Cortisol is more than just a “stress hormone”. It helps to control inflammation, blood glucose, metabolism and give us a feeling of energy.
Pulsing to the beat of a daily rhythm, cortisol is highest in the morning about 30 minutes after we wake up, helping to give us a burst of energy to face the day. It then declines throughout the day, bottoming out around midnight.
But cortisol is responsive to our lives too, so physical or psychological stressors can cause it to spike. When we exercise, are unwell or are feeling distressed over finances, work, relationships or what we see on our screens, our brain’s threat detector, the amygdala, sends a distress signal to our brain’s control centre, the hypothalamus. To keep the body on high alert, the hypothalamus then stimulates a cascade of hormones from the “master gland” in the brain, the pituitary, down to the adrenal glands, which sit atop the kidneys and secrete cortisol. This is known as the HPA-axis.
“In general, the more stressful the activity, the higher the cortisol,” says Associate Professor Warrick Inder, an endocrinologist at the University of Queensland medical school. “For example, doing a speech might raise your cortisol a little, running a 1500-metre race a moderate amount and being really sick with blood poisoning [septic shock] in intensive care generally increases cortisol a lot.”
Once the stressor has passed, our body turns off the stress response and cortisol levels return to baseline, says Professor Divya Mehta, the team leader of the Stress Genomics Group at Queensland University of Technology.
“In chronically stressed individuals, the body does not recognise that the stressor has passed, resulting in abnormally high levels of cortisol and a constant fight or flight state,” she adds.
This is detrimental to our health in many ways, causing inflammation and negatively affecting gene activity and function, our immune system and our mental wellbeing.
Despite this, our adrenal glands do not get fatigued, Inder says. “Adrenal fatigue is not a real condition … Cortisol is not depleted by stress.”
So what exactly is happening?
Short of Cushing’s and Addison’s, and beyond a healthy stress response is a grey area, says Duncan Topliss, director of the department of endocrinology and diabetes at Melbourne’s Alfred Hospital.
“In the day-to-day life of an ordinary healthy person, stress is more a psychological feeling,” Topliss says. “It doesn’t necessarily impinge on the endocrinological.” However, he adds, severe chronic distress can cause dysfunction, and the HPA-axis can be disrupted.
What can cause HPA-dysfunction?
Rather than “adrenal fatigue”, experts recognise that some forms of chronic or traumatic stress can cause cortisol dysregulation or HPA-dysfunction, where cortisol fires at the wrong times – at night when we’re trying to go to bed instead of in the morning, for instance – or remain elevated.
Along with chronically high levels of stress, shift work can disrupt the natural rhythm of HPA-axis, as can severe childhood trauma.
“Athletes who overtrain and have relative energy deficiency syndrome [known as REDs] tend to have chronically high cortisol levels,” Inder says. “And people with depression also have high cortisol levels.”
These high levels are fully reversible when the depression is treated (with antidepressants, for example) or exercise toned down and diet improved, Inder says.
And herein lies the key.
Instead of stressing over cortisol levels or being sold expensive supplements that have not been assessed properly, we’re better off attending to the root cause of our stress to whatever extent we can, says Professor Matthew Kiernan, chief executive of Neuroscience Research Australia.
Regulating cortisol levels
There is an interplay between biochemical, lifestyle and psychological factors, Kiernan says. “If you go and see the GP and all the levels are normal, then that’s the end of the discussion, and we’re back into [our usual] lifestyle and what else is going on in that person’s life.”
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Not all stressors are within our control, but getting our natural rhythm in sync by waking up in the morning and getting some sunlight, exercising during the day to help us sleep at night, and eating a healthy diet while reducing caffeine and alcohol consumption can all help. Calming practices such as box breathing, 3-4-5 techniques (inhale for three counts, hold for four counts and exhale for five) and meditation can help too.
“Our research has shown that simple lifestyle factors such as increased social support and exercise can reduce and reverse some of the impacts of stress,” Mehta says.
“The key is to find methods and techniques that help alleviate stress and work for you.”
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