In the haywire period after a major relationship ended, I found myself in a variety of clinches with assorted young men – chaps in their early twenties as compared with my late thirties. There was much to bemoan, such as flakiness and unreliability that often bordered on rudeness and dishonesty, but there was much to learn too. In the latter category was the chance to observe close-up what Gen Z is really like, how they tick. Or, more accurately, how they TikTok – TikTok being the Chinese-owned social media site that features super-short videos. The British Government last week (rather belatedly) banned it from state-issued devices for fear of Chinese infiltration. With this measure, the UK is now in line with more than half of US states and the European Commission.

Being vigilant about Chinese security breaches is crucial, but there is something woefully ironic about this ban. For Chinese spying is not the only clear and present danger posed by TikTok; perhaps it isn’t even the most serious, given that we’re hardly going to escape Chinese threats with the odd lily-livered move like this.

The site’s menace to young brains – the brains of our future – should be treated as a real and imminent threat. When children look at an infinite feed of 21-34 seconds-long videos that snatch back and forth in disjointed, shallow bursts of content for their entertainment and education, they are doing worse than wasting time. They are killing their brains’ ability to function. The term “TikTok brain” has arisen specifically in reference to the lowered concentration span, and increased depression and anxiety that arise from obsessive use of the app. And obsessively is how it tends to be used, for, like most social media, it is habit-forming.

Much damage has already been done. Numerous studies have now shown that social media, especially Instagram and TikTok, rots away at the core of cognitive function – focus. Not only is it hard to work, or love or finish tasks without focus, it also makes people miserable. As the Hungarian psychologist Mihaly Robert Csikszentmihalyi understood, the ability to attain “flow” – total absorption in a productive activity outside oneself – is crucial to mental wellbeing.

No wonder there is a sudden vogue for diagnosing ADHD (Attention Deficit Hyperactivity Disorder) in adults as well as children. In some cases, there is an innate developmental issue underpinning the diagnosis. But increasingly, ADHD can be hard to distinguish from brains that have been rewired by constant scrolling, refreshing, updating, posting, and tab-opening – all those micro-doses of dopamine and ever-more bitesize nuggets of information.

That this all makes us depressed and uneasy and anxious is hardly a surprise when you throw into the mix other effects of excessive use, such as sleep disturbance, family conflict, social isolation and poor work or school performance.

The sharpest and most poisonous end of social media use is found lodged in that most vulnerable of groups: teenage girls. Studies repeatedly show that girls are far more susceptible to outside influence than boys, and, as they hit adolescence, are far more concerned about their place in the social pecking order than boys. Instagram and TikTok target these exact things: showing what all the other girls are doing and how good they can make themselves look. Crucially, all this comes with a public rating system of likes and adulatory comments. Not only are their peers forced to look at all this, it creates a pressure to exhibit oneself too in order to compete. All must create content, and it better be popular.

While on one hand all this means teenage girls wield far more power than boys, and always have, on the other they are more likely to be trodden far lower and turned into nervous, depressed wrecks.

Anorexia has historically been one manifestation of this, and now it’s gender confusion. I interviewed trans whistleblower psychologist Erica Anderson recently for The Sunday Telegraph, and she expressed grave concerns about the effect of TikTok specifically on adolescent girls wondering and worrying about their bodies. They seem to be bombarded with pro-trans content on the site, with trans influencers telling them they’re boys. Some have responded to this by seeking out testosterone and breast binding.

What to do? Is this just the market operating freely, an invisible hand that should be left alone? Or should we treat TikTok like smoking and severely restrict it, as well as banning it for under-16s? It clearly can be harmful. TikTok is eroding children’s ability to process information and the basic stimuli of life.

Learning, courtesy of my paramours, about Gen-Z’s digital habits was informative, interesting and rather terrifying. Leaning over a 23 year old’s phone as he took me through his favourite TikToks and gave me a crash course in how to use the site, I found my eyes glazing over and my brain developing a sort of confused, hazy feeling. It all seemed so busy and noisy and yet so infantile, and so unrewarding.

If, like me, you were lucky enough to be a child in an age of boring afternoons reading books, then you might also find TikTok useful for understanding society, but completely alien – if not downright repulsive.

If, however, you’re a child or a member of Gen-Z, then the gulf between you and the pleasure of having a mind, and using it productively, might soon be too enormous to bridge. Like Chinese theft of British government data, this is genuinely terrifying.