What Causes Tiredness And Fatigue?


“I’m constantly tired and fatigued”, is how you may be feeling Dear Reader. And you are asking, “why am I so tired”, or even worse, “why am I always tired”? We are going to explore in great detail as to what causes tiredness and fatigue.

The reasons for feeling tired and / or fatigued are many. They could be general, affecting the whole body, mind or soul. But tiredness or fatigue can also be caused by conditions affecting one body system or even one organ.

We will therefore divide this discussion into two articles. In this first article, we will discuss general causes of feeling tired. In the next article, which can be found (here), we will explore systems and organs of the body which can cause tiredness or fatigue.

Kindly note: these articles are for information and guidance. They cannot substitute the professional assessment of a Healthcare Worker. Tiredness and fatigue can be symptoms of serious underlying conditions, which do need to be thoroughly excluded.

Before we go deeper into this discussion, let us present items that can be acquired online. They help to treat or even prevent specified causes of tiredness. These are items that every person should have readily available, or be able to acquire easily, e.g. by clicking on the links.

DISCLOSURE: This post contains affiliate link(s). An affiliate link means the Author may earn a small commission if you make a purchase through such a link. This is at no cost to You, Esteemed Reader. Read full Disclosure Statement


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A staggering 60% of the adult human body is composed of WATER! There are variations between children and adults, men and women, etc. But at least half of our bodies should be composed of water, for a healthy existence.

All of the body’s organs contain water, at varying proportions. But importantly, the vital organs such as the heart, the lungs, the brain, the kidneys and the liver are roughly three quarters (3/4) water!

A 70kg man, who is regarded as a standard or physiological human being, contains 42 litres of water. He needs to take in 5 litres of water everyday. His almost 6 litres of blood, are made up 50% of water.

The above facts are the basis of water therapy. What is water therapy? It is the use of pure drinking water throughout the day, starting first with 1.5 litres, 45-60 minutes before Breakfast.

We need to adhere to water intake throughout the day. This is becoming ever more important because of climate change and global warming. The increasing global temperatures cause us to lose more water via the kidneys and sweat.

We also need to take more water during increased physical activity like exercise and manual work. These are activities that are essential to life, health and wealth. We must just ensure that we support them by taking 5-10% more water than our normal, physiological intake.

Water is essential to keep our organs, tissues and the cellular building blocks in a state of vitality. Water flushes toxins out of our kidneys and our guts. It keeps body surfaces moist and lubricated.

A lot of people are tired because THEY LACK WATER in their bodies. It’s as simple as that. And unfortunately, many people fail to heed the call to drink adequate pure, clean drinking water (not beverages).

Sadly, many people give all kinds of excuses for not taking (enough) water, including simple dislike of water, one of Nature’s greatest wonders! In my experience having travelled the world, the understanding of the need to drink water is most lacking in Developing Countries. And these are countries that frequently also have a shortage of water supply infrastructure.

There are ways in which we as Healthcare professionals can measure whether people have enough water in their bodies. One of them is the urine concentration (measured as Specific Gravity). The great majority of people, especially in poor countries, have concentrated to highly concentrated urine!


Tiredness, increased thirst, frequent urination and weight loss are classic symptoms of Diabetes. This disease causes a high level of sugar in your bloodstream. It is very prevalent worldwide, and increasing.

There are two types of diabetes: Type I and Type II. Type I Diabetes is from deficiency of insulin and generally presents in childhood and adolescence. Type II Diabetes is a relative deficiency of insulin, or insensitivity to it, and generally presents from the mid-forties.


This is another very common reason for people to feel tired, lethargic and fatigued. What’s anaemia? Anaemia in simple terms is called “weak blood”.

Blood has two main constituents: the watery plasma, and the thick cellular component. Anaemia results either from an overall shortage of all the constituents, or from too few of the Red Blood Cells. It can also be from dilution of the Red Blood Cells by too much relative plasma constituent.

Blood, through the Red Blood Cells, has a critical function of transporting oxygen to all parts of the body. When the blood is weak, it cannot perform this function well, and body cells are starved of oxygen. Tiredness is therefore a symptom of anaemia, as is shortness of breath.

The causes of anaemia can be divided into three broad groups:

1. Anaemia due to blood loss

This causes an Iron Deficiency Anaemia, the commonest type of anaemia globally. Iron Deficiency Anaemia can also be caused by poor absorption of iron for various reasons.

2. Anaemia due to decreased Red Blood Cell production

  • Iron Deficiency Anaemia
  • Anaemia due to folic acid deficiency
  • Anaemia due to Vitamin B12 deficiency
  • Aplastic anaemia (blood cells not being formed)
  • Anaemia of chronic disorders
  • etc

3. Anaemia due to high or rapid Red Blood Cell destruction

  • Thalassaemia
  • Sickle cell disease
  • etc

Anaemia is unfortunately very under-recognised and under detected globally. It can be picked up by a Healthcare professional through history taking, examination and a bedside, finger-prick blood test.

Treatment involves treating the anaemia according to its severity, and finding and treating the cause of the anaemia. Anaemic patients can return to full functionality and well-being.


Feelings of tiredness, low energy and hopelessness are characteristic of depression or major depressive episode. These symptoms are very common worldwide, because depression has a high annual incidence globally.

The proposed mechanism by which depression causes these symptoms, as well as the treatment of depression, are discussed in this article.


The thyroid is a gland situated at the front of our necks. It has a critical role of regulating the metabolic functions of the body. This it does by means of the thyroid hormones, T4 and T3.

The thyroid gland can and does become diseased. It may be hyperactive (hyperthyroidism), or underactive (hypothyroidism). It is hypothyroidism that we are mostly interested in, for purposes of this discussion.

In hypothyroidism, the circulating thyroid hormones are low or not potent enough. They therefore are unable to stimulate the body’s metabolic functions enough. This results in lethargy, fatigue and tiredness.

There are other symptoms and signs of hypothyroidism, that may differentiate this cause of tiredness from others. These include cold intolerance, constipation and increased menstrual flow. The thyroid gland may be swollen, the skin and hair may be coarse, and the eyebrows may be sparse.

Hypothyroidism can be detected by a Healthcare professional through history taking and examination, and confirmed by blood testing which is a bit specialised.

Hypothyroidism is, like anaemia, a potentially life-threatening condition. It can be treated by thyroid hormone replacement therapy over a period that is usually months to years. Normal functioning can be achieved, even before the thyroid hormone levels go back to perfectly normal.


Several vitamin deficiencies can cause feelings of tiredness and fatigue. But the most well-known are deficiencies of B Vitamins (hypovitaminoses B). There can be a deficiency of one type of B Vitamins, but frequently it is several of them that are low on blood testing.

B Vitamins, as discussed above, can cause weakness of blood (anaemia). This can also be caused by Vitamin C, which is essential for iron absorption. Vitamin D, acquired from sunshine, is also essential for energy.

B Vitamins, on their own right, can cause tiredness and fatigue. This is because the B Vitamins play certain critical roles in the Central Nervous System. They act as “coenzymes” to certain biochemical processes in the brain and its connections.


The minerals in the body, especially in the bloodstream, are kept at an incredibly controlled normal range. But for various reasons, that balance sometimes gets lost, and the minerals become low or high.

Trace elements are needed in minute quantities in the body. But they too must be at certain levels.

Minerals or trace elements can be low due to decreased intake or increased losses. When this happens, symptoms may begin to be felt at a certain critical level, and worsen as the levels drop further.


The above discussion of the general causes of tiredness and fatigue is not exhaustive, but covers the overwhelming majority of the causes.

To summarise the general (affecting the whole body) causes, they are:

  • insufficient water in the body
  • diabetes mellitus
  • anaemia
  • psychological factors such as depression
  • thyroid disease especially hypothyroidism
  • vitamin deficiencies
  • deficiencies of minerals and trace elements

In the next article, we will look into the SYSTEMATIC and ORGAN-SPECIFIC causes of tiredness and fatigue.


Comments, questions or indeed any contribution are very welcome. They go a long way to improving this website that is at your service, Esteemed Reader.

Kindly take a minute or so to share your thoughts on this or any other article on this website. And thanks in advance!

8 Replies to “What Causes Tiredness And Fatigue?”

  1. Hello Doctor Lekhanya, thanks for sharing I thought 2 litres was enough but now I get it. 5 litres a day that’s it.

  2. A very well researched post here. It is quite evident enough that there are enough evidential points here to value what you discussed here. Honestly, this is really great here. Thank you so much for all shared here. Really quite worthy in all. Focusing energy on gaining good health is integral. Thanks

    1. Hi Nath,

      Thanks for reading through the article and providing valuable input.

      The article is going to be expanded a little bit more!

  3. Hello Dr Teboho Lekhanya, thanks for sharing this amazing piece of information. I have to say that some of the common things that happen to us didn’t come about just getting stresses and all, some are from very Little and common things we have failed to notice and this article has really made things clearer to me. Thanks for the knowledge 

  4. Hello doctor, this is a very wonderful post on the causes of fatigue and tiredness in many people and I really think that you are right to write this because many people have always thought that it would be nice to know the reasons for the exhaustive nature that they possess. I feel elated to learn about tiredness and fatigue and all its causes too. Nice job.

    1. Hi Suz,

      Thanks for your input. Glad you found the article useful.


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