Fatigue generally refers to the feeling of tiredness and low energy. A fatigued person lacks the motivation to carry out daily activities, feels excessively sleepy and has a persistent, unexplained exhaustion. Even when one has had sufficient sleep, they still wake up not feeling refreshed. Fatigue is often a symptom of other health conditions, especially sleep disorders such as narcolepsy, hypersomnia, insomnia, and excessive daytime sleepiness. It can also be caused by medical conditions such as depression, allergic rhinitis, anemia, and obesity. The condition is treated by addressing the underlying health factors that may be causing it.


Fatigue is unexplained tiredness that is constant and affects a person’s daily activities. Its symptoms are commonly similar to those of a cold or flu. The individual feels drained even after having had enough sleep. The common characteristics of fatigue are:

    • Tiredness
  •          Sleepiness
  •         Low energy
  •          Lack of motivation
  •         Non-restorative sleep
  •         Shortness of breath
  •         Muscle weakness
  •         Irritability
  •          Impaired thinking

Types of fatigue

Fatigue is categorized into three categories, based on the areas of the body that it affects.

1.     Physical Fatigue

Physical fatigue affects the muscles making it difficult for a person to engage in physical activity for a long period of time.

2.     Mental Fatigue

Mental fatigue affects the brain, thus affecting a person’s productivity and cognitive function. This condition is often referred to as burnout.

3.     Metabolic Fatigue

Metabolic fatigue occurs during intense exercise when the substrates needed for the generation of ATP are depleted. The metabolic by-products also accumulate in the muscles causing fatigue.

Causes of fatigue

Fatigue is often associated with medical conditions such as:

1.     Chronic fatigue syndrome (CFS)

The Chronic Fatigue Syndrome is a disorder that causes severe fatigue, weakness, poor memory, low levels of concentration, insomnia, and muscle pain. The condition is persistent and lasts for over six months. People with CFS experience unexplainable tiredness that affects their normal activities. The causes of the condition are usually unknown and it is treated by addressing the symptoms.

2.     Allergies

Allergies are signs of the immune system responding to substances in the environment that may or may not be harmful to the body. They are common in the general population and can be triggered by different agents in the environment, such as pollen, molds, insects, and weather conditions. Allergies can cause fatigue by either affecting a person’s sleep patterns or causing the release of chemicals that lead to tiredness. Avoiding allergens and using medications can help prevent the occurrence of these symptoms.

3.     Depression

Fatigue is commonly associated with depression. A depressed person will feel sad, hopeless, and tired. The person lacks motivation, thus has little or no interest in normal activities. They experience unexplained exhaustion most of the time. The person also finds it difficult to fall asleep at night, thus suffers from insomnia. They are, therefore, exhausted during the day because of a lack of sleep.

4.     Cardiovascular disease

Some heart illnesses may cause this vital organ to fail in its blood pumping actions causing erratic blood supply to some organs. People who suffer from heart disease can get tired very quickly, even when performing easy tasks. They lack the energy to carry out simple activities, such as walking up a flight of stairs. They require to rest frequently and experience labored breathing when carrying out tasks.

5.     Rheumatoid arthritis

Rheumatoid arthritis is an inflammatory disorder that causes joint damage. It is characterized by painful, swollen joints, bone erosion, and deformity. The condition can also affect other parts of the body, including the heart, blood vessels, and lungs. People who have rheumatoid arthritis experience mental and physical exhaustion. The chemicals found in swollen tissues are similar to those produced when one has the flu, and they cause feelings of fatigue.

6.     Sleep apnea

Sleep apnea is a sleep disorder that causes a person’s breathing to temporarily halt for short periods when asleep and begin again. The individual’s breathing is obstructed by abnormalities in the nasal and sinus passages, thus preventing air from getting into the body. The condition causes the person to wake up frequently during the night, thus they do not get restorative sleep, which leads to sleepiness and fatigue during the day.

7.     Obesity

Obesity is excessive body fat accumulation that poses a risk to one’s health. It increases the risk of fatigue because the individual carries more weight. The person’s endurance of physical activity is significantly reduced, thus they get tired quickly. Obesity is also associated with many other complications that cause fatigue, including sleep apnea, cardiovascular disease, and hypothyroidism.

8.     Anemia

Anemia is characterized by a significant decrease in the number of red blood cells and hemoglobin in the body. Red blood cells transport oxygen in the body, thus, if their numbers reduce, the body does not get sufficient oxygen supply. Anaemic people experience fatigue, shortness of breath, and weakness. A reduction in the number of red blood cells is commonly caused by a lack of iron, which is an important component of these cells.

9.     Underactive thyroid

The thyroid gland controls metabolism in the body. It is responsible for the rate of conversion of food into energy for use in the body. A person who has hypothyroidism (an underactive thyroid) lacks energy because their energy conversion process is slow. Thus, they get tired easily and in many cases gain excess weight. 

10.    Urinary tract infections (UTIs)

UTIs are infections in the urinary system that affect different parts, including the kidneys, bladder, ureters, and the urethra. The infections are characterized by pain, irritability and a burning sensation. Individuals with UTIs also feel weak, fatigued, and drained. Fatigue often occurs when the infections spread to the kidneys.

11.  Diabetes

Diabetes, a group of diseases that alter glucose levels in the blood, causes feelings of tiredness in both high and low blood sugars. When the blood sugar levels are high, it indicates that the body has insufficient insulin to transport glucose to cells for energy synthesis. Hence, the glucose remains in the bloodstream as cells are starved of energy causing one to feel fatigued. When the blood sugar levels are low, the body has a glucose deficiency. Hence, organs lack the energy to carry out their different functions causing one to feel fatigued.

Non-medical causes of fatigue

1.     Insufficient sleep

Lack of sufficient sleep at night leads to a person feeling drowsy, unmotivated, and fatigued during the day. Insufficient sleep can be caused by poor sleep hygiene, such as taking caffeine before bed, drinking alcohol, sleeping in a noisy environment, and performing other tasks, such as working, while in bed. Medical conditions, such as sleep apnea, obesity, and depression, can also affect a person’s sleep time leading to fatigue.

2.     Poor nutrition

The foods one consumes affect their health. Poor nutrition can cause the immune system to be weak, leading to an increased risk of other health conditions. Foods with high amounts of sugar cause a spike in the blood sugar levels, which later drops suddenly and leaves the person feeling fatigued. Not eating enough food also causes low energy levels in the body, thus leading to fatigue. 

3.     Excess Caffeine

Caffeine is a stimulant and is, thus taken to increase alertness. Consuming too much caffeine, however, increases a person’s heart rate and blood pressure. It also leads to anxiety and insomnia. When the stimulating effects of caffeine wear off, the individual feels exhausted and lacks motivation.

4.     Dehydration

Lack of water can cause a person to be fatigued. When a person is dehydrated, the volume of the blood reduces, thus making it difficult to get a sufficient supply of blood throughout the body. Blood is needed for the transport of oxygen and, therefore, low volumes of blood cause the body organs to lack oxygen. The person feels tired and runs out of breath easily. A well-hydrated person has clear or pale yellow urine, while when dehydrated, the urine is dark.


There is no actual test for fatigue and instead, a variety of medical tests are carried out to find the health conditions that may be causing it. The common tests carried out to identify the cause of fatigue are:

1.     Blood tests

These are tests carried out on the blood to identify health conditions such as anemia, diabetes, and hypothyroidism. Blood tests are used by doctors to evaluate how different organs in the body are functioning.

2.     Immunological tests

The body produces antibodies to fight unwanted substances. Immunological tests identify the presence of these antibodies and are used to determine the underlying health condition that an individual may be having.

3.     Overnight sleep study

When a patient complains of non-restorative sleep, studies are carried out to identify any underlying sleep disorder. Sleep disorders, such as sleep apnea, interrupt one’s sleep leading to fatigue. In an overnight sleep study, the different elements that are related to sleep, including brain waves, breathing, and muscle activity are examined to identify any abnormalities.

4.     Exercise stress test

An exercise stress test involves intense exercises during which the response of the heart is recorded and examined. The test shows how the heart is functioning and is used to identify cardiovascular diseases. The common exercise stress test involves running on a treadmill with an electrocardiogram (EKG) machine attached to monitor the heart rate.


Fatigue often occurs as a symptom of an underlying health condition and, therefore, the medical treatment options available are dependent on the underlying cause.  There is no specific medication for fatigue, thus doctors prescribe medication for treating the causal illnesses. For example, sleep apnea is treated using positive air pressure machines and surgery, diabetes is treated using medications to control the blood sugar levels, UTIs are treated using antibiotics, and iron supplements are used to treat anemia.

Alternative non-medical options of treatment

1.     Losing weight

People who have excess body fat are more susceptible to fatigue. The excess weight makes it difficult to perform daily activities and the person gets tired easily. One can lose weight by exercising regularly and eating healthy foods.

2.     Quit smoking

Smoking is associated with many health conditions and is known to lower a person’s quality of life. Nicotine is a stimulant, thus can help a person to stay alert and more active. It, however, masks exhaustion. Thus when the stimulant’s effects end, the person feels tired and lacks motivation. Smoking also aggravates sleep disorders, such as sleep apnea, thus causing sleep disturbances. Avoiding smoking, both active and passive (second-hand smoke), can improve a person’s quality of life and reduce fatigue.

3.     Don’t take alcohol

Alcohol has sedative effects, thus relaxes the muscles in the body. Relaxed muscles in the respiratory system can block the movement of air leading to sleep disturbances. Alcohol also increases the bathroom trips taken because it is a diuretic. The frequent trips to the bathroom interrupt one’s sleep, and the loss of liquid through urination causes dehydration. The person gets dehydrated and does not get enough sleep, thus leading to fatigue. Avoiding alcohol can prevent fatigue and help the person to be more active.

4.     Iron supplements

Iron is one of the components in the red blood cells. It, therefore, helps in the transport of oxygen throughout the body. A deficiency in iron reduces the amount of oxygen in the body and causes fatigue. Taking iron supplements can help increase the iron levels in the body, thus prevent a lack of oxygen.

5.     OTC sleep supplements

A good night time sleep is restorative and helps people to feel refreshed at the start of a wakeful episode. Hence, poor night time sleep can cause fatigue and tiredness during the day. One can take OTC sleep supplements to help get adequate sleep at night to feel adequately relaxed through the night and energetic during the day. Melatonin pills are common sleep supplements as they boost the hormone’s levels in the body leading to uninterrupted sleeping episodes.

6.     Proper nutrition

Consuming healthy foods can help one to feel more energetic, thus preventing fatigue. Some food groups that can help with fatigue are:

a.      Starchy carbohydrates

Starchy carbohydrates are a healthy source of energy and essential nutrients. Commonly available starchy carbohydrates are:

  •         Brown rice
  •         Potatoes
  •         Pasta
  •         Bread

b.      Iron-rich foods

The lack of iron leads to iron-deficiency anemia that causes fatigue. Iron can be obtained through foods that are rich in iron, including:

  •         Red meat
  •         Green leafy vegetables
  •          Wholegrains
  •         Nuts
  •          Beans


Fatigue is a condition in which the individual lacks the energy and motivation to carry out daily activities. It is commonly associated with many health problems including obesity, diabetes, chronic fatigue syndrome, allergies, depression, rheumatoid arthritis, anemia, and urinary tract infections. Fatigue commonly occurs as a symptom of other health conditions and is rarely an independent condition. It can occur as either physical, mental, or metabolic fatigue, depending on the part of the body that it affects. The diagnosis of the condition involves identifying the underlying cause of the problem. Blood tests, immunological tests, sleep studies, and exercise stress tests are used to determine the cause of one’s fatigue. The treatment is also aimed at the underlying causes, because there is no specific treatment for fatigue. One can also manage fatigue by avoiding alcohol, quitting smoking, losing weight, getting sufficient sleep, and using supplements that increase energy or enhance sleep quality.



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