Screen time and dry eye in medical students: A chain mediation mechanism of sleep-emotion

Objective: To examine the association between screen time and dry eye symptoms among medical students, and to test the chain mediating roles of emotional problems and sleep disturbances.

Methods: A total of 416 medical students were recruited through convenience sampling. Dry eye, sleep quality, depression, and anxiety were assessed using the Ocular Surface Disease Index (OSDI), Pittsburgh Sleep Quality Index (PSQI), Patient Health Questionnaire-9 (PHQ-9), and Generalized Anxiety Disorder-7 (GAD-7), respectively. Chain mediation analysis was conducted using the SPSS PROCESS macro (Model 6), with the bootstrap method applied for 5,000 resamples.

Results: The prevalence rates were 80.3% for dry eye symptoms, 53.6% for sleep disturbances, 51.9% for depression, and 37.7% for anxiety. Screen time was not significantly correlated with OSDI scores (r=0.059); however, it showed significant positive correlations with PSQI, PHQ-9, and GAD-7 scores (r=0.156–0.214, all P 0.01). The direct effect of screen time on dry eye was non-significant (effect=−0.168, 95% CI: −0.750 to 0.413), whereas the total indirect effect was significant (effect=0.506, 95% CI: 0.261 to 0.768). All three mediation pathways were significant: the specific indirect effect via sleep disturbances alone was 0.216 (42.8%), via emotional problems alone was 0.193 (38.2%), and via the sleep disturbances → emotional problems chain was 0.096 (19.0%).

Conclusion: Screen time exerts a complete indirect effect on dry eye symptoms through the chain mediation of sleep disturbances and emotional problems. Interventions should prioritize sleep management to disrupt the vicious cycle of "screen exposure → sleep disturbance → emotional distress → aggravated dry eye."

Keywords: Screen Time, Video Display Terminal, Dry Eye, Emotional Problems, Sleep Disturbances, Chain Mediation, Medical Students.