0275 Associations Between Sleep Architecture, Cortisol, and Body Composition over 6 Months in Black Emerging Adults

Abstract Introduction Cortisol awakening response (CAR), diurnal slope (DS), and total daily output (TDO) are metrics of the hormone, cortisol. Emerging adults (ages 18-28 years old) experience poor sleep, which is linked to a blunted CAR, flatter DS, and obesity risk. Little data exists on these measures in Black emerging adults, despite higher risks of poor sleep and obesity. This analysis aims to examine relationships between sleep architecture, cortisol metrics, and body mass and composition changes over 6 months in Black emerging adults. Methods In a repeated measures design, 14 Black emerging adults (12 females; age, 21±2.5 years; height, 166±9.3 cm; body mass, 73.0±12.9 kg; body fat, 27.4±10.8%) completed an initial (BLN) and 6-month follow-up (6MO) visit. In-home sleep over 2 nights was captured with polysomnography. Salivary cortisol was collected at wake, 30-, 45-min post-wake, 12pm, and 7pm on 2 days. CAR area under the curve (AUC) was calculated with the wake, 30-, and 45-min post-wake samples with respect to wake (AUCi) and to ground (AUCg). DS was calculated as the slope using wake, 12pm, and 7pm samples. TDO AUC was calculated using all samples with respect to ground. Body mass and composition were assessed with BodPod. Paired t-tests evaluated differences in all variables between BLN and 6MO. Pearson correlations assessed relationships between sleep stage duration, cortisol metrics, and body mass and composition at each timepoint, and 6-month changes in these variables. Results There was an increase in body mass (MD: 2.7 kg, 95%CI [1.0, 4.4], p< 0.01), but not fat mass (p>0.05). REM sleep duration was positively associated with TDO at BLN (r = 0.57, p=0.03) but not at 6MO. REM sleep duration at BLN was also positively associated with 6-month changes in body mass (r=0.55; p=0.03). Greater increases in slow-wave sleep (SWS) duration were associated with a more positive DS (r = 0.73; p< 0.01). Conclusion These results suggest that greater amounts of REM sleep are associated with greater cortisol output and body weight changes, whereas greater amounts of SWS are associated with better DS profiles. Support (if any)