Circadian Rhythms: Attributes, Disruption, and Implementation in Cardiometabolic Health

It is a well-known fact, proved by evidence, that all the organisms consist of an internal biological clock, right from the singlecelled organisms to humans. In the hierarchy of classification of vertebrate, these rhythms have shown to play an important role concerning the physiological aspects of all organisms. Not only are these rhythms related to sleep, seasonal migration, reproduction, etc., in animals, but also, in humans, circadian rhythms control various vegetative functions including regulation of temperature, cardiac activity, endocrine secretion, blood pressure (BP), oxygen utilization, metabolic rate, menstrual and ovarian cycles, and other body functions. The change in the normal pattern of the circadian clock because of genetic, behavioral, and various environmental factors can produce cardiovascular, metabolic, and endocrinal disorders including hypertension and diabetes. The concentration of glucose in plasma displays circadian variation; in the morning hours, it is the highest. Since the level of insulin depends on the feeding behavior, the glucose concentration follows the daily rhythm of intake of food. On the contrary, BP and other cardiovascular reflexes have characteristic and diurnal circadian rhythms. Circadian trends are exhibited in many cardiovascular pathophysiological conditions like stroke, myocardial infarction, rhythm disorders, and bed death syndrome. There is enough evidence to show that disruption of circadian rhythms can act as a risk factor for the development of cardiovascular diseases. Recent research also suggests that the circadian clock and associated central as well as peripheral genes are responsible for glucose and lipid metabolic rhythms.