Adolescents who spend at least two hours a day on social media are more likely to experience depressive symptoms and poorer wellbeing, with the strongest effects in early adolescence, according to new research.
The decade-long study, led by Murdoch Children's Research Institute (MCRI) , found that higher levels of social media use between the ages of 12-18 years were associated with small but noticeable increases in mental health problems one year later, underscoring the need for policies that reduce excessive screentime.
MCRI and Deakin University Dr Nandi Vijayakumar said the findings added much needed insight into the potential impacts of social media on young people's mental health, particularly during the early teenage years.
The longitudinal study followed almost 1,200 children in Melbourne from age nine to 19 who participated in the Child to Adult Transition Study (CATS) . The study collected annual data, prior to Australia's age-restrictions, on social media use and mental health outcomes including depression, anxiety, wellbeing and self-harm.
Published in the Medical Journal of Australia , it found adolescents who used social media for at least two hours a day were at increased risk of experiencing high depressive symptoms and poor wellbeing at the following annual assessment, compared with those who used these platforms for less than one hour a day. The strongest impact on mental health was seen in girls 12–13 years old.
Dr Vijayakumar said the results supported a focus on early adolescence as a critical window for intervention.
"Early adolescence stands out as a time when higher levels of social media use are linked to a greater risk of mental health problems one year on," she said.
"While the increases in risk were modest in our study, even small effects can have important public health implications when large numbers of young people are exposed. This is why early adolescence may be the key time to intervene."
MCRI Professor Susan Sawyer said the findings supported the need for a balanced approach to social media policies and practices.
"Concerns about the impact of social media on adolescent mental health have fuelled community and policy debates globally and driven Australia's world-first social media legislation," she said. "Despite all this, robust evidence of population-level impacts has remained limited, making our findings particularly significant."
Many adolescents report positive experiences with social media around social belonging and self-expression. But high levels of mental health problems, cyberbullying and exposure to harmful online content have sparked widespread alarm.
"Our results don't suggest that social media is universally harmful but it's not without some harms," Professor Sawyer said. "It reinforces the need for age-appropriate limits, better education and literacy programs and clearer parental guidance."
Previous MCRI-led research has showed almost three quarters of adolescents in Australia experience clinically significant depression or anxiety symptoms , noting that beyond clinical care, wider preventive strategies were urgently required.
MCRI and Deakin University are also monitoring the impact of Australia's social media age-restrictions on teenagers' phone use, screentime, mental health and wellbeing.
The Connected Minds Study involves 13- to 16-year-olds who use social media apps such as Instagram, TikTok, Snapchat and YouTube, and their parents. They are sharing their experiences before and after the changes came into effect on 10 December 2025.
Researchers from The Royal Children's Hospital, the University of Melbourne, UCL Great Ormond Street Institute of Child Health in London, Imperial College London, London North West University Healthcare NHS Trust, University of Bristol, University of Oxford and Curtin University also contributed to the study.
Publication: Nandita Vijayakumar, S Ghazaleh Dashti, Louise Canterford, Susan Ellul, Anthony Parissi, Anne-Lise Goddings, Russell M Viner, Paul Moran, Rohan Borschman, Lisa K Mundy, Ellie M Robson and Susan M Sawyer. 'The effects of social media on adolescent mental health: findings from a population-based cohort study in Australia,' Medical Journal of Australia. DOI: 10.5694/mja25.01399
*The content of this communication is the sole responsibility of MCRI and does not reflect the views of the NHMRC.
