One of the ills of our time has a name that many know all too well: stress. Caused by work, family obligations, and the frenetic pace of modern life, it's everywhere. But did you know that behind it lies a key hormone: cortisol? Nicknamed the "stress hormone," cortisol plays an essential role in our survival by helping us react to difficult situations. However, when produced in excess or over a long period, it can become a veritable silent poison for our body and mind. Sleep disorders, weight gain, a weakened immune system… the effects of poorly managed cortisol are numerous and insidious. So, how can we control this hormone to preserve our well-being? Let's discover together the keys to good cortisol management so that stress is no longer an invisible enemy, but a controlled ally.
What is cortisol?
Cortisol is a hormone secreted by the adrenal glands from cholesterol . Its secretion follows a circadian rhythm with a peak early in the morning, between 6 and 8 a.m., and a gradual decrease throughout the day to become almost zero in the middle of the night.
Cortisol plays a pivotal role in many physiological processes:
Immune function and inflammation : it is capable of inhibiting certain immune system responses and it has anti-inflammatory effects.
Glucose metabolism : it helps maintain blood glucose levels by increasing gluconeogenesis (glucose synthesis by the liver) and insulin resistance.
Lipid and protein metabolism : it stimulates the breakdown of proteins and fats in most tissues (excluding the nervous system).
The cardiovascular system : it regulates blood pressure and vascular tone, causes vasoconstriction and increases cardiac output.
The urinary system : it has a diuretic effect.
Brain and neuromuscular function : it promotes wakefulness, alertness, motivation and can also influence cognition.
The digestive system : it can affect the microbiota, intestinal transit time and permeability, as well as nutrient availability.
Another role of cortisol is to cope with stress :
During stress, the HPA (Hypothalamic-Pituitary-Adrenal) axis is activated. The hypothalamus then stimulates the pituitary gland, which in turn stimulates the adrenal glands responsible for cortisol secretion. This cortisol then acts on various target organs while exerting what is called "feedback control" to regulate its release. Simply put: by binding to receptors, it sends the information to the hypothalamus and pituitary gland that there is a sufficient quantity to have an effect. They then stop activating its secretion.
Legend: CRH (Corticotropin-releasing hormone); ACTH (Adrenocorticotropic hormone)
In critical moments, the body needs immediate energy for its survival . This mobilization of energy is accompanied by the suppression of long-term processes not essential to this immediate survival , for example digestion, growth, reproduction and the immune system.
Stress, perceived as a threat, triggers the release of catecholamines (adrenaline and noradrenaline) and cortisol . Cortisol has a powerful anti-inflammatory effect and mobilizes glucose to promote survival and motivate success. It also plays a role in consolidating fear-based memories, thus promoting avoidance of future threats.
According to Hans Selye's model , when faced with a stressful situation, several stages follow one another:
Step 1: The alarm phase
The body's first reaction is to secrete adrenaline. This molecule helps the body respond to what is interpreted as an attack. As a result, glucose is released into the bloodstream, and the heart and breathing rate increase to optimize the supply of sugar and oxygen to the muscles, thus converting sugar into energy: the body is ready to mobilize, and the fight-or-flight response becomes possible. This binary choice in the face of stress, and all the metabolic reactions that precede it, have their origins in the time when humans had to fight for their survival and their primary concerns were eating and not being eaten.
Step 2: The resistance phase
This process begins after a few minutes when the stressful situation persists. The body will then try to adapt to the situation and ensure a sufficient energy supply to cope. It is at this point that cortisol will be released and play its role. It will be accompanied by other hormones such as endorphins, dopamine, and serotonin.
In general, the situation returns to normal, the body regains its equilibrium and resumes a natural metabolism, but in the case of chronic stress and therefore repeated or continuous exposure, a third phase appears:
Step 3: The exhaustion phase
By constantly secreting stress hormones and maintaining a high energy expenditure, the body will simply become exhausted. Its resources become insufficient, and this final phase will lead to fatigue and a weakened immune system, as well as increasing the risk of developing conditions such as hypertension, type 2 diabetes, asthma, or depression.
Cortisol therefore plays a crucial role in the body's stress response by enabling it to cope and maintain internal balance , but if it is secreted in excess , in the context of chronic stress for example, it can become harmful to health .
Cortisol and civilizational stress
As we mentioned, our bodies are programmed to react to stress in two ways: fight or flight . However, nowadays , work overload, relationship difficulties, and financial problems have replaced predators as stressors. Most of the time, fighting or fleeing in these situations is, or seems to be, impossible . The situations persist, and the stress continues. Cortisol is released and regulates its secretion via negative feedback to maintain an effective level, until the receptors to which cortisol binds become fatigued from overuse and refuse to bind it. Consequently, the information no longer reaches the hypothalamus or pituitary gland, which can no longer determine if cortisol secretion is sufficient. The stressor, however, remains; the HPA axis is still stimulated. Cortisol therefore continues to be released, again and again, resulting in widespread inflammation (the body becoming less sensitive to its anti-inflammatory effects) which can lead to, among other things, pain, depression, persistent fatigue, sleep disturbances and a decrease in immune defenses.
How to take action for a better balance
The best way to address cortisol dysregulation is to address chronic stress . Several complementary approaches can reduce its impact:
Relaxation:
To better manage emotions, practicing activities such as meditation , yoga , or breathing exercises (like heart coherence) can be beneficial. These activities all share the common goal of refocusing attention on the body and its sensations, thus shifting the focus away from sources of stress and improving well-being. Initial results on mindfulness meditation, for example, show a decrease in blood pressure, insulin resistance, and inflammation, as well as improvements in blood sugar and lipid levels. All of these physiological effects contribute to better health.
Physical activity:
It reduces sympathetic hyperactivity and activates the parasympathetic nervous system , decreases inflammatory processes in the brain, and enhances cognitive abilities and memory processes impaired by stress. It improves mood by promoting the secretion of dopamine, serotonin, and endorphins . All these mechanisms lead to numerous benefits for mental health, including stress reduction and increased resilience, decreased fatigue, and improved sleep quality, making physical activity (when not practiced excessively) a cornerstone for better stress management and, more generally, for good health.
Food:
Some studies have highlighted a link between diet quality and the presence of stress, anxiety, and depression. Frequent consumption of processed foods (very low in vitamins and high in sugar, particularly fructose, which is responsible for inflammation, intestinal dysbiosis, and insulin resistance, leading to mood disorders and anxiety) or excessive consumption of meat and processed meats has been associated with a higher risk of stress. Similarly, while sugar consumption may provide initial relief, it should be limited. The detrimental impact of fructose, in particular, which is found in abundance in processed foods, on anxiety has been studied. Therefore, a diet rich in vitamins and minerals (fruits and vegetables, a small portion of raw food at the beginning of meals, steaming, etc.) and omega-3 fatty acids (small oily fish; eggs from hens fed flaxseed; vegetable oils such as rapeseed; nuts and seeds) is recommended.
Managing one's energy:
Often, feelings of stress and anxiety result from poor energy management. We want to do everything well and quickly, neglecting moments of rest and recovery. Sleep is when the body and mind recover the most , so it's essential to take care of it, but we shouldn't stop there. A walk in nature, a creative activity, a massage, a bath, or a simple nap —it's also important to take these short breaks, even if it means scheduling them as we would our usual activities . Similarly, it's beneficial to incorporate short breaks during our work sessions . The Pomodoro Technique, which involves focusing on your work for 25 minutes, then taking a 5- to 10-minute break, and repeating the process, then taking a longer 20- to 25-minute break after two hours of work, can be a useful approach, but everyone is free to find the technique that works best for them.
Cortisol plays a vital role in our bodies and our ability to cope with stressful situations. However, when produced in excess over a prolonged period, it can become a silent poison, disrupting our physical and mental balance. By understanding how cortisol influences our body and mind, we can better manage its negative effects. A balanced diet, appropriate physical activity, relaxation techniques, and good sleep are all key to restoring hormonal balance and better managing daily stress. So, rather than simply suffering the effects of stress, let's adopt sustainable habits now to strengthen our long-term health!
Sources:
https://www.fedecardio.org/je-m-informe/reconnaitre-les-differentes-formes-de-stress/
https://fr.wikipedia.org/wiki/Hans_Selye
https://www.greenplantation.fr/a/consequences-negatives-de-la-reactivation-de-l-axe-hpa-et-de-la-cafeine-en-tant-que-regulateur-de-cet-axe )
https://www.sciencedirect.com/science/article/abs/pii/S1261694X23002870
https://hal.univ-lorraine.fr/hal-01947127
https://presse.inserm.fr/omega-3-et-gestion-du-stress-les-liens-se-resserrent/24627/
https://www.ncbi.nlm.nih.gov/books/NBK507250/
https://fr.wikipedia.org/wiki/Technique_Pomodoro
