Smartphones at Age 12 Linked to Depression, Obesity and Poor Sleep

We are rapidly gaining a clearer picture of how smartphones shape childhood, and a new study of pre-teens nearing adolescence offers further unsettling evidence.

US researchers have discovered that having a phone at age 12 was linked to a greater likelihood of depression, obesity and inadequate sleep than not owning one.

The iPhone arrived less than 20 years ago, meaning that many children now moving into their teenage years have never experienced a world without phones. Research such as this aims to untangle their effects.

"Our findings suggest that we should view smartphones as a significant factor in teen health, approaching the decision to give a child a phone with care and considering potential impacts on their life and health," says child and adolescent psychiatrist Ran Barzilay, from the Children's Hospital of Philadelphia.

Smartphones at age 12 and health outcomes

Information from 10,588 young people, gathered for an ongoing investigation into adolescent brain development, gave researchers a snapshot of participants' health at 12. It also supplied some indication of the differences made over the following year by receiving a phone, or not receiving one.

After accounting for factors including demographic background and socioeconomic status, the team found that nearly 6.5 percent of 12-year-olds with phones had received a depression diagnosis, compared with around 4.5 percent of those without phones. While apparently modest, this gap was statistically meaningful.

For obesity, the equivalent figures were approximately 18 percent among smartphone users and 12 percent among 12-year-olds without the devices.

Sleep results showed a similar divide: 47 percent of 12-year-olds who had phones said they were not getting enough sleep-less than nine hours per night-against 31 percent of peers without phones.

Children who owned a phone by 13 were more likely to report mental health issues, including depression, and insufficient sleep than those who did not. Over that year, however, there was no clear shift in obesity risk.

Benefits, limitations and future smartphone research

The researchers acknowledge that phones can offer benefits, as previous studies have indicated, but say more should be done to ensure these devices are used responsibly.

"For many teens, smartphones can play a constructive role by strengthening social connections, supporting learning, and providing access to information and resources that promote personal growth," says Barzilay.

"Likewise, some families may view a smartphone as a necessity for safety or communication."

The data also include important qualifications. Depression was measured as any episode experienced during the child's life to that point, so in some instances it may have happened before they acquired a phone.

Nor can an observational study of this kind establish cause and effect. Even so, the strength of the links, alongside the differences recorded between ages 12 and 13 as some children got phones while others did not, warrants further study.

The results align with what is known about smartphones in adults: they may increase stress, make people feel more distracted and exhausted, and alter how our brains are wired.

Future research will examine how screen time and different app types influence these outcomes, whether the findings continue across longer stages of adolescence, and which countermeasures might be introduced.

"It's critical for young people to have time away from their phones to engage in physical activity, which can protect against obesity and enhance mental health over time," says Barzilay.

The research was published in Pediatrics.