Fatigue

====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>