A crackdown on youngsters playing online games offers opportunities for research. Credit: VCG/Getty

Parents beware: a Chinese smash-hit computer game so addictive that state media labels it “poison” is on the march. The multi­player game Honour of Kings has some 200 million users already, mostly in China, and reports suggest that it could be launched to eager teenagers in Europe and the United States later this year.

Although free to download, the mobile-device game encourages players to spend on character upgrades and equipment. Many do, making it the most lucrative game of its type in the world. But faced with a media backlash and complaints from parents, the company that produces Honour of Kings this month announced some severe restrictions on its use. Tencent Holdings in Shenzhen, China, has limited users under 12 years old to a single hour’s play a day, and has stopped them playing at all after 9 p.m.. Those aged between 12 and 18 get just two hours. (The restrictions are possible because players must register and log in.)

It’s not just in China that teenagers are seeing their use of mobile devices curtailed. Elsewhere, schools are making a stand, too. Stroud High School in Britain made headlines this month when it announced that pupils aged 12–14 would not be allowed to use their phones during the school day; those aged 15 and 16 can use them only at lunchtime. Headteacher Mark McShane told parents that the move was to reduce the possible negative impact of social media on their children’s mental health and well-being.

These impacts — and others attributed to the increasing ubiquity of electronic devices — are the latest battleground in a long-running dispute over the effects of visual and interactive media on minds and the brain. From video nasties to nasty video games, how and how much the thoughts and behaviours of young people (and some not so young) are influenced by what they see on their screens is a regular source of disagreement.

Abuse of online games does not have to rot the brain to be a disorder worth investigating.

Groups of academics warn of the dangers; other groups play them down. Both sides point to what evidence they can find to support their stance, and argue that there is insufficient information to back up the opposition’s viewpoint. Guidelines are sketchy. Last year, the American Academy of Pediatrics updated its advice and now discourages media use, except for video-chatting, by children younger than 18 months. For children aged 2–5, it recommends that parents limit screen time to one hour a day of “high-quality” programming.

All involved insist that more research is necessary — they are split only on what should happen in the meantime. And that is a question of politics and personality as much as it is an issue for science.

To make progress, more precision is needed to define just what the groups are arguing about. Although a popular topic with parents and a common public debating point, the effects of ‘screen time’ — and possible limits on access to it — seem too vague to allow much meaningful science. And there are as many claimed benefits as dangers. Equally, whereas many people diagnose themselves with ‘Internet addiction’, the point at which normal (useful and productive) activity becomes a scientific and medical problem is not easily categorized, defined or compared. (The same is true of many behavioural addictions. This does not make them not real, just difficult to frame.)

Computer games such as Honour of Kings might offer an opportunity here. Data are available on who plays and for how long. Interventions such as the restrictions in China can in theory be tracked, subject to proper privacy safeguards. And, although still controversial, attempts have been made to constrain and diagnose one problem behaviour that can emerge: a condition called Internet gaming disorder. It was included for the first time in the 2013 edition of the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, but only as a topic worthy of further attention.

Cynics may scoff, but abuse of online games does not have to rot the brain to be a disorder that is worth investigating. For teenagers, even apparently mild effects such as sleep disruption can quickly cascade into reduced attention and poorer performance at school.

That was one reason why South Korea started a national experiment in 2011, when it banned under-16s from accessing online video games after midnight. The country labelled the policy as the Shutdown Law rather than as an experiment but, nonetheless, it gave scientists an opportunity to do some of the research that all agree is necessary.

Last week, scientists published some of the first results (L. Changjun et al. Telematics Inform. http://doi.org/b9sq; 2017). And, typically, they allow both sides of the debate to claim victory. Internet use rose after the shutdown (maybe teenagers logged on more during the day to compensate?), but addictive behaviour fell. And sleep increased, although by an average of just 1.5 minutes each night. The impact, the scientists say, was statistically significant, but hardly enough to justify the firm hand of the nanny state. Honours are even. For now.