Relationships between sleeping habits, sedentary leisure activities and childhood overweight and obesity.

The aim of this study is to show how sedentary leisure activities and a decrease in hours of sleep interact to lead to an increase in the body mass index (BMI) in children. A random sample of 291 nine-year-old and ten-year-old schoolchildren from Asturias (Spain) was taken. A cross-sectional design was used, the children's weight and height were measured and an individual interview was carried out. Using path analysis, a model was tested in which bedtime, the number of hours spent sleeping and sedentary leisure activities were the independent variables and the BMI was the dependent variable. The results show that sedentary leisure activities and hours spent sleeping are predictors of a greater BMI in children. Moreover, the effect of the time spent sleeping is mediated by sedentary leisure activities. That is to say, it is those children who go to bed late and who use that extra time to watch the television or play with the computer that tend to have a greater BMI. Attention should be drawn to the importance of this fact and to the implications it may have for education and children's health.