Data from just 6 minutes of walking, collected via motion sensors in smartphones, may be enough to predict someone’s risk of dying in the next five years.

Previous studies have estimated level, measured by wearable motion sensors in devices like fitness watches. Yet despite the growing popularity of smart watches and fitness trackers, they are still mostly worn by an affluent minority.

Most people own smartphones with similar sensors, but calculating mortality risk from activity data they gather is difficult because people don’t tend to carry their phones all day, says at the University of Illinois Urbana-Champaign.

To find an alternative predictor that is measurable with smartphones, Schatz and his colleagues looked at data from 100,655 participants in the UK Biobank study, which has been collecting information on the health of middle-aged and senior adults living in the UK for more than 15 years. As part of that study, participants wore motion sensors on their wrists for one week. About 2 per cent of the participants died during the following five years.

The researchers ran motion sensor and death data on about one-tenth of participants through a machine learning model, which developed an algorithm that estimated five-year mortality risk using acceleration during a 6-minute walk.

“For many diseases, specifically heart or lung diseases, there’s a very characteristic pattern where people slow down when they’re out of breath and speed up again in short doses,” says Schatz.

They then tested the model using data from the other participants and determined its c-index score – a metric commonly used in biostatistics to assess accuracy – was 0.72, which is comparable to other metrics of estimating life expectancy, like daily physical activity or health risk questionnaires.

“This predictor is as strong as or stronger than traditional risk factors,” says at Johns Hopkins University in Maryland.

While this study used wrist-worn motion sensors, smartphones are also capable of measuring acceleration during short walks, says Schatz, who is currently planning a larger study using smartphones. “If people carry phones around, you could do a weekly or daily prediction and that’s something you cannot get by any other method,” he says.

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Know any teenagers? Chances are they will have a phone on them – and that is a big mental health problem. At least, that is the impression you get from , saying that one in four teenagers are addicted to their smartphone.

We have seen headlines like this before. This time they are based on a paper finding that 23 per cent of teens are using their phones in a problematic way. An accompanying press release said that this was “consistent with a behavioural addiction”.

The paper also found that those with problematic use were three times more likely to report feeling depressed, anxious or that they weren’t getting enough sleep. The narrative is irresistible: smartphones are giving our children mental health problems.

But perhaps we should stop and think before we get too alarmed. It is highly debatable whether anyone can be addicted to their phone – or to using the internet or playing computer games. Some researchers in the field say it is possible, while others say it is meaningless to use the term addiction in this context.

The new paper, which is a summary of 41 previous studies of phone use, doesn’t shed light on this almost philosophical question, except to confirm that some teens are on their phones an awful lot. I suspect that their families knew this anyway.

The researchers looked at studies that used surveys to assess people’s behaviour. The most common survey includes several questions that could merely indicate high levels of phone use without it necessarily being a pathological medical condition.

Questions include whether people use their phone for longer than they had intended, whether it had caused them to miss some planned schoolwork, or if they had been told by others they were using it too much.

Can this really identify addiction? Substitute “phone” for “book” and you can imagine a keen reader answering yes to many of these questions, but we don’t tend to despair about reading addicts.

When I put this to one of the study authors, Nicola Kalk of King’s College London, she said the surveys were widely used. She also cited examples of teenagers who spend so much time gaming on their phones that they won’t even stop to get washed or leave the house.

That certainly would be disturbing behaviour, but this study doesn’t tell us anything about the number of teenagers in such an extreme state.

Another concern is that the studies included in the review were unrepresentative, says Amy Orben at the University of Cambridge. That is because Kalk’s team scanned the database of all studies on phone use by using “addictive” as one of the search terms. Studies that found low levels of problematic use may have been overlooked, says Orben.

Kalk and co-author Ben Carter, also at King’s College London, agree that this is a limitation but say the findings still suggest a pattern that requires further investigation.

The other claim, that phones are making young people depressed, isn’t supported at all; the studies merely show a correlation between phone use and reported mental health issues, not that phones are the cause.

It is quite plausible that feeling depressed because you don’t have many school friends makes you more likely to game or talk to people online as way of coping. If that is the case, any parents who respond to the latest headlines by taking their child’s phone away might be making things worse.

To be fair to Kalk’s team, they do state in their paper they have only found an “association” between phone use and mental health issues, but the fact that this is no proof of causation has been glossed over in much of the media coverage. It is almost as if journalists can’t resist a good story about teenagers and their phones. You might say we are addicted.

“It is being positioned as all things to everybody, the Swiss army knife of the mobile world”

Marketing buzzword

“You could use 5G to download vast amounts of data, but it’s not clear that anyone would want to”

The 5G conspiracy

New 5G networks are barely on the streets, but that hasn’t stopped the rise of baseless conspiracy theories. “These towers are weaponry,” a YouTuber incorrectly insists in a video with nearly 1 million views, as he attempts to “expose” mobile networks and 5G as a government-designed “kill grid” poised to harm people en masse. In some cities, people have scrawled anti-5G graffiti on phone boxes or mobile masts. While research continues to be carried out on any possible effects of electromagnetic radiation on human health in certain scenarios, there is . The anti-5G conspiracy theorists are themselves a symptom of the hype and uncertainty surrounding the technology, says psychologist Oliver Mason at the University of Surrey, UK, who has studied technophobia. Paranoia is bound to creep in when change is promised, especially when the details or potential consequences of that change are unclear, he says. “Technology is a lovely breeding ground as we’ve got pretty much no idea what is possible.”