The Truth About Cortisol: Why Stress Isn’t the Enemy

Let's look at what cortisol is in the simplest of terms.

So cortisol is a hormone produced in the adrenal glands, and they sit just above the kidneys.

Very, very simply, when your brain detects that something requires action through a hormonal process, it tells your adrenal glands, "Hey, we need cortisol." And then cortisol then circulates around the body and helps prepare the-- prepare you to deal with whatever the demand you're facing, right? That's it in its simplest of forms.

Now, this could be many different things causing this response: a difficult meeting, a deadline, public speaking, an argument, a lack of sleep or lack of recovery, a heavy training session, running a marathon, HIIT, caloric restriction, being ill, getting on a plane, and even the simplest thing of waking up in the morning, going from a sleep state to a wake state.

All of these things will inherently need a stress response or a cortisol response.

Key one here for understanding, exercise itself is a stressor that acutely raises cortisol, and that's not inherently harmful.

So what does cortisol actually do? What are the things that cortisol actually does? So this is where cortisol isn't actually the enemy.

Okay, so what does cortisol do? Cortisol helps you to regulate energy availability, so it helps ensure glucose and other fuels are available when your body needs them.

It helps regulate blood pressure and cardiovascular function, so particularly important when you're responding to a physical or psychological challenge in life.

It helps regulate inflammation and immune activity, so cortisol has a powerful effect on the immune system.

It helps regulate your metabolism.

It influences how your body handles carbohydrates, fats, proteins, all the macronutrients, et cetera.

Cortisol also helps regulate brain function.

So cortisol interacts with areas involved in attention, learning, memory, emotional processing.

Interestingly, the relationship isn't simply more cortisol equals worse cognition.

Moderate acute increases can help with many aspects of cognition focus, where excessive levels of cortisol can impair these functions.

So it's all about balance with cortisol.

It is all about balance.

But one thing I get asked about a lot is to begin with looking at, let's just dive into the sleep-wake cycle, 'cause this is where a lot of people get a bit confused with cortisol, 'cause they're all like, "Well, cortisol is a stress response, it's bad for me," et cetera.

So one thing you need to be aware of, your cortisol should be and needs to be high in the morning when you wake up.

So I'm just gonna-- I just wanna bust some myths around this.

So cortisol is not supposed to remain flat or low throughout the day.

It has a strong link to circadian rhythm.

So generally at night we do want low cortisol to get into a deep, restful, restorative sleep.

However, in the hours before waking up, cortisol starts increasing, and in the morning it gets to a high peak.