The UK government's plans for regulation of the internet and social media contained a long list of online harms. Among them was excessive screen use by teenagers.
On the Tech Tent podcast this week, we ask whether there is convincing evidence that spending hours staring at smartphones and other screens is damaging the mental health of young people.
If you read news headlines - or indeed the government's Online Harms White Paper - you might think that the case against screen time was a no-brainer.
But this week, a study by the Oxford Internet Institute suggested that it had little obvious effect on the mental wellbeing of teenagers, even if they were spending hours staring at screens at bedtime.
"We look at general wellbeing," one of the researchers, Amy Orben, tells us. "We do not find a relationship between digital screen use 30 minutes, one hour and two hours before bed and a decrease in wellbeing."
The research examined data from more than 17,000 teenagers in the UK, Ireland and the United States.
Ms Orben tells us that, unlike some other studies, their work does not rely solely on what people report about their own screen time.
"People are really bad at estimating how much they use phones and technology in their everyday life," she explains
"We've actually seen in previous research that the overlap between their self-reported phone use and their actual use when it is tracked is absolutely minimal."
Robust study
Critics have pointed out that some of the Oxford data dates back to 2011. Since then, adolescents' screen time and the nature of what they are viewing has changed.
There is plenty of anecdotal evidence that no matter how long teenagers are spending looking at screens, they are encountering material about issues such as anorexia and self-harm that could prove damaging to their mental health.
The Oxford researchers are confident that their study is robust in its finding that any correlation between screen time and mental health is very small.
"That crucially does not mean that I'm saying that there might not be a type of digital technologies that is harmful, or is very beneficial," says Ms Orben. But she says more research is needed.
"I think this study is only a first step. We need to be asking better questions."
Meanwhile, whatever the evidence, the drive to regulate the internet is gathering pace.