The effect of Stress

Stress can cause fatigue through various ways. We are happy to explain how this works. Let’s get more into stress. Is stress  always wrong? Or can stress also have a positive influence?

Many people think that stress is always wrong. That is not true. Short-term acute stress has a positive effect on your health, but long-term and chronic stress makes you sick and tired.

Most people in modern society suffer from psychological stress such as work pressure and relationship problems, but there are certainly more forms of stress.


Good to know: everything that brings the body out of balance is called a stressor.

Stress in the Prehistoric Times

In prehistoric times, heat, cold, hunger and thirst were often present. They are therefore called original stressors. They never continued for a long time (months) because people started to move towards solving the stressor. The original stressors are healthy stresses that can promote your health. Nowadays these healthy stressors are hardly present and they have been replaced by unhealthy stressors such as high work pressure, exposure to chemical toxins and the consumption of unhealthy (non-human) food. Since these new stressors are almost always present, they chronically unbalance the body.


What’s the price? Disturbances will occur in the metabolism.

For example, chronic stress leads to inflammation and can slow down thyroid function. What’s the sequel? A shortage of energy, so fatigue.


But how exactly does this work?

Stress makes your digestion system  "permeable".

In evolution, stress has always been the result of danger. In the end, only one thing was really important: survival. During this stress situation the body has an increased need for sugar, salt and water.


How does the body take care of this in case of stress? By making your intestines more permeable during stress. These substances sugar, salt and water can then be quickly and easily absorbed into the blood from the intestines via the so called small “holes” in the intestines. Via the blood these substances not only go to the muscles, but also to the brain. It allows you to make the right choices (with your brain) and take adequate action, so fight and flight (with your muscles).


The effect of stress on your intestines (ie making the intestines permeable) is a normal healthy response. This is no problem at all with short-term acute stress. The bowel recovers and the cavities close when the stress is resolved and gone.


When is it a problem? You already feel it coming: with long-term chronic stress.

Chronic stress makes you tired

During chronic stress, the intestine is permeable for a long time. In addition to sugar, fresh water and water, unwanted substances such as toxins and pathogens also leak into the system. Again with acute stress this is not a problem, but with chronic stress the leakage of these unwanted substances is a burden on your immune system. The immune system sees these unwanted substances as intruders and wants to make them harmless. It does this with an inflammatory response of the immune system.


But what has this to do with fatigue?

An active immune system uses a lot of energy. During the day the immune system should be calm and only at night it should be quite active. This has to do with the energy distribution in the body. The brain, muscles and the immune system cannot all be active at the same time (and thus receive energy), this is at the expense of the supply of energy to the other systems.


An example:

In chronic stress, the immune system is not only active at night, but also during the day. Normally, energy goes to the brain and muscles during the day. If the immune system is also very active during the day, then the immune system demands all the energy. The energy supply to the immune system always takes precedence over the brain and muscles because the immune system needs enough energy to protect you against pathogens.


What is consequence? Indeed, a lack of energy in the brain and muscles. This leads to mental and physical fatigue. A lack of energy in the brain can also lead to sleeping problems. And if you don’t sleep well, you get more and more tired.


Stress hormones can also directly disrupt sleep.

Cortisol counteracts the production of sleep hormone.

In chronic stress, the production of the stress hormone cortisol initially increases. Cortisol is the counterpart of the sleep hormone melatonin. Normally, the cortisol level is high in the morning and decreases during the day. The opposite is true for melatonin. In the morning, the melatonin level is low and increases during the day. It should be high in the evening.


When the cortisol level does not drop sufficiently in the evening, the effect of melatonin is counteracted. This leads to sleep problems and then to fatigue.


This is not all, a shortage of cortisol can also make you tired.

Reduced cortisol production leads to morning fatigue

Normally, a cortisol peak occurs early in the morning. This is called the Coristol Awakening Response (CAR). It ensures that you wake up quickly being clear and ready for the day.


When you are chronically stressed, the cortisol production can decrease at a certain point, so that you no longer have a cortisol peak in the morning. Because of this you do not wake up by yourself (but through your alarm clock) and you do not become fresh and clear minded. You stay tired in the morning and need coffee to wake up.

What do I have to remember?

Chronic stress can lead to an energy shortage in various ways, namely through:

• Activation of the Immune System

• Counteract the effect of the sleep hormone melatonin

• Reducing morning cortisol production (CAR)


  • De Punder, K. & Pruimboom, L (2015) stress induces endotoxemi and low grade inflammation by increasing barrier permeability. Frontiers in immunology, 6, 223
  • Richard de Leth, Oersterk, April 2021