Circadian rhythm is a biological clock that regulates various physiological and pathological processes in the body. It is believed that any disturbance in circadian rhythm leads to impairment in some physiological systems, such as the endocrine, reproductive, renal, and cardiovascular systems. Various internal and external factors can alter circadian homeostasis and metabolism in a tissue-specific manner, and any disruption in these temporal interactions can result in the development of some chronic disorders. Circadian rhythm plays a crucial role in the pathogenesis of diseases, including cardiovascular disease, neurodegenerative disease, mood disorders, sleep disorders, diabetes mellitus, metabolism disorders, and cancer. This review aims to provide a brief overview of the basic circadian processes and an overview of current and future research directions in circadian rhythm and its related treatments.