Cortisol and stress: how they affect the body

What is cortisol?

Cortisol is a steroid hormone produced by the adrenal glands. Its level changes during the day: it is highest in the morning, when you wake up, and lowest at night.

Cortisol release is a natural process, and its short-term effect is not harmful – on the contrary, it is very useful. In the body, cortisol:

• keeps blood circulation under control;
• helps you recognise danger and respond to it;
• regulates blood sugar levels;
• supports learning, cognitive processes and concentration;
• reduces inflammation and helps wounds heal.

What does chronic stress change in the body?

During stress, a rise in the stress hormones cortisol and adrenaline is a natural reaction – it helps a person protect themselves from danger. In chronic stress, however, stress hormone levels stay high all the time. This harms the body, above all the cardiovascular system, and blood pressure rises.

A person under stress becomes less physically active and tends to stay still. Insulin resistance then increases and fat builds up around the abdomen. Ultimately, insulin resistance can lead to obesity, and obesity to diabetes.

Try not to let stress lead to these consequences:

• eat a healthy, regular diet;
• go for walks and increase your physical activity;
• pay attention to your sleep routine;
• stay away from stress as much as possible.

How are stress, weight and sleep connected?

Stress is one of the most important causes of weight gain. Under stress, cortisol production increases, which makes you feel hungry more often. Fat cells in the abdominal area are especially sensitive to this hormone, so with chronic stress fat is stored mainly around the belly.

Chronic stress, tension and lack of sleep reinforce one another. When cortisol is high, the body stays tense even at night and it becomes hard to sleep well. Waking up often, falling asleep late and being unable to sleep deeply may indicate that the melatonin–cortisol rhythm is disrupted.

Poor sleep also disrupts the hunger and satiety hormones: hunger grows stronger and the feeling of fullness weakens. This can lead to increased appetite, unhealthy eating and weight gain. Cortisol also raises blood glucose – which is why stress affects blood sugar as well.

Which signs need attention?

When cortisol stays high for a long time, the following signs may appear:

• weight gain, especially around the abdomen;
• high blood pressure;
• constant fatigue and tension;
• insomnia, difficulty concentrating;
• mood swings, anxiety or low mood;
• menstrual cycle disorders;
• acne and other skin changes;
• frequent urination and excessive thirst;
• muscle weakness;
• susceptibility to infections, falling ill often.

When should cortisol be tested?

If you have had these signs for a long time, it is important to have your cortisol level checked. With this kind of fatigue, rather than taking vitamins on your own, the adrenal hormones – cortisol, ACTH, DHEA-S and others – should be tested in a laboratory.

Because cortisol levels change during the day, the timing and type of test (blood, urine or saliva, sometimes a test with medication) are chosen by the doctor. A decision should not be based on a single result.

Not only stress but also diseases can raise cortisol. The condition with high blood cortisol is Cushing’s syndrome or Cushing’s disease; the condition caused by a lack of this hormone is Addison’s disease. Both are serious and must be investigated and treated by an endocrinologist.