By Line Bloch, 14. June 2016
This article is a part of a series in 5 parts, taking you through the physics of stress, and how to prevent it. Start here – and dig deeper into each element.
The most important hormones when it comes to stress are – as you perhaps already know – Adrenaline and Cortisol.
But what do they do to us and how do they actually work? Are they dangerous and why?
To put it short; while adrenaline is useful and mostly harmless, cortisol is not meant to play with. Under normal, healthy conditions, we have a daily rhythm of cortisol levels in our blood. Highest level in the morning and lowest around midnight. It starts to rise again at 3-4 am. This is why you wake up at the middle of the night if you are under pressure*.
Cortisol formation and release into the blood, is triggered by events that is perceived dangerous. It is the ultimate survival hormone, as it mobilizes everything the body has for the single purpose of surviving from an immediate threat. Cortisol makes us instant superheroes.
Cortisol makes us instant superheroes
But it also means that everything not critically needed for immediate survival is shut down.
Let’s look into what cortisol actually does to the body:
Short term effects
Short term effects on the brain
Overall, cortisol increases our focus, our mental strength and our courage. It ‘opens up’ the blood-brain barrier, so that more electrolytes and glucose can get into the brain. It reduces the level of pain we feel, but it also narrows our focus to only the immediate danger.
Cortisol stimulates the amygdala as a feedback mechanism to strengthen emotional memory creation. Hippocampus have quite many cortisol-receptors, and is as such very sensitive to cortisol. Together with adrenaline it improves the memory on the dangerous event as a mean to remember what to avoid in the future, but cortisol also reduces the ability to take in new information in the situation and to be creative.
What happens if we get too much for too long?
As cortisol shuts down the functions in the body that is not needed for immediate survival, and draws resources from tissue and organs not relevant for fight or flight, it is obvious, that too much cortisol over a longer period of time is not optimal for us. Beside from the exhaustion of being in alert-state, let’s look into the consequences:
In the brain, too much cortisol overstimulates the amygdala. Amygdala have shown to grow after a period with elevated cortisol levels in the blood. The result is feeling more fear, more anger, more sadness and anxiety. Even panic attacks.
Long-term exposure to cortisol results in damage to cells in the hippocampus and this damage impairs learning, short-term memory and creativity: You lose your ability to learn new. You have little or no short-term memory. You will find it more and more difficult to remember what you used to know. And you stop being creative.
Eventually, it will lead to numb-ness in the brain: depression.
Science still discuss if these effects are reversible or not, but my qualified guess is, that the longer the exposure, the longer it takes to recover. Three weeks of holiday are not enough.
Cortisol is a steroid-based hormone and is synthesized from cholesterol. It belongs to a group of hormones called glucocorticoids. Cortisol is made in the adrenal cortex of the adrenal gland, which is near the kidney.
Its systematic name is (11β)-11,17,21-trihydroxypregn-4-ene-3,20-dione