Objective: To explore the stability of circadian rhythm and its correlation with depression and the longitudinal effects in college students. Methods: From September to November

2018 to 2020

an online questionnaire was issued to assess the circadian rhythm

depression

sleep quality

physical symptoms and life event stress of the freshmen

and they were followed and repeatedly evaluated for two years. Logistic regression model was established to analyze the independent correlation factors of depression in baseline assessment. Mixed effect model was established to analyze the stability of circadian rhythm

longitudinal change of depression and the influencing factors of depression. Results: The detection rate of depression was 24.2%

52.1% (4 301/8 244) of college students were eveningness

45.0% (3 708/8 244) were intermedia circadian rhythm

and 2.9% (235/8 244) were morningness. Binary Logistic regression analysis suggested that eveningness (OR=1.526)

worse sleep quality (OR=1.540)

more serious physical symptoms (OR=1.115)

and more stressful life events (OR=1.046) were more likely to have depression mood. The results of mixed effect model suggest that circadian rhythm was still a stable individual characteristic

although the score of morningness-eveningness questionnaire decreases by 1.948 points per year on average. While the standard score for depression increased by an average of 0.104 points per year

analysis of the fixed effects of the model suggested that baseline eveningness (β01=0.028)

sleep quality (β02=0.052)

physical symptoms (β03=0.017)

and life event stress (β04=0.007) positively predicted the increase of standard depression scores. Moreover

students with poorer sleep quality (β12=-0.012) and more stressful life events (β14=-0.002) had a faster increase rate of standard depression score. Conclusion: Although the circadian rhythm is a stable individual characteristic

it will change over time in the college students

and eveningness is one of the important predictors of depression

prompting that circadian rhythm is a crisis intervention for college students’mental health.