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.