REPEATED DEVICE-BASED MEASURES OF DAILY MOVEMENT, SEDENTARY BEHAVIOR, AND SLEEP AT 6 MONTHS POSTPARTUM: THE PETALS-2 COHORT

Abstract STUDY OBJECTIVES Appropriate duration and high-quality sleep is essential for overall well-being and may be improved through engaging in daytime physical activity (PA). Yet the postpartum period is a particularly challenging time for these health behaviors, and sleep in this population has received little attention in scientific literature. This study examined the associations of daily physical activity (PA) and sedentary behavior (SED) with postpartum sleep measures, both obtained from wrist-worn ActiGraph devices. METHODS Data come from the PETALS-2 cohort, a racially and ethnically diverse longitudinal cohort of postpartum mothers who delivered at Kaiser Permanente Northern California in 2018-2019. Participants (N=136) wore ActiGraph wGT3X-BT devices on their non-dominant wrists for 7 days at 6 months postpartum. ActiGraph data were processed in RStudio using validated algorithms for device wear time, PA metrics (i.e., minutes of moderate to vigorous physical activity [MVPA], light physical activity [LPA], and sedentary behavior [SED]), bedrest), and sleep quality metrics (i.e., nightly sleep duration; frequency of sleep interruptions; sleep efficiency [defined total nocturnal sleep/total sleep period x 100%]; and average duration of sleep interruptions). We estimated associations using mixed effects models in SAS, adjusted for participant characteristics and daytime bedrest. RESULTS Participants engaged in a median of 66 min/day (Q1-Q3: 36.0-101.0) of MVPA and 340.0 min/day (Q1-Q3: 272.0-422.0) of SED; neither were associated with sleep duration. In the adjusted model, for every additional 10-minutes of daily LPA, there was 0.12% higher sleep efficiency; in contrast, every additional 10-minutes of SED was associated with 0.10% lower sleep efficiency (both P<0.05). For each additional 10 min of daily MVPA, LPA, and SED, the average length of sleep interruptions was 0.65 min shorter, 0.52 min shorter, and 0.36 min longer, respectively (all P <.05). CONCLUSIONS More daytime PA, regardless of intensity, may modestly improve sleep quality, while more daytime SED may diminish sleep quality at 6 months postpartum. Statement of Significance Sleep is a vital aspect of health and a challenge for many in the postpartum period. In our study, we used device-based data over the course of 7 days to examine the relationship between daily levels physical activity and sedentary behavior with sleep in free-living individuals at 6 months postpartum. We showed that engaging in greater levels of light-intensity physical activity was linked to slight improvements in sleep efficiency, and greater levels of any intensity of physical activity led to a slightly shorter average duration of sleep interruptions at 6 months postpartum. This is, to our knowledge, the first study to estimate device-based associations of daily activity, regardless of intensity (and including sedentary behavior), with sleep, while adjusting for key demographic characteristics and daytime bedrest.