BACKGROUND: Body weight is determined by sustained changes in energy balance (EB), reflecting the difference between energy intake (EI) and energy expenditure (EE). Insufficient sleep negatively impacts body weight control to favor weight gain. African American young adults have a higher risk for insufficient sleep and obesity, but little data exists on these measures in this population. The purpose of this analysis is to examine the relationship between sleep duration and efficiency with baseline and 6-month changes in parameters of energy balance, body mass, and body fat in African American female young adults.METHODS: In a repeated measures design, 12 African American female young adults (age, 21±2.6 y; height, 164±6.6 cm; weight, 72.5±13.9 kg; body fat, 29.1±9.9%) completed an initial (BLN) and 6-month (6M) visit. Seven days of actigraphy-derived sleep efficiency and sleep duration were calculated using the Sadeh algorithm at BLN. Physical activity EE (PAEE) and moderate-to-vigorous physical activity (MVPA) were measured with actigraphy and calculated using the Freedson VM3 Combination and Freedson (1998) algorithms, respectively. Resting metabolic rate and thermic effect of food were measured via indirect calorimetry. Ad libitum EI was measured using 3 days of provided meals. Body mass and body fat were assessed via BodPod. Paired t-tests evaluated differences in EB parameters, body mass, and body fat between BLN and 6M. Pearson r correlations assessed the relationship between baseline sleep measures with changes in parameters of EB, body mass, and body fat at BLN over 6M.RESULTS: There was a significant increase in body mass (MD: 2.8 kg, 95%CI[0.82, 4.74], p=0.01), MVPA (MD: 45.2 min/d, 95%CI[0.94, 89.5], p=0.05), and PAEE (MD: 327.1 kcal/d, 95%CI[73.5, 580.6], p=0.02), but not body fat (MD: 2.2 kg, 95%CI[-1.3, 5.7], p=0.20) from BLN to 6M. Greater sleep efficiency at BLN was associated with a decrease in body fat (r = 0.59, p=0.04) and a more negative EB (r = 0.72, p=0.01) from BLN to 6M. There were no associations between sleep variables and changes in body weight (p>0.05).CONCLUSIONS: In this sample of African American females, greater baseline sleep efficiency was associated with a greater decrease in body fat and a more negative energy balance, suggesting that those with better sleep efficiency may have less risk of weight and fat mass gains during the key developmental period of young adulthood.

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