Project Summary High asleep systolic blood pressure (SBP) and a non-dipping blood pressure (BP) pattern (a <10% decrease in SBP from being awake to asleep) are very common, each with a prevalence >30%, and both are associated with a 1.5 to 3-fold increased risk for cardiovascular disease (CVD) morbidity and mortality. Circadian and sleep-related factors are two of the most likely contributors to high asleep SBP and non-dipping BP. A better understanding of both circadian and sleep contributions, as well as the alignment between sleep behaviors and chronotype, to asleep BP levels and rhythms will allow for the development of interventions to lower asleep BP, restore BP dipping, and reduce BP-related CVD. The overall objective of the proposed study is to determine the associations of chronotype and sleep-related factors with mean BP, and BP dipping (Aim 1); the association of alignment between sleep timing and chronotype with mean BP, and BP dipping (Aim 2); and the association of circadian phase and amplitude with BP dipping under constant conditions (Aim 3). The proposed study, titled “Sleep and Circadian Contributions to Nighttime Blood Pressure (SCN-BP)” will achieve Aims 1 and 2 by collecting sleep and circadian data using questionnaires and wrist actigraphy as part of a large, diverse cohort of research participants at 3 sites (the University of Alabama at Birmingham [UAB], Columbia University Medical Center, and Kaiser Permanente Southern California). SCN-BP will then enroll participants who successfully complete Aims 1 and 2 at UAB to complete a 30-hour Constant Routine (CR) Protocol to determine circadian phase and amplitude, as well as BP levels under constant conditions. Findings from the proposed study will provide data that are critical to understand two of the most likely factors that contribute to high asleep BP and non-dipping BP, as well as generate preliminary data to examine the impact of non-sleep factors (e.g., feeding) on asleep BP levels and dipping. The proposed study is unique in that it will combine population science approaches in Aims 1 and 2 with basic/clinical science approaches in Aim 3 in a large, diverse sample sufficiently powered to examine differences by age, sex, race/ethnicity, and antihypertensive medication use. The proposed study will allow for the development of interventions to lower asleep BP, restore BP dipping, and reduce BP-related CVD.

Project Narrative High blood pressure and blood pressure that does not decrease by at least 10% during sleep are both associated with cardiovascular disease and death. The overall objective of the proposed study is to determine specific sleep and circadian rhythm factors that contribute to high blood pressure during sleep. A better understanding of these factors will help us design specific interventions to lower blood pressure during sleep and reduce cardiovascular disease and death.