Life Saving

Cortisol is an acute hormone. It literally saves our life. The classic example is someone being chased by a tiger. We secrete cortisol in that scenario because we need to save our life. So, what is really happening? Biochemically, cortisol travels to our liver to make new blood sugar to ensure we survive the event. Cortisol turns off pain recognition, so even if we are injured, we can still fight and survive. Cortisol is also time limited. Meaning, when we experience an acute stress, we have an elevation of cortisol, again to do all those physiologic processes. And then that cortisol should return to a baseline shortly after. Again, cortisol, in every sense of the word, is our acute stress hormone. It is useful to read part 1 first, it can be found here.

Breaking it down

Cortisol serves as our catabolic hormone to get through our day. Catabolic means to break down. A primitive example is when we had to survive each day searching for our shelter, food and water. That’s a catabolic process. Go back to when the sun rises, we want to do everything we can as early as possible so that we can survive. As the day goes on, we’re settled in, we have our shelter, we have some food. We don’t need to be as stressed. We don’t need to have as much energy and we don’t need to do as much. By the end of the day, the cortisol, just like the sun is setting, to allow us to go to sleep because then we need to recover so that we can do it all over again.

During the day, we are catabolic (breakdown) and anabolic (repairing) at night. Anabolic involves growth, healing, mending, rejuvenation, repair, which happens when we go to bed. Our hormone balance is really dictated by this catabolic /anabolic balance.

Building it up again

Keep in mind this concept of being hardwired. The sun rises in the morning. This is when cortisol starts to peak around 6:00 a.m. And again, as the day goes on, that cortisol lowers in our body. The lowest point is around 10:00 p.m. This is around when we should be going to sleep, the sun has set and its dark. When cortisol levels are low, the three most anabolic hormones – testosterone, growth hormone, and melatonin increase. Those three anabolic hormones are also potently anti-inflammatory. When you have an elevated cortisol in the evening, you blunt the response or the output of three anabolic hormones, testosterone, growth hormone, melatonin (there are more, but let’s keep it simple). Doing so over time will impair your ability to sleep, recover, mend, repair all those good things you need to do to lead a quality life.

You’ve probably heard that the most critical hours of sleep are between the hours of 10:00 p.m. and 2:00 a.m. Why? It’s debatable what’s more of an anabolic hormone, testosterone or growth hormone. But the largest pulse of growth hormone by our pituitary gland is between the hours of 10:00 p.m. and 2:00 a.m. Again, that falls in line with the cortisol first being at its lowest point around 10:00 p.m.

Melatonin, another anti-inflammatory hormone and strong antioxidant takes about 12 hours to reset. This is why it is so critical to get up with the sunrise. Also, children produce about 10 times more melatonin than do adults. Let’s look at how this works. Say, for example, you get out of bed at 10:00 a.m. and don’t get sunlight. This is a big deal because your supra-optic chiasm needs to get light in order for the pineal gland to slow down its production of melatonin and begin the process to reset melatonin. In this case, your melatonin will not start to be secreted by the pineal gland until 10 or 11pm that night. You’re not going to feel as tired as such you’re not going to sleep as well. When you get early morning sun at 7:00 a.m., now your melatonin is starting to secrete at 7:00 or 8:00 p.m., which is much more in line with having a low point of cortisol around 10:00 p.m., an increase in melatonin, and then the peak of growth hormone between the hours of 10:00 p.m. and 2:00 a.m. We’ll go back more into this, but it’s a good way to categorize being catabolic during the day and anabolic during the night. Again, lots of cortisol in the morning as the day goes on, and we don’t need as much cortisol. And then lots of anabolic hormones while we sleep at night to repair, again the three big ones, growth hormone, testosterone, melatonin.


Next time, How cortisol is secreted in the brain

Special thanks to Peter Defty for helping with edits, you can find him at