The first phone for kids? Not before the age of 13. Here’s what the damage on cognitive performance is of just one hour of social media a day

Scientific studies are increasingly solid: adolescent brains are not equipped to handle exposure to social media algorithms. Even just one hour a day on Instagram or TikTok leads to worse cognitive performance. A total ban is not useful, example (and healthy alternatives) are

In elementary schools around the world there is an invisible but clear dividing line. Half of children already have a smartphone. The other half didn’t. Parents who have chosen to wait are aware that they are fighting an increasingly difficult battle because the social pressure is very strong: and little boy without a phone feels excluded. But perhaps, right now, science is proving these tenacious parents right. Ten years ago, the negative effects of screens on developing brains were unknown. Smartphones arrived so quickly that we basically conducted a un mass experiment on our children without knowing it. But today there is much more knowledge and it is possible to act.

Ran Barzilay is a professor of psychiatry at the University of Pennsylvania and the father of three children. The first two received a smartphone before the age of twelve. The third, who has nine, will have to wait. What has changed between one child and another? The answer is simple: data. Between June and December 2025, some large-scale scientific studies began precisely map what happens to the brains of adolescents exposed to screens early. And the results all converge in the same direction: weaker memory, reduced attention, slower processing speed, impaired sleep. They are not opinions but measurements conducted on a very large sample that are changing the way parents, doctors and legislators look at smartphones. On December 10, Australia became the first country in the world to ban social media for children under 16. Last Friday the state of New York approved a law that will force technology giants to warn minors with specific “labels” of the risks of anxiety and depression caused by the abuse of social media.

The first phone after the age of 13

Barzilay’s research, published in Pediatrics and based on the National Institutes of Health’s ABCD (Adolescent Brain and Cognitive Development) project, analyzed data from more than 10,500 American children. The most surprising discovery? Those who receive a telephone at the age of twelve instead of thirteen show a 60% higher risk of developing sleep disorders and a 40% higher risk of becoming obese.

A single year difference seems ridiculous on paper, but in the developing brain it can shift cognitive trajectories that then become difficult to correct. The adolescent brain, in fact, works on precise timing. Twelve months in a critical developmental stage can make the difference between a healthy cognitive trajectory and an impaired one. As Barzilay tells the parents who come to him: “It’s not something you can ignore.” The conclusions follow those of another international study published last July in the Journal of Human Development and Capabilities, which found that receiving a smartphone before the age of 13 «is associated with worse mental health outcomes in young adulthood with theincreased suicidal thoughts, detachment from reality, poorer emotional regulation and decreased self-esteem». The authors’ hypothesis is that under the age of 13 the prefrontal cortex, responsible for impulse control and thought, is not sufficiently developed to deal with the social bombardment driven by perverse algorithms.

The risks of compulsive use: difference between social media and video games

In June 2025, the magazine Jama published a study with a distinction: it is not the total time spent online, but compulsive use increases the risk of suicide. Young people who experience discomfort when separated from their smartphones and have difficulty reducing their use have a two to three times higher risk of suicidal behavior in the future compared to those who use social media in a controlled way. The work also highlighted differences in the type of online activity with related risks: while children who abuse video games manifest internalized mental health problems such as anxiety, depression and social withdrawal those who exaggerate with social media tend to be more aggressive and transgressive.

Lost attention (even with just one hour of social media a day)

Another research published in Jama examined the use of social media and the cognitive performance in children aged 9 to 13 years dividing them into three groups based on social media use: little or no, low but increasing, high and increasing.

The researchers measured cognitive performance using standardized tests: reading aloud, memory of visual sequences, vocabulary. Kids in the “tall and growing” group showed measurable declines in all areas. But the most alarming aspect is that even kids with only an hour of social media a day showed worse performance than those who didn’t use them at all.

“It’s like going from excellent to good on a test,” Jason Nagata, lead author and professor of pediatrics at the University of California, San Francisco, explains to the Washington Post. «A few percentage points on the test, sure. But enough to change a teenager’s educational trajectory. And if you multiply these modest differences by millions of brains that spend three, four, five hours a day on TikTok and Instagram, the problem becomes enormous.”

Another very recent study published as a preprint in Pediatrics in December investigated the attention deficitisolating the specific effects of social media compared to other digital activities. The result was unequivocal: Video games and streaming videos showed no significant correlations with attention deficit. Social media yes.
Torkel Klingberg, professor of cognitive neuroscience at Karolinska Institutet in Sweden and co-author of the study, explains it this way: «Social media provides constant distractions. If it’s not the messages themselves, it’s the thought of having a new one.” The adolescent brain, exposed to continuous streams of notifications, messages and short content, develops clear and measurable symptoms of inattention. It’s a vicious neurological cycle. The brain adapts, of course. But adaptation goes both ways. If you constantly train distraction, the ability to concentrate deteriorates. Klingberg emphasizes that cognitive skills are not fixed, they depend on use: «If you train them, they improve. If you ignore them, they get worse.”
The problem is that social media, as Riccardo Luna explained very well, are designed precisely to maximize usage time, not to train useful cognitive skills. Each notification is a reinforcement that prompts the brain to check again. And again. And again. It’s a system perfectly calibrated to capture attention, but devastating for the development of that same attention.

Evidence of attention deficit is also physicalas highlighted by a Japanese study published in Translational Psychiatry last October. Researchers at Fukui University followed 11,878 children aged 9-10 over a two-year period, using advanced MRI to monitor structural changes in the brain. The results showed that increased screen time was associated with reduced cortical volume and slowed growth in brain regions key to cognitive function. It’s not just about behavior or performance: the physical structure of the brain changes, and excessive exposure to screens can delay brain maturation and cause more severe symptoms of attention deficit hyperactivity disorder (ADHD).

What can we do

Faced with this far from reassuring picture, the good news is that there are concrete strategies to protect our children. There is no need to demonize technology or completely give up smartphones. You need to use them consciously.
–Delay access: the first and most important strategy is to delay the age of the first smartphone. Barzilay’s data are clear: every year of delay in early adolescence counts. If possible, wait at least until you’re thirteen, even better until you’re fourteen or fifteen. At that stage, the prefrontal cortex is more developed and better equipped to handle algorithmic temptations.
-Set a good example: Laura Turuani, psychologist and psychotherapist at the Minotauro Institute in Milan, expert in adolescents and family dynamics, underlines that the most effective way to manage the use of screens is not a ban, but an example. Children imitate their parents, especially in their nocturnal habits. “If adults can’t get away from the phone first, how can they expect kids to do it?” observes Turuani. «Education comes through coherence, predictability and ability to lead by example. Bans, alone, only risk fueling opposition or a sense of guilt.” Research shows that Reducing device use by even just an hour a day has better and longer-lasting effects than drastic attempts at total elimination. The adolescent brain responds better to gradual changes than sudden shocks: it is a question of neuroplasticity, the brain adapts slowly and not on command.
-Create screen-free moments: the bedroom should be a “sanctuary” without devices. Dinner should be a time for face-to-face conversation. These rules apply to the whole family, including parents.
–Prioritize the quantity of contents: an hour spent watching an educational documentary has a different impact than an hour spent scrolling TikTok. A strategic video game that requires planning and problem solving trains the brain differently than a digital slot machine designed to be addictive. It is useful to help children develop a critical sense of content.
-Smart parental controls: parental controls should not be tools of total surveillance, but supports for autonomous management. Various apps allow you to set daily limits, block certain applications at certain times, monitor usage without completely invading your privacy but the goal is gradually build self-regulationdo not impose permanent external control.
– Building attractive alternatives: the most effective way to reduce screen time is not to ban it, but to offer more attractive alternatives, even if it can be very tiring. Sports, music, art, time with friends in real life. If the only alternative to the smartphone is boredom, the battle is lost from the start.