Circadian Rhythms & Cardiovascular Health

Circadian rhythms are endogenous ~24-hour timing systems that coordinate sleep-wake cycles, metabolism, endocrine signaling, and cardiovascular physiology. Since the molecular clock machinery was identified, circadian biology has become a major focus of cardiovascular research. Numerous cardiovascular parameters, including heart rate, blood pressure, vascular tone, myocardial metabolism, and cardiac function, exhibit robust daily oscillations. Disruption of circadian rhythmicity has been associated with increased risk of hypertension, arrhythmias, myocardial infarction, atherosclerosis, and heart failure, making circadian regulation an important area in both basic and translational life sciences research^[1][2][3].
At the mechanistic level, the core molecular clock is driven by heterodimerization of CLOCK and BMAL1, which activates transcription of Per and Cry genes. Accumulating PER and CRY proteins subsequently inhibit CLOCK/BMAL1 activity, forming the central transcription-translation feedback loop. Additional regulation is provided by REV-ERB and ROR family members that control BMAL1 expression and stabilize circadian oscillations. Cardiomyocyte intrinsic clocks regulate ion-channel expression, heart rate, myocardial metabolism, mitochondrial function, and intracellular signaling pathways. Loss of BMAL1 disrupts circadian homeostasis and contributes to cardiac remodeling, while circadian regulation of SCN5A, KCNH2, HCN4, and other ion-channel genes influences cardiac electrophysiology and rhythm stability^{[4][5][6][7][8][9]}.
In disease applications, circadian biology is extensively investigated in hypertension, myocardial infarction, arrhythmias, heart failure, and cardiometabolic disorders. Circadian misalignment caused by shift work, sleep disorders, jet lag, or irregular behavioral schedules is associated with elevated cardiovascular risk. Therapeutic strategies targeting REV-ERB, ROR, BMAL1, and related clock components, together with chronotherapy approaches that optimize treatment timing, are emerging areas in cardiovascular drug discovery. Important knowledge gaps remain, including cell-type-specific clock mechanisms in cardiovascular tissues, limited human validation of molecular findings, and insufficient clinical evidence for circadian-targeted therapies. Future studies integrating molecular clock networks, biomarkers, and precision chronotherapy may improve cardiovascular prevention and treatment strategies^{[1][2][3][5][10]}.