The Effects of Cortisol on Sleep

You need to have just right amounts of cortisol. In the morning, your cortisol is highest. That's the awakening response. And then throughout the day, it'll gradually decline as cortisol goes down and something else called adenosine goes up. When you have high levels of adenosine in your system, when you've been thinking all day and working all day, you tend to not think as clearly or be as motivated than you do earlier in the day. Circadian rhythms are regulated by the superchiasmatic nucleus or the SCN in the hypothalamus.