10 Causes of Fatigue

By jolene
Reviewed: Dr. Mera
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Fatigue can be described as a gradual feeling of tiredness that can be alleviated by rest. Fatigue is a common and nonspecific symptom that has various causes.

Fatigue can be divided into physical and mental fatigue. Physical fatigue is the temporary inability of a muscle to maintain the maximal physical performance while mental fatigue is the transient decrease in optimal cognitive performance.

Patients experiencing fatigue may appear to be lethargic or sleepy. Fatigue has been observed to contribute to accidents as it impacts a driver’s reaction time, attention, and awareness. Studies have shown that drowsy drivers are three times more likely to be involved in a road traffic accident. Drivers who have been awake for over 20 hours are thought to be equivalent to drivers who have a blood alcohol concentration of 0.08 percent. This article looks at 10 important causes of fatigue.

Cause #1: Sleep Deprivation

Sleep deprivation occurs when there is inadequate or insufficient sleep. It can be an acute or chronic condition with varying levels of sleep deprivation. Chronic sleep deprivation can result in fatigue, clumsiness, daytime sleepiness, weight gain or weight loss, and a negative impact on cognitive functions.

Complete sleep deprivation is rare unless due to specific issues caused by surgery or fatal familial insomnia. However, brief episodes of microsleeps cannot be avoided. In animal models, long-term sleep deprivation can cause death. Other possible symptoms include aching muscles, headaches, malaise, and increased blood pressure.


Cause #2: Multiple Sclerosis

Multiple sclerosis is a condition where demyelination occurs in the neurons of the spinal cord and brain causing psychiatric, mental, and physical issues. It can cause fatigue, blindness, double vision, issues with coordination, and muscle weakness.

Multiple sclerosis can be progressive or relapsing. Progressive forms get more severe with time while relapsing forms occur as repeated isolated attacks with symptoms that may disappear between episodes. Management is aimed at the improvement of function and prevention of complications.

Cause #3: Stress

Stress refers to the response of the body to different conditions or situations such as a physical or psychological barrier. There are two main systems when the body responds to stress: hypothalamic pituitary adrenal axis and autonomic nervous system.

The activation of the fight or flight response through the sympathetic nervous system channels energy to body systems that are more relevant when adapting to stress, while the parasympathetic nervous system is there to help return the body to normal conditions. Through the different mechanisms, stress alters the body’s immune function, memory functions, metabolism, and susceptibility to disease. Too much stress can result in fatigue.


Cause #4: Jet Lag

Jet lag describes a condition that is due to alterations of the circadian rhythms due to rapid long-distance travel (east to west or west to east). This condition may last several days until the affected individual has fully adjusted to the new time zone.

It may take up to one day per time zone crossed. Jet lag has been observed most among aircraft crew, pilots, and frequent travelers. Those with jet lag often experience sleep disturbance, fatigue, difficulty waking up, poor concentration, headaches, irritability, indigestion, and poor appetite. For jet lag to occur, a change of three or more time zones may be required.

Cause #5: Depression

Depression is a mental disorder where there is a depressed mood for a minimal of two weeks.

Patients with depression often experience anhedonia, low self-esteem, fatigue, pain, and hallucinations. Depression is significant as it can have a negative impact on life, work, and education. It is also a risk factor for suicide.


Cause #6: Infectious Mononucleosis

Infectious Mononucleosis caused by the Epstein Bar Virus (EBV) is a known cause of fatigue. Even though, most patients show no symptoms, the ones that do, refer prolonged malaise and fatigue as the main symptoms of this condition.

Other symptoms associated with this condition are a sore throat, fever, chills and abdominal pain in cases where the spleen becomes enlarged.

Cause #7: Hypoglycemia

Hypoglycemia or low blood sugar occurs when the blood sugar levels drop below normal levels. Symptoms of hypoglycemia include shakiness, anxiety, palpitations, confusion, hunger, sweating, fatigue, and weakness.

The commonest cause of hypoglycemia is due to a dosage problem with diabetic medications. The risk of hypoglycemia is more significant among diabetics who have drunk alcohol or eaten less than usual.


Cause #8: Anemia

Anemia refers to the decrease in red blood cells or hemoglobin in the blood resulting in a decreased ability to carry oxygen. Anemia that develops gradually usually has very vague and unnoticeable symptoms such as fatigue, shortness of breath, and weakness.

Anemia that occurs suddenly will result in more significant symptoms such as fainting, increased thirst, loss of consciousness, pallor, and fatigue. Anemia can occur due to decreased production of red blood cells, increased blood loss, or increased breakdown of red blood cells. Examples include gastrointestinal bleeding, trauma, and thalassemia.

Cause #9: Nutritional Deficiency

Many different minerals and vitamins are required for the development of the body and prevention of disease. These nutrients are not naturally produced in the body and have to be obtained from the diet.

A nutritional deficiency occurs when the nutrient cannot be absorbed or if there are insufficient nutrients for absorption. Nutritional deficiencies can lead to various issues such as skin disorders, digestion problems, dementia, and defective bone growth. It also results in fatigue as certain nutritional deficiencies such as iron or vitamin B12 deficiency can lead to anemia.

Cause #10: Chronic Fatigue Syndrome

This condition is characterized by a prolonged state of fatigue that gets worse after demanding physical activity. The symptoms must be present for more than 6 months and the diagnosis can only be made after ruling out all other possible causes.

There is no known cause for this condition although, many studies relating viral infections and Chronic Fatigue Syndrome have been made.


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