In our study, associations between sleep duration and daily activity and behavior routine were examined. Many studies have suggested that media exposure such as computer game playing, Internet use, and television viewing may contribute to the increase in sleep loss among adolescents [17], [30] and [39], which were consistent with our finding. Furthermore, our data provided evidence that physical activity was related to sleep duration among adolescents. The literature on this topic is scarce and worthy of further research [31]. In addition, our study supported previous findings that poor bedtime hygiene practices (e.g. irregular bedtime) were strong predictors for insufficient sleep duration [30], [40] and [41]. There has been a general understanding of the importance of sleep hygiene for optimal sleep duration [17], [40] and [41].