Appropriate Circadian-Circasemidian Coupling Protects Blood Pressure from Morning Surge and Promotes Human Resilience and Wellbeing

Abstract

Background Blood pressure (BP) variability is involved in the appraisal of threat and safety, and can serve as a potential marker of psychological resilience against stress. The relationship between biological rhythms of BP and resilience was cross-sectionally assessed by 7-day/24-hour chronobiologic screening in a rural Japanese community (Tosa), with focus on the 12-hour component and the “circadian-circasemidian coupling” of systolic (S) BP. Subjects and Methods Tosa residents (N = 239, 147 women, 23–74 years), free of anti-hypertensive medication, completed 7-day/24-hour ambulatory BP monitoring. The circadian-circasemidian coupling was determined individually by computing the difference between the circadian phase and the circasemidian morning-phase of SBP. Participants were classified into three groups: those with a short coupling interval of about 4.5 hours (Group A), those with an intermediate coupling interval of about 6.0 hours (Group B), and those with a long coupling interval of about 8.0 hours (Group C). Results Residents of Group B who showed optimal circadian-circasemidian coordination had less pronounced morning and evening SBP surges, as compared to residents of Group A (10.82 vs 14.29 mmHg, P < 0.0001) and Group C (11.86 vs 15.21 mmHg, P < 0.0001), respectively. The incidence of morning or evening SBP surge was less in Group B than in Group A (P < 0.0001) or Group C (P < 0.0001). Group B residents showed highest measures of wellbeing and psychological resilience, assessed by good relation with friends (P < 0.05), life satisfaction (P < 0.05), and subjective happiness (P < 0.05). A disturbed circadian-circasemidian coupling was associated with elevated BP, dyslipidemia, arteriosclerosis and a depressive mood. Conclusion The circadian-circasemidian coupling of SBP could serve as a new biomarker in clinical practice to guide precision medicine interventions aimed at achieving properly timed rhythms, and thereby resilience and wellbeing.

Evidence for conservation of primordial ∼12-hour ultradian gene programs in humans under free-living conditions

“…While these data provide evidence in support of a ∼12h gene program in humans, larger studies will be needed to determine how variable the ∼12h programs are in the human population, the degree to which they are sensitive to aging or environmental stressors as observed for circadian rhythms, and most importantly whether disruption of ∼12h rhythms is a causal determinant of disease pathobiology. Aside from the identification of ∼12h pathways related to fundamental cellular processes, several pieces of evidence suggest that ∼12h rhythms are important for maintenance of homeostasis: (i) when we adjusted for detection sensitivity by matching sampling frequency to period length, the number of putative ∼12h genes was similar to the circadian program; and (ii) prior human studies suggest ∼12h rhythms in physiological metrics of relevance to human health and disease, including heart rate variability, blood pressure, hormone levels, and cognitive function [6, 8, 58, 59]. As such, our discovery of ancient ∼12h gene programs in humans provides rationale for future studies to determine whether ∼12h rhythms should be viewed alongside circadian rhythms as a core molecular determinant of health and disease.…”

“…Aside from the identification of ~12h pathways related to fundamental cellular processes, several pieces of evidence suggest that ~12h rhythms are important for maintenance of homeostasis: (i) when we adjusted for detection sensitivity by matching sampling frequency to period length , the number of putative ~12h genes was similar to the circadian program; and (ii) prior human studies suggest ~12h rhythms in physiological metrics of relevance to human health and disease, including heart rate variability, blood pressure, hormone levels, and cognitive function [6,8,58,59]. As such, our discovery of ancient ~12h gene programs in humans provides rationale for future studies to determine whether ~12h rhythms should be viewed alongside circadian rhythms as a core molecular determinant of health and disease.…”