Why You Should Care About Your HPA Axis (and Find More Contentment)

by Ram

Taking Flight by Marie Lossky
(@Marie.Lossky on Instagram)

Recall the time when you were extremely irritable, anxious, moody, or facing some severe emotional upheaval. It was so severe that that all you wanted to do was drop everything and head to a quiet place that was far, far away from family, work, friends, etc. All you were looking for was some quietness and peace. Now if you wish to understand the cause or point fingers at something, you can blame it on your HPA axis. 

The HPA (hypothalamic–pituitary–adrenal) axis is a complex network of cellular interactions that trigger numerous biochemical responses and involves three main endocrine glands: the hypothalamus (aka the master gland), the pituitary gland (a pea-shaped structure located below the hypothalamus), and the adrenal glands (small organs on top of the kidneys). The physiological role of the HPA axis and the hormones associated with it are very fundamental, and similar systems exist in lower organisms as well. The hormones regulated by the HPA axis include: 

1. Vasopressin and Corticotropin Releasing Hormone (CRH). These are produced and secreted by the hypothalamus in response to either physical or psychological stress. While vasopressin controls water metabolism through its action on the kidneys, CRH regulates appetite, attention, and feelings of anxiety. Furthermore, it regulates the secretion of Adrenocorticotropic Hormone (ACTH).
2. Adrenocorticotropic Hormone (ACTH). This is released by the pituitary gland, and stimulates the adrenal glands to increase production of Glucocorticoids.
3. Glucocorticoid. These are a class of corticosteroids that regulate glucose metabolism and the immune system. Cortisol (or hydrocortisone) is the most important human glucocorticoid.
4. Cortisol. This is released in response to stress and low blood-glucose concentration, and regulates blood sugar, the immune system, and the metabolism of fat, protein, and carbohydrates. Cortisol also activates the body’s response to stress, injury, sleep deprivation, physical exhaustion, and anxiety. Low levels of the hormone has beneficial effects, such as protecting the body from stressful situations, providing more energy, increasing physical and mental performance, and memory recall. However, sustained high levels of cortisol can have deleterious effects. 

In short, the HPA axis coordinates effectively to modulate the stress response. Additionally, the HPA axis via all the above-mentioned hormones regulates other bodily processes, including digestion, mood, emotions, libido, metabolism, energy, and the immune system. So it appears that nearly all of the body’s physiological reactions and mental status are controlled by all of the above-mentioned hormones that are in turn regulated by the HPA axis. Each component of the HPA axis also has a negative feedback operation to keep the entire system in balance. Thus, any time there is an elevation/reduction in the levels of cortisol, this triggers the feedback loop to increase/reduce the output of CRH, which in turn raises/lowers the levels of ACTH and cortisol.

So when we define a person being a “yogi” or an individual existing in a state of equanimity (see 7 Ways to Cultivate Equanimity with Yoga), we are referring to those people whose HPA axis with its feedback loop works in a state of harmony. Any disturbance in this cycle or the feedback loop system and we are in an acute or chronic state of emotional turbulence. If the HPA axis is underactive, it results in a low production of the hormones, resulting in poor metabolism and brain function. Or, take the situation where an individual is facing a physical/emotional crisis, characterized by over production of cortisol. If the crisis is chronic, the sustained over-production of cortisol eventually desensitizes the HPA axis so it no longer responds to the feedback loop by “calming down.” In a chronically anxious or stressed state, we don’t give the HPA axis time to reset itself back to state of equilibrium, and as a result we get stuck in the sympathetic nervous system overdrive mode. A combination of the desensitized HPA axis and overdrive of the sympathetic nervous system triggers several diseases, including but not limited to abnormal moods, emotional upheaval, chronic fatigue, depression, OCD, multiple sclerosis, and thyroid abnormalities. 

Older individuals are more susceptible to a dysfunctional HPA axis and adverse effects of an elevated cortisol because of the poor functioning of the feedback system. Furthermore, a sustained over-activation of the HPA axis also causes destruction to the brain and body owing to elevated levels of cortisol. Hence, an elevated cortisol level in older adults is dangerous, as it can trigger mental or behavioral probles, as well as other physical problems (Reducing Cortisol Improves Anxiety). Thus, understanding the status of the HPA axis will help us to control our emotions and knee-jerk reactions, and bring ourselves back into a more relaxed state of mind and equanimity (see It's Complicated: Moving Toward Equanimity). 

There are several ways to reset the HPA axis and improve at all levels. Gentle physical exercises, being out in nature, proper sleep, and a nourishing diet are some of the practices that balance the body and mind thereby providing an overall sense of wellness. Additionally if you have a yoga and meditation practice, this helps as well in curbing the negative effects of the HPA axis (see Reducing Cellular Stress with Yoga). Yoga and mindfulness-meditation offer several benefits:

• Decreases in stress and anxiety
• Improvement in cognitive functioning and cardiovascular health
• Reduction in cortisol levels
• Reduction in pro-inflammatory molecules
• Decrease in systolic blood pressure

(See Mindfulness-Based Stress Reduction for Low-Income, Predominantly African American Women With PTSD and a History of Intimate Partner Violence.) Additionally, according to Rapid stress reduction and anxiolysis among distressed women as a consequence of a three-month intensive yoga program, stressed individuals who practiced yoga and mindfulness reported better sleep, were more attentive and experienced reduced trauma. 

Researchers hypothesize that yoga and mindfulness stimulate the relaxation response and reset the HPA axis by altering cerebral blood flow and improving endothelial function that in turn lowers inflammation. The relaxation induced from yoga and mindfulness may also stimulate the production of endogenous opiates and cannabinoids that not only trigger the feel-good response but also stabilize the mood. In short, a daily practice of yoga and mindfulness will not only stabilize your HPA axis but also bring with it contentment, a sense of accomplishment, and improved health. Time to roll out your yoga mat!

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