Unravelling the neurophysiological integration of circadian rhythms and autonomic control of the heart

The sympathetic (“fight or flight”) and parasympathetic (“rest and digest”) branches of the autonomic nervous system (ANS) act in concert to provide rapid and precise control over our physiology, including cardiovascular function. Daily rhythms in ANS activity are a critical mechanism by which the circadian system coordinates peripheral tissue function and aligns our biology with the external environment. However, it remains unclear how daily rhythms in ANS activity are imposed and how they are integrated with acute ANS response to changes in external or internal state. Understanding circadian control over autonomic activity and output to the heart is vital. It is now well-established that severe cardiac events (e.g. sudden cardiac death) occur more frequently at certain times of day, and that circadian dysfunction (e.g. shift-work) increases risk of cardiovascular disorders and adverse cardiac events. My previous work has revealed distinct circadian and non-circadian routes of autonomic control over cardiac electrophysiology, altered cardiac conduction in response to circadian misalignment, and inherent time-of-day-dependent susceptibility of the heart to ventricular arrhythmia. This project will delineate neural pathways and mechanisms that deliver circadian autonomic regulation of cardiac function and reveal how and where autonomic control of the heart is impacted during circadian disruption.