0018 Prospective Associations Between Rest-Activity Rhythms and Changes in Blood Pressure Across Mid to Late Adolescence

Abstract Introduction Delayed sleep timing has been associated with higher blood pressure among adolescents. However, rest-activity rhythms (RAR), which incorporate both sleep and physical activity, have been rarely explored. Methods The dataset included 558 adolescents (mean age 13.98, SD = 2.15) from the Mexico City-based ELEMENT cohort. Participants completed 7-day wrist actigraphy at the adolescent baseline (T1) visit. R package GGIR was used to derive RAR variables (Amplitude, IS, IV, Up Mesor, Down Mesor, Mesor, L5, L5 time, M10, M10 time, Acrotime, and Relative Amplitude). Blood pressure (systolic, SBP; and diastolic, DBP) was measured at two time-points approximately two years apart (T1 and T2). Linear regression models with RAR variables as continuous exposures and changes in SBP/DBP as outcomes, were adjusted for confounders. Sex stratified models were also tested. False detection rates (FDR) were controlled with the Benjamini Hochberg method. Results We found several associations related to timing of activity. Later L5 (“least active 5 hours”) starting time was associated with positive two year increases in DBP (Beta = 0.265 with SE 0.07 and P < 0.001) and higher SBP (Beta = 0.191, SE 0.08; P = 0.017). In contrast, later Up Mesor (transition from lower to higher activity) was associated with negative two-year changes in SBP and DBP (Beta=-0.37, SE 0.16; P=0.02; and Beta=-0.40, SE 0.14; P=0.003, respectively). Similarly, later M10 (most active 10 hours) was associated with negative two-year changes in SBP (Beta = -0.727, SE 0.20; P < 0.001) and DBP (Beta = -0.709, SE0.23; P = 0.002). All DBP associations remained significant with FDR adjustment. Finally, there were sex differences, such that the M10 association was more prominent in males and the L5 and Up Mesor associations were more prominent in females. Conclusion We found associations between timing of activity throughout the 24-hour day, but not other RAR metrics, with prospective changes in blood pressure. In line with prior research, later low activity periods (i.e., sleep) associated with higher blood pressure. In contrast to expectation, later timing of higher activity periods associated with relative reductions in blood pressure over time in a sex-specific manner. Support (if any) R01HL169893