Stratified and sensitivity analyses
In stratified analysis, we did not find any differential association of
chronotype with odds of depressive symptoms, according to age, sex,
annual income, education, passive smoking, physical activity, living
children, infertility treatment time, cause of infertility, frequency of
insomnia, nocturnal wake frequency, daytime napping, social jetlag, and
nighttime sleep duration (all p for interaction >
0.05). As illustrated in Figure 2 .
In addition, we performed repeated analyses to test the robustness of
the results by excluding individuals who worked shift or night, the
association of morning and neutral chronotypes with the risk of
depressive status were similar to the main analysis (OR = 0.51, 95% CI:
0.30-0.87, P trend <0.001; OR = 0.32, 95% CI:
0.18-0.58, P trend <0.001, respectively). As
illustrated in Table S2 .