Circadian rhythm

Circadian rhythms are our physical, mental, and behavioral patterns that follow a 24-hour cycle. These rhythms are a product of our internal biological clocks in relationship with external cues—mostly sunlight and darkness, but also exercise, food, and medication. Our control room or "master clock" is a structure of some 20,000 neurons called the suprachiasmatic nucleus (SCN) located inside the hypothalamus region of the brain, which is connected to biological clocks in almost all of our tissues and organs. Following a schedule that most closely aligns with our natural biological rhythm is important for health, and a less robust circadian rhythm is associated with aging.