At what age is social media use most harmful to mental health?

The MJA study found the strongest effects in 12-to-13-year-olds, where the association between heavy social media use and depression and anxiety was roughly double that seen in older teens. This does not mean older adolescents are unaffected — the research found persistent depression associations into the 14-to-18 age band — but the early adolescent years appear to be the highest-risk window. Australia's social media ban targets under-16s partly on this basis.

Does Australia's social media ban for under-16s solve the problem?

The researchers who conducted the MJA study are explicit that age-based restrictions alone are unlikely to eliminate all risks. Platform design — algorithmic amplification, infinite scrolling, notification architecture — and digital literacy education also need to be part of the response. The ban creates a structural floor; it does not substitute for conversations between parents, young people, GPs, and schools about healthy digital habits.

Two hours of social media a day raises teens' depression risk — MJA study

What just happened

A Melbourne longitudinal study published in the Medical Journal of Australia on 11 June 2026 found that adolescents using social media for more than two hours each day face a significantly higher risk of depression, anxiety, and other mental health problems one year later — compared with those keeping use under one hour daily.

The study tracked 1,195 Melbourne students annually from ages 12 to 18. It is one of the few Australian longitudinal investigations on this question — meaning it followed the same young people over time, rather than taking a cross-sectional snapshot of different people at different ages. That design gives it more purchase on causality than most of the literature in this space, though the researchers are careful to note that causation cannot yet be definitively established.

The headline finding is the size of the effect at age 12-13. For girls in this youngest cohort, more than two hours of daily social media use was associated with approximately 11 additional cases of high depressive symptoms per 100 adolescents. That is not a marginal signal. For context: roughly one in nine girls in this age group with high social media use developed elevated depressive symptoms that would not have appeared at lower usage levels.

The study measured multiple outcomes: depressive symptoms, anxiety, wellbeing, and self-harm indicators. The two-hour threshold was consistent across several of these domains, not just depression.

The both-and

This research arrives in the wake of Australia’s social media ban for under-16s, introduced in December 2025. Understanding what the evidence does and does not say matters — because the policy debate is still live and the science is more nuanced than a single threshold figure suggests.

What the evidence supports

The two-hour threshold carries clinical weight. The Deakin University and University of Melbourne researchers found the strongest risk associations in the 12-13 age band, across both genders, though girls bore a disproportionately higher burden of depressive symptoms at this age. Effects were also detectable in older teens (14-18), particularly for ongoing depression — suggesting the vulnerability does not simply resolve once young people reach 16.

The Australian study is notable for what it controls for. The researchers used statistical methods to reduce confounding variables — attempting to rule out the alternative explanation that kids with pre-existing depression use social media more, rather than social media causing depression. The residual association after those adjustments is the signal worth attending to.

A parental survey conducted alongside the research found that 59% of parents felt the law supported their rule-setting efforts, and 38% endorsed 16 years as the preferred starting age. The survey also revealed that 39% of parents changed their views on appropriate access age after the law was introduced.

What the evidence does not resolve

The researchers emphasise that age-based restrictions alone are unlikely to be sufficient. The ban limits access by age, but it does not address platform design — algorithmic content amplification, infinite scrolling, and notification architecture are the structural features most consistently implicated in extending use beyond healthy thresholds. Young people aged 16 and 17, who are now permitted on platforms, also need support that goes beyond a legal permission gate.

The causal picture also remains incomplete. Longitudinal data reduces but does not eliminate the possibility that pre-existing mental health vulnerability drives both higher social media use and worse outcomes — a bidirectional relationship where the causal arrows run both ways. This is not a reason to dismiss the findings; it is a reason to combine platform-level interventions with clinical and family-level support, rather than treating the age ban as a complete solution.

What this means in the consulting room

The two-hour threshold in the MJA study is specific enough to be clinically actionable. In routine adolescent mental health presentations — particularly in younger teens — asking about daily social media use duration (not just whether they “use it”, but how long) gives information that matters clinically.

A parent who reports their 12-year-old spends three to four hours per day on social media alongside low mood now has an evidence anchor for a conversation about reduction. The framing available to both GPs and parents has sharpened: this is no longer a vague “screens are bad” conversation; it is a specific threshold with a published Australian evidence base.

2 cents

For parents of early adolescents (ages 10-14): two hours is the threshold the current evidence points to. There is no need to frame this as a confrontation — the clinical context (“Australian researchers found two hours per day is a meaningful threshold for depression risk at this age”) gives a teenager something factual to engage with, rather than an abstract parental rule.

For GPs: routine inquiry about daily social media use duration is a low-cost addition to a mental health screen for adolescents. It is not a standalone diagnostic instrument. But it is a piece of information that can orient a conversation about sleep, social connection, activity patterns — the modifiable behaviours that cluster around mental health risk in this group.

For anyone designing adolescent health programs: the research supports both the age ban and the need for complementary approaches. Digital literacy education, platform accountability for algorithmic design, and peer-to-peer support programs are named by the researchers as equally necessary parts of a complete response.

This is general health information, not personal clinical advice.

Verdict

Verdict: yes — worth knowing about.

This is Australian longitudinal data, published in the MJA, with a specific and actionable threshold (two hours per day) in the age group (12-13) where the effect is largest. For a country that has already enacted an under-16 social media ban, this research gives parents and clinicians a more precise signal to work with — and a reminder that the ban alone is not the ceiling of the required response. The two-hour threshold is the clearest clinical takeaway from the study.

If you or someone you know is struggling, support is available 24/7: Lifeline 13 11 14 · Beyond Blue 1300 22 4636 · 13YARN 13 92 76.