JMIR Publications

ABSTRACT

Background:

Daytime sleepiness is prevalent among adolescents and linked to various health and functional impairments. Prior research has identified digital media use and insufficient sleep as key predictors, with evidence suggesting that screen use may contribute to poor sleep. However, the reciprocal, longitudinal associations among screen time, sleep, and daytime sleepiness remain understudied.

Objective:

This study examines between- and within-person reciprocal longitudinal associations among adolescents’ screen time, bedtime, and daytime sleepiness. It also investigates whether screen time restriction moderates these associations—specifically, whether the potential adverse effects of screen time on bedtime and daytime sleepiness are less pronounced over time for adolescents who limit their screen use before sleep.

Methods:

A panel study was conducted across three six-month-spaced waves in a sample of 2,500 Czech adolescents (50.0% girls; mean age 13.43, SD 1.69 years). A random intercept cross-lagged panel models (RI-CLPM) were used to examine between- and within-person reciprocal longitudinal associations among screen time, bedtime, and daytime sleepiness. A multigroup extension of the RI-CLPM was used to test whether screen time restriction before sleep at Wave 1 moderated these longitudinal associations.

Results:

The findings revealed that at the between-person level, adolescents with higher typical screen time reported later bedtimes (r=0.23, P<.001) and greater daytime sleepiness (r=0.25, P<.001). At the within-person level, no direct associations between screen time and daytime sleepiness were observed (W1→W2 β=.02, P=.71; W2→W3 β=.02, P=.66). An increase in screen time at Wave 1 was linked to delayed bedtimes at Wave 2 (β=.14, P=.025), which subsequently predicted higher screen time at Wave 3 (β=.24, P<.001). Additionally, temporary within-person spikes in screen time consistently coincided with delayed bedtimes (W1 r=.16, P<.01; W2 r=.23, P<.001; W3 r=.09, P<.05). Screen time restrictions before sleep did not moderate longitudinal associations (Δχ2(6)=5.254, P=.512)

Conclusions:

Findings of this study advance understanding of the reciprocal longitudinal associations between adolescents’ screentime and sleep, revealing bidirectional and mutually reinforcing links between screen time and bedtime over time, but not with daytime sleepiness. Elevated screen time and poor sleep tend to co-occur across time and between individuals, likely reflecting stable personal or environmental factors. Screen time restrictions before sleep do not appear to mitigate the negative impact of screen use on sleep over time. These results suggest that interventions should prioritize promoting consistent sleep schedules and overall sleep-supportive lifestyles, rather than focusing solely on reducing screen use.