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Fatigue

Fatigue describes a state of tiredness (which is not sleepiness), exhaustion[1] or loss of energy.[2][3]

This article is about the medical term. For other uses, see Fatigue (disambiguation).

Fatigue

Exhaustion, weariness, tiredness, lethargy, listlessness

Avoid known stressors and unhealthy habits (drug use, excessive alcohol consumption, smoking), healthy diet, exercise regularly, medication, hydration, and vitamins

In general usage, fatigue often follows prolonged physical or mental activity. When fatigue occurs independently of physical or mental exertion, or does not resolve after rest or sleep, it may have other causes, such as a medical condition.[4]


Fatigue (in the medical sense) is associated with a wide variety of conditions including autoimmune disease, organ failure, chronic pain conditions, mood disorders, heart disease, infectious diseases, and post-infectious-disease states.[5] However fatigue is complex and in up to a third of primary care cases no medical or psychiatric diagnosis is found.[6][7][8]


Fatigue (in the general usage sense of normal tiredness) can include both physical and mental fatigue. Physical fatigue results from muscle fatigue brought about by intense physical activity.[9][10][11] Mental fatigue results from prolonged periods of cognitive activity which impairs cognitive ability. Mental fatigue can manifest as sleepiness, lethargy, or directed attention fatigue,[12] and can also impair physical performance.[13]

Features[edit]

Common features[edit]

Distinguishing features of medical fatigue include

Measurement[edit]

Fatigue is currently measured by many different self-measurement surveys.[72] One example is the Fatigue Severity Scale.[73][74][75] There is no consensus on best practice,[76] and the existing surveys do not capture the intermittent nature of some forms of fatigue.


Nintendo announced plans for a device to possibly quantitatively measure fatigue in 2014,[77] but the project was stopped in 2016.[78]

Causes[edit]

Drug use[edit]

Caffeine and alcohol can cause fatigue.[79] A 2023 Korean study found that alcohol consumption was the variable with the most significant impact on overall fatigue.[80] A 2020 Norway study found that 69% of substance use disorder patients had severe fatigue symptoms.[81]

Unknown[edit]

In up to a third of fatigue primary care cases no medical or psychiatric diagnosis is found.[6][7][8] Tiredness is a common medically unexplained symptom.[7]

Sleep disturbance[edit]

Fatigue can often be traced to poor sleep habits.[82] Sleep deprivation and disruption is associated with subsequent fatigue.[83][84] Sleep disturbances due to disease may impact fatigue.[85][86]

Medications[edit]

Fatigue may be a side effect of certain medications (e.g., lithium salts, ciprofloxacin); beta blockers, which can induce exercise intolerance, medicines used to treat allergies or coughs[82]) and many cancer treatments, particularly chemotherapy and radiotherapy.

Psychological stress and conditions[edit]

Adverse life events have been associated with fatigue.[14]

Association with diseases and illnesses[edit]

Fatigue is often associated with diseases and conditions. Some major categories of conditions that often list fatigue as a symptom include physical diseases, substance use illness, mental illnesses, and other diseases and conditions.

Prevalence[edit]

2023 guidance stated fatigue prevalence is between 4.3% and 21.9%. Prevalence is higher in women than men.[6][143]


A 2021 German study found that fatigue was the main or secondary reason for 10–20% of all consultations with a primary care physician.[144]


A large study based on the 2004 Health and Retirement Study (HRS), a biennial longitudinal survey of US adults aged 51 and above, with mean age 65, found that 33% of women and 29% of men self-reported fatigue.[145]

in the primary care setting, a medical or psychiatric diagnosis is found in at least two-thirds of patients;

the most common diagnoses are , upper respiratory infection, iron-deficiency anaemia, acute bronchitis, adverse effects of a medical agent in the proper dose, and depression or other mental disorder, such as panic disorder, and somatisation disorder;

viral illness

the origin of fatigue may be central, brain-derived, or peripheral, usually of a neuromuscular origin—it may be attributed to physical illness, psychological (e.g., psychiatric disorder), social (e.g., family problems), and physiological factors (e.g., old age), occupational illness (e.g., workplace stress);

when unexplained, clinically evaluated chronic fatigue can be separated into and idiopathic chronic fatigue.[6]

ME/CFS

2023 guidance[6] stated the following:


A 2016 German review found that


A 2014 Australian review recommended that a period of watchful waiting may be appropriate if there are no major warning signs.[147]


A 2009 study found that about 50% of people who had fatigue received a diagnosis that could explain the fatigue after a year with the condition. In those people who had a possible diagnosis, musculoskeletal (19.4%) and psychological problems (16.5%) were the most common. Definitive physical conditions were only found in 8.2% of cases.[148]

Possible purposes of fatigue[edit]

Body resource management purposes[edit]

Fatigue has been posited as a bio-psycho-physiological state reflecting the body's overall strategy in resource (energy) management. Fatigue may occur when the body wants to limit resource utilisation ("rationing") in order to use resources for healing (part of sickness behaviour)[132] or conserve energy for a particular current or future anticipated need, including a threat.[14]

Evolutionary purposes[edit]

It has been posited that fatigue had evolutionary benefits in making more of the body's resources available for healing processes, such as immune responses, and in limiting disease spread by tending to reduce social interactions.[124]

Needs for research[edit]

Differentiating characteristics of fatigue due to different causes[edit]

Whilst fatigue may vary considerably by person, it may be possible to identify distinguishing characteristics linking it to different causes.[190][34][191]

Impact of phsychological factors[edit]

The possible influence of personal psychological factors on fatigue formation is another possible area of research.[192]

Byung-Chul Han

ISBN

U.S. National Cancer Institute

Fatigue – Information for Patients