Non-linear relationship between social jetlag and depressive symptoms among Chinese college students

Abstract

This study aims to elucidate the relationship between social jetlag and depressive symptoms in college students, with a focus on identifying specific cut points that significantly heighten the risk of depression. A cross-sectional study was conducted among 2,006 students from Jiangsu College of Nursing between October and November 2024. Social jetlag was calculated based on the difference between the midpoints of sleep on workdays and weekends. Depressive symptoms were assessed using the Patient Health Questionnaire-9 (PHQ-9). Multivariate logistic regression was applied to examine the relationship between social jetlag and depressive symptoms, adjusting for potential confounders. The prevalence of depressive symptoms (PHQ-9 ≥ 10) among participants was 10.1%. A non-linear relationship was observed between social jetlag and depressive symptoms, with the risk of depression increasing significantly beyond a threshold of 1.2 h of social jetlag. Specifically, individuals with social jetlag ≥ 1.2 h had 72% higher odds of depressive symptoms compared to those with lower levels (OR = 1.72, 95% CI: 1.24-2.38). Subgroup analyses revealed that this association was consistent across both grade and gender. Sensitivity analyses further affirmed the robustness of these findings. This study suggests a non-linear association between social jetlag and depressive symptoms in college students, with a marked increase in depression risk for those with social jetlag ≥ 1.2 h. Longitudinal studies are needed to clarify the causal pathways and identify modifiable factors for targeted interventions.

Keywords: Cross-sectional; Depression; Non-linear; Sleep; Social jetlag; Student.

Fig. 1

The exposure-response relationships between social jetlag and odd ratio of depressive symptoms among college students. The red solid line represents the odds ratio (OR) of depressive symptoms as a function of social jetlag, while the shaded area indicates the 95% confidence interval. The dashed red vertical line marks a social jetlag of 1.2 h, indicating an increased risk threshold. The black dashed horizontal line represents an odds ratio of 1, indicating no increased or decreased risk.

Fig. 2

Subgroup analysis of the odds ratio for depressive symptoms among college students by body mass index (BMI), gender, and grade. BMI is categorized as < 18.5 kg/m², 18.5–24 kg/m², and ≥ 24 kg/m² (red markers). Gender is divided into female and male (green markers), while grade is categorized as freshman and sophomore (blue markers). The vertical dashed line represents an odd ratio of 1, indicating no difference in risk.