Analysis: Cortisol plays a role in essential functions in your body, but the hormone can cause health issues when we experience prolonged stress
"I'm mesmerised by cortisol", says Dr Samantha Dockray, Senior Lecturer in the School of Applied Psychology at UCC. "It forms so many of the measures that I do in research, because it's such a great indicator of emotional processes and what is going to be the health consequences. We always think about it as the direct pathway from your emotions to whether or not you’ll have diabetes, whether or not you'll have a heart attack, whether or not you'll have dementia, whether or not you're gonna gain weight over the next couple of years."
"Not everyone's gonna keel over or have a heart attack because they've got too much cortisol, or because they've got too much stress. The challenge for us as researchers is figuring out: why does it happen more for some people than others?"
Cortisol is often referred to as the 'stress hormone’ for its role in the body’s stress response. But it’s also a normal part of how we function. Cortisol, a steroid hormone produced in the adrenal glands, plays a role in our sleep-wake cycle, with levels naturally rising and peaking during the first hour of the morning after we wake up, and falling throughout the day so that they’re at the lowest in the evening. "It’s kind of what helps us get up and go, that's one of the reasons it's good with stress," says Dockray. It also has a whole range of separate functions, including regulating blood glucose levels.
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What happens in the body when cortisol is too high?
When we experience stress, even for just a minute, a rise in cortisol can be detected in the blood and in the saliva, says Dockray. The brain sends signals for the body to produce more cortisol as a way for the body to manage the situation. The increase in cortisol is determined by how intense the stress is as well as how long it is experienced for. "Cortisol then is circulated through the body and reconfigures what's going on with metabolic processes, so that there's more glucose in the blood to help the body manage, for example, the use of the muscles, what's going on with the brain."
But cortisol is also known to suppress certain aspects of the immune system. In an evolutionary sense, your body's got more pressing concerns when under stress, explains Dockray. As such, cortisol diverts attention away from managing threats from illnesses and viruses. "That's part of the problem with cortisol and stress, is that it's very functional, it does its job really well. But if the person's under too much stress for too long we start to see negative outcomes." The changes in blood glucose levels can effectively move someone towards a more pre-diabetic state, says Dockray.
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When you've got too much cortisol, one of the things it does is it reprograms the retention of calories as fat, for example. "Particularly around the waist, which we know isn't good," Dockray explains. "Then what happens with cortisol is that it starts to drive the development of more cortisol receptors, so it attracts more cortisol, which makes more fat, which attracts more cortisol, which attracts more fat, and it kind of goes on in that process." This is why people sometimes talk about 'cortisol belly'.
Cortisol is "really an incredible thing because the chemical structure means that it can get into any cell in the body and transform the way that cell is working, and then, when that cell is replicated, what the next cell does. So because it can get into a blood cell, a skin cell, a muscle cell, a gut cell, it can change the function of any physiological system in the body."
There's no universally 'normal' level of cortisol, it changes from person to person. But the cost of being in a stressed state can be calculated, this is what researchers refer to as the allostatic load. "It’s this framework that helps us understand why stress eventually puts us in a pre-diabetic state, cardiovascular risk state, a higher risk of dementia", explains Dockray.
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"Cortisol disrupts the other physiological processes - metabolism, immune system, the nervous system as well - and we can have a way of scoring that and it's called the allostatic load. Allostatic load gives us this sense of: how can we see how much stress someone's had in their life and how that's going to affect them. In the allostatic load model, the prime mover of it all is cortisol. Cortisol is the hormone that drives the rest of it."
What are the signs of high cortisol levels?
Most people won't know themselves that they have high cortisol levels, she says. "We don't have a signal. When we think about our awareness of our heartbeat, we can feel our heart racing, we can feel our blood pressure rise, we've got all these signals. But with cortisol there is no signal that our cortisol is high. It's very much silent in that way," Dockray says. But if someone is feeling stressed, the "likelihood is that they've got high cortisol".
Sleep
People with high cortisol levels are more likely to have sleep disruption because the body’s not winding itself down to a space where they can sleep, Dockray says. "If we have too much cortisol in the evening we'll find it hard to sleep, because we're kind of rolling around in a metabolically volatile state."
READ: Here's what happens to your body when you're stressed
Food
Your food cravings could be another indicator of high cortisol. "A person overtime might realise, for example, that they’re more likely to choose high salt, high calorie foods. That's something that cortisol drives us towards."
What can you do to help bring cortisol down?
The only way to bring cortisol levels down is ultimately to address the stress itself and find a different way to manage it, says Dockray. But there are practices that can help regulate your cortisol levels, though they can be hard to execute when you're under stress. The kinds of food and things you eat don't really help, says Dockray, but it's important to get a good night's sleep. Getting out into the morning light can help as well. It's all about "managing that emotional processing of stress and that's the hard part."
Move more
For a lot of people under stress the last thing they want to hear is that they need to be doing 50 laps in the pool and a good two hour walk, says Dockray. "But they're the kinds of things that help with cortisol, in part because it's starting to reshape metabolic processes, and that will help bring cortisol to normal."
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The views expressed here are those of the author and do not represent or reflect the views of RTÉ
