Electronic Screen Use and Sleep Duration and Timing in Adults.

Importance: Electronic screen use before bed may disrupt circadian rhythms, leading to poorer sleep. Objective: To investigate the association between screen use before bed and sleep outcomes among adults. Design, Setting, and Participants: This cross-sectional study included participants in the American Cancer Society Cancer Prevention Study-3, a prospective cohort of men and women from 35 US states and Puerto Rico, who responded to a 2018 survey. Analyses were conducted from February 3, 2023, to January 10, 2025. Exposures: Self-reported electronic screen use in the hour prior to bed. Main Outcomes and Measures: Self-reported sleep-wake times (used to calculate duration), sleep quality, and chronotype. Mean differences for sleep duration and bedtimes, and prevalence ratios for sleep quality were calculated by screen use using multivariable linear and Poisson regression, respectively. Whether these associations differed by chronotype was also examined. Results: Of the 122 058 participants (97 658 women [80.0%]; median [IQR] age, 56 [47-62] years; range, 27-85 years), 70 638 (57.9%) reported a morning chronotype. Daily screen use before bed was reported by 50 289 participants (41.2%), whereas 21 275 (17.4%) reported no screen use. Compared with no screen use, daily screen use prior to bed was associated with a 33% higher prevalence of poor sleep quality (prevalence ratio, 1.33; 95% CI, 1.27-1.39) and 7.64 fewer minutes of sleep on workdays (95% CI, 6.65-8.63 minutes). The association was more pronounced among participants with evening chronotypes (8.36 minutes; 95% CI, 4.94-11.78 minutes) vs those with morning chronotypes (5.64 minutes; 95% CI, 3.98-7.29 minutes). Daily screen use was associated with 5.04 fewer minutes of sleep (95% CI, 4.03-6.05 minutes) on nonworkdays. Daily screen users with morning chronotype went to bed 9.33 minutes later (95% CI, 7.61-11.06 minutes), and those with evening chronotypes went to bed 15.62 minutes later (95% CI, 11.93-19.31 minutes) on workdays. Results were similar for nonworkdays. Conclusions and Relevance: Daily screen use was associated with later bedtimes and approximately 50 minutes less sleep each week. Associations were greater among those with evening chronotypes, who are at risk for poor sleep due to social jetlag (ie, misalignment between circadian rhythms and social commitments). These findings confirm disruptions to sleep from electronic screens are not limited to children and adolescents. Further work is needed to understand the best mechanisms for intervention.