HPA Axis – Adrenal Fatigue – what’s going on?

What is HPA Axis Dysregulation?

You may be familiar with the term “Adrenal Fatigue” and it probably conjures up images of a state of total physical and mental exhaustion as a result of exposure to high cortisol, one of our stress hormones.  However, the picture is a little more complicated and in this blog I hope to give you a better understanding of what is going on in the body and the mind.

When tests are carried out for Adrenal Fatigue it is most common to see spikes of the hormone cortisol.  Even when cortisol is low, it’s not necessarily due to the adrenals being “fatigued” or ‘exhausted’ and unable to produce the hormone.

We know there are many other mechanisms for regulating cortisol production including in the brain and central nervous system.  Regulation of inflammation and blood sugar dysregulation are other issues that need to be addressed when considering the body’s response to stress.

HPA Axis dysregulation (HPA-D) is the scientific term for Adrenal Fatigue.  The HPA refers to ‘hypothalamic-pituitary-adrenal’ indicating the parts of the body that are involved: the hypothalamus is the part of the brain that is responsible for many essential hormones; the pituitary is known as the master gland as it produces hormones that control other glands; and the adrenals are glands that produce many different hormones including our sex hormones.

HPA-D refers to a myriad of signs and symptoms that include extreme fatigue, sleep disruption, inability to perform exercise and slow recovery from exercise – often associated with extreme muscle pain and exhaustion, low libido, brain fog and inability to concentrate, a weakened immune system and inability to cope with stress.

HPA-D is caused by many different factors in our modern lifestyle.  These can include a low nutrient-dense diet, sleep deprivation, chronic stress, lack of exercise (or too much), and general inflammation.

HPA-D affects virtually all cells and tissues in our bodies which contributes to the many and varied symptoms individuals experience.

What triggers HPA-D?  

There are four primary triggers of HPA-D, listed below.

1.    Perceived Stress. There are four root causes that determine HPA response (stress). NUTS is an often-used acronym for this.

  • Novelty of the event 
- new situations can increase stress
  • Unpredictability – when things change frequently and we feel outside our comfort zone
  • Perceived Threat to body or ego – things that make us lose face, embarrass us, or threaten us physically
  • Sense of loss of control – When we feel that we have no control over a situation

So perceived stress could include work, relationships, money, anxiety, panic attacks and other neurological problems.  Psychological stress is considered to be more harmful because it tends to last longer and there is a feeling of being out of control.

2.     Circadian Disruption – our Circadian rhythms are physical, mental and behavioural changes that follow a roughly 24-hour cycle, responding primarily to light and darkness.  The HPA axis and circadian rhythm are closely associated and have the ability to profoundly impact one another.

  • Sleep deprivation, artificial light exposure (blue light from hand held devices), night-time light exposure, not getting enough exposure to natural light during the day, jet lag, shift work, caffeine, alcohol, recreational drugs.

3.     Blood sugar imbalance. There’s a direct relationship between the HPA axis and body processes, so a disruption of one will harm the other.

  • Diet lacking in nutrients, poor sleep, and lack of exercise.
  • Visceral fat (hidden fat around the organs) caused by elevated cortisol, which triggers inflammatory 
  • Hypoglycemia (low blood glucose) leads to HPA axis activation,  and can also cause 
increased cortisol.

4.     Inflammation. Cortisol exerts a powerful anti-inflammatory in the body so acute or chronic inflammation 
triggers the HPA axis and increases cortisol.

Trigger Effect
Exercise Overtraining initially increases cortisol but may then cause chronicallylow cortisol.
Being sedentary can lead to sleep disorders and contribute to metabolic dysfunction.
Social Isolation Social support (family, friends, community) lessens the impact of stress.Lack of social support is a major stressor and has been shown to reduce lifespan.
Gut Issues There are multiple Gut-HPA interactions:
Intestinal permeability (leaky gutSyndrome) is often caused by chronic exposure to stress, leading to HPA activation.Beneficial bacteria play a role in regulating the HPA axis.
Food Intolerances Induce intestinal permeability and may cause inflammation throughout the body.
Chronic Infection Increases inflammation.
Environmental Toxins Wide range of effects, including endocrine disruption and oxidative stress.
Thyroid Function Hypothyroidism (low thyroid function) increases cortisol levels.
Drugs (caffeine, antidepressants, steroids, etc.) Dysregulate the HPA axis in multiple ways.

Long term exposure to stress can have a huge impact on many areas of an individual’s health and is not easily resolved in a short time period.

As well as making changes to the diet and nutritional status – by ensuring a nutrient dense diet including healthy fats, proteins and fibre and reducing exposure to refined, processed and high sugar foods – it is important to make changes to lifestyle and habitual behaviours.

HPA axis dysfunction can be a risk factor for many health conditions including cardiovascular health, insulin resistance, diabetes and poor immune function so needs to be addressed for the long term health of the individual.



Ref: Chris Kresser

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