Circadian rhythm refers to the natural, internal process that regulates the sleep-wake cycle and other bodily functions over a roughly 24-hour period. This biological clock is driven by light and darkness cues in the environment, particularly the release of melatonin hormone from the pineal gland. Research in circadian rhythms focuses on understanding how these internal clocks function and how they influence various physiological processes, such as metabolism, hormone regulation, and cognitive function. Disruptions to circadian rhythms, often caused by shift work, jet lag, or certain medical conditions, can lead to health issues including sleep disorders, mood disorders, and metabolic disturbances. Scientists are exploring ways to optimize circadian rhythms for improved health and well-being.