General Characteristics of Participants across chronotype
The characteristics of the 1022 (96.2%) subjects included in present
study are shown in Table 1 . Overall, participants included a
total of 608 females (59.5%) and 514 males (40.5%), with 44.7% (n =
457) of individuals aged 30 to 34 years. According to the MEQ scores,
approximately 9.39% of the participants were identified as evening
chronotype, while 68.2% were neutral chronotype and 29.06% were
morning chronotype. Significant differences were found for age, passive
smoking, education, annual income, frequency of insomnia, daytime
napping, and living children compared to these three groups (all p
<0.05). Specifically, participants in the evening chronotype
were more likely to be younger, to be free of passive smoking, had a
high or vocational school education level, a higher annual income, more
frequent insomnia, never daytime napping, lower level of physical
activity as well longer sleep and social jetlag times and shorter
infertility treatment times. In addition, we observed that 527
individuals reported mild and above depressive symptoms, representing
51.6% of the total subjects, with a trend toward a decrease in
depressive symptoms as the chronotype from evening to neutral and then
to morning. The characteristics of participants according to depressive
phenotype are shown in Table S1 .