What is stress from a physiological perspective

Stress is the body's natural response to any challenge or change in the environment. When the brain receives a signal of a potential threat - physical or psychological - the HPA (hypothalamic-pituitary-adrenal) axis is activated. As a result of this reaction, the body mobilises resources for action, resulting in, among other things, an accelerated heart rate, increased blood pressure and increased muscle tension. Thus prepared, the body is ready to face a threat or escape from a dangerous situation as quickly as possible - a phenomenon known colloquially as the 'fight or flight' response.

The environmental factors causing this reaction are called stressors. These can be noises, aggressive behaviour, a fast moving car or even a first date. Usually, the more stressors, the stronger the feeling of stress.

According to the American Psychological Association's (APA) 2018 annual stress survey, the average stress level in the United States was 4.9 on a scale of one to 10. The survey found that the most common stressors were employment and financial issues.

The stress hormone

Under stress, the body releases certain hormones that act as chemical signals instructing individual systems what to do. The main stress hormone is cortisol. Under normal circumstances, its levels fluctuate throughout the day, with the highest in the morning and the lowest in the evening, allowing us to get up and go to sleep without any problems. However, in stressful situations, especially those of long duration, the adrenal glands produce excessive amounts of cortisol, leading to a number of adverse symptoms. Excessive cortisol levels are associated with, among other things, sleep problems, excessive fat accumulation in the abdominal area and a weakened immune system.

Impact on the immune system

Short-term stress can have a mobilising effect, helping to overcome sudden challenges. However, when stress becomes chronic, the body remains in a state of constant alertness, which over time leads to negative health consequences, including a weakened immune system. Chronic stress particularly affects:

• Excess cortisol: Reduces the effectiveness against viruses, bacteria and other pathogens.
• Increased inflammation: Stress contributes to an increase in pro-inflammatory cytokines, which in the long term can increase the risk of chronic diseases, including autoimmune diseases.
• Changes in the gut microbiota: Stress affects hormonal balance and nervous system function, which affects the balance of gut bacteria. An imbalance of the microbiota can lead to greater susceptibility to infections or digestive problems.

Positive vs. negative stress

Not all stress is harmful. In small doses, it can have a motivational and protective function. Such brief, intense stress, known as eustress, mobilises the body, increases concentration, boosts energy and improves the ability to cope with challenges.

As opposed to eustress, distres is a form of chronic stress that negatively affects health. Chronic stress weakens the body, leading to constant fatigue, sleep problems, irritability and even the occurrence of depressive states.

Simple ways to reduce stress

1. Ensure a restorative night's sleep: Adequate length and quality of sleep are fundamental in regulating cortisol levels.
2. Find your favourite form of exercise: Regular physical activity (e.g. walking, running, yoga) helps to lower cortisol levels and supports immune system function.
3. Introduce relaxation techniques: breathing exercises and meditation effectively calm the nervous system.
4. Support your gut microbiota: A balanced diet rich in vegetables, fruit, fibre and probiotics (e.g. pickles) supports the immune system and alleviates the effects of stress.
5. Say stop: sometimes it is worth saying no to extra duties or tasks to avoid mental overload.

Summary

Stress is not just an emotional state - it is first and foremost a powerful physiological response that involves our entire body and affects virtually every organ. Long-term stress, exacerbated by persistently high cortisol levels, not only weakens the immune system, but also increases the risk of chronic diseases. This is why it is so important to learn to recognise the symptoms of stress and implement strategies to help reduce it.