Objective: To explore the relationship between social jetlag and depressive symptoms in junior high school students, as well as the potential gender differences, so as to provide a reference for developing effective interventions for depressive symptoms and promoting adolescents mental health. Methods: In October 2024, a total of 3 516 students from grades 7 to 9 were recruited from 4 junior high schools in Chongqing Municipality using a combination of cluster sampling and convenience sampling. A questionnaire survey was conducted using the Center for Epidemiologic Studies Depression Scale (CES-D) and the Munich Chronotype Questionnaire (MCTQ). Statistical analyses included the χ 2 test, binary Logistic regression analysis, and stratified Logistic regression analysis. Results: The detection rate of depressive symptoms among the junior high school students was 34.3%. The number of students with social jetlag >2 h was 714 (20.3%), >1-2 h was 1 455(41.4%), and ≤1 h was 1 347(38.3%). Results from the binary Logistic regression analysis showed that compared to the group with social jetlag ≤1 h, the risk of depressive symptoms in the group with social jetlag >2 h was higher ( OR=1.59, 95%CI=1.28-1.98, P <0.01). Gender stratified analysis revealed that among females, the risk of depressive symptoms was higher in the groups with social jetlag of >1-2 h and >2 h compared to the ≤1 h group ( OR = 1.34 and 2.05, 95% CI =1.03-1.75 and 1.48-2.83, both P <0.05). However, among males, the associations were not statistically significant ( OR =1.11 and 1.29, 95% CI =0.86-1.43 and 0.95-1.77, both P >0.05). Conclusions Social jetlag is positively associated with depressive symptoms in junior high school students, demonstrating a threshold effect and gender differences. The findings suggest that reducing social jetlag may decrease the risk of depressive symptoms in adolescents, and targeted intervention measures should be developed considering different gender characteristics.

Objective: To explore the mediating role of balanced time perspective in the relationship between social jetlag and depressive symptom among junior high school students, so as to privide a basis for improving their mental health. Methods: In October 2024, a method of combining convenient sampling with cluster sampling was used to select 3 438 junior high school students from two districts(Yubei District and Kaizhou District) in Chongqing. The Center for Epidemiological Studies Depression Scale (CES-D), Munich Chronotype Questionnaire (MCTQ), and Balanced Time Perspective Inventory (BTPI) were administered for the survey. Statistical analyses included t-test, ANOVA, and Spearman correlation analysis, and conduct a mediation effect analysis using the Process program. Results: The mean score of depressive symptom among junior high school students was 15.00(9.00, 23.00 ), social jetlag was 1.18(0.72, 1.83) hours, and balanced time perspective score was -0.18(-2.82, 2.93). Social jetlag among junior high school students was positively correlated with depressive symptom score ( r =0.17), while balanced time perspective was negatively correlated with social jetlag ( r =-0.15) and depressive symptom score ( r =-0.68) (all P <0.01). Mediation analysis showed that balanced time perspective partially mediated the relationship between social jetlag and depressive symptom ( β=0.68, P <0.01) among junior high school students, accounting for 53.97% of the total effect. Conclusions Social jetlag of junior high school students influences depressive symptoms by affecting balanced time perspective. Efforts should be made to improve adolescents balanced time perspective for reducing the impact of social jetlag on depressive symptom.