Impact of Extrinsic Sleep Disruption During Pregnancy and the Postpartum Period on Systemic and Cardiovascular Adaptations

Introduction: Sleep is emerging as an important process necessary for optimal cardiovascular health. During pregnancy, poor sleep is often observed in the form of insomnia, frequent night awakenings, short sleep duration, and sleep-disordered breathing. While some acute alterations in sleep regulation may accompany healthy pregnancies, extrinsic factors that drive poor sleep health may increase the risk for adverse pregnancy outcomes. Despite this, little is known of how sleep changes during pregnancy, how this is further impacted by extrinsic sleep disruption, and how these factors impact adaptive changes in maternal physiology. Therefore, the goal of this study was to examine the extent to which pregnancy and the postpartum period impact murine sleep and determine the impact of extrinsic sleep disruption through shiftwork on maternal systemic and cardiovascular adaptations. Methods: 12-week-old C57BL/6N female mice were subjected to timed pregnancy and examined at non-pregnancy (NP), mid-pregnancy (MP; 7–9 days gestation), late-pregnancy (LP; 16–18 days gestation), labor and delivery (19–21 days gestation), and 1-week postpartum with lactation (PB). Using indirect calorimetry (Sable Promethion), we assessed changes in systemic metabolism and rest/activity patterns, as a proxy for sleep. To examine sleep during pregnancy, we first examined rest-activity patterns in response to a normal 12:12 light/dark (L/D) cycle, and then, to examine the impact of extrinsic sleep disruption, we employed a 10:10 L/D cycle to simulate shiftwork. All samples were collected at 10 am (equivalent to zeitgeber time (ZT) 4). Results: Cardiac RNA-seq data in response to normal L/D cycle showed that several circadian transcripts, including Arntl, Dbp, Per1, Per2, Per3, Cry1, Cry2, and Ciart, and circadian clock-controlled metabolic transcripts were changed in expression in the heart at different stages of pregnancy compared with NP (n = 4 mice/group), indicating an impact on sleep health. Of note, changes in many of these transcripts correlated with changes in both heart and liver growth. Indirect calorimetry in response to a normal L/D cycle revealed that MP and PB were associated with significant changes in respiratory exchange ratio (RER; p< 0.001), energy expenditure (p< 0.001), pedestrian locomotion (pedometers; p< 0.001), and all locomotion (all meters; p< 0.001); suggesting increased activity and reduced sleep in MP and PB. Although LP was not associated with changes in pedmeters, it was associated with increased all meters (p< 0.001). PB was the only time point associated with increased water and food consumption (p< 0.001). Introduction of a shiftwork model of sleep disruption during pregnancy significantly impacted calorimetry parameters, suggesting that shiftwork disrupts pregnancy-induced sleep patterns. Conclusion: Sleep is disrupted during mid-pregnancy and early postpartum, which is closely associated with changes in the expression of several circadian and metabolic transcripts and cardiac growth, with sleep patterns and RER being further disrupted with shift work. Funding Sources: This work was supported by a National Institutes of Health Grant R01 HL163003 and a University of Louisville School of Medicine Grant. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.