0242 Pre-Bedtime Smartphone Use Predicts Higher Within-Person Likelihood of Late-Night Smartphone Use Among Adolescents: The SBU MEDiA Study

Abstract Introduction Nighttime digital media can adversely impact sleep through sleep displacement and/or disruption. One potential mechanism causing nighttime use is that “usage begets usage:” media use prior to bedtime may prime an individual to use their smartphone again during the nighttime. To test this hypothesis, we examined whether objectively measured smartphone use prior to bedtime predicted a higher likelihood of late-night smartphone use at the daily, within-person level among a national, diverse sample of adolescents. Methods Adolescents who owned or were the primary user of a personal smartphone from across the U.S. (n=229; 47%F, 46%M, 7% other) were recruited into the Stony Brook University Measuring Electronic Devices in Adolescents (MEDiA) Study. Participants answered a survey querying sociodemographic characteristics and sleep timing and then installed RealityMeter, which passively measured objective smartphone use (M±SD=16.8±13.7 days). Multilevel logistic models with random intercepts nested within individuals assessed whether person-mean-centered total (M=18.51m), social media (e.g., TikTok, Instagram, Facebook, YouTube; M=8.53m), and non-social media (e.g., messaging, gaming, streaming videos/movies; M=9.99m) smartphone use ≥30 minutes in the hour before the sample-mean of self-reported bedtime ("pre-bedtime," defined as 22:24-23:23 for school nights; 23:24-0:23 for non-school nights) predicted higher likelihood of ≥30 minutes of usage during the night (0:00-5:00 school nights; 1:00-6:00 non-school nights; M=46.74m) at the within-person, nightly level (≥30 minutes of usage: pre-bedtime total=28.5%, social media=10.0%, non-social media=11.6% of evenings; nighttime total=40% of nights). Results Within-person findings demonstrated that on evenings when adolescents engaged in ≥30 minutes of pre-bedtime smartphone use compared to when they did not engage in ≥30 minutes pre-bedtime use, likelihood of ≥30 minutes nighttime smartphone use was higher, with overlapping confidence intervals for the three categories of pre-bedtime media use: total pre-bedtime media (OR=1.45; 95%CI=1.19-1.77), social media (OR=1.23; 95% CI 0.92-1.65), and non-social media (OR=1.38; 95%CI=1.04-1.84) use. Conclusion After evenings when adolescents used their smartphone prior to sleeping, they had a higher likelihood of using their smartphone later that same night, which increases the risk of later bedtimes and opportunity for sleep disruption. Reducing pre-bedtime smartphone use may serve as a strategy to reduce nighttime use and improve sleep, health, and wellbeing. Support (if any) Della Pietra Family Foundation