Covariates
All covariates were derived from self-reported baseline questionnaires. We searched the previously relevant literature and used a directed acyclic graph to select potential confounders35(Figure S2 ). Specifically, the following covariables are considered in the analysis: age (≤29, 30-34, and ≥35 years), sex (male, female), annual income (<30,000, 30,000~60,000, ≥60,000), education (middle school or below, high/ vocational school, college degree or above), passive smoking (never, occasionally, frequently), physical activity (low, moderate, vigorous), living children (yes or no), infertility treatment time (≤6, 7~12, 13~24, >24 month), cause of infertility (male, female, both, and unexplained), frequency of insomnia (never, occasionally or ≤3 per month, ≥4 per month), nocturnal wake frequency (never, occasionally, ≥1 per night), daytime napping (never, <1 and ≥1h ), social jetlag (<1 and ≥1h), and nighttime sleep duration (<8 and ≥8h).