Suprachiasmatische

The suprachiasmatic nucleus (SCN) is a tiny region located in the hypothalamus of the brain, positioned directly above the optic chiasm, the point where the optic nerves from each eye partially cross. Its primary function is to act as the master circadian pacemaker, governing the body's internal 24-hour cycles, known as circadian rhythms. The SCN is responsible for generating and coordinating these rhythms, which influence a wide range of physiological and behavioral processes.

The nucleus receives direct information about environmental light from specialized cells in the retina via a neural pathway called the retinohypothalamic tract. This light input allows the SCN to synchronize the body's internal clock with the external day-night cycle. In response to light signals, the SCN adjusts the timing of circadian rhythms to ensure they are aligned with the solar day. This master clock then coordinates peripheral clocks found in other organs and tissues throughout the body.

Through this synchronization, the SCN regulates critical functions such as the sleep-wake cycle, hormone secretion (particularly melatonin), body temperature, and metabolism. Proper function of the suprachiasmatic nucleus is essential for maintaining health and well-being, as it ensures that an organism's internal biological processes are optimally timed to predictable environmental changes.