Phone Addiction: What It Is and What Happens to Teens' Brains

The phenomenon appears in the literature under more than one name. A 2024 review calls it “mobile phone addiction” and notes that other studies prefer “problematic smartphone use” (PSU). The review defines it as excessive use that slips out of a person’s control, with knock-on effects on social life and psychological or behavioral problems, and describes it through three traits: withdrawal, tolerance, and loss of control. The same review points out that it isn’t included in the DSM, psychiatry’s standard diagnostic manual, and that no single diagnostic standard is accepted worldwide: assessment rests mainly on scales built by different researchers for different populations.

A 2019 meta-analysis published in BMC Psychiatry pooled 41 studies, 30 of them run in Asia, covering more than 41,000 children and young people; the authors included only studies whose participants had a mean age of 25 or under. It puts the median rate of problematic use at 23.3%, roughly one in four of the young people studied. Ranked from the lowest rate to the highest, the middle half of the studies fell between 14.0% and 31.2% (the interquartile range), and 31 of the 41 found a rate between 10% and 30%. Those studies used 24 different questionnaires and widely varying definitions of problematic use.

Why it develops

The studies reviewed up to 2024 don’t give a complete answer. The 2024 review in Frontiers in Psychiatry summarizes what researchers have observed in the brains of people with this behavior. It names dopamine and serotonin as key neurotransmitters in the reward system and reports that in people with phone addiction that system is less active, a finding it sets alongside what is seen in depressive disorders. The dorsolateral prefrontal cortex is involved in cognitive control and emotion regulation, and the review describes it as central to inhibiting a response. Among the interventions it surveys is electrical stimulation of this area: the review says it could strengthen that ability, and the study it cites was run on college students with smartphone addiction.

The same review names teenagers as the age group most at risk. It doesn’t explain why, and it flags a limitation of its own: the research so far is mostly cross-sectional, relies on self-reported data, and draws largely on Asian participants, so it can’t establish what causes what.

The American Psychological Association’s advisory, published in May 2023, is about social media, which is one part of phone use, and it adds a point about development. From early adolescence, it says, the brain grows steadily more sensitive in the areas tied to wanting attention, feedback, and reinforcement from peers; the regions that self-control depends on, by contrast, aren’t fully developed until adulthood. The APA therefore recommends that in early adolescence, roughly ages 10 to 14, an adult keep track of how a child uses social media. The same document doesn’t treat social media as good or bad in itself: a lot depends on what a teenager does there and on the environment they grow up in.

Practical example: a thirteen-year-old is studying when the phone lights up with a like. They put the homework aside for a second, and the second turns into much longer than planned. Both behaviors, when they keep recurring, are on the APA’s list of indicators of problematic social media use: carrying on even when you realize it’s getting in the way of something you need to do, and spending more time online than you meant to.

The same advisory asks that teenagers get dedicated training before they start using social media. One of the skills it lists is learning how mis- and disinformation are spread. In a separate passage it describes algorithms as the instructions that decide which posts reach each user.

The warning signs

Since the behavior isn’t in the DSM, there’s no diagnostic checklist to go by. One thing studies do measure is nomophobia, a term coined in 2008 in a UK Post Office study (from “no-mobile-phone phobia”) to describe the discomfort tied to the fear of being without a phone. A systematic review with meta-analysis and meta-regression published in 2022 estimates how common the symptoms are, by level, among participants in 52 studies from 20 countries:

These percentages count people who score above a cut-off on a questionnaire, not people who have been diagnosed. Nine studies in ten use the same tool, the Nomophobia Questionnaire, which picks up higher rates than other instruments when symptoms of any level are counted (97.59% versus 66.52%). Participants had a mean age of 22, and most fell within a narrow age range; in the authors’ analysis, severe symptoms were most likely among university students in non-Western cultures. Results vary widely from one study to the next: the index the meta-analysis uses to gauge that spread (I²) is above 99% for the estimates at all three levels, and the authors treat anything over 75% as high heterogeneity.

The authors describe nomophobia as a behavioral addiction and suggest adding it to future editions of three diagnostic manuals: the DSM, the International Classification of Diseases (ICD), and the International Classification of Sleep Disorders (ICSD). As of 2022, then, it wasn’t in any of those.

Then there’s sleep. The APA advisory notes that technology use, especially in the hour before bed, is associated with disrupted sleep. For teenagers, it adds, too little sleep is associated with disruptions to neurological development and emotional functioning, and with suicide risk.

Effects on psychological wellbeing

The 2019 meta-analysis found that problematic smartphone use is associated with higher odds of depression (odds ratio 3.17), anxiety (OR 3.05), higher perceived stress (OR 1.86), and worse sleep quality (OR 2.60). An odds ratio is a measure of statistical association. The four values rest on a subset of the 41 studies: 20 looked at mental health, and the odds ratio for depression was calculated from four. The authors rate the methodological quality of the individual studies as poor in 22 cases and moderate in 19; the quality of the evidence, which they assess outcome by outcome with a method called GRADE, they put at moderate for depression and low for anxiety, stress, and sleep.

Of the 41 pooled studies, 38 have a cross-sectional design: they capture a population at a single point in time and can’t establish what came first. The authors themselves write that reverse causality can’t be ruled out, meaning that feeling unwell may be what drives heavier phone use. In these studies anxiety, depression, stress, and sleep are measured with questionnaires the participants filled in, and the authors say the symptoms may fall below the clinical threshold.

An OR of 3.17 indicates that, within the sample observed, people with problematic smartphone use report depressive symptoms more often; it doesn’t show that the phone causes the depression, and it can’t predict what will happen to any one person.

In the same meta-analysis, the group most likely to show problematic use was girls aged 17 to 19; that is a frequency seen in the samples studied.

Who to turn to

This Recap doesn’t offer a self-help approach. For young people, the APA recommends routine screening for signs of problematic social media use. When the distress is real, for yourself or for a teenager in your care, the next step is to talk to a professional: a psychologist, pediatrician, or family doctor.