suprachiasmatic nucleus (SCN), which regulates our biological clock. The biological clock is more than a mere timekeeper; it controls when the major organ systems turn on and off during the course of the day. It is both clock and conductor. The SCN is part of the hypothalamus, and together they function as a master conductor to regulate the symphony of our appetites as they rise and fall—our hunger, thirst, sexual longings, cravings for sleep—by adjusting our hormones. They also influence our levels of arousal and our nervous system.
