Screen time and sleep disorder in preschool children: identifying the safe threshold in a digital world

Sleep disorder is a common problem in children that can jeopardize their health and well-being. With the popularity of electronic devices such as portable tablets and smartphones in the 21st century, children are spending much more time on screen, but the impact of such change on children's sleep disorder has been less investigated so far. This study aims to examine the dose-response association between time spent on different electronic devices and children's sleep disorder.

The design of this study is a cross-sectional study.

We randomly selected 2278 children aged 3-6 years from 15 kindergartens in Tongling, China. The potentially non-linear association between screen-viewing time (i.e. television [TV], computer, iPad, Phone) and the risk of sleep disorder was examined using a logistic generalized additive model.

We observed a J-shaped association between TV viewing time and the risk of sleep disorder, with a threshold of 1 h/day. For each 1 h/day increment in TV viewing time over the threshold, the risk of sleep disorder increased by 12.35% (95% confidence interval: 1.87-23.92%). This association seemed to be greater for girls than boys and for TV viewing at weekend than on weekdays, but the difference was not statistically significant (P-value>0.05). We did not find adequate evidence of an adverse effect of more time spent on computer, iPad and Phone.

This study suggests a positive but non-linear relationship between time spent on watching TV and sleep disorder in Chinese preschool children. Setting the TV viewing time limit less than 1 h/day may help reduce the risk of developing sleep disorder. Further investigation is also needed to examine and compare the effects of heavy use of other electronic devices on sleep disorder.