Screen habits among youth may increase depression levels through poor sleep
Young people with high screen time develop poorer sleep habits, which in turn can lead to increased levels of depression – especially among girls. This is shown in a study from Karolinska Institutet published in PLOS Global Public Health.
In the autumn of 2024, the Swedish Public Health Agency launched recommendations regarding screen use for young people, partly to promote better sleep habits. Previous studies have pointed to a connection between screen time, sleep habits, and depression levels in young people. However, depression and sleep disorders often go hand in hand, and the causal relationships are not fully established.
In the current study, researchers followed 4,810 middle school students in Stockholm County. The adolescents answered a health survey with questions about, among other things, screen habits during leisure time, sleep duration, sleep quality, sleep times, and depressive symptoms. Each participant completed the survey on three separate occasions over twelve months. The measurements took place between 2016–2019.
Deteriorated sleep habits within three months
The recommendation from the Swedish Public Health Agency is that adolescents, aged 13–18, should limit their screen time to a maximum of 2–3 hours per day. The study found that the average middle school student (2016–2019) in Stockholm County spent about 3–4 hours per day in front of screens during their leisure time.
Among the adolescents who reported more screen time during leisure time than the average, a shorter sleep duration and poorer sleep quality were observed. Screen time also caused a significant shift in the adolescents' sleep times – which mainly seemed to shorten the night sleep in connection with Monday mornings. The deteriorations occurred within three months for both boys and girls.
Increased risk of higher depression levels
Participants who reported longer daily screen time than average had an increased risk of higher depression levels. Although the effect of screen time on depression was small and only explained a small part of future depression levels, it was still persistent over time.
"In our study, we found that adolescents who reported longer screen time developed poorer sleep habits. Which in turn led to increased levels of depression, especially among girls," says the study's first author Sebastian Hökby, doctoral student at the National Centre for Suicide Research and Prevention and the Department of Learning, Informatics, Management and Ethics, Karolinska Institutet, and the Center for Health Economics, Informatics and Healthcare Research at Region Stockholm.
Among boys, screen time was directly linked to elevated depression levels the following year, regardless of how much sleep problems the screen time caused. For girls, on the other hand, only indirect screen time effects could be seen. Among girls, 38–58 percent of future depression levels were explained by the fact that screen time first had a disruptive effect on their sleep.
"The study's results suggest that reduced screen time would likely improve adolescents' sleep and that public health, in terms of the prevalence of depression, would likely improve for especially Swedish girls and young women, but possibly also for boys and young men," says Sebastian Hökby.
Publication
Adolescents’ screen time displaces multiple sleep pathways and elevates depressive symptoms over twelve months Hökby S, Alvarsson J, Westerlund J, Carli V, Hadlaczky G (2025) Adolescents’ screen time displaces multiple sleep pathways and elevates depressive symptoms over twelve months. PLOS Global Public Health 5(4): e0004262. https://doi.org/10.1371/journal.pgph.0004262