If you’ve been losing sleep or feeling on the edge for a while now without entirely knowing how to deal with it, you should know you’re not the only one. According to Mental Health Foundation’s 2018 study(1), 74% of people in the UK had felt so stressed out that year that they were overwhelmed or unable to cope.

Stress and anxiety are, unfortunately, very much a part of the modern human experience today. Now that we’ve explored the various factors contributing to stress and anxiety, let’s take a closer look at the physiology behind the stress response and the role of cortisol in the human body.

What is cortisol and what is its role in our physiology? 

Cortisol, belonging to the glucocorticoid class of hormones(2), is involved in the ‘fight or flight’ response(3) and is released by the adrenal glands when one undergoes a stressful situation. This is why it’s also known commonly as the ‘stress’ hormone. 

All physiological processes which are not essential for immediate survival are inhibited, and energy (in the form of glucose) is temporarily made available from storage sites like the liver and muscles for use for either ‘fight’ or ‘flight’. Once one or the other has occurred and the threat has been mediated, the hormonal imbalances eventually get resolved.

How does the stress response work? 

When faced with a stressful situation, adrenaline (also known as epinephrine) is released into the bloodstream from the sympathetic nervous system. Like clockwork, the hypothalamus sounds the ‘alarm’(4), so to speak, and this, in turn, leads to the adrenal glands releasing glucocorticoids(5) (or cortisol). 

Sourced from stored fat from muscles and the liver, glucocorticoids increase blood glucose – back when we were hunter gatherers, this was what helped us escape from advancing prey and effectively saved our lives! They also inhibit all physiological processes that are not absolutely essential to survival at that moment, such as digestion, reproduction and the functioning of growth hormones. 

As Dr. Sapolsky has wryly put it in his podcast ‘The Pervasive Effect of Stress: Is it killing you?’(6), “You have better things to do than digest breakfast when you’re trying to avoid being someone’s lunch.” 

Cortisol and epinephrine team up to increase blood pressure and heart rate, which ensures that the glucose is carried to the large muscles that would need it the most to either ‘fight’ or take ‘flight’. “You (also) think more clearly, and certain aspects of learning and memory are enhanced(7),” adds Dr. Sapolsky. “All of that is spectacularly adapted if you’re dealing with an acute physical stressor — a real one.”

If you’re finding that all the ‘hormone speak’ is getting too technical – don’t get your own cortisol levels up over it! Head over to Today’s Dietitian to check out a great step-by-step breakdown of how our stress response works(8). So what is the effect of this ‘hormonal cascade’ and how is it rooted in the ancient wiring of the human body?

How do elevated cortisol levels affect your whole body – in the short-term and long-term?

Elevated cortisol levels for a short duration might actually have a positive effect – it might help you finish that difficult marathon or perform well at your next appraisal at work. Elevated cortisol levels over a long period of time, however, can lead to negative results such as: 

  • Blood Sugar Imbalance and Diabetes
  • Weight Gain and Obesity
  • Immune System Suppression
  • Gastrointestinal Problems
  • Cardiovascular Disease
  • Fertility Issues

If you’d like to dig deeper into the effects of elevated cortisol levels over a long period of time, go right ahead and sink your teeth into this

How do we look at stress beyond the ‘ancient wiring’ of our physiology?

Cortisol is actually a pretty fascinating hormone in nutritional science for the important role it plays in our physiology. Read more about how cortisol and weight gain here.

In the modern world, physical stressors have been replaced with day-to-day issues such as traffic woes, work stress, financial issues and the many demands of juggling life, work and relationships. These threats are valid enough, but hardly compare to the threat of a predator from Palaeolithic times. 

Your body continues to respond to these stressors in the same way, though, and it becomes a real problem when you’ve been marinating in high cortisol levels over a long, sustained duration. Chronic stress can wreak havoc on your body and mind(9), leading to conditions such as:

  • Anxiety
  • Depression
  • Digestive problems
  • Headaches
  • Heart disease
  • Sleep problems
  • Weight gain
  • Memory and concentration impairment
  • Lowered immunity levels and Infection(10)

We explore the relationship between stress and sleep in another article in this series and also how stress affects individuals in different ways

In the end, it seems like it’s high time we tap into the benefits of stress management practices such as better food habits, meditation and regular physical exercise to help manage stress levels and live a healthier and fuller life.