Fatigue (also called exhaustion, lethargy, languidness, languor, lassitude, and listlessness or ) is a state of awareness describing a range of afflictions, usually associated with physical and/or mental weakness, though varying from a general state of lethargy to a specific work-induced burning sensation within one's muscles. Physical fatigue is the inability to continue functioning at the level of one's normal abilities.^[1][2][3] It is ubiquitous in everyday life, but usually becomes particularly noticeable during heavy exercise Physical exercise is any bodily activity that enhances or maintains physical fitness and overall health or wellness. It is performed for various reasons. These include strengthening muscles and the cardiovascular system, honing athletic skills, weight loss or maintenance and for enjoyment. Frequent and regular physical exercise boosts the immune. Mental fatigue, on the other hand, rather manifests in somnolence Somnolence is a state of near-sleep, a strong desire for sleep, or sleeping for unusually long periods (cf. hypersomnia). It has two distinct meanings, referring both to the usual state preceding falling asleep, and the chronic condition referring to being in that state independent of a circadian rhythm. The disorder characterized by the latter (sleepiness).

Fatigue is considered a symptom A symptom is a departure from normal function or feeling which is noticed by a patient, indicating the presence of disease or abnormality. A symptom is subjective, observed by the patient, and not measured, as opposed to a medical sign A medical sign is an objective indication of some medical fact or characteristic that may be detected by a physician during a physical examination of a patient, because it is reported by the patient instead of being observed by others. Fatigue and ‘feelings of fatigue’ are often confused.^[4]

Types

Physical fatigue

Physical fatigue or muscle weakness (or "lack of strength") is a direct term for the inability to exert force with one's muscles Muscle is the contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to produce force and cause motion. Muscles can cause to the degree that would be expected given the individual's general physical fitness Physical fitness comprises two related concepts: general fitness and specific fitness (a task-oriented definition based on the ability to perform specific aspects of sports or occupations). Physical fitness is generally achieved through exercise, correct nutrition and enough rest.

A test of strength is often used during a diagnosis Medical diagnosis refers both to the process of attempting to determine the identity of a possible disease or disorder and to the opinion reached by this process of a muscular disorder before the etiology Etiology is the study of causation, or origination. The word is derived from the Greek αἰτιολογία, aitiologia, "giving a reason for" (αἰτία, aitia, "cause"; and -λογία, -logia) can be identified. Such etiology depends on the type of muscle weakness, which can be true or perceived as well as central or peripheral. True weakness is substantial, while perceived rather is a sensation of having to put more effort to do the same task. On the other hand, central muscle weakness is an overall exhaustion of the whole body, while peripheral weakness is an exhaustion of individual muscles.

Mental fatigue

In addition to physical, fatigue also includes mental fatigue, not necessarily including any muscle fatigue. Such a mental fatigue, in turn, can manifest itself both as somnolence Somnolence is a state of near-sleep, a strong desire for sleep, or sleeping for unusually long periods (cf. hypersomnia). It has two distinct meanings, referring both to the usual state preceding falling asleep, and the chronic condition referring to being in that state independent of a circadian rhythm. The disorder characterized by the latter (decreased wakefulness Wakefulness is a daily recurring brain state in which an individual is conscious and engages in coherent cognitive and behavior responses to the external world such as communication, ambulation, nutritional ingestion and procreation. Being awake is the opposite of being asleep in which most external inputs to the brain are excluded from neural) or just as a general decrease of attention Attention is the cognitive process of selectively concentrating on one aspect of the environment while ignoring other things. Attention has also been referred to as the allocation of processing resources, not necessarily including sleepiness. It may also be described as a more or less decreased level of consciousness An altered level of consciousness is an measure of arousal other than normal. Level of consciousness is a measurement of a person's arousability and responsiveness to stimuli from the environment. A mildly depressed level of consciousness may be classed as lethargy; someone in this state can be aroused with little difficulty. People who are.^{[citation needed]} In any case, this can be dangerous when performing tasks that require constant concentration, such as driving a vehicle A vehicle is a device that is designed or used to transport people or cargo. Most often vehicles are manufactured (e.g. bicycles, cars, motorcycles, trains, ships, boats, and aircraft). For instance, a person who is sufficiently somnolent may experience microsleeps A microsleep is an episode of sleep which may last for a fraction of a second or up to thirty seconds. Often, it is the result of sleep deprivation, mental fatigue, depression, sleep apnea, hypoxia, narcolepsy, or hypersomnia. Microsleeping can occur at any time, typically without significant warning. However, objective cognitive testing should be done to differentiate the neurocognitive deficits of brain disease from those attributable to tiredness.

Differential diagnosis

The majority of people who have fatigue do not have an underlying cause discovered after a year with the condition. In those who do have a possible diagnosis musculoskeletal (19.4%) and psychological problems (16.5%) are the most common. Definitive physical conditions were only found in 8.2%.^[5]

Fatigue is typically the result of working Labour economics seeks to understand the functioning and dynamics of the market for labour. Labour markets function through the interaction of workers and employers. Labour economics looks at the suppliers of labour services , the demanders of labour services (employers), and attempts to understand the resulting pattern of wages, employment, and, mental stress Stress is a term in psychology and biology, first coined in the 1930s, which has in more recent decades become a commonplace of popular parlance. It refers to the consequence of the failure of an organism – human or animal – to respond appropriately to emotional or physical threats, whether actual or imagined, overstimulation and understimulation, jet lag Jet lag, medically referred to as "desynchronosis," is a physiological condition which is a consequence of alterations to circadian rhythms; it is classified as one of the circadian rhythm sleep disorders. Jet lag results from rapid long-distance transmeridian travel, as on a jet plane or active recreation, depression Major depressive disorder is a mental disorder characterized by an all-encompassing low mood accompanied by low self-esteem, and by loss of interest or pleasure in normally enjoyable activities. The term "major depressive disorder" was selected by the American Psychiatric Association to designate this symptom cluster as a mood disorder, and also boredom Boredom is an emotional state experienced during periods lacking activity or when individuals are uninterested in the opportunities surrounding them. The first record of the word boredom is in the novel Bleak House by Charles Dickens, written in 1852, in which it appears six times, although the expression to be a bore had been used in the sense of, disease A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal disfunctions, such as autoimmune diseases and lack of sleep Sleep deprivation, a sleep disorder characterized by having too little sleep, can be either chronic or acute. Long-term sleep deprivation causes death in lab animals. A chronic sleep-restricted state can cause fatigue, daytime sleepiness, clumsiness and weight loss or weight gain. Approximately 50 to 70 million Americans are reportedly affected by. It may also have chemical causes, such as poisoning In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism. Legally and in hazardous chemical labeling, poisons are especially toxic substances; less toxic substances are labeled " or mineral A mineral is a naturally occurring solid chemical substance that is formed through geological processes and that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not have a specific chemical composition or vitamin A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. In other words, an organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on the circumstances and the particular organism. For deficiencies. Massive blood loss frequently results in fatigue. Fatigue is different from drowsiness, where a patient feels that sleep is required. Fatigue is a normal response to physical exertion or stress, but can also be a sign of a physical disorder.

The sense of fatigue is believed to originate in the reticular activating system The reticular activating system is an area of the brain (including the reticular formation and its connections) responsible for regulating arousal and sleep-wake transitions of the lower brain. Musculoskeletal A musculoskeletal system is an organ system that gives animals (including humans) the ability to move using the muscular and skeletal systems. The musculoskeletal system provides form, support, stability, and movement to the body structures may have co-evolved with appropriate brain structures so that the complete unit functions together in a constructive and adaptive fashion.^[6] The entire systems of muscles, joints, and proprioceptive Proprioception , from Latin proprius, meaning "one's own" and perception, is the sense of the relative position of neighbouring parts of the body. Unlike the exteroceptive senses by which we perceive the outside world, and interoceptive senses, by which we perceive the pain and movement of internal organs, proprioception is a third and kinesthetic functions plus parts of the brain evolve and function together in a unitary way.^[7]

Temporary fatigue is likely to be a minor illness Illness is a state of poor health. Illness is sometimes considered a synonym for disease. Others maintain that fine distinctions exist. Some have described illness as the subjective perception by a patient of an objectively defined disease like the common cold The common cold (viral upper respiratory tract infection , acute viral rhinopharyngitis, acute coryza, or cold) is a contagious, viral infectious disease of the upper respiratory system, caused primarily by rhinoviruses and coronaviruses. Common symptoms include a sore throat, runny nose, and fever. There is no cure; however, symptoms usually as one part of the sickness behavior Sickness behavior is a coordinated set of adaptive behavioral changes that develop in ill individuals during the course of an infection. They usually accompany fever and aid survival. Such illness responses include lethargy, depression, anorexia, sleepiness, hyperalgesia, reduction in grooming and failure to concentrate. Sickness behavior is a response that happens when the immune system An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own healthy cells and tissues in order to function fights an infection An infection is the detrimental colonization of a host organism by a foreign species. In an infection, the infecting organism seeks to utilize the host's resources to multiply, usually at the expense of the host. The infecting organism, or pathogen, interferes with the normal functioning of the host and can lead to chronic wounds, gangrene, loss. Chronic fatigue, on the other hand, meaning of six months or more duration, is a symptom of a large number of different diseases or conditions. Some major categories of diseases that feature fatigue include:

• Autoimmune diseases Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. In other words, the body actually attacks its own cells. The immune system mistakes some part of the body as a pathogen and attacks it. This may be restricted to certain organs or involve a particular tissue in such as celiac disease Coeliac disease is an autoimmune disorder of the small intestine that occurs in genetically predisposed people of all ages from middle infancy onward. Symptoms include chronic diarrhoea, failure to thrive (in children), and fatigue, but these may be absent, and symptoms in other organ systems have been described. A growing portion of diagnoses are, multiple sclerosis Multiple sclerosis is a disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms. Disease onset usually occurs in young adults, and it is more common in females. It has a prevalence that ranges between 2 and 150 per 10, and spondyloarthropathy Spondyloarthropathies are inflammatory joint diseases of the vertebral column associated with the MHC class I molecule HLA-B27. The term seronegative spondylarthropathy is used by medical practitioners because this set of conditions may mimic rheumatoid diseases such as rheumatoid arthritis, but serological tests are typically negative for
• Blood disorders Hematology, also spelled haematology, is the branch of biology , pathology, clinical laboratory, internal medicine, and pediatrics that is concerned with the study of blood, the blood-forming organs, and blood diseases. Hematology includes the study of etiology, diagnosis, treatment, prognosis, and prevention of blood diseases. The lab work that such as anemia Anemia is a decrease in normal number of red blood cells (RBCs) or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin deficiency and hemochromatosis Historically, the term haemochromatosis was initially used to refer to what is now more specifically called haemochromatosis type 1 (or HFE-related hereditary haemochromatosis). Currently, haemochromatosis (without further specification) is mostly defined as iron overload with a hereditary/primary cause, or originating from a metabolic disorder
• Cancer Cancer /ˈkænsər/ (medical term: malignant neoplasm) is a class of diseases in which a group of cells display uncontrolled growth (division beyond the normal limits), invasion (intrusion on and destruction of adjacent tissues), and sometimes metastasis (spread to other locations in the body via lymph or blood). These three malignant properties
• Chronic fatigue syndrome Сhronic fatigue syndrome is the most common name given to a variably debilitating disorder or disorders generally defined by persistent fatigue unrelated to exertion and not substantially relieved by rest, and accompanied by the presence of other specific symptoms for a minimum of six months. The disorder may also be referred to as post-viral (CFS)
• Depression Major depressive disorder is a mental disorder characterized by an all-encompassing low mood accompanied by low self-esteem, and by loss of interest or pleasure in normally enjoyable activities. The term "major depressive disorder" was selected by the American Psychiatric Association to designate this symptom cluster as a mood disorder and other mental disorders that feature depressed mood Depression is a state of low mood and aversion to activity. The Diagnostic and Statistical Manual of Mental Disorders defines a depressed person as experiencing feelings of sadness, helplessness and hopelessness. In traditional colloquy, feeling "depressed" is often synonymous with feeling "sad", but both clinical depression
• Eating disorders Eating disorders are a group of conditions characterized by abnormal eating habits that may involve either insufficient or excessive food intake to the detriment of an individual's physical and emotional health, binge eating disorder, bulimia nervosa, anorexia nervosa being the most common specific forms in the United States, Though primarily, which can produce fatigue due to inadequate nutrition
• Endocrine disease Endocrine diseases are disorders of the endocrine system. The branch of medicine associated with endocrine disorders is known as endocrinology like diabetes mellitus Diabetes mellitus —often simply referred to as diabetes—is a condition in which a person has a high blood sugar (glucose) level, either because the body doesn't produce enough insulin, or because body cells don't properly respond to the insulin that is produced. Insulin is a hormone produced in the pancreas which enables body cells to absorb and hypothyroidism Hypothyroidism is the disease state in humans and in vertebrates caused by insufficient production of thyroid hormones by the thyroid gland. Cretinism is a form of hypothyroidism found in infants
• Fibromyalgia Fibromyalgia is a medical disorder characterized by chronic widespread pain and allodynia, a heightened and painful response to pressure. Fibromyalgia symptoms are not restricted to pain, leading to the use of the alternative term fibromyalgia syndrome for the condition. Other symptoms include debilitating fatigue, sleep disturbance, and joint
• Heart disease
• Infectious diseases such as infectious mononucleosis and influenza
• Leukemia or lymphoma
• Neurological disorders such as Parkinson's disease and post-concussion syndrome
• Physical trauma and other pain-causing conditions, such as arthritis
• Sleep deprivation or sleep disorders
• Uremia
• Hepatic failure

Medications

• Certain medications, e.g. lithium salts, ciprofloxacin
• Beta blocker medication causes fatigue, especially after exertion, inducing exercise intolerance.
• Many cancer treatments cause fatigue, particularly chemotherapy and radiotherapy

Diagnostics approach

After deciding to see a doctor for guidance and treatment against fatigue, the physician will look at a person's medical history along with the evaluation of the fatigue itself. When evaluating sleep, questions will be asked regarding the quality of sleep, emotional state of the person, sleep pattern, and stress level. Questions about a person's diet, exercise level, and the symptoms that they are experiencing will also be asked. The quality of sleep a person is receiving is important. Certain points like if there is a pattern of fatigue consistent with the same time of the day or if it progressively worsens throughout the day are looked at. It is important that a patient take note of specific areas of sleep and fatigue before the visit so that they have answers to the right questions. The amount of sleep, the hours that are set aside for sleep, and the number of times that a person awakes during the night are important. Other tests that might be ordered by the physician include blood tests to check for infection or anemia, urinalysis to look for signs of liver disease or diabetes, and tests to monitor the function of the thyroid. A common exam that monitors the levels of seven common substances found circulating in the blood is also used. It consists of the four electrolytes:sodium, potassium, chloride, and bicarbonate, along with two waste products of metabolism (cleared by normally functioning kidneys) which are BUN and creatinine, and lastly, the source of energy for your body's cells, glucose. ^[8]Specific tests will be run to check for HIV and female patients will also be required to receive a pregnancy test.

See also

Other fatigue-related articles

• Fatigue (safety)
• Sleep deprived driving
• Combat stress reaction (Battle fatigue)

Other medical symptoms and conditions

• Malaise
• Asthenia
• Paresis
• Debility
• Muscle fatigue
• Eye circles

Notes

1. ^ Gandevia SC (1992). "Some central and peripheral factors affecting human motoneuronal output in neuromuscular fatigue". Sports medicine (Auckland, N.Z.) 13 (2): 93–8. doi:10.2165/00007256-199213020-00004. PMID 1561512.
2. ^ Hagberg M (1981). "Muscular endurance and surface electromyogram in isometric and dynamic exercise". Journal of applied physiology: respiratory, environmental and exercise physiology 51 (1): 1–7. PMID 7263402.
3. ^ Hawley JA, Reilly T (1997). "Fatigue revisited". Journal of sports sciences 15 (3): 245–6. doi:10.1080/026404197367245. PMID 9232549.
4. ^ Berrios GE (1990). "Feelings of fatigue and psychopathology: a conceptual history". Compr Psychiatry 31 (2): 140–51. doi:10.1016/0010-440X(90)90018-N. PMID 2178863. http://linkinghub.elsevier.com/retrieve/pii/0010-440X(90)90018-N.
5. ^ Nijrolder I, van der Windt D, de Vries H, van der Horst H (November 2009). "Diagnoses during follow-up of patients presenting with fatigue in primary care". CMAJ 181 (10): 683–7. doi:10.1503/cmaj.090647. PMID 19858240. PMC 2774363. http://www.cmaj.ca/cgi/pmidlookup?view=long&pmid=19858240.
6. ^ Edelman, Gerald Maurice (1989). The remembered present: a biological theory of consciousness. New York: Basic Books. ISBN 0-465-06910-X.
7. ^ Kelso, J. A. Scott (1995). Dynamic patterns: the self-organization of brain and behavior. Cambridge, Mass: MIT Press. ISBN 0-262-61131-7.
8. ^ EMedicine Health. "Fatigue Exams and tests" 2010-01-25.

References

• Gandevia SC (1992). "Some central and peripheral factors affecting human motoneuronal output in neuromuscular fatigue". Sports medicine (Auckland, N.Z.) 13 (2): 93–8. doi:10.2165/00007256-199213020-00004. PMID 1561512.
• Hagberg M (1981). "Muscular endurance and surface electromyogram in isometric and dynamic exercise". Journal of applied physiology: respiratory, environmental and exercise physiology 51 (1): 1–7. PMID 7263402.
• Hawley JA, Reilly T (1997). "Fatigue revisited". Journal of sports sciences 15 (3): 245–6. doi:10.1080/026404197367245. PMID 9232549.
• Edelman, Gerald Maurice (1989). The remembered present: a biological theory of consciousness. New York: Basic Books. ISBN 0-465-06910-X.
• Kelso, J. A. Scott (1995). Dynamic patterns: the self-organization of brain and behavior. Cambridge, Mass: MIT Press. ISBN 0-262-61131-7.

External links

• Fatigue — Information for Patients, U.S. National Cancer Institute
• Tiredness — Information leaflet from mental health charity The Royal College of Psychiatrists

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