Too much screen time can mess with teens’ sleep, and that might be a major reason why depression is on the rise, especially among girls.
A study tracking over 4,800 adolescents found that screen use disrupted both the quality and timing of sleep, which in turn predicted depressive symptoms. For girls, poor sleep was the main link between screens and mood struggles, while boys were affected more directly. The researchers say reducing screen time could ease the mental health burden for young people.
Screen Time, Sleep, and Teen Depression
Too much screen time can disrupt teenagers’ sleep, and that loss of sleep may increase the risk of depression, especially in girls. That’s the finding of a new study published in PLOS Global Public Health by Sebastian Hökby and colleagues at Karolinska Institutet in Sweden.
The Swedish Public Health Agency recently recommended that adolescents limit their recreational screen time to two or three hours per day, in part to support healthier sleep. Previous research has linked high screen use to poor sleep and mental health issues in teens, but the exact relationships between these factors have been unclear, especially since sleep problems and depression often occur together.
Tracking Teens Over Time
In this new study, researchers followed 4,810 Swedish students between the ages of 12 and 16. They collected data on screen habits, sleep patterns, and symptoms of depression at three points over a one-year period.
The researchers found that increased screen time led to deteriorated sleep within three months, impacting both the duration and quality of sleep. Screen time was also found to postpone sleep times towards later hours – disrupting multiple aspects of the human sleep-wake cycle at once.
Among boys, screen time had a direct adverse effect on depression after twelve months, while among girls the depressive effect was mediated through sleep disturbances. Sleep could explain about half (38%-57%) of the association between screen time and depression in girls. Boys who spent more time on screens also experienced sleep disruptions, but these were not strongly associated with later depression.
Sleep as a Key Link
The authors summarize: “In this study, we found that adolescents who reported longer screen times also developed poorer sleep habits over time. In turn, this led to increased depression levels, especially among girls.”
They add: “Our results do suggest that less[…] screen time seems healthier, in line with previous World Health Organization statements…if screen times were somehow reduced, for example through public health policies, our results imply that the high burden of depressive states among young Swedish women, and maybe young men, would likely decrease.”
Reference: “Adolescents’ screen time displaces multiple sleep pathways and elevates depressive symptoms over twelve months” by Sebastian Hökby, Jesper Alvarsson, Joakim Westerlund, Vladimir Carli and Gergö Hadlaczky, 2 April 2025, PLOS Global Public Health.
DOI: 10.1371/journal.pgph.0004262
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