Mediating role of television time, diet patterns, physical activity and sleep duration in the association between television in the bedroom and adiposity in 10 year-old children

Borghese et al. International Journal of Behavioral Nutrition and Physical Activity Mediating role of television time, diet patterns, physical activity and sleep duration in the association between television in the bedroom and adiposity in 10 year-old children Michael M Borghese 0 1 Mark S Tremblay 0 1 Peter T Katzmarzyk Catrine Tudor-Locke John M Schuna Jr Genevive Leduc 1 Charles Boyer 1 Allana G LeBlanc 1 Jean-Philippe Chaput 0 1 0 School of Human Kinetics, Faculty of Health Sciences, University of Ottawa , Ottawa, ON , Canada 1 Healthy Active Living and Obesity Research Group, Children's Hospital of Eastern Ontario Research Institute , 401 Smyth Road, Ottawa K1H 8L1ON , Canada Background: Having a TV in the bedroom is associated with adiposity in children. It is not known how lifestyle behaviours (television viewing time, diet patterns, physical activity, and sleep duration) mediate this association. The objective of this study was to examine the mediating role of these lifestyle behaviours in the association between TV in the bedroom and percent body fat (% BF). Methods: Cross-sectional data from 1 201 children (57.3 % female; mean age = 9.8 years) from Ottawa, Canada and Baton Rouge, USA were examined. % BF was directly measured. Accelerometers were used to determine physical activity and sleep duration (24-h, 7-day protocol). Questionnaires were used to assess TV viewing time and healthy/unhealthy diet patterns (derived using factor analysis from food frequency questionnaire data). Results: Canadian boys and girls with a TV in their bedroom had a higher % BF, watched more TV and had unhealthier diets. American boys and girls with a TV in their bedroom watched more TV, while boys had a higher % BF and a more unhealthy diet, and girls had less MVPA. In Canadian girls, TV viewing time mediated the association between having a TV in the bedroom and adiposity, independent of diet patterns, MVPA, and sleep duration. Other lifestyle mediators were not significant in Canadian boys or in US children. Conclusion: TV viewing is a mediating lifestyle behaviour in the association between TV in the bedroom and adiposity in Canadian girls. Future research is needed to identify lifestyle behaviours as intermediate mediators. Diet; Lifestyle habits; Mediation; Obesity; Screen-based media - Introduction Young people now spend more time with media than they do in school and, other than sleeping, TV viewing is the leading activity for children and adolescents [1]. Previous work has shown a clear link between increased TV viewing time and poor health indicators in children and youth, including decreased fitness, lowered scores for self-esteem and pro-social behaviour as well as unfavorable body composition [2]. The omnipresence of screens (especially TV) in childrens lives poses a potential health risk, and society as a whole has a role to play to mitigate these risks. Interventions that may be capable of addressing this risk by reducing childrens screen time are being tested [3, 4]. Recent estimates suggest that 71 % of American children and adolescents have a TV in their bedroom [5]. The American Academy of Pediatrics suggested in 2013 that parents should remove TVs from childrens bedrooms (along with internet connected electronic devices), thereby reducing their access [6]. This is largely because evidence suggests that the presence of a TV in childrens bedrooms increases TV viewing time [7], risk of substance use, and adiposity [6, 8], as well as other health risks. While it may seem intuitive that bedroom TVs exert their effect on childrens adiposity through increased TV viewing time, there is evidence to suggest that this effect exists beyond that which can be explained by TV viewing time alone [9, 10]. Having a TV in the bedroom is also associated with unhealthy food choices [11], lower levels of moderate-tovigorous physical activity (MVPA) [12], and poor sleep habits [13, 14] in children. However, this evidence is mixed [10], and the mechanisms behind the association between TV in the bedroom and adiposity in children are unclear. Previous studies have focused primarily on the association of bedroom TVs and a specified outcome measure without considering potential mediating or moderating effects of other factors, despite the fact that these variables are generally interrelated. We are aware of two other studies that have examined the potential mediating effects of childrens lifestyle behaviours on the association between having a TV in the bedroom and adiposity. However, neither of these studies used objective measures of physical activity and sleep duration, and both used BMI as a measure of obesity instead of adiposity [7, 15]. While these analyses provide many insights, the literature is limited in examining the influence of TV in the bedroom on diet patterns in children; studies have examined the link with sugar-sweetened beverage consumption [7, 11], but the association with childrens habitual diet patterns has not been addressed. Thus, a comprehensive evaluation of the potential associations between having a TV in the bedroom and lifestyle behaviours using objective measures is warranted. Accordingly, the purpose of this study was to examine the association between having a TV in the bedroom and percent body fat (% BF) in both Canadian and American children, considering the following lifestyle behaviours as mediating factors: TV viewing time, diet patterns, MVPA, and sleep duration. It was hypothesized that children with a TV in their bedroom would have higher % BF and total TV viewing time, poorer diet patterns, lower MVPA, and shorter sleep duration than those with no TV in their bedroom. It was also hypothesized that the aforementioned lifestyle behaviours would independently mediate the association between TV in the bedroom and % BF in children. It is crucial that mediation analyses using cross-sectional data have a strong theoretical/conceptual foundation. The conceptual model for the mediating role of lifestyle behaviours in the association between having a TV in the bedroom and adiposity in children is based on previous evidence from longitudinal [9 ,10, 14, 16, 17] and intervention studies [18, 19]. Furthermore, this mediation approach has previously been used with cross-sectional data to answer similar research questions [15, 20]. While crosssectional mediation analysis can be informative in the context of existing conceptual models, potential mediating factors should not be interpreted as being causal, but rather informative for further hypothesis generation. Methods Participants The International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE) is a multi-national, cross-sectional study conducted in 12 countries. The primary purpose of ISCOLE is to construct a statistical model which can predict adiposity in children based on dietary habits and physical activity, as well as other environmental variables. Data from the NHANES 20 (...truncated)