediterranean diet (MD), sport practice, and time spent on screen devices were assessed by an ad hoc questionnaire. Linear regression analyses were applied, adjusting for several covariables. Poisson regression was applied between the sexes. A p value < 0.05 was considered statistically significant. RESULTS: Cell phone use was more associated with sleep time (13%). In boys, time spent on cell phones (prevalence ratio [PR] = 1.09; p < 0.001) and videogames (PR = 1.08; p = 0.005) had a higher prevalence ratio. When psychosocial health was included in the models, we found the greatest association (Model 2: PR = 1.15; p = 0.007). For girls, time spent on the cell phone was significantly associated with sleep-related problems (PR = 1.12; p < 0.001), and adherence to the MD became the second most important in the model (PR = 1.35; p < 0.001), followed by psychosocial health and cell phone use (PR = 1.24; p = 0.007). Time spent on WhatsApp was associated with sleep-related problems only among girls (PR = 1.31; p = 0.001) and was the most important variable in the model along with MD (PR = 1.26; p = 0.005) and psychosocial health (PR = 1.41; p < 0.001). CONCLUSIONS: Our results suggest a relationship between cell phones, video games, and social networks with sleep-related problems and time.

Reciprocal Longitudinal Relationship Between Fitness, Fatness, and Metabolic Syndrome in Brazilian Children and Adolescents: A 3-Year Longitudinal Study.

PURPOSE: To verify the reciprocal longitudinal relationships between cardiorespiratory fitness (CRF), percentage body fat (%body fat), and metabolic syndrome in Brazilian primary school students. METHOD: This longitudinal study involved 420 children and adolescents followed for 3 years (2011-2014). The continuous Metabolic Syndrome (cMetSyn) score was calculated by summing adjusted z scores of glucose, systolic blood pressure, total cholesterol/high-density lipoprotein cholesterol ratio, triglycerides, and waist circumference. The CRF was assessed using running/walking tests, and %body fat was assessed through sex-specific 2-site skinfold thickness. Cross-lagged panel models were used to analyze longitudinal reciprocal relationships between CRF and %body fat with cMetSyn. RESULTS: Results indicated that 2011 %body fat significantly predicted both 2014 CRF scores and 2014 cMetSyn scores (P < .001); however, 2011 CRF only predicted 2014 %body fat (P < .001) but not 2014 cMetSyn (P = .103). Furthermore, 2011 cMetSyn predicted 2014 %body fat (P = .002). The model explained 36%, 48%, and 37% of the variance in 2014 CRF, %body fat, and cMetSyn, respectively. CONCLUSION: The results suggest a reciprocal inverse relationship between %body fat and metabolic syndrome risk and that %body fat may play a more important role in the risk of developing metabolic syndrome compared with CRF.

Low levels of cardiorespiratory fitness and abdominal resistance are associated with metabolic risk in schoolchildren.

Background Low levels of physical fitness are associated with metabolic disorders in adults. However, this relationship has been little explored in children and adolescents. The aim of the present study was to investigate whether there is an association between physical fitness related to health and the presence of metabolic risk in schoolchildren. Methods The sample for this cross-sectional study was composed of 1251 schoolchildren of both genders between 7 and 17 years of age. Three indicators of physical fitness related to health were evaluated: cardiorespiratory fitness (CRF), flexibility and abdominal resistance. The continuous metabolic syndrome score (cMetS) was calculated by using the sum of the Z scores of the following indicators: body mass index (BMI), systolic blood pressure, glucose, total cholesterol, high- and low-density lipoprotein cholesterol (HDL-c and LDL-c) and triglycerides. Subsequently, the cMetS was dichotomized, considering the presence or absence of metabolic risk. The data were analyzed using prevalence ratio (PR) values and 95% confidence intervals (CI), using Poisson regression. Results A higher prevalence of metabolic risk was found among students with low levels of CRF (PR: 1.48; CI: 1.10-1.98) and abdominal resistance (PR: 1.45; CI: 1.08-1.95). No association with flexibility was found. Conclusions Low levels of CRF and abdominal resistance are associated with the presence of metabolic risk in schoolchildren.