What is the function of the suprachiasmatic nucleus (SCN) in the brain?

The suprachiasmatic nucleus (SCN) plays a crucial role in controlling circadian rhythms, which are the natural, internal processes that regulate the sleep-wake cycle and other behavioral patterns in a roughly 24-hour cycle. Located in the hypothalamus, the SCN receives direct inputs from the retina, allowing it to respond to light cues from the environment. This enables the SCN to synchronize the body's biological clock with the external light-dark cycle, influencing various physiological processes such as hormone release, sleep cycles, and even body temperature. By regulating these rhythms, the SCN helps maintain overall homeostasis and adapt behaviors to the daily cycle of light and darkness, ensuring that the body operates optimally throughout the day and night.