Circadian Rhythm Disruptions and Cardiovascular Disease Risk: The Special Role of Melatonin.

Circadian rhythms are endogenous biological cycles that regulate essential cardiovascular functions, including blood pressure, heart rate, vascular tone, and metabolic homeostasis. Disruption of these rhythms due to factors such as shift work, artificial light at night, irregular sleep-wake cycles, or mistimed eating has been increasingly recognized as an independent risk factor for cardiovascular disease. A growing body of evidence links circadian misalignment to key pathophysiological mechanisms, including endothelial dysfunction, oxidative stress, inflammation, and autonomic imbalance. Melatonin, a hormone produced primarily by the pineal gland, plays a central role in circadian regulation and exhibits potent antioxidant, anti-inflammatory, and cardiometabolic properties. This narrative review synthesizes current findings on the interplay between circadian disruption and cardiovascular risk, with a particular emphasis on the mechanistic and therapeutic role of melatonin. We also highlight the potential of chronotherapeutic strategies, such as timed melatonin supplementation, antihypertensive dosing, and time-restricted eating, to restore circadian alignment and improve cardiovascular outcomes. Despite promising data, translation into clinical practice remains limited. Future research should focus on identifying practical circadian biomarkers, refining chronotherapy protocols, and integrating circadian variables into risk models and clinical workflows.