Cortisol is a hormone, often referred to as the stress hormone, that is released by the adrenal glands, which are located on top of the kidneys. It is a crucial part of the body’s response to stress and threats, and has a wide range of effects on the body.
Here’s a more detailed look at cortisol’s role and effects:
- Release: When a person experiences stress or perceives a threat, the brain sends signals that trigger the release of cortisol into the bloodstream. The hypothalamus, pituitary, and adrenal glands are key components in this process, and this system is known as the HPA axis. The process begins in the hypothalamus which releases corticotropin-releasing hormone (CRH). CRH stimulates the pituitary gland to release adrenocorticotrophic hormone (ACTH). ACTH travels to the adrenal glands and stimulates the adrenal cortex to secrete cortisol.
- Fight-or-Flight Response: Cortisol plays a central role in the fight-or-flight response, which is the body’s natural reaction to danger. This response prepares the body to either confront or escape from a perceived threat. As part of this, cortisol increases blood sugar levels, providing the body with extra energy. It also increases amino acids in the blood, which are crucial for tissue repair that may be needed during stressful situations. The body will readjust bodily functions that don’t directly contribute to success in a fight or flight situation.
- Survival: Cortisol is released to motivate action to make bad feelings stop, and commands attention until the person does something to stop it. A mammal’s brain is wired to anticipate pain and act to prevent it. The brain strives to make good decisions about investing energy because that’s a scarce resource. When energy investment fails, cortisol makes it feel like a survival threat.
- Impact on the Brain: When cortisol is released, neurons connect, making it easier for cortisol to be released the next time. Cortisol creates a sense of urgency, making people feel as if they will die if they do not do something to make it stop. When a person succeeds at relieving it, the brain is good at finding another potential threat to protect from. Cortisol can promote threat seeking behaviour. The brain can be flooded with evidence of threat, triggering more cortisol release. The brain has more neural connections going from the cortex to the eyes, meaning that it is more equipped to tell the eyes what to look for than to take in whatever comes along. Cortisol also affects the prefrontal cortex, the area of the brain associated with higher-level thinking. Too much cortisol can reduce the resources available for the prefrontal cortex to function effectively.
- Effects on the Body:
- Metabolism: Cortisol increases glucose production in the blood to supply energy. It can also promote fat build-up around the waist and hips.
- Immune System: Cortisol has an anti-inflammatory effect and can dampen immune activity to keep it within safe bounds. However, chronically elevated cortisol can impair immune function. It can also inhibit the activity of inflammatory cells involved in wound healing.
- Cardiovascular system: Cortisol increases heart rate and blood flow and brings extra oxygen and glucose to the muscles.
- Other Effects: Chronically high cortisol levels can decrease bone and muscle mass, impair memory and learning, destroy brain cells and accelerate the aging process. It is also associated with increased risk of intestinal ulcers, and osteoporosis and hip fractures. It can also disrupt sleep.
- Positive Role: Cortisol is not solely negative. Short-term stress responses and the resulting rise in cortisol can be beneficial for focus and getting things done. Cortisol is also part of the body’s natural pain management system, and it blocks pain.
- Chronic Stress: If the body is exposed to constant or prolonged stress, the body may not return to functioning normally. This can lead to chronically elevated cortisol levels which can cause a range of physical and mental health problems.
- Burnout: Over time, the stress response may not be switched off. Burnout is when stress builds up over time and one of the common symptoms associated with this condition is anxiety.
- Mental disorders: Higher levels of cortisol are associated with mental disorders, such as anxiety, depression, ADHD and PTSD. People with mental disorders may find it difficult to calm down and may show abnormalities in their brain’s grey and white matter.
- Hormonal Balance: Cortisol levels go up when negative emotions or stress are experienced and go down when positive emotions like love are felt. The ratio of cortisol to dehydroepiandrosterone (DHEA), the vitality hormone, is often considered a biological marker of stress and aging. High DHEA levels are linked to increased feelings of well-being and vitality. Reducing negative emotions will produce less cortisol and more DHEA.
In summary, cortisol is a key hormone in the body’s stress response system. While essential for immediate reactions to danger and having some benefits, chronic overproduction of cortisol can be harmful to both mental and physical health.