Smartphones, once devices relegated to adults have become an important part of young adults’ lives. The use of smartphones before bed has been on the rise since, well, smartphones existed but the negative health impacts, especially on adolescents, has become the focus of many new studies. Researchers from China wanted to look into the impact of screen time before bed on sleeping patterns, emotional problems, and their general sleep.

The researchers took data from two different studies that were conducted on high school students in China. The studies had a total of 4,053 participants, roughly 60% were male. Participants were asked about emotional problems, chronotype (eg. early bird vs night owl), screen time before bed, and social jetlag (misalignment of biological and social rhythms).

The results of the study found, unsurprisingly, that teens who used their screen more before bed, tended to sleep later and have a later chronotype (being night owls) which led to more social jetlag. These factors combined to elevate their vulnerability to emotional issues. These results point to disturbances in adolescents’ circadian rhythms being a key connection to psychological difficulties. The researches also found those with later chronotypes encounter more obstacles trying to adapt to early social routines, creating a dissonance between their internal clock and external demands, causing more emotional challenges.

This study, as all do, has some caveats. It was self-reported so it is prone to bias and was a cross-sectional study, so a causal link couldn’t be determined. While the results may be pretty obvious, it is important to make sure we fully understand the links between factors to better fix the problem. The study made it clear that screen use before bed is not a good idea for adolescents (and well, anyone really).