The master clock is a small group of about 20,000 nerve cells in the brain called the suprachiasmatic nucleus (SCN)
- Sleep-Wake Cycles: It determines when you feel alert versus sleepy by communicating with the pineal gland.
- Body Temperature: It regulates the slight dip in core temperature at night and the rise in the morning.
- Hormone Release: Beyond cortisol and melatonin, it influences the timing of growth hormones and metabolic processes.