Parents imagine there will be a precise moment when their child is finally ready for a cell phone. Some tidy milestone that signals the rules can ease up. But no such moment arrives. A recent study in Pediatrics (Barzilay et al., 2025) makes that uncertainty sharper. Drawing on data from more than 10,000 participants in the Adolescent Brain Cognitive Development Study, researchers found that children who have smartphones by age 12 face higher risks of depression, obesity, and disrupted sleep. The pattern is steady. The earlier a child gets a phone, the greater the risk. And that risk keeps rising, year by year, starting as early as age 4.
Ran Barzilay, the study’s lead author and a child psychiatrist at Children’s Hospital of Philadelphia, told ABC News (2025) that experts have been urging parents to wait. His reasons go beyond research. He has a 9-year-old who wants a phone, and he feels the weight of that decision the same way any parent would.
The study pulls from data collected between 2016 and 2022, a period shaped by the rise of always-on platforms and the growing idea that a smartphone marks the unofficial start of adolescence. Researchers from Penn, Berkeley, and Columbia studied how the age of first smartphone use was connected to later health outcomes. Twelve-year-olds with phones reported more depression, more obesity-related patterns, and more insufficient sleep than peers without phones. Thirteen-year-olds who had only recently been given a phone also showed worse mental health, even after controlling for earlier issues. This is correlation, not proof of cause, but the signal is unmistakable. Something about early phone use nudges kids toward trouble.
The Science Already Pointed This Way
Even before this new work, other studies kept circling the same concern. A Canadian cohort study found that higher daily screen use at age two predicted more behavioral problems at age five (Madigan et al., 2019). A Norwegian study showed that social media use in early adolescence raised the risk of later depressive symptoms, especially for girls (Boers et al., 2019). Sleep researchers have warned for years that screens in the bedroom scramble natural rhythms, and a meta-analysis of 50 studies found consistent links between evening screen access and worse sleep quality (Carter et al., 2016). Add to that a JAMA Pediatrics study showing that heavy early screen exposure correlates with altered brain white matter, a key factor in language and self-regulation (Hutton et al., 2020).
The science forms a landscape. It tells us screens are powerful, maybe too powerful for a young mind. The new Pediatrics study fits smoothly into that picture but brings something sharper: the timing. Risk accumulates with every earlier year a child receives a device. The very idea of a 4-year-old entering a smartphone timeline feels almost absurd; yet, in real homes, the reasons unfold in familiar ways. A phone quiets a meltdown during a commute. It fills the space while dinner cooks. It helps a parent juggling too many tasks at once.
Barzilay is not interested in shaming parents. His own older children got phones before 12. Families work with what they have. A phone for safety, a phone because every other kid already has one, a phone because saying no becomes a daily battle. But the study does suggest that giving kids more time may not be a small thing. Waiting a year or two could change the arc of their health and well-being.
Where Screens Hit Hardest: Emotion, Sleep, and the Shape of Daily Life
Mental health researchers often describe screens not as villains but as amplifiers. They take what kids already feel and intensify it. A lonely child scrolls through everyone else’s edited joy. A child who tends to worry cannot escape the steady drip of alerts. A teen struggling with body image falls into a churn of stylized faces and perfect weekends. Adults fall in the same traps, but most of us know, at least dimly, what is happening. Kids don’t.
Sleep is another pressure point. Every parent knows what a tired kid looks like: shorter temper, more anxiety, less resilience. Screens delay bedtime. They trick the brain with light when darkness should be signaling rest. The Pediatrics study shows how easily one shift leads to another until a child’s days and nights tilt off balance.
So what do we do in our families? Keep phones out of bedrooms at night. Build routines that include non-screen activities. These ideas only work well when they start early. Once a child has had free rein with a device, rolling things back becomes difficult for everyone involved. The day-to-day reality, of course, is even more complicated. Any parent can picture the negotiation, the pleading, the comparisons to friends who already have one. The science offers a compass. Living by it is the actual work.
Smartphones are here to stay; childhood, too. Our goal must be to keep one from overshadowing the other. Families can do that through timing, boundaries, conversations, and the small everyday decisions that shape a home. This new research doesn’t solve the puzzle. But it makes the questions honest and our choices grounded.