Three months after Australia's under-16 ban, a BMJ evaluation found little drop in teen use

More than 80% of children were still using a restricted online platform, Australia's online watchdog reported ^[7]; fewer than one in five were off them ^[8]. That share limits what any Australian study of adolescent mental health can currently detect.

The evaluation published in the BMJ found little evidence of substantial reductions in social media use three months after the ban took effect, and found many young people were continuing to use restricted platforms and finding ways around age verification ^[6]. Early findings point to age verification by the companies as the significant implementation problem ^[21]. A before-and-after comparison of teen mental health in Australia is therefore comparing two periods in which most teenagers were on the platforms. A null result would be ambiguous between two different conclusions: the restriction does not help, or the restriction did not happen. Writing in STAT, an author who works at Wellcome said it is too early to say whether Australia's ban has improved young people's mental health ^[20].

Behavioral economist Leonardo Bursztyn and colleagues found that many teenagers continued to believe their peers were using restricted platforms, and reported they would be more willing to stop if more of their peers stopped too ^[9]. Compliance, on that finding, is a coordination problem. The effect on any one teenager may depend on how many others quit, and a single nationwide start date leaves researchers one value of that share to work with.

The outcome side is harder still. The author argues restrictions will affect young people differently by age, by whether they already have mental health problems, by sleep patterns, and by gender, socioeconomic background and whether they live in an urban or rural area ^[10]. Social media can be an important source of community, so restrictions may land differently on people from marginalized backgrounds, including those who identify as LGBTQ+ ^[11].

If mental health does move, the reason matters. The author points to two candidate pathways for any improvement: teenagers meeting up with friends in real life more often, or getting more sleep ^[12]. Researchers, the author wrote, need to look at "whether changing young people's digital environments leads to meaningful changes in their mental health and wellbeing" ^[13].

Meta's settlement is a second intervention, on its own timetable. Alongside a payment of up to $18 billion to resolve US claims that Facebook and Instagram harmed children ^[4], the company will introduce "safety by design" features for young people, such as concealing the number of likes on posts ^[5]. The author raises the question of whether those features meaningfully change young people's behavior or experiences online, and the published evidence does not yet answer it ^[18].

The UK plans to introduce its ban in spring 2027 ^[14], roughly 15 months after Australia's ^[15]. That leaves time to measure a baseline before the rule lands. Wellcome, the London-based philanthropic foundation where the author works and one of the biggest funders of mental health research in the world ^[16], will fund evaluations of the UK ban's impact on youth mental health, with research teams working with tens of thousands of teenagers and the work guided by young people who have experience of both social media use and mental health ^[17]. Almost half of all mental health problems emerge by the age of 18 ^[19].