Maternal sleep disorders in the third trimester could lead to decreased MR expression by up-regulating MTNR1B methylation, and then resulting in elevated cortisol and increased GR expression by down-regulating NR3C2 methylation, which could increase the incidence of maternal postpartum sleep disorders, finally, the maternal postpartum sleep disorder could result in the high incidence of infant sleep disorder. The gene discussed is NR3C2; the disease is sleep disorder.