Beyond Screen Time: Associations of Smartphone Use Patterns With Sleep and Cognitive Function In Adolescents—A Systematic Review

Abstract

Background: Smartphone exposure among adolescents differs by timing, device proximity, nighttime checking, problematic engagement, and media multitasking. These patterns may relate differently to sleep and cognitive outcomes.

Methods: PubMed/MEDLINE, journal publisher sources, and reference lists were searched for relevant primary studies available through July 2026. Eleven observational and longitudinal studies were included. Studies were synthesized by exposure pattern and outcome without meta-analysis because of heterogeneous measures and overlapping cohorts.

Results: Eleven primary studies were included. Nighttime screen use exceeding two hours was associated with sleep deprivation (adjusted odds ratio [aOR] 5.23, 95% confidence interval [CI] 3.03–9.00; n = 2,513). Keeping a smartphone outside the bedroom was associated with lower odds of insufficient sleep (OR 0.64, 95% CI 0.47–0.87; n = 1,959). Problematic social-media use trajectories were associated with lower picture-sequence memory scores (β = −0.24, 95% CI −0.35 to −0.13; n = 4,809). Greater social-media browsing preceded a small reduction in cognitive control (β = −0.06, P = 0.020; n = 9,747).

Conclusions: Nighttime use, bedroom placement, and problematic engagement show more specific associations with adolescent sleep and cognitive outcomes than total screen time. Most evidence is observational and does not establish causality.