Compared with their peers in Australia (mean 8.28 h during school days) [32], Belgium (mean 10.00 h) [18], Chinese adolescents slept ~20 min to nearly 2 h and 30 min fewer. The difference in sleep duration could have physiological significance since previous research showed that modest change in sleep duration (~40 min on three consecutive nights) can improve (in the case of extension) or worsen (in the case of restriction) adolescents' neurobehavioral functioning [33]. Accordingly, efforts to examine factors related to sleep duration and to develop effective interventions to increase the duration of Chinese adolescents' sleep would seem necessary.