Chronobioethics for Circadian Medicine: Promoting Cardiovascular Health

Ambulatory blood pressure (BP) and heart rate (HR) monitoring (ABPM) was performed to investigate the involvement of biological clocks in vascular aging cross-sectionally in 625 citizens (368 women, aged 23-79 years) and longitudinally in 15 citizens (12 women; mean age of 59.3 years) who underwent repeat ABPM after 6.3 years. Vascular aging, estimated by systolic BP (SBP) and pulse pressure (PP), increased with age (p < 0.0001), with a steeper increase at night than during the daytime (0.3362 vs. 0.2765 mmHg/year). Day-to-day variability in morning and evening home SBP also increased with age (p = 0.0127 and 0.0137, respectively). An intensified biological clock mode emerged nonlinearly with age and may protect against early vascular aging. Variance transposition, defined as a shift in the dominant biological rhythm from the circadian to another rhythm, also occurred nonlinearly with age. Circadian-to-circasemidian and circadian-to-circaseptan HR variance transpositions were more frequent in younger subjects and preceded circadian acrophase advance, whereas BP variance transposition predominated in older subjects. Subjects with a normal circadian period (23.5-24.5 h) exhibited less frequent HR, SBP, and DBP variance transposition. In conclusion, SBP and PP increased first at night, whereas reinforced biological clocks improved BP profiles and slowed or even reversed vascular aging.