Fatigue

==Definition==
Fatigue in a medical context is used to cover experiences of low energy that are not caused by normal life.<ref name="Mayo-Clinic-Fatigue-2023"/><ref name="Cancer-terms-2023"/>

A 2021 review proposed a definition for fatigue as a starting point for discussion: ''"A multi-dimensional phenomenon in which the biophysiological, cognitive, motivational and emotional state of the body is affected resulting in significant impairment of the individual's ability to function in their normal capacity"''.<ref name="pmid34599320" />

Another definition is that fatigue is ''"a significant subjective sensation of weariness, increasing sense of effort, mismatch between effort expended and actual performance, or exhaustion independent from medications, chronic pain, physical deconditioning, anaemia, respiratory dysfunction, depression, and sleep disorders"''.<ref name="pmid37180990">{{cite journal |last1=Camera |first1=Valentina |last2=Mariano |first2=Romina |last3=Messina |first3=Silvia |last4=Menke |first4=Ricarda |last5=Griffanti |first5=Ludovica |last6=Craner |first6=Matthew |last7=Leite |first7=Maria I |last8=Calabrese |first8=Massimiliano |last9=Meletti |first9=Stefano |last10=Geraldes |first10=Ruth |last11=Palace |first11=Jacqueline A |title=Shared imaging markers of fatigue across multiple sclerosis, aquaporin-4 antibody neuromyelitis optica spectrum disorder and MOG antibody disease |journal=Brain Communications |date=2 May 2023 |volume=5 |issue=3 |pages=fcad107 |doi=10.1093/braincomms/fcad107 |pmid=37180990 |pmc=10171455 }}</ref>

===Terminology===
The use of the term "fatigue" in medical contexts may carry inaccurate connotations from the more general usage of the same word. More accurate terminology may also be needed for variants within the umbrella term of fatigue.<ref>{{cite journal | pmc=8142120 | year=2020 | last1=Hubbard | first1=A. L. | last2=Golla | first2=H. | last3=Lausberg | first3=H. | title=What's in a name? That which we call Multiple Sclerosis Fatigue | journal=Multiple Sclerosis (Houndmills, Basingstoke, England) | volume=27 | issue=7 | pages=983–988 | doi=10.1177/1352458520941481 | pmid=32672087 }}</ref>

===Comparison with other terms===
====Tiredness====
Tiredness which is a normal result of [[Work (human activity)|work]], mental [[Stress (medicine)|stress]], [[anxiety]], overstimulation and understimulation, [[jet lag]], active [[recreation]], [[boredom]], or [[Sleep deprivation|lack of sleep]] is not considered medical fatigue. This is the tiredness described in MeSH Descriptor Data.<ref>{{Cite web|url=https://meshb.nlm.nih.gov/record/ui?ui=D005221|title=MeSH Browser|website=meshb.nlm.nih.gov|access-date=2024-01-25|archive-date=2023-05-08|archive-url=https://web.archive.org/web/20230508182945/https://meshb.nlm.nih.gov/record/ui?ui=D005221|url-status=live}}</ref>

====Sleepiness====
Sleepiness refers to a tendency to fall asleep, whereas fatigue refers to an overwhelming sense of tiredness, lack of energy, and a feeling of exhaustion. Sleepiness and fatigue often coexist as a consequence of sleep deprivation.<ref>{{Cite book|url=http://www.ncbi.nlm.nih.gov/books/NBK2645/|title=Patient Safety and Quality: An Evidence-Based Handbook for Nurses|first=Ann E.|last=Rogers|chapter=The Effects of Fatigue and Sleepiness on Nurse Performance and Patient Safety |series=Advances in Patient Safety |editor-first=Ronda G.|editor-last=Hughes|date=April 11, 2008|publisher=Agency for Healthcare Research and Quality (US)|via=PubMed|pmid=21328747}}</ref> However sleepiness and fatigue may not correlate.<ref>{{Cite journal|url=https://pubmed.ncbi.nlm.nih.gov/9256516/|title=Fatigue and sleep disorders|first1=K. L.|last1=Lichstein|first2=M. K.|last2=Means|first3=S. L.|last3=Noe|first4=R. N.|last4=Aguillard|date=August 11, 1997|journal=Behaviour Research and Therapy|volume=35|issue=8|pages=733–740|via=PubMed|doi=10.1016/s0005-7967(97)00029-6|pmid=9256516}}</ref> Fatigue is generally considered a longer-term condition than sleepiness (somnolence).<ref name="pmid16376590">{{cite journal | vauthors = Shen J, Barbera J, Shapiro CM | title = Distinguishing sleepiness and fatigue: focus on definition and measurement | journal = Sleep Medicine Reviews | volume = 10 | issue = 1 | pages = 63–76 | date = February 2006 | pmid = 16376590 | doi = 10.1016/j.smrv.2005.05.004 }}</ref>