Parents want to know how much their teenager’s phone is really disrupting sleep, mood and daily functioning. Experts on adolescent sleep and media use are pointing to specific ways screen time reshapes stress hormones, mental health and nightly routines.
How Does Phone Use Affect Teen Sleep?
Cellphone use before bed delays the natural drop in cortisol that teenagers need to fall asleep, according to Alice Hoagland, PhD, director of the Insomnia Clinic at the Rochester Regional Sleep Disorder Center.
“Cellphones will further delay an adolescent’s sleeping phase,” Hoagland said, per Rochester Regional Health. “The moment someone gets on a cellphone, they are essentially preventing their cortisol levels from naturally declining because they are becoming stimulated by the phone itself or the content on the phone.” A 2021 study also found teens who used social media more frequently had later bedtimes a year later, with problematic use linked to delayed sleep. Puberty already shifts melatonin release later in the day, so many teens do not feel tired until near midnight even though their bodies need about nine hours of sleep.
What Is Problematic Media Use in Adolescents?
Problematic media use is excessive or dysregulated screen use that starts interfering with a teen’s daily functioning, according to Sarah Domoff, assistant professor in the Department of Psychology at the University at Albany.
“Problematic media use includes excessive or dis-regulated use of screens, including social media or other forms of digital media such as gaming,” Domoff told Campus Insights Media. She said the behavior crosses into concerning territory when it disrupts sleep, school performance or relationships. Design choices on many apps actively push teens to keep scrolling. “Even though someone only wanted to be on the phone for 15 minutes to watch one short video, all of a sudden, it’s 45-60 minutes later and they are still ‘going down the rabbit hole’ of watching videos,” Hoagland said.
Can Social Media Affect a Teen’s Mental Health?
A 2025 CDC study of nearly 2,000 U.S. teenagers found those who logged four or more hours a day of recreational screen time were more likely to report anxiety and depression symptoms, poorer sleep and less physical activity than peers with lower screen use.
The study also linked heavier non-schoolwork screen use to irregular sleep routines, weight concerns and weaker peer support. Domoff cautioned that the picture is not entirely negative. “It’s very complicated, the relationship between social media use and mental health,” she told Campus Insights Media. Positive engagement, like building connections or learning new skills, can benefit some youth, while social comparison and triggering content can worsen mental health concerns for others, she said.
How Can Parents Talk to Teens About Phone Use?
Start with curiosity rather than confrontation, Yann Poncin, MD, a child psychiatrist, told Yale Medicine. He suggested asking teens what they think, such as, “It seems like you’re on the phone so much that I don’t see you just doing homework like you used to do, so I’m just worried how healthy this is for you in terms of getting your stuff done. What do you think about that?”
Linda Mayes, MD, chair of the Yale Child Study Center, compared the approach to how families once handled TV. “Research showed that watching TV in and of itself wasn’t bad, but it began to have potentially negative effects on kids’ behavior when it was used as a babysitter,” Mayes said. She recommended asking teens how social media is working for them rather than banning it outright, so they feel comfortable coming to a parent when something goes wrong. Hoagland offered a simple nighttime fix. “Keep the phone away from the bedside is a good way of avoiding that situation,” she said.
The video Social Media’s Impact on Children and Teens featuring Sarah Domoff, assistant professor in the Department of Psychology at the University at Albany, was first published on Campus Insights Media.
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