The stress hormones: Cortisol

Photo by Jeremy Bishop on Unsplash

By Line Bloch, 14. June 2016

Welcome to part 4 of a series of 5

This series takes you through the physics of stress, and how to prevent it. Start here – and dig deeper into each element.

Cortisol makes us instant superheroes

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.

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

  • It increases glucose levels in the blood, so that the big muscles and the brain, have more easily available energy. It does so, by making the liver create glucose from proteins and lipids (gluconeogenesis). This means that is forces the breakdown of proteins into amino acids and at the same time inhibits synthesis of new proteins.
  • Collagen that makes up the structure in our skin, the blood vessels and our joints, is the most abundant protein in our bodies. Cortisol stimulates degradation of collagen, to free up amino acids for energy. Also stored lipids are broken down and released into the blood as fatty acids.
  • Cortisol increases blood pressure, so that the glucose and other nutrients gets as quickly as possible to the brain and the muscles needed for fight or flight.
  • Cortisol increases blood coagulation, so that we don’t bleed to death if wounded – but slows down the overall healing process.
  • Cortisol reduces the inflammatory response and the overall immune response in the body, so that you don’t waste energy in fighting something that can wait. This is why you get ill in weekends and the first days of your holiday, if working under pressure. It is the immune system starting up again when cortisol levels are lowered.
  • Cortisol reduces bone formation and it inhibits collagen formation as we need the energy to something else. And it suppresses the reproductive system. You don’t have time for kids, when you are fighting against monsters.

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.

Facts on Cortisol

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

Read More Nerdy Stuff

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:

  • Cortisol makes the blood thick with many fatty acids and amino acids, the blood pressure high and the blood easily coagulating. This is the fast lane to blood cloths and other heart disease.
  • Collagen is being broken down and not replaced. Your skin will fracture and the joints loosen.
  • With your immune response set on ‘low’, you obviously get ill easier.
  • Reduced bone formation leads to osteoporosis.

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 fearmore angermore sadness and anxiety. Even panic attacks.

Long-term exposure to cortisol results in damage to cells in the hippocampus and this damage impairs learningshort-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.

*A trick on how to deal with the ‘cortisol-sleep’, i.e .when you wake up at 3-4 O’clock; is acceptance. Know, that this is why you wake up: Because cortisol levels in your blood is rising again. Basic physiology.

If you are in times with lot of pressure, your body is in a sensitive and hyperactive state, and it takes very little to alert the brain. Rising levels of cortisol is perceived as if it is time to out and fight the monster. But don’t listen. Instead praise the body for still working as intended, accept that it’s just cortisol levels rising and ‘now let me go back to sleep’.

This was part 4 of a series of 5

This series takes you through the physics of stress, and how to prevent it.

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