No Screens Before Bed: Teen Smartphone Use at Bedtime Predicts Overnight Phone Activity

CONFERENCE REPORTER
CLINICAL CONVERSATIONS

At the SLEEP 2026 annual meeting, researchers presented findings from a study that showed that bedtime smartphone use predicts overnight phone activity in teens. On evenings when adolescents used their smartphone before bedtime more than their own usual, they used their smartphone for longer later that same night, compared with nights when they used their phones less before bedtime.¹

Results from within-person analyses show that on nights when adolescents used their smartphones for an additional 20 minutes in the hour before bedtime (10:23 PM–11:23 PM on school nights and 11:25 PM–12:25 AM on non-school nights), they had 8-9 more minutes of late-night (midnight–5:00 AM on school nights and 1:00 AM–6:00 AM on non-school nights) use later that same night. On average, adolescents with greater pre-bedtime smartphone use had greater late-night use; adolescents with an average of 20 minutes of pre-bedtime smartphone use had 37-41 minutes of average late-night use. Moreover, teens used their smartphones for an average of 46 minutes each late night.

Psychiatric Times spoke with presenter Gina M. Mathew, PhD, a senior post-doctoral associate at the Renaissance School of Medicine at Stony Brook University in Stony Brook, New York, to learn more.

Psychiatric Times: Talk to us about that data that will be presented at SLEEP 2026 on pre-bedtime smartphone use. Is there a finding that surprised you? Can you share some information about the overall impact of bedtime smartphone use in teens?

Gina M. Mathew, PhD: Generally speaking, we were not surprised that pre-bedtime smartphone use predicted smartphone use later that same night within adolescents. Our hypothesis was that “use begets use.” However, we were surprised that the associations were similarly large across both social media and non-social media.

Pre-bedtime smartphone use can delay bedtime through several mechanisms, with the most notable being time displacement (more screen time delaying bedtime and therefore "displacing" sleep) and nighttime interruptions (noises from one's device interrupting sleep and reducing sleep quality). Interactive screen-based activities such as video gaming before bedtime may be particularly harmful. Many teens are not getting the minimum 8 hours of sleep nightly required for optimal health and wellbeing, and use of electronic devices may contribute to that deficit.

PT: What impact do you think increased screen time and sleep disruption is having on youth mental health?

Mathew: Studies have shown that screen time, sleep, and poor mental health are related among youth. Screen time may cause poor sleep health, which in turn could lead to more negative mental health outcomes, such as depressive and anxious symptoms. Certain groups, such as girls or those with pre-existing mental health conditions, may be particularly vulnerable to these negative effects. More experimental research is needed to help elucidate the causal effects of screen use.

PT: What clinical implications do you think this data will have, particularly for clinicians treating youth? Do you have any recommendations for reducing pre-bedtime phone use?

Mathew: We found that on nights when teens used their smartphones before bedtime more than their own usual, they had more late-night use. These findings suggest that "use begets use." One strategy to reduce late-night use and thereby potentially improve sleep would be to limit screen use close to bedtime. Boredom is a prime reason cited for using screen-based media, so finding a relaxing yet enjoyable activity before bedtime such as reading a physical book or playing with pets could help reduce pre-bedtime screen use. Policies such as banning nighttime social media use among teens would also be helpful. Clinicians could recommend that parents set household rules around the use of electronic media, particularly around or after bedtime, such as keeping devices outside of the bedroom.

PT: Our June cover discusses the addictive potential of social media. Can you talk to us about your findings specifically related to social media? I was very interested to see the 3 category breakdown of smartphone use.

Mathew: Yes, as I mentioned previously, we had expected to see larger effect sizes for social media versus non-social media, but effect sizes were similar. Research, including from our own team, has found that "interactive" screen-based activities, such as social media, are more harmful to sleep health. One potential reason for the lack of differences among types of media in the current study may be the heterogeneity among the various social media apps. For example, there is a vast difference between Snapchat and YouTube.

PT: You are also presenting on poorer actigraphic sleep health and insomnia symptoms. Can you share some of the details of what you found?

Mathew: Yes, we have another presentation on a large, longitudinal study called the Future of Families and Child Wellbeing Study. We demonstrated that poorer sleep according to wrist actigraphy, especially greater sleep variability, and more insomnia symptoms among youth were associated with worse health and wellbeing across a 7-year follow-up from adolescence to young adulthood. For example, we found that for each additional hour of adolescent actigraphic "social jetlag," a misalignment of sleep timing across the week, the odds of at least one overnight hospital stay during young adulthood were nearly 2.5 times higher.

PT: We also noted your research found that over one-third of adult respondents believe heavy use of digital technology leads to sleep-related symptoms. Can you discuss age and gender differences within this data? Why do you think that is?

Mathew: Last year we presented data at this conference in which we had data from over 35,000 adults from 35 countries around the world. When these adults were asked about the effects of using too much technology, about 40% agreed with the statements that too much technology produces decreased sleep quality or tiredness. Agreement with this statement was higher among younger than older adults and among females compared to males. The age difference is potentially due to higher device use among youth, and the gender difference may be due to the different types of media that women are consuming compared to men.

PT: Is there anything else you’d like to share?

Mathew: One great thing people can do for themselves and their families is to limit access to electronic media once in bed. Charging phones in another room will reduce the temptation to grab one's phone and look “just one last time.”

We appreciate the opportunity to share our research at SLEEP and with you, and we are grateful to our funder, the Della Pietra Family Foundation.

Dr Mathew is a senior post-doctoral associate in public health at the Renaissance School of Medicine at Stony Brook University in Stony Brook, New York.

Reference

1. Mathew G, Rodriguez I, Reichenberger D, et al. 0242 Pre-bedtime smartphone use predicts higher within-person likelihood of late-night smartphone use among adolescents: the SBU MEDiA study. Sleep. 2026;49(Suppl 1):A106-A107.