The purpose of this systematic review was to (i) estimate the prevalence and dose of television (TV) viewing, video game playing and computer use, and (ii) assess age-related and (iii) secular trends in TV viewing among youth (<= 18 yr). Ninety studies published in English language journals between 1949 and 2004 were included, presenting data from 539 independent samples (the unit of analysis). Results suggest contemporary youth watch on average 1.8-2.8 h of TV per day, depending on age and gender. Most (66%) are 'low users' (< 2 h day(-1)) of TV but 28% watch more than 4 h day(-1). Boys and girls with access to video games spend approximately 60 and 23 min day(-1), respectively, using this technology. Computer use accounts for an additional 30 min day(-1). Age-specific data suggest TV viewing decreases during adolescence, but those considered 'high users' at young ages are likely to remain high users when older. For children with access to a television set, the number of hours spent viewing does not appear to have increased over the past 50 years. Read more...

Objective: To examine patterns of inactivity and snacking and their relationship with overweight status in Chinese children. Research Methods and Procedures: The study population was drawn from the 1997 China Health National Survey (1385 children, ages 6 to 11 years), conducted with a representative sample from nine provinces. The 2000 Centers for Disease Control and Prevention BMI charts were used to calculate "at risk of overweight" as those above the 85th percentile. Three days of 24-hour recall dietary data and detailed questions on physical activity and inactivity for the previous 7 days were used. Results: 9.4% of the children were classified as overweight. Weekly mean and range of hours spent watching television/ videos, playing video games, studying, and in inactive transport were 5.1 (0 to 35), 0.3 (0 to 10), 4.7 (0 to 60), and 0.14 (0 to 4.2), respectively. Television/video viewing and studying did not differ in any meaningful manner between overweight and normal weight children. Snacking is inconsequential in China, comprising only 0.9% of energy intake. Discussion: Chinese children are less overweight, less inactive, and less likely to ingest calories as snacks than children in the U.S. The absence of impact of these measures of inactivity, which are below an hour per day for the average Chinese child, indicate the possible value of limiting television viewing and other types of inactivity in other countries. Modern Western-style television programming and advertising started to come to China after 1997; therefore, extensive changes in television viewing patterns are expected to emerge. Read more...

Objective: To assess the relationship between short sleep duration and obesity-related variables in children involved in the 'Quebec en Forme' Project. Design: Cross-sectional study. Subjects: A total of 422 children (211 boys and 211 girls) aged between 5 and 10 years from primary schools in the City of Trois-Rivieres (Quebec) were selected to participate in this study. Measurements: Body weight, height and waist circumference were measured. The children were classified as normal, underweight, overweight or obese, according to body mass index (BMI) per age. An exhaustive questionnaire was administered by telephone to the parents of children. Results: The percentage of overweight/obesity was 20.0% in boys and 24.0% in girls. When compared to children reporting 12-13 h of sleep per day, the adjusted odds ratio for childhood overweight/obesity was 1.42 (95% confidence interval 1.09-1.98) for those with 10.5-11.5 h of sleep and 3.45 (2.61-4.67) for those with 8-10 h of sleep after adjustment for age, sex, and other risk factors. Parental obesity, low parental educational level, low total family income, long hours of TV watching, playing videogames or computer utilization, absence of breastfeeding and physical inactivity were also significantly associated with childhood overweight/obesity. In addition, we observed a significant negative association adjusted for age between sleep duration and body weight (-0.33, P < 0.01), BMI (-0.12, P < 0.01) and waist circumference (-0.24, P < 0.01) in boys. Conclusion: An inverse association was observed between sleep duration and the risk to develop childhood overweight/obesity. Longitudinal research will be required to confirm a potential link of causality between these variables. Read more...