TOPLINE:

Youth acquiring a smartphone at 13 years of age had an increased risk for insufficient sleep but not for depression or obesity at 14 years of age. However, those who used a smartphone for extended durations exceeding 5 hours per day had higher odds of all three health outcomes. Placing smartphones outside the bedroom at bedtime was associated with a reduced risk for sleep insufficiency.

METHODOLOGY:

• Researchers conducted a cohort analysis of 1959 youth (41.0% girls; 84.8% White individuals) who did not own a smartphone until they were 13 years old to assess the link between smartphone acquisition at approximately 13 years of age and health outcomes. The data were collected from the Adolescent Brain Cognitive Development (ABCD) study across 21 sites in the US.
• Between the 3-year (mean age, 12.7 years) and 4-year (mean age, 14.0 years) assessments, 1230 participants acquired a smartphone and 729 did not.
• Smartphone ownership was identified through caregiver responses about whether their child had an iPhone or Android device. Participants reported how much time they used their smartphones each day during the school year; nighttime use was evaluated based on whether smartphones were placed outside the bedroom at bedtime.
• The outcomes assessed at 14 years of age were depression, obesity (defined as BMI at or above the 95th percentile for age and sex), and insufficient sleep (defined as less than 8 hours of sleep per night).

TAKEAWAY:

• Smartphone acquisition at 13 years of age was associated with insufficient sleep at 14 years of age (adjusted odds ratio [aOR], 1.29; 95% CI, 1.03-1.62) but not with depression or obesity.
• Among youth who acquired smartphones, each SD difference in the total smartphone time was associated with increased risks for depression (aOR, 1.22; 95% CI, 1.01-1.80), obesity (aOR, 1.34; 95% CI, 1.09-1.65), and insufficient sleep (aOR, 1.28; 95% CI, 1.12-1.47).
• Participants who used smartphones for more than 5 hours per day had higher odds of depression (aOR, 2.27; 95% CI, 1.16-4.43) and obesity (aOR, 2.66; 95% CI, 1.38-5.13) than those who used smartphones for less than 2 hours per day. Both participants who used smartphones for 2-5 hours (aOR, 1.63; 95% CI, 1.22-2.18) and those who used smartphones for more than 5 hours (aOR, 1.99; 95% CI, 1.28-3.09) had higher odds of insufficient sleep.
• Placing smartphones outside the bedroom at bedtime was associated with lower odds of insufficient sleep (aOR, 0.64; 95% CI, 0.47-0.87).

IN PRACTICE:

“[The] findings suggest that while smartphone acquisition at age 13 years by itself is not independently associated with worse outcomes, certain usage patterns may still bear risks,” the authors wrote. “The most practical way to protect adolescent health in this digital era is to allow age-appropriate smartphone access while actively managing both smartphone time and nighttime phone access,” they added.

SOURCE:

The study was led by Ziv Bren, MD, of the Department of Child and Adolescent Psychiatry and Behavioral Sciences at the Children’s Hospital of Philadelphia in Philadelphia. It was published online on June 8, 2026, in JAMA Pediatrics.

LIMITATIONS: 

Participants reported their smartphone usage and sleep, which may be subject to recall bias. The group mostly came from higher-income backgrounds and does not represent the entire US adolescent population, which may affect how well the results apply to everyone. The yearly assessment also made it hard to determine exactly when the participants got their smartphones in the past year.

DISCLOSURES:

The ABCD Study received support from the National Institutes of Health and additional federal partners through multiple grant awards. Some authors disclosed receiving support from the National Institute of Mental Health or the Huo Family Foundation. One of the authors disclosed serving on advisory boards for Children and Screens and Taliaz Health, in which he also held equity. Another author disclosed that her spouse is the founder and CEO of Kidas.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.