As it turns out, the link between mental health and overuse of mobile technology is harder to prove than you might think. (Also read: Is your teenager dealing with deeper emotional or psychological issues? Watch out for these signs and red flags)

What screen time does to teenagers

A new study conducted in South Korea attempts to measure this link using self-reported screen time, a methodology that, despite being very common in this line of research, has come under criticism by tech researchers in recent years. The study, published in the journal PLoS One on December 6, looked to examine what increased screen time means for teenagers’ mental health.

This is not a new question — for years, researchers have been trying to quantify the degree to which mobile technology — and social media in particular — is bad for youngsters. But it marks the first time researchers have tried to track this potential relationship at a national scale.

The researchers used two surveys conducted by Korea’s health department in 2017 and 2020, respectively, asking over 40,000 teenagers how many hours per day they spend on their phones on average. The teens were also asked about mental health, substance use and obesity.

As expected, they found that their screen time increased significantly between 2017 and 2020, from 30% reporting screen times over 4 hours per day in 2017 to over 55% in 2020. They also found that all three categories tested — negative mental health outcomes, substance use and obesity — increased the more time the children spent on their phones.

The study’s results are consistent with what we already know about the subject. The corelation is uncontestable between mental health and increased use of mobile technology. But the paper’s shortcomings— outlined by the researchers themselves — are significant. “The reported usage time may not be an estimate of the actual usage time and could be underestimated due to the tendency to provide socially desirable and acceptable answers,” they wrote.

Additionally, the researchers didn’t track what exactly these youngsters were doing on their phones in the first place. Were they looking at TikToks? Having long video calls with friends? Playing games? They addressed that too: “We could not specify the smartphone usage time according to the purpose (e.g., social media use, text messaging, education, online shopping), which could have affected the health outcomes,” they wrote.

‘Meaningless’

Peter Etchells, a professor of psychology and science communication at Bath Spa University in the UK, said that measuring screen time as a concept is “pretty meaningless.” “It covers literally anything and everything, and for many years now, researchers have been calling for a more nuanced approach that more fully considers the specific content and context of use,” he told DW in an email.

Being a simple number, screen time is easy to measure in research papers, he said. “But if you imagine two people reporting three hours of screen time per day, those three hours can cover such a varied range of activities, it’s nonsensical to try and correlate that simple number with something else, like well-being,” he said.

Etchells, who is working on a book on the science of screen time next year, said the question researchers should be asking isn’t what the relationship between increased screen time and mental health may be, but rather: “Why is it the case that some people encounter difficulties when they use digital technology, and other people appear to thrive?”

He is basically saying that when it comes to measuring phones’ impact on mental health, the important metric to use isn’t time spent using the technology, but rather what we are doing when we are using it, and how those activities may or may not impact mental health.