Cortisol – Stress or Activation

Cortisol is considered the stress hormone - is this bad marketing?

Cortisol is a key hormone in the human body and brain. But in a lot of popular literature, it is considered the stress hormone. This is not just the popular literature, a standard way to measure stress physiologically in academic research is to measure levels of cortisol in saliva. So is cortisol just the stress hormone?

When I first got involved in neuroscience cortisol was touted as the stress hormone and mostly still is. But, as with many things, when you get a little deeper into the topic it becomes a little more complex.

The most important aspect to consider of cortisol is that there is a natural daily rhythm. You start the day with high cortisol, and this decreases noticeably after a few hours and decreases over the day with its lowest level in the evening and during sleep. The second thing to consider is that having too low cortisol levels is also bad for you, known as Addison’s disease. So, this shows us that cortisol is a natural part of a daily lives and that too little of it is also a bad thing. So, let’s look at what cortisol actually is, what it does, and that critical relationship to stress and the negative impacts from neuronal growth, to various neurodegenerative disorders, and to pathological stress responses.