Giving a mobile phone to someone under the age of 12 increases the risk of depression and obesity, according to a new study.

A new study led by Children's Hospital of Philadelphia, published on Monday in the magazine Pediatrics, reveals that children who receive a smartphone before age 12 present greater risks of depression, obesity and lack of sleepThe research, based on data from more than 10.000 teenagers en United StatesIt raises new questions about the appropriate time to introduce mobile phones to children and their potential long-term health effects.

Clear risks: more depression, more obesity, and worse sleep

The study found that 12-year-olds who already owned a smartphone had a 31% higher chance of depression, a 40% higher chance of obesity y a 62% higher probability of sleep deprivation compared to their peers without a phone. The researchers observed that the earlier the age of mobile phone acquisition, the greater the health risks, especially related to weight gain and sleep problems.

Dr Ran Barzilay, lead author and child psychiatrist at CHOP, noted that these results “They force us to treat smartphones as a relevant factor in adolescent health“They insist that the decision to give a mobile phone to a child should be considered carefully due to its potential impact on their lives and well-being. The team suggests that the combination of constant screen exposure, sedentary lifestyles, and social pressure may be amplifying vulnerabilities that were not previously seen at such young ages.”

A hyperconnected generation before adolescence

The results are published at a time when Half of all American children own a smartphone by age 11, an age that coincides with the median observed in the study. The research was based on the Adolescent Brain Cognitive Development Study, the largest longitudinal project on juvenile brain development in the United States, with assessments collected between 2016 and 2022.

Smartphone ownership was especially prevalent among girls, as well as among Black and Hispanic children from low-income households. The authors note that the results appear to be specific to smartphones and not simply to access to technology, since the analysis adjusted for the influence of other devices such as tablets or smartwatches.

Even so, not all experts believe it can be stated that the phone is the direct cause of the problems detected. Dr. Jacqueline Nesi, a professor at Brown University, warned that “Obtaining definitive causal evidence in such complex phenomena is virtually impossible."although he believes the results offer sufficient reasons for families to consider delaying the arrival of their first mobile phone."

Experts call for parental supervision and clear rules

Dr. Barzilay acknowledged that almost all teenagers will eventually own a phone, but emphasized that the determining factor is not possession, but how, when and under what supervision It is used. She pointed out the importance of children maintaining daily periods of disconnection to promote physical activity, a protective factor against obesity and a key tool for mental health. She also stressed the need for parents to monitor the content their children access and ensure that the device does not interfere with their sleep, a problem that is becoming increasingly common among pre-teens and teenagers.

Sleep, the first victim of mobile phones

One of the most alarming findings of the study is the impact of smartphones on sleep. Research cited by the team indicates that Nearly 17% of children aged 11 to 12 were woken up in the last week by phone notifications, according to Dr. Jason NagataA pediatrician at the University of California, San Francisco, explains that the combination of blue light, nighttime messages, and constant stimulation disrupts the natural sleep rhythm, impairs the quality of deep sleep, and directly affects cognitive performance and emotional well-being.

For specialists, removing phones from the bedroom at night remains one of the simplest, most effective and affordable interventions to reduce the negative impact of the device on children's health.

The study published in Pediatrics This study provides one of the most comprehensive views to date on the risks associated with early smartphone use, not only because of the large sample size—more than 10.000 adolescents—but also because of its longitudinal approach. Although causality remains difficult to establish, the consistency of the results reinforces the idea that early access to mobile phones fosters a series of habits and dynamics that can have cumulative effects on emotional, physical, and cognitive health.