Time Spent on Social Media Applications in Relation to Depressive Symptoms During Emerging Adulthood and the Mediating Role of Sleep Quality: Cross-Sectional Observational Study.

Background: The link between social media use and depressive symptoms remains bidirectional. Findings in this area are often compromised by methodological limitations related to measurement and sample size. As a result, it is challenging to assess dose-response relationships and potential causal pathways. Objective: This study aims to use objective measurement methods to assess the dose-response relationship and potential mechanisms between social media use and depressive symptoms. Methods: This study was conducted in 6 universities in 2022. Social media use duration was assessed based on the monitoring of mobile phone systems, and depressive symptoms were evaluated by the Self-Rating Depression Scale. Logistic regression and restricted cubic spline were used to assess the relationship between social media use and depressive symptoms. Mediation analysis was used to elucidate the biological pathways of sleep quality in the abovementioned relationship. Results: A total of 7401 college students were included in the final analysis, with 4.93% of moderate to severe depressive symptoms. After adjusting for variables such as sociodemographic characteristics and health-related characteristics, there was a significant association between individuals with longer weekly social media use time and depressive symptoms (odds ratio [OR>48h] 1.769, 95% CI 1.303-2.400). Similarly, the association between instant messaging-based social media use duration and depressive symptoms was also significant (OR>24h 1.728, 95% CI 1.225-2.437), while no associations were observed for content-based social use (OR>24h 1.251, 95% CI 0.932-1.680). Restricted cubic splines regression demonstrated a J-type relationship between social media use duration and depressive symptoms. Additionally, sleep quality played a partial mediating role in the relationship between social media use duration and depressive symptoms, with the mediating effect values ranging from 24.10% to 25.25%. Conclusions: Prolonged social media use duration might be associated with an increased prevalence of depressive symptoms in emerging adulthood and may increase the odds of depression by affecting sleep quality, suggesting that early prevention and intervention regarding social media use might help to ameliorate depressive symptoms.