Should a 13 Year Old Have a Smartphone? What 10,588 Young Adolescents Showed

The short answer: the associations point the same way, and none of them is proof

If you are looking for a study that stamps age 13 as safe or unsafe, this one does not do that, and no honest reading of it can. What Barzilay and colleagues at Children's Hospital of Philadelphia, UC Berkeley and Columbia did instead is more useful: they took the largest long-running study of US child development, the ABCD Study, and asked what smartphone ownership around ages 12 and 13 actually came with — for depression, for weight, and for sleep.

Every comparison they ran pointed the same direction. Owning a smartphone at 12 was associated with worse outcomes on all three measures. Getting a first smartphone during the following year was associated with worse mental-health symptoms and worse sleep at 13, in the analysis that best accounts for where each child started. And the younger a child had been when the first phone arrived, the higher the odds of obesity and insufficient sleep at 12. Those are associations in observational data, with all the caution that requires — and they are consistent enough, in a sample this large, that they deserve a parent's attention rather than a shrug.

Should a 13 year old have a phone? What ownership at 12 was linked to

Start with the snapshot at age 12, because 13-year-olds are usually decided about a year earlier. Of the 10,588 children, 6,739 owned a smartphone at the age-12 assessment and 3,849 did not. Ownership was reported by caregivers, and a smartphone meant the child's own iPhone or Android — not a tablet or a laptop, and the researchers adjusted their models for ownership of those other devices, along with family income and parent education, pubertal development, and how much parents monitored their children.

Compared with the children without a smartphone, the owners had higher odds of all three outcomes: depression, odds ratio 1.31; obesity, odds ratio 1.40; and insufficient sleep, odds ratio 1.62. An odds ratio of 1.62 means the odds of the outcome were about three-fifths higher in the owning group — for sleep, the largest gap of the three. These are group comparisons at a single point in time, so on their own they carry the weakest version of the argument: children who own phones at 12 might differ from children who do not in ways no adjustment fully captures. That is exactly why the study's second test matters more.

Is it ok for a 13 year old to have a phone? The year-after test

Here is the part of the study built for the 13 question. The researchers took only the children who did not own a smartphone at age 12 — 3,486 of them — and split them by what happened next. By the age-13 assessment, 1,546 had acquired their first smartphone in the past year. The other 1,940 still had none. Both groups started the year phoneless, and the researchers controlled for each child's baseline mental health and sleep, measured before anyone in this comparison got a phone.

A year on, the children who had acquired a smartphone had greater odds of reporting clinical-level psychopathology — odds ratio 1.57 — and of insufficient sleep, odds ratio 1.50, compared with the children who remained phoneless. In plain terms: two groups of children who looked similar at 12, one of which got phones and one of which did not, had measurably separated by 13 on mental-health symptoms and sleep, in the direction nobody would choose.

This design is stronger than a snapshot, because it accounts for where each child started. It is still not a trial. Nobody assigned phones at random — the authors are explicit that a trial like that would not have been possible — so families who handed over a phone during that year may still differ from families who waited, in ways the data cannot see. It is the best-controlled evidence we have on getting a phone at 13, and it is not proof of cause.

Smartphones, teen depression, obesity and sleep: how the outcomes were measured

So what were the outcomes, exactly? Depression at age 12 meant a lifetime depression diagnosis from the KSADS, a structured diagnostic interview — not a mood questionnaire. The mental-health outcome in the year-after test was different, because the diagnostic interview was not run at that wave: it was a clinical-threshold score (T-score of 65 or higher) on the Brief Problem Monitor, a standard symptom scale covering internalising, externalising and attention symptoms. Obesity meant a measured body mass index above the 95th percentile — height and weight taken at the study visit, not guessed. Insufficient sleep meant the young person reported sleeping less than 9 hours a night.

Against those measures, the age pattern fills in. Among owners, each earlier year of first getting a smartphone was associated with higher odds of obesity (odds ratio 1.09 per earlier year) and insufficient sleep (1.08) at 12 — small per year, compounding across years. The equivalent link for depression did not meet the study's own corrected significance threshold, and the authors report that openly. Context for how ordinary this decision now is: the median age of first smartphone acquisition in the cohort was 11, ownership rose from 63.6% at about age 12 to 77.2% at about 13 and 89.1% at about 14, and the associations held up across the study's sensitivity checks — including when young people with problematic smartphone use were removed from the analysis, which means the results were not carried by a small group of heaviest users.

What this research can't tell you

It cannot prove the phone caused any of this. The data are observational. Families who give a 12-year-old a smartphone may differ from families who wait — in stress, in routines, in things no dataset records — and the authors themselves urge caution about drawing causal conclusions, even from their best-controlled analysis.

It measured owning, not using. A smartphone in this study is a device a caregiver said the child owned. The study says nothing about what any child did on a phone — no apps, no social media, no hours of use — so it cannot rank platforms or set a screen-time limit.

It does not certify any age. No age was tested as an intervention. The study does not show that waiting until 14 would have changed these outcomes, and it does not show that 13 is a safe age either. What it shows is what ownership at 12, and acquisition by 13, were associated with in this cohort.

The authors are not calling for bans. They state plainly that they are not advocating restrictions on young people's access to smartphones. They call for oversight, and they note that there may be real costs for some young people who do not own phones in a world where friendship runs through them — a cost this study did not measure.

Its data are American and predate today's apps. The ABCD assessments used here ran from 2016 to 2022 across 21 US sites. The phones changed since; the developmental questions probably did not, but the study cannot tell you about a specific app or handset in 2026.

For context, the AAP's own guidance does not set an age either. HealthyChildren.org, the American Academy of Pediatrics' parent site, frames the first-phone decision as readiness rather than a birthday — what the phone is for, whether your child can handle the responsibility and impulse control, what benchmarks would show responsible use, and whether a simpler device would do the job for now. That guidance and this study agree more than they clash: neither names a safe age. The study adds outcome numbers at 12 and 13 that the readiness guidance does not try to quantify.

Smartphone rules for a 13 year old: putting the study to work

This section is strategy, not findings: it takes what the study measured and turns it into decisions a family can actually make:

• Protect sleep first — it is the study's most consistent signal. Insufficient sleep was the outcome linked to ownership at 12, to earlier acquisition, and to getting a phone by 13. Sleeping under 9 hours is the study's own definition of not enough. A phone that charges overnight outside the bedroom is the single rule most directly aimed at the finding.
• Decide social media separately from the phone. The study measured owning a handset, not opening accounts. A first phone can be calls, texts and maps while the social-media decision waits for its own conversation — nothing in this research requires the two to arrive together.
• Set the benchmarks before the phone arrives. Agree in advance what responsible use looks like — grades steady, sleep protected, phone down at meals and in class — and what happens if those slip. The AAP's readiness guidance makes the same point, and its PhoneReady Questionnaire is a free way to structure the talk; the study's authors point parents to it too.
• Watch the year after, not just the handover. The study's design is a reminder that the change to watch for shows up over the following year: mood, symptoms, and above all sleep. If those slide after a phone arrives, that is information about your child that matters more than any population average — and a reason to tighten the rules, or talk to your pediatrician.
• Keep the costs of waiting in the picture too. By 13, over three-quarters of the children in this cohort owned a smartphone. A child who is the only one without can pay a social price the study did not measure. Rules, timing and a simpler starter device are all middle options between "full smartphone now" and "nothing until high school."

Frequently Asked Questions

The takeaway

The largest US study of child development followed children through the very year parents argue about, and the pattern was consistent: owning a smartphone at 12, and getting a first one by 13, went with higher odds of depression, obesity, mental-health symptoms and too little sleep — modest odds, honestly labelled as associations, in the one dataset big enough to see them clearly. That does not settle the decision for your family, and the researchers say so themselves. It does say the decision deserves more than a shrug in either direction — and that if a phone arrives at 13, sleep is the first thing to guard.