Social media use has been linked to depression, especially in teenage girls. But a new study argues that the issue may be more complex than experts think, CNN reports.

The research, published Tuesday in the journal The Lancet Child & Adolescent Health, involved interviews with almost 10,000 children between the ages of 13 and 16 in England. The researchers found that social media may harm girls' mental health by increasing their exposure to bullying and reducing their sleep and physical exercise.

"Our results suggest that social media itself doesn't cause harm, but that frequent use may disrupt activities that have a positive impact on mental health such as sleeping and exercising, while increasing exposure of young people to harmful content, particularly the negative experience of cyber-bullying," study co-author Russell Viner of the UCL Great Ormond Street Institute of Child Health said in a statement.

In other words: Social media itself might not be to blame for mental health issues; rather, it takes away from girls' sleep quality and exercise while exposing users to cyberbullying, and that's what leads to lower well-being and problems with mental health.

Bob Patton, a lecturer in clinical psychology at the University of Surrey, said this means strategies focusing only on reducing social media use as a tool to improve well-being or mental health might not help.

"Building strategies to increase resilience to cyberbullying and that promote better sleep and exercise behaviours may well be what is needed to reduce both physical and psychological harms," Patton, who was not involved in the research, said in a statement.

For boys, the impact on their mental health seems to be due to other reasons, so further research is needed, the authors said.