In one of the largest and most comprehensive studies investigating the link between objective parameters of sleep and biological rhythms with peripartum mood and anxiety to date, we prospectively investigated the trajectory of subjective and objective sleep and biological rhythms, levels of melatonin, and light exposure from late pregnancy to postpartum and their relationship with depressive and anxiety symptoms across the peripartum period.One hundred women were assessed during the third trimester of pregnancy, of whom 73 returned for follow-ups at 1-3 weeks and 6-12 weeks postpartum. Participants were recruited from an outpatient clinic and from the community from November 2015 to May 2018. Subjective and objective measures of sleep and biological rhythms were obtained, including 2 weeks of actigraphy at each visit. Questionnaires validated in the peripartum period were used to assess mood and anxiety.Discrete patterns of longitudinal changes in sleep and biological rhythm variables were observed, such as fewer awakenings ( = 23.46, < .001) and increased mean nighttime activity ( = 55.41, < .001) during postpartum compared to late pregnancy. Specific longitudinal changes in biological rhythm parameters, most notably circadian quotient, activity during rest at night, and probability of transitioning from rest to activity at night, were most strongly linked to higher depressive and anxiety symptoms across the peripartum period.Biological rhythm variables beyond sleep were most closely associated with severity of depressive and anxiety symptoms across the peripartum period. Findings from this study emphasize the importance of biological rhythms and activity beyond sleep to peripartum mood and anxiety. Objective: Methods: Results: Conclusions: F P F P
