Where is the suprachiasmatic nucleus (SCN) located?

The suprachiasmatic nucleus (SCN) is a tiny group of neurons located in the hypothalamus, specifically above the optic chiasm. It plays a crucial role in regulating circadian rhythms, which are the physiological processes that follow a roughly 24-hour cycle, responding primarily to light and dark cues in the environment. The SCN receives direct input from the retina, allowing it to synchronize the body's internal clock with the day-night cycle. This positioning within the hypothalamus makes it central to the regulation of sleep-wake cycles and various hormonal, metabolic, and behavioral rhythms.

This anatomical context is essential for understanding how the SCN influences the body’s internal timing mechanisms and helps maintain overall homeostasis related to sleep and wakefulness.