Fatigue, also referred to as tiredness, exhaustion, lethargy, and listlessness, describes a physical and/or mental state of being tired and weak. Although physical and mental fatigue are different, the two often exist together - if a person is physically exhausted for long enough, they will also be mentally tired.
When somebody experiences physical fatigue, it means they cannot continue functioning at their normal levels of physical ability. Mental fatigue, however, is more slanted towards feeling sleepy and being unable to concentrate properly.
Fatigue is a symptom, rather than a sign. A symptom is something the patient feels and describes, such as a headache or dizziness, while a sign is something the doctor can detect without talking to the patient, such as a rash. Fatigue is a non-specific symptom, i.e. it may have several possible causes.
Contents of this article:
Mental and physical fatigue
Physical fatigue - the person's muscles cannot do things as easily as they used to. Climbing stairs or carrying laden supermarket bags may be much harder than before. Physical fatigue is also known as muscle weakness, weakness, or lack of strength. Doctors usually carry out a strength test as they go about diagnosing and trying to find out the causes of individual cases of physical fatigue.
Psychological (mental) fatigue - concentrating on things has become harder. When symptoms are severe the patient might not want to get out of bed in the morning, or perform his/her daily activities. Mental fatigue often appears together with physical fatigue in patients, but not always. People may feel sleepy, have a decreased level of consciousness, and in some cases show signs similar to that of an intoxicated state. Mental fatigue may be life threatening, especially when the sufferer has to perform some tasks, such as driving a vehicle or operating heavy machinery. Fatigue among training doctors is a serious public health concern; both for the health of the junior doctor and patients under their responsibility.
Why am I so tired?
The possible causes of fatigue are virtually endless. Most diseases listed in medical literature include malaise or fatigue as one of the potential symptoms. Causes are sometimes classified under several lifestyle problems and/or some broad disease entities.
Below are some (by no means all) possible causes of fatigue:
1) Mental health (psychiatric)
Moving home can be one of life's most stressful events.
Grief (bereavement), eating disorders, alcohol abuse, drug abuse, anxiety, moving home, boredom, and divorce.
A certain amount of stress can invigorate us, in fact, most of us need some kind of mental pressure to get going. However, when stress levels become excessive, they can easily cause fatigue. Stress and worry are two emotions that commonly cause tiredness. Stress can reach a point in which the sufferer flounders and is "unable to see the light at the end of the tunnel", which leads them towards despair. Despair is draining, and will eventually cause fatigue if it is present for long enough. Not being in control over a situation can be frustrating, annoying, and very tiring.
Having a baby in the house, especially if he/she wakes up a lot during the night, can interfere with the parents' sleep.
Some antidepressants, antihypertensives, steroids, antihistamines, medication withdrawal, sedatives, and anti-anxiety drugs.
Statin medications are among the most widely used prescription drugs sold worldwide. Researchers from the University of California, San Diego, published a report in Archives of Internal Medicine showing that statins can cause fatigue.
4) Heart and lung conditions
5) Sleep problems
Some jobs are more closely linked to a risk of fatigue than others. Examples include the police, doctors, nurses, firefighters, and shift-workers in general whose sleep patterns are "unnatural" for humans. The problem of fatigue is exacerbated if the shift-routines are regularly changed.
6) Infectious diseases, infections
7) Chemicals and substances
Vitamin deficiencies, mineral deficiencies, poisoning.
Consuming too many caffeinated or alcoholic beverages may make it harder to get to sleep, or stay asleep, especially if you drink them close to bedtime.
8) Various diseases, conditions, states and treatments
Cancer, chemotherapy, radiotherapy (radiation therapy), chronic fatigue syndrome, fibromyalgia, systemic lupus, rheumatoid arthritis, obesity, massive blood loss, and weakened immune systems. Chemotherapy for breast cancer most likely is the cause of prolonged fatigue years after their treatment, scientists at the Moffitt Cancer Center found.
9) Chronic pain
Patients with chronic pain typically wake up tired, even after having slept for a long time. For many, pain disrupts their sleep, which also leaves them tired. The combination of disturbed sleep and having to endure persistent pain can be extremely draining, leaving the patient exhausted for much of the time. Some diseases and conditions where pain is the main symptom, such as fibromyalgia, are also linked to other conditions, such as sleep apnea, restless leg syndrome, which further worsen symptoms of fatigue.
Breast cancer-related fatigue is a common condition. However, researchers from the Prince of Wales Hospital in Randwick, Australia, found that it runs a self-limiting course and is not as long-lasting as people had thought.
10) Other possible causes of fatigure
Changes in neuronal structure interactions - a Swiss scientist demonstrated that there is an association between muscle fatigue and changes in the interaction between neuronal structures.
Fatigue can become self-perpetuating. An individual who feels tired may not exercise; lack of exercise can cause fatigue. Also, lack of exercise may eventually make it harder and more tiring to perform a physical chore.
Overweight and underweight - overweight/obesity is a rapidly growing problem in much of the world today. Obese people are much more likely to experience fatigue, for various reasons - having to carry a lot of weight is tiring, obese people are have a higher risk of developing diseases and conditions where fatigue is a common symptom, such as diabetes and sleep apnea. Being underweight may mean there is less muscle strength; the very thin person may tire more easily.
How common is fatigue?
Fatigue can affect people at any age.
Experts say that 10% of people globally at any one time are suffering from persistent tiredness. Persistent tiredness affects females more than males. Primary care physicians (GPs, general practitioners) in the USA and UK say they frequently see patients who come in complaining of extreme tiredness or fatigue.
The National Institutes of Health, USA, informs that approximately one in every five Americans claims to have fatigue that is severe enough to interfere with daily normal life. More cases of fatigue have a mental than physical cause, according to collected data.
Fatigue can also affect healthy individuals after intense mental and/or physical activity.
British researchers found that undiagnosed chronic fatigue syndrome may be the reason why nearly 1% of non-truant children miss extended time off school.
What is the difference between fatigue and sleepiness?
Fatigue is usually a more chronic (long-term) condition than somnolence (sleepiness). Sleepiness is generally caused by not enough proper, restful sleep, or a lack of stimulation. Sleepiness can be a symptom of a medical condition. Fatigue, especially chronic fatigue, is usually linked to a greater medical problem.
People who suffer from fatigue feel they lack motivation and energy. Even though fatigue and drowsiness are not the same, drowsiness, or the desire to sleep, is a common symptom that accompanies fatigue. Apathy may also accompany fatigue.
On the next page we look at the symptoms of fatigue and how fatigue is diagnosed. On the final page we discuss the potential treatment options and how to overcome the feelings of tiredness and fatigue.