Cortisol is often referred to as the stress hormone, but its role extends far beyond that. In this article, we will explore what cortisol is, examine its key functions, and then look at the causes and consequences of both excess and deficiency.
What Is Cortisol?
Often labeled as the “stress hormone”, cortisol is a steroid hormone produced by the adrenal gland. It plays a crucial role in regulating numerous vital processes within the body.
Hormones are often compared to messengers that can influence our health, as well as our physiology and cellular metabolism. Their production is carefully controlled by the body, as any imbalance—whether an excess or a deficiency—can lead to potentially serious disorders.
More specifically, cortisol production is continuously regulated by the hypothalamic-pituitary-adrenal (HPA) axis.
It follows a circadian rhythm, fluctuating throughout the day. Cortisol levels peak early in the morning (around 8 AM) and reach their lowest between midnight and 4 AM, typically three to five hours after falling asleep.
How Is Cortisol Produced in the Body?
Its production relies on three key players in the brain. Let’s take a closer look:
The first is the hypothalamus, a pea-sized region of the brain that releases a substance known as CRH (corticotropin-releasing hormone), which stimulates another part of the brain.
CRH then activates the pituitary gland, which in turn produces ACTH (adrenocorticotropic hormone).
ACTH signals the adrenal cortex to produce cortisol. The body carefully regulates cortisol levels—when cortisol levels drop, CRH and ACTH increase to stimulate production, and when cortisol levels are too high, their release decreases.
While excessive cortisol is widely known to be harmful, it is equally important to recognize that insufficient cortisol production can also have negative effects on the body.
What Are the Functions of Cortisol?
Cortisol plays several essential roles in maintaining overall homeostasis, meaning the general balance of our body. Let’s take a closer look at its functions.
Regulates Blood Sugar Levels
During fasting conditions, cortisol helps increase blood sugar levels while limiting glucose consumption—likely prioritizing the nervous system—by reducing peripheral uptake through insulin resistance.
Suppresses Immune System Activity
Cortisol can suppress immune system activity, making it particularly useful in reducing inflammation. In fact, this is why cortisone (hydrocortisone) is known as a powerful anti-inflammatory.
Regulates Fat Metabolism and Promotes Storage
Cortisol plays a role in fat storage, favoring its accumulation. This is one of the reasons why people often say that stress can lead to weight gain.
Additionally, cortisol regulates fat and protein metabolism. Excessively high and prolonged levels can reduce muscle absorption of amino acids, stimulate protein breakdown in tissues, and inhibit protein synthesis.
Inhibits Bone Formation and Collagen Synthesis
Cortisol appears to inhibit bone formation and collagen synthesis. This explains why cortisone treatments and hypercortisolism can lead to various bone issues, such as osteoporosis and tissue degeneration.
Influences Mineral Absorption
Finally, cortisol increases sodium and water absorption in the intestines while enhancing potassium excretion.
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Excess and Deficiency of Cortisol
Under normal conditions, cortisol levels are low in the evening and rise in the morning, although this can vary depending on an individual's lifestyle. Peaking in the morning, cortisol gradually decreases throughout the afternoon, reaching its lowest levels in the evening.
Around 8 AM, cortisol levels typically range between 50 and 200 ng/ml. By evening, these values are cut in half.
Potential Causes of Excess Cortisol
Several factors, such as chronic stress, can lead to elevated cortisol levels. In severe and persistent cases, this condition is known as hypercortisolism and can be triggered by multiple factors, including:
- Chronic stress, severe trauma, or prolonged exposure to stressful events
- Viral infections, due to HPA axis activation by cytokines
- Excessive caffeine intake
- Prolonged sleep deprivation
- Intense, transient aerobic exercise (high VO2 max) or prolonged physical activity, which promotes gluconeogenesis and glycemic stability; however, cortisol levels decrease after a meal
- Genetic predispositions and mutations
- Cortisone regeneration in adipose tissue
- Anorexia nervosa
- Excessive alcohol consumption
Why Is Excess Cortisol Harmful?
The body's response to stressful situations triggers a rise in cortisol levels. However, when stress becomes chronic, cortisol activity tends to "stabilize".
In people experiencing chronic stress, the body's circadian rhythm of cortisol production is altered. Instead of peaking in the morning and declining throughout the day, those under prolonged stress often experience a dip in cortisol levels in the morning and a spike in the evening, the opposite of a normal pattern.
Additionally, prolonged stress can lead to cortisol resistance, which prevents it from effectively performing its anti-inflammatory function. This means that although there may be an excess of circulating cortisol, its effectiveness is reduced.
Over time, this condition inevitably leads to various negative effects, such as:
- Reduced collagen synthesis
- Weakened immune defenses
- Chronic fatigue
One of the most significant consequences of hypercortisolism, which should not be overlooked, is difficulty sleeping.
Normally, cortisol levels drop at night, allowing the body to relax and recharge. However, as we have seen, excessive cortisol levels in the evening can disrupt the sleep cycle, making it harder to fall asleep.
As a result, even when feeling exhausted, falling asleep becomes difficult, leading to fatigue the next morning. This is due not only to lack of sleep but also to abnormally low cortisol levels in the morning.
What Factors Reduce Cortisol?
There are several ways to lower cortisol levels. Below, we provide a list of activities along with dietary supplements that have been shown to regulate cortisol levels, as well as certain anxiolytic plants and compounds.
- Post-endurance exercise, magnesium supplementation helps lower serum cortisol levels.
- Omega-3 fatty acids: Fish oil, particularly krill oil, due to its high content of omega-3s (eicosapentaenoic and docosahexaenoic acids).
- Relaxation activities such as massage, music therapy, and meditation.
- Ashwagandha: A plant native to India that helps lower cortisol levels in the body.
- High doses of ascorbic acid (liposomal vitamin C) reduce circulating cortisol levels during and immediately after treatment.
Cortisol Deficiency
Low cortisol levels can result from various factors, including adrenal insufficiency (both primary and secondary), Addison’s disease, Hashimoto’s thyroiditis, tuberculosis, or adrenal fatigue.
Key symptoms of cortisol deficiency include:
- Increased weakness and fatigue
- Muscle pain
- Low blood pressure, dizziness, and fainting
- Significant weight loss
- Abdominal pain, diarrhea, or constipation
- Difficulty concentrating
- Irritability
- Nausea and vomiting
- Anxiety
- Apathy
- Hypoglycemia
- Dehydration
- Skin hyperpigmentation
- Hair loss
Conclusion
Cortisol plays a crucial role in the body, making it essential to maintain balanced blood levels. While our body usually regulates cortisol naturally, prolonged exposure to chronic stress can disrupt these levels, leading to harmful consequences. Fortunately, there are effective ways to rebalance cortisol, including relaxation techniques, a healthy diet, quality sleep, and targeted dietary supplements.
References :
- Lauren Thau, Jayashree Gandhi, Sandeep Sharma - Physiology, Cortisol - StatPearls - August 29, 2022
- Mary J. Allen, Sandeep Sharma - Physiology, Adrenocorticotropic Hormone (ACTH) - StatPearls - August 15, 2022
- Carol Jones and Christopher Gwenincorresponding - Cortisol level dysregulation and its prevalence—Is it nature's alarm clock ? - Physiol Rep. 2021 Jan; 8(24): e14644.
- Do Yup Lee, Eosu Kim, and Man Ho Choi - Technical and clinical aspects of cortisol as a biochemical marker of chronic stress - BMB Rep - 2015 Apr; 48(4): 209–216.
- Lindsay T. Hoyt, Katharine H. Zeiders, Katherine B. Ehrlich and Emma K. Adam - Positive upshots of cortisol in everyday life - Emotion - 2016 Jun; 16(4): 431–435
- Bhardwaj Nikunaj, Mishra Nishant Kumar, Bhardwaj Divye - Impact of Preconception Paternal Stress on Offspring - Invertis Journal of Science & Technology ; 2018, Volume : 11, Issue : 3