Cortisol is the main stress hormone. It is a natural built-in alarm system, playing a crucial role in driving and, in many cases, perpetuating the stress response.
Cortisol is released by the adrenal glands in response to a particular event or thought the brain as identified as a stressor, which activates the stress response, also known as the “fight-or-flight” response.
The hypothalamus, the ‘ruler’ sitting in our brain, tells the pituitary gland (the commandant in chief) to ready the adrenals, activating the sympathetic nervous system and triggering the stress response. This pathway is also called the HPA axis, the hypothalamus-pituitary-adrenal axis.
As the above illustration shows, the HPA axis is controlled by negative feedback producing a high concentration of stress hormones in circulation which inhibits the hypothalamus and pituitary, effectively shutting down the stress response. The state of alarm is lifted and all systems in the body return to their normal functioning.
However, under certain circumstances, stress can become chronic. Reliving traumatic experiences, rumination, anxiety (anticipatory stress), and depression can relentlessly fuel the stress response, as well as chronic infections and gut disorders (a cause and an inevitable symptom of stress. Whenever the “fight-or-flight” mode is activated, all secondary systems, including digestive capabilities are switched off), and metabolic disorders (i.e. diabetes, obesity, and cardiovascular disease).
The common factor in all these conditions is inflammation, and inflammation in itself is a stressor for the body.
Chronic stress keeps the brain on high alert, activating the HPA axis, and ordering the adrenals to produce more stress hormones.
- Dilation of the pupils
- Increased heart rate, blood pressure, and red blood cell production to supply the body with oxygenated blood and nutrients
- Reduced blood flow to the skin, visceral organs, and kidney
- Bronchodilation, to allow more airflow through the lungs
- Reduced digestive functions (e.g. decreased enzyme production and function, gut motility, and more), to divert energy to other parts of the body
- Glycogenolysis and gluconeogenesis (the breakdown of glycogen, protein, lipids, and other substances) to increase glucose levels in the circulation and available stores for tissues requiring energy
- Decreased insulin sensitivity
- Protein catabolism and amino acid mobilisation (muscle wastage)
- Decreased immune response
- Increase sweating to help cool down the body
Elevated Cortisol levels for extended periods negatively affect virtually every aspect of physiology and lead to HPA axis dysregulation (also known as adrenal fatigue, a widely used non-medical term).
As a result of cortisol, high levels of glucose remain in the circulation. At the same time, body cells shut down insulin receptors to keep blood glucose levels high (insulin is the key to opening the door to glucose). In the long-term, this may lead to insulin resistance. The pancreas has exhausted its resources by producing extreme levels of insulin to which the cells are not responding. All because cortisol is a dominant hormone, and the stress response is constantly activated.
As a dominant hormone, cortisol can also prevent the release or function of other hormones, including melatonin.
Melatonin is released in the evening as normal levels of cortisol drop and helps us fall asleep. As cortisol levels remain high, melatonin release is delayed, and people often experience a second wind around 6:00 pm and may find it difficult to quiet down and sleep. Usually, people feel “wired-and-tired.” It seems they cannot switch off and may chronically suffer from insomnia (it may take more than 30 minutes to fall asleep or may wake up several times in the night, or find it difficult to go back to sleep).
If we understand that chronic stress is a response to a beast waiting for us at the entrance of the cave where we’re hiding, it’s easy to imagine that we would only sleep with one eye opened (literally). This is how anxiety is identified by the body. It is continuously on high alert because the danger is imminent.
When the body remains on high alert, it mobilises every possible resource to provide the required energy to face or run away from danger. But, since we’re able to activate the stress response with mere thoughts, there isn’t an actual danger to run from and the energy is not used but instead is stored in adipose tissue around the waist and visceral organs. The best stores for immediate release whenever the stress response is activated (fat is sent to the liver to produce glucose). This leads to increased belly fat (apple-shaped body).
One of the biggest problems with hyperglycemia (high blood sugar) is the inevitable hypoglycemia (low blood sugar) that follows, because of the delay in insulin response. And so, we may crash, feeling extremely tired, and instinctively reach for highly calorific snacks and stimulants (e.g. caffeine and sugar). This creates a vicious cycle, also known as the ‘energy roller coaster,’ with highs and extreme lows. In itself a stressor for the body. In fact, hypoglycaemia is one of the biggest stressors in the body, forcing an immediate release of cortisol to increase blood sugar levels.
As fatigue sets in, consumption of caffeine and sugar usually increases too. It may be difficult for people to wake up in the morning and keep their energy levels stable during the day. A greater intake of caffeine also interferes with adenosine, a neurotransmitter involved in sleep (levels increase from the time we wake up until we eventually feel tired and fall asleep). Furthermore, people who have difficulties sleeping are also more likely to snack past their bedtime and exceed their daily calorie intake, which, research shows, is directly linked to obesity and diabetes, and many other health problems, including stress-related mood disorders and impaired cognitive function.
It may also go a lot deeper. Thyroid function and thyroid hormones can also be affected, leading to chronic fatigue and further weight gain. Metabolism is slowed down, all the while people feel like eating more to “boost” energy levels.
Cortisol also prevents T3 function (the active form of the thyroid hormone), by pulling the hand break in the like of reverse T3 (rT3). The aim is to preserve energy to run away from danger, and so the engine is over-revving but it’s going nowhere until there is no more fuel and all resources have been exhausted over time, and the engine stalls (e.g. adrenal exhaustion, autoimmunity, and cognitive dysfunction).
You are more and more stressed. You shun nutritious foods. You exercise less. You lose muscle mass and put on more and more weight. You sleep less and less, and snack more and more.
And the cycle continues. Until you break the cycle.
At Nutrunity UK, our mission is to help people take control of their health and blood sugar levels and give them all the tools they need to achieve their goals. Book your free online consultation (wherever you are in the world).
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