Sleep Characteristics During the First Year Postpartum in a Cohort of Black and White Women.

Study Objectives: The postpartum period is a unique time when sleep deficiency often occurs. Black and White adults are reported to have differences in sleep characteristics, but little is known if these differences exist in the postpartum period. Therefore, the purpose of this study was to examine sleep characteristics in a cohort of Black and White women from 6-8 weeks to 12 months postpartum. Methods: Participants were 49 Black and 85 White women who gave birth to an infant at ≥37 weeks gestation. Participants were instructed to wear an Actiwatch for 7 days at 6-8 weeks, 4, 6, 9, and 12 months postpartum. Mixed-effects linear models with a race by time interaction were used to examine if characteristics differed between races over time. Results: Only bedtime varied by race. White women had a later bedtime at 6-8 weeks compared to 6 months, but no significant change occurred for Black women. For the entire sample, average nighttime sleep duration increased from 385 minutes at 6-8 weeks to 404 minutes at 4 months postpartum. Percent sleep during the sleep interval and wake after sleep onset (WASO) improved by 6 and 9 months, respectively. However, average WASO remained >45 minutes and sleep efficiency <85% at all timepoints for both Black and White women. Compared to White women, Black women had significantly shorter sleep duration (range: 40.6-59.9 minutes shorter across all timepoints, p<0.0001) and time in bed (range: 17.5-67.6 minutes shorter, p=0.0046), and lower percent sleep (range: 0.7%-1.2% lower, p=0.0407) and sleep efficiency (range: 2.6%-5.7% lower, p=0.0005). Sociodemographic factors were associated with sleep outcomes in Black and White women while behavioral factors were associated with sleep outcomes in White women only. Conclusion: While there were improvements in nighttime sleep duration and quality, sleep duration remained suboptimal, and quality remained poor throughout the first year postpartum. In this sample, differences existed in factors associated with sleep outcomes between Black and White women.

Metabolic consequences of sleep and circadian disruption during pregnancy and postpartum.

Physiological changes during pregnancy may predict future cardiovascular and metabolic diseases; thus, identifying mechanisms driving cardiometabolic impairments, as well as potential interventions to improve health during pregnancy, is crucial. We discuss how sleep and circadian disruption during pregnancy and postpartum affect cardiometabolic risk, and identify future research directions.

Physical Activity Participation of Black and White Women during the First Year Postpartum: Results and Study Recruitment Strategies.

Background: Little is known about how physical activity participation changes throughout the first year postpartum. This may be due to the difficulty in recruiting this population. The aims of this study were first to describe the recruitment methods and second to examine physical activity in the first year postpartum. Methods: Black and White women who gave birth to a singleton infant at ≥37 weeks gestation were recruited by a variety of strategies. At 6-8 weeks (baseline) and 4, 6, 9, and 12 months postpartum, women were instructed to wear an accelerometer for 7 days. Results: Active recruitment with interactions between staff and potential participants was more successful than non-active strategies for enrolling women. Throughout the first year postpartum, physical activity counts and light and moderate-to-vigorous physical activity increased from baseline (165.2 and 21.5 min, respectively) to 12 months (185.0 and 27.6 min, respectively). Sedentary time decreased from 775.3 min at baseline to 749.4 min per day at 12 months. In this sample, Black participants had lower physical activity (counts per minute per day) and greater sedentary time than White participants. Conclusions: Active strategies were more successful in recruiting women into the study. Of those who enrolled, physical activity levels increased over time. Identifying barriers to physical activity that may change over the postpartum period will help develop more targeted interventions to increase physical activity.

Associations between Sleep and Body Composition in Older Women and the Potential Role of Physical Function.

Purpose: The relationship between sleep and adiposity in older women remains unclear partly due to the reliance of body mass index as a measure of adiposity. The purpose of this study was to investigate associations between objectively measured sleep characteristics and body composition measured by dual energy x-ray absorptiometry (DXA) in older women. A secondary purpose was to examine if physical function mediates this relationship. Methods: Non-obese older women (ages 60-75 years, n=102) were included in the study. Total sleep time (TST), time in bed (TIB), sleep efficiency (SE), and wake after sleep onset (WASO) were determined by actigraphy. A battery of tests was used to assess physical function. Results: With adjustment for age, there was a negative association between TST and TIB with lean mass. Both grip strength and dominant leg extension were associated with TST, TIB, and lean mass; the associations between TST and TIB with lean mass were lost after adjusting for grip strength or leg extension strength. Additionally, SE was negatively associated with total, gynoid, and trunk lean mass, and there was a positive association between TST and percent trunk fat, and WASO and gynoid lean mass, with age adjusted. Conclusions: Sleep characteristics, TST, TIB, SE, and WASO, were associated body composition measures in this sample of older women. The relationship between TST and TIB with body composition was mediated, in part, by grip strength and leg extension strength.

Body weight and fat trajectories of Black and White women in the first postpartum year.

OBJECTIVE: The aim of this study was to examine changes in body weight and fat in Black and White women during the first postpartum year and to determine whether there is preferential retention of fat mass and abdominal fat. METHODS: Body composition was quantified by dual-energy x-ray absorptiometry in Black (n = 49) and White (n = 85) women at 6 to 8 weeks, 6 months, and 12 months after delivery of a singleton infant. RESULTS: Weight, fat mass, percent body fat, and fat in the trunk, android, gynoid, and limb regions decreased from 6 to 8 weeks to 12 months in White women, but not in Black women (fat mass, adjusted mean [SE]: 29.6 [1.3] to 26.9 [1.3] kg in White women and 34.5 [1.5] to 36.8 [1.8] kg in Black women). In the entire sample, fat mass was higher at 6 months than at 6 to 8 weeks, independent of weight change; visceral fat was higher at 12 months (686 [45] g) than at 6 to 8 weeks (611 [42] g) and 6 months (626 [43] g); and android fat was higher at 12 months than at 6 months, independent of fat change. CONCLUSIONS: Black women were less likely than White women to lose weight and fat in the postpartum period. There was preferential retention of fat in the abdominal area.

Measurement of Physical Activity with Wrist-Worn ActiGraph GT3X+ in Older Women.

Higher wear compliance has been seen with wrist placed accelerometers versus hip placed. Performance of wrist placed ActiGraph GT3X+ accelerometer (GT3X+, ActiGraph LLC, Pensacola, FL) in assessing physical activity (PA) remains unclear. PURPOSE: This study examined GT3X+'s performance in measuring PA energy expenditure (PAEE) and classifying PA intensity in older women. METHODS: Women [n = 89, age = 65.6 (4.3)] wore GT3X+ and SenseWear Armband Mini (SWAM, BodyMedia Inc. Pittsburgh, PA) for 2 weeks. Concurrently, doubly labeled water (DLW) determined total daily energy expenditure (TDEE). Resting energy expenditure (REE) was determined by Indirect Calorimetry. Data was processed using manufacturer-provided software. Bivariate correlations, Intra Class Correlations, and Bland-Altman plots were performed to evaluate agreement between GT3X+ and criterion measures for sedentary time, light and moderate-to-vigorous PA (determined by SWAM) and PAEE (determined by SWAM and by DLW and REE). Epoch-by-epoch analysis evaluated discrepancy and agreement of PA intensity classification between GT3X+ and SWAM. RESULTS: For PAEE, GT3X+ showed moderate correlations with criterion measures (r = 0.413, 0.400 with SWAM; r = 0.564, 0.501 with DLW and REE), but Bland-Altman plots showed large variability. When estimating time spent in PA intensity, GT3X+ underestimated sedentary time and overestimated PA intensity compared to SWAM. During epoch-by-epoch analysis, GT3X+ misclassified light intensity PA as moderate-to-vigorous PA 72% of the time. Counts per minute showed strong correlations with criterion measures (r = 0.68, 0.625 for SWAM and DLW and REE respectively). CONCLUSION: Current equations and cut points do not provide accurate measures of PA with wrist-worn GT3X+ in older women.

Glycemic variability: Importance, relationship with physical activity, and the influence of exercise.

Glycemic variability is a more sensitive assessment of glycemic health as opposed to traditional clinical measurements. It considers all blood glucose concentrations over a given period to better account for glucose oscillations that occur and provides clinicians with insight into how individuals regulate and/or maintain their glycemic health. The advancement of continuous glucose monitoring (CGM) allows for the measurement of free-living glucose concentrations while providing a more reliable assessment of treatment of dysregulated glycemic. CGM coupled with management of lifestyle behavioral factors, such as reduced sedentary behavior and increased physical activity and regular exercise, potentially offers a previously untapped method for promoting improved glycemic health through greater regulation of glucose concentrations. The aim of this review is to critically evaluate the evidence regarding the measurement of glycemic variability and summarize the current understanding of the relationship between glycemic variability, sedentary behavior, physical activity, the influence of a single exercise session or repeated exercise sessions, and exercise training. This review considers information pertaining to the strengths and limitations for measuring glycemic variability and provides insight into future study designs aimed at evaluating the relationship between sedentary behavior and physical activity with, as well as the influence of exercise on, glycemic variability as a primary outcome.