A new study from Sweden has found that spending too much time on screens can lead to poor sleep and increased depression in teenagers—especially in girls.
The research, published in PLOS Global Public Health, highlights how screen time affects sleep quality, and how those sleep problems can raise the risk of depression.
The study was led by Sebastian Hökby and a team from Karolinska Institutet. It involved 4,810 Swedish students aged 12 to 16, who were followed for one year.
Researchers collected data about their screen use, sleep habits, and symptoms of depression at three different points in time.
The findings showed that teens who spent more time using screens—such as watching videos, playing games, or browsing social media—had worse sleep within just three months.
Their sleep was shorter and of lower quality, and they tended to stay up later at night.
This shift in sleep patterns affected the natural body clock and made it harder for teens to get the rest they need.
Over time, these sleep problems led to more signs of depression, especially in girls.
For boys, screen time also had a negative effect, but in their case, the connection between screen use and depression was more direct and not as strongly linked to sleep.
The study found that sleep issues explained about 38% to 57% of the connection between screen time and depression in girls.
This means that improving sleep habits might lower depression risk in teenage girls, even if their screen time can’t be completely cut down.
The researchers say their findings support the idea that reducing screen time could be good for teenagers’ health.
They agree with recent recommendations from the Swedish Public Health Agency, which suggest that teens should limit their daily screen time for fun to no more than two or three hours.
The researchers concluded that too much screen use can gradually harm sleep, which in turn may lead to emotional struggles, especially for girls. They suggest that public health efforts to reduce screen time might help lower the number of teens struggling with depression—especially among young women.
This study adds to growing evidence that limiting screen time and protecting healthy sleep routines are important steps for supporting teen mental health.
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