The circadian rhythm is an endogenous biological process that regulates various physiological and behavioral functions by maintaining an approximately 24-hour cycle. This internal clock system coordinates cycles such as sleep-wake patterns, body temperature fluctuations, and the secretion of hormones. It is governed by complex molecular mechanisms within the biological system, ensuring that metabolic and cellular processes operate in predictable cycles relative to the Earth's rotation. Disruption of this rhythm, often due to changes in light exposure or shifts in routine, can lead to disruptions in overall physiological balance and function.