Circadian rhythms are the natural, internal processes that follow a roughly 24-hour cycle, influencing various biological functions such as sleep-wake patterns, hormone release, and body temperature. These rhythms are driven by an internal clock in the brain, primarily located in the suprachiasmatic nucleus (SCN) of the hypothalamus, and can be influenced by external cues like light and temperature. Understanding circadian rhythms is crucial for grasping how sleep and dreaming are regulated and how disruptions can impact overall health.