Adolescent smartphone use, sleep, and physical activity: daily associations between sensor-based measures in the adolescent brain cognitive development (ABCD) study

• Published in: Psychiatry research Vol. 349; p. 116523
• Main Authors: Alexander, Jordan D., Nguyen-Louie, Tam T., Gupta, Suhaani, Cummins, Kevin M., Wade, Natasha E.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01.07.2025
• Subjects: Adolescence; Adolescent; Adolescent Behavior - physiology; Exercise - physiology; Female; Fitbit; Humans; Male; Passive Sensor Data; Physical activity; Sedentary Behavior; Sleep; Sleep - physiology; Smartphone - statistics & numerical data; Smartphone use; App; Adolescence; Sleep; METs; Physical activity; OS; EARS App; Fitbit; Smartphone use; Passive Sensor Data; ABCD Study
• ISSN: 0165-1781; 1872-7123; 1872-7123
• DOI: 10.1016/j.psychres.2025.116523

•This study used continuous, passive-sensor measures of smartphone use, sleep, and physical activity, improving ecological validity and robustness to reporting biases over the existing, largely cross-sectional, self-report-based literature.•Greater smartphone use predicted reduced step counts, fewer minutes of moderate to vigorous exercise, more minutes spent sedentary, delayed sleep and waketimes, and reduced sleep quantity.•Relationships remained significant within subjects, such that on days when participants used their smartphones more than their average level, they also exercised less, were more sedentary, and exhibited both reduced and delayed sleep.•Both within and between-person relationships were moderated by time of day, with daytime and evening smartphone use more predictive of physical activity and late-night use more predictive of sleep outcomes.•This study offers additional evidence for potential adverse health consequences of excessive adolescent smartphone use, including sleep impairments and reduced physical activity, though replication via randomized controlled experiment would substantially strengthen evidence for causality. Potential health consequences of adolescent smartphone use are a growing public concern. Improving upon existing, largely self-report-based research, this study investigated relationships between adolescent smartphone use, sleep, and physical activity using passive sensor measures. Over three weeks, 791 Adolescent Brain Cognitive Development (ABCD) Study participants (Mage=14.12, 53 % female) provided smartphone application and keyboard use data via the Effortless Assessment Research System (EARS) application, and sleep and physical activity data via Fitbit device. Mixed-effects models found that daytime/evening application use (6:00AM–7:59PM) predicted reduced exercise, more time sedentary, and fewer daily steps (Standardized β=-0.21−0.07, P<.001). Late-evening use (8:00PM-9:59PM) modestly predicted increased sedentary time and reduced steps (Standardized β=-0.05−0.02, P<.001). Late-night use (10:00PM–5:59AM) predicted reduced sleep, delayed sleep onset, delayed waking, increased sedentary time, and fewer daily steps (Standardized β=-0.16−0.27, P<.001). After disaggregating within and between-person smartphone use, within-person relationships remained significant, with associations of similar magnitude to the initial analyses (daytime/evening use: standardized ꞵ=-0.22–0.07, P<.001; late-evening use: standardized ꞵ=-0.05–0.02, P<.001; late-night use: standardized ꞵ=-0.16–0.24, P≤.002), indicating daily-level relationships unattributable to between-subject differences. Examining smartphone use effects by hour relative to sleep onset indicated that only use recorded after initial sleep onset significantly predicted sleep, while use recorded 3–12 hours before sleep onset significantly predicted step counts. Using passive sensor data, we found significant associations between adolescent smartphone use, physical activity, and sleep which differed by time of day and remained significant within subjects. Experimental replication is recommended to strengthen tentative causal claims.