Editing Shift work (section)

==Health effects==

{{Main|Shift work sleep disorder}}
[[File:Your Brain Health and the Workplace.webm|thumb|A video on the health effects of shift work]]
Shift work increases the risk for the development of many disorders. [[Shift work sleep disorder]] is a [[circadian rhythm sleep disorder]] characterized by [[insomnia]], [[hypersomnia|excessive sleepiness]], or both. Shift work is considered essential for the diagnosis.<ref name=":1" /> The risk of [[diabetes mellitus type 2]] is increased in shift workers, especially men. People working rotating shifts are more vulnerable than others.<ref name="Shift work & DM">{{cite journal|last1=Yong|first1=Gan|title=Shift work and diabetes mellitus: a meta-analysis of observational studies|journal=Occupational and Environmental Medicine|date=2014|doi=10.1136/oemed-2014-102150|pmid=25030030|url=http://oem.bmj.com/content/early/2014/06/12/oemed-2014-102150.abstract|access-date=11 August 2014|volume=72|issue=1|pages=72–78|doi-access=free}}</ref>

Women whose work involves night shifts have a 48% increased risk of developing breast cancer.<ref name=":3">{{Cite news|url = http://www.medscape.com/viewarticle/768414|title = Running on Empty: Fatigue and Healthcare Professionals|last = Caruso|first = Claire C.|date = August 2, 2012|work = NIOSH: Workplace Safety and Health|publisher = Medscape and NIOSH}}</ref><ref name=":4">{{Cite journal 
| last1 = Megdal | first1 = S. P. 
| last2 = Kroenke | first2 = C. H. 
| last3 = Laden | first3 = F. 
| last4 = Pukkala | first4 = E. 
| last5 = Schernhammer | first5 = E. S. 
| title = Night work and breast cancer risk: A systematic review and meta-analysis 
| doi = 10.1016/j.ejca.2005.05.010 
| journal = European Journal of Cancer 
| volume = 41 
| issue = 13 
| pages = 2023–2032 
| year = 2005 
| pmid = 16084719 
}}</ref> This may be due to alterations in circadian rhythm: [[melatonin]], a known tumor suppressor, is generally produced at night and late shifts may disrupt its production.<ref name=":4" /> The WHO's [[International Agency for Research on Cancer]] listed "shift work that involves circadian disruption" as probably carcinogenic.<ref>{{Cite web|url=http://www.iarc.fr/ENG/Press_Releases/pr180a.html|archiveurl=https://web.archive.org/web/20080411185859/http://www.iarc.fr/ENG/Press_Releases/pr180a.html|url-status=dead|title=Press Release N° 180|archivedate=April 11, 2008|website=www.iarc.fr}}</ref><ref>{{cite web |url=http://www.publicbroadcasting.net/wnpr/news.newsmain?action=article&ARTICLE_ID=1191176&sectionID=760 |title=The health of night shift workers |access-date=2007-11-30 |author=WNPR, Connecticut Public Radio |publisher=Connecticut Public Radio, WNPR |archive-date=2008-02-22 |archive-url=https://web.archive.org/web/20080222202956/http://www.publicbroadcasting.net/wnpr/news.newsmain?action=article&ARTICLE_ID=1191176&sectionID=760 |url-status=dead }}</ref> Shift work may also increase the risk of other types of cancer.<ref>{{Cite journal 
| last1 = Parent | first1 = M. -E. 
| last2 = El-Zein | first2 = M. 
| last3 = Rousseau | first3 = M. -C. 
| last4 = Pintos | first4 = J. 
| last5 = Siemiatycki | first5 = J. 
| title = Night Work and the Risk of Cancer Among Men 
| doi = 10.1093/aje/kws318 
| journal = American Journal of Epidemiology 
| volume = 176 
| issue = 9 
| pages = 751–759 
| year = 2012 
| pmid = 23035019 
| doi-access = free 
}}</ref> Working rotating shift work regularly during a two-year interval has been associated with a 9% increased the risk of early menopause compared to women who work no rotating shift work. The increased risk among rotating night shift workers was 25% among women predisposed to earlier menopause. Early menopause can lead to a host of other problems later in life.<ref>{{Cite journal|title=Women who work nights are 9% more likely to have an early menopause|date=2019-03-01|journal=Human Reproduction|volume=34|issue=3|pages=539–548|doi=10.1093/humrep/dey390|pmid=30753548|last1=Stock|first1=D.|last2=Knight|first2=J. A.|last3=Raboud|first3=J.|last4=Cotterchio|first4=M.|last5=Strohmaier|first5=S.|last6=Willett|first6=W.|last7=Eliassen|first7=A. H.|last8=Rosner|first8=B.|last9=Hankinson|first9=S. E.|last10=Schernhammer|first10=E.|pmc=7210710|doi-access=free}}</ref><ref>{{Cite journal|last1=Stock|first1=D.|last2=Hankinson|first2=S. E.|last3=Rosner|first3=B.|last4=Eliassen|first4=A. H.|last5=Willett|first5=W.|last6=Strohmaier|first6=S.|last7=Cotterchio|first7=M.|last8=Raboud|first8=J.|last9=Knight|first9=J. A.|last10=Schernhammer|first10=E.|date=2019-03-01|title=Rotating night shift work and menopausal age|journal=Human Reproduction|language=en|volume=34|issue=3|pages=539–548|doi=10.1093/humrep/dey390|pmid=30753548|pmc=7210710|issn=0268-1161|doi-access=free}}</ref>  A recent study, found that women who worked rotating night shifts for more than six years, eleven percent experienced a shortened lifespan. Women who worked rotating night shifts for more than 15 years also experienced a 25 percent higher risk of death due to lung cancer.<ref>{{Cite web|url=https://www.huffingtonpost.com/2015/01/06/rotating-shift-work-health_n_6417644.html|title=Why Working The Night Shift Has Major Health Consequences|date=2015-01-06|website=HuffPost|language=en|access-date=2019-03-09}}</ref>

Shift work also increases the risk of developing [[cluster headache]]s,<ref>{{Cite journal 
| last1 = Beck | first1 = E. 
| last2 = Sieber | first2 = W. J. 
| last3 = Trejo | first3 = R. 
| title = Management of cluster headache 
| journal = American Family Physician 
| volume = 71 
| issue = 4 
| pages = 717–724 
| year = 2005 
| pmid = 15742909
}}</ref> [[Myocardial infarction|heart attacks]],<ref name="Vyas2012">{{cite journal|author1=Vyas MV |author2=Garg AX |author3=Iansavichus AV |author4=Costella J |author5=Donner A |author6=Laugsand LE |author7=Janszky I |author8=Mrkobrada M |author9=Parraga G |author10=Hackam DG |title=Shift work and vascular events: systematic review and meta-analysis|journal=British Medical Journal (Clinical Research Edition)|volume=345|pages=e4800|date=July 2012|pmid=22835925|pmc=3406223|doi=10.1136/bmj.e4800}}</ref> [[fatigue (medical)|fatigue]], [[Stress (biology)|stress]], [[sexual dysfunction]],<ref name="fido2008">{{Cite journal |author1=Fido A |author2=Ghali A |title = Detrimental effects of variable work shifts on quality of sleep, general health and work performance|journal = Med Princ Pract |year=2008|volume=17 | issue = 6 |pages=453–7|url = http://www.websciences.org/cftemplate/NAPS/archives/indiv.cfm?ID=20083138|type = Abstract |doi=10.1159/000151566|pmid=18836273 |doi-access=free |url-access=subscription }}</ref> depression,<ref name=":2">{{cite journal |last1=Slanger |first1=Tracy E |last2=Gross |first2=J. Valérie |last3=Pinger |first3=Andreas |last4=Morfeld |first4=Peter |last5=Bellinger |first5=Miriam |last6=Duhme |first6=Anna-Lena |last7=Reichardt Ortega |first7=Rosalinde Amancay |last8=Costa |first8=Giovanni |last9=Driscoll |first9=Tim R |last10=Foster |first10=Russell G |last11=Fritschi |first11=Lin |last12=Sallinen |first12=Mikael |last13=Liira |first13=Juha |last14=Erren |first14=Thomas C |title=Person-directed, non-pharmacological interventions for sleepiness at work and sleep disturbances caused by shift work |journal=Cochrane Database of Systematic Reviews |issue=8 |pages=CD010641 |date=23 August 2016 |volume=2016 |doi=10.1002/14651858.CD010641.pub2 |pmid=27549931 |pmc=8406755 }}</ref> [[dementia]], [[obesity]],<ref name=":1" /> [[metabolic disorder]]s, [[Gastrointestinal disease|gastrointestinal disorders]], [[musculoskeletal disorder]]s, and reproductive disorders.<ref name=":3" />[[File:Child Labor in United States 1908, 12 hour night shifts.jpg|thumb|Children going to a 12-hour night shift in the United States, 1908]]
Shift work also can worsen chronic diseases, including [[sleep disorder]]s, [[digestive disease]]s, [[cardiovascular disease|heart disease]], [[hypertension]], [[epilepsy]], [[mental disorder]]s, [[substance abuse]], [[asthma]], and any health conditions that are treated with medications affected by the circadian cycle.<ref name=":3" /> [[Lighting|Artificial lighting]] may additionally contribute to disturbed [[human homeostasis|homeostasis]].<ref>{{cite journal |last1=Navara |first1=Kristen J. |last2=Nelson |first2=Randy J. |title=The dark side of light at night: physiological, epidemiological, and ecological consequences |journal=Journal of Pineal Research |date=October 2007 |volume=43 |issue=3 |pages=215–224 |doi=10.1111/j.1600-079X.2007.00473.x |pmid=17803517 |doi-access=free }}</ref> Shift work may also increase a person's risk of smoking.<ref name=":3" />

The health consequences of shift work may depend on [[chronotype]], that is, being a [[lark (person)|day person]] or a [[night owl (person)|night person]], and what shift a worker is assigned to.  When individual chronotype is opposite of shift timing (day person working night shift), there is a greater risk of circadian rhythms disruption.<ref>{{cite journal |last1=Adan |first1=Ana |last2=Archer |first2=Simon N. |last3=Hidalgo |first3=Maria Paz |last4=Di Milia |first4=Lee |last5=Natale |first5=Vincenzo |last6=Randler |first6=Christoph |title=Circadian Typology: A Comprehensive Review |journal=Chronobiology International |date=24 September 2012 |volume=29 |issue=9 |pages=1153–1175 |doi=10.3109/07420528.2012.719971 |pmid=23004349 |s2cid=7565248 |url=http://epubs.surrey.ac.uk/805776/1/Adan_2012%20Final.pdf }}</ref> Nighttime workers sleep an average of one–four hours less than daytime workers.<ref>{{cite book |doi=10.1016/B978-1-4377-1703-7.10029-5 |chapter=Shift Work Disorder |editor1-first=Teri J. |editor1-last=Barkoukis |editor2-first=Jean K. |editor2-last=Matheson |editor3-first=Richard |editor3-last=Ferber |editor4-first=Karl |editor4-last=Doghramji |title=Therapy in Sleep Medicine |url=https://archive.org/details/therapysleepmedi00mdte |url-access=limited |pages=[https://archive.org/details/therapysleepmedi00mdte/page/n394 378]–389 |year=2012 |last1=Ftouni |first1=Suzanne |last2=Sletten |first2=Tracey L. |last3=Barger |first3=Laura K. |last4=Lockley |first4=Steven W. |last5=Rajaratnam |first5=Shantha M.W. |isbn=978-1-4377-1703-7 }}</ref>

Different shift schedules will have different impacts on the health of a shift worker. The way the shift pattern is designed affects how shift workers sleep, eat and take holidays. Some shift patterns can exacerbate fatigue by limiting rest, increasing stress, overworking staff or disrupting their time off.<ref>{{cite book|url=https://www.amazon.co.uk/Fatigue-Shift-Work-Tools-Techniques-ebook/dp/B00NGWRMKA/|title=Fatigue and Shift Work (Tools And Techniques) eBook: Dr Angela Moore, Alec Jezewski: Amazon.co.uk: Kindle Store|date=9 September 2014|access-date=3 February 2016}}</ref>

Muscle health is also compromised by shift work: altered sleep and eating times, changes to appetite-regulating hormones and total energy expenditure, increased snacking and binge drinking, and reduced protein intake can contribute to negative protein balance, increases in insulin resistance and increases in body fat,<ref>{Sooriyaarachchi P, Jayawardena R, Pavey T, King N. Shift work and body composition: a systematic review and meta-analysis. Minerva Endocrinology. 2021 Jun. https://doi.org/10.23736/s2724-6507.21.03534-x</ref> resulting in weight gain and more long-term health challenges.<ref>{{Cite journal|last1=Lamon|first1=Séverine|last2=Zacharewicz|first2=Evelyn|last3=Condo|first3=Dominique|last4=Aisbett|first4=Brad|date=March 2017|title=The Impact of Shiftwork on Skeletal Muscle Health|journal=Nutrients|language=en|volume=9|issue=3|pages=248|doi=10.3390/nu9030248|pmid=28282858|pmc=5372911|doi-access=free}}</ref>{{Main|Effects of sleep deprivation on cognitive performance}}
Compared with the day shift, injuries and accidents have been estimated to increase by 15% on evening shifts and 28% on night shifts. Longer shifts are also associated with more injuries and accidents: 10-hour shifts had 13% more and 12-hour shifts had 28% more than 8-hour shifts.<ref name=":3" /> Other studies have shown a link between fatigue and workplace injuries and accidents. Workers with sleep deprivation are far more likely to be injured or involved in an accident.<ref name=":1" /> Breaks reduce accident risks.<ref>{{Cite journal|last1=Fischer|first1=Dorothee|last2=Lombardi|first2=David A.|last3=Folkard|first3=Simon|last4=Willetts|first4=Joanna|last5=Christiani|first5=David C.|date=2017-11-26|title=Updating the "Risk Index": A systematic review and meta-analysis of occupational injuries and work schedule characteristics|journal=Chronobiology International|language=en|volume=34|issue=10|pages=1423–1438|doi=10.1080/07420528.2017.1367305|pmid=29064297|s2cid=39842142|issn=0742-0528|url=https://figshare.com/articles/journal_contribution/5872302 }}</ref>

One study suggests that, for those working a night shift (such as 23:00 to 07:00), it may be advantageous to sleep in the evening (14:00 to 22:00) rather than the morning (08:00 to 16:00). The study's evening sleep subjects had 37% fewer episodes of attentional impairment than the morning sleepers.<ref>{{cite journal |last=Santhi |first=N |author2=Aeschbach D, Horowitz TS, Czeisler CA |year=2008 |title=The impact of sleep timing and bright light exposure on attentional impairment during night work |journal=J Biol Rhythms |volume=23 |issue=4 |pages=341–52 |pmid=18663241 |doi= 10.1177/0748730408319863 |url=http://www.websciences.org/cftemplate/NAPS/archives/indiv.cfm?ID=20082344 |format=abstract online |access-date=2008-08-05 |pmc=2574505}}</ref>

There are four major determinants of cognitive performance and alertness in healthy shift-workers:  circadian phase, [[sleep inertia]], acute sleep deprivation and chronic [[Sleep debt|sleep deficit]].<ref name=Barger>{{cite journal |last1=Barger|first1=Laura|last2=Lockley |first2=SW|last3=Rajaratnam |first3=SMW|last4=Landrigan |first4=CP|title=Neurobehavioral, Health, and Safety Consequences Associated With Shift Work in Safety-Sensitive Professions|journal=Current Neurology and Neuroscience Reports|year=2009|volume=9|pages=9:155–164|pmid=19268039|issue=2 |doi=10.1007/s11910-009-0024-7|s2cid=22518201}}</ref> 
* The circadian phase is relatively fixed in humans<!--direct quote needed-->; attempting to shift it so that an individual is alert during the circadian [[bathyphase]] is difficult.  Sleep during the day is shorter and less consolidated than night-time sleep.<ref name=":1" /> Before a night shift, workers generally sleep less than before a day shift.<ref name=":2" />
* The effects of [[sleep inertia]] wear off after two–four hours of wakefulness,<ref name=Barger /> such that most workers who wake up in the morning and go to work suffer some degree of sleep inertia at the beginning of their shift.  The relative effects of sleep inertia vs. the other factors are hard to quantify; however, the benefits of napping appear to outweigh the cost associated with sleep inertia.
* Acute sleep deprivation occurs during long shifts with no breaks, as well as during night shifts when the worker sleeps in the morning and is awake during the afternoon, prior to the work shift.  A night shift worker with poor daytime sleep may be awake for more than 18 hours by the end of his shift.  The effects of acute sleep deprivation can be compared to impairment due to alcohol intoxication,<ref name=":1" /> with 19 hours of wakefulness corresponding to a BAC of 0.05%, and 24 hours of wakefulness corresponding to a BAC of 0.10%.<ref name=":3" /><ref>{{cite journal | last1 = Dawson | first1 = D | last2 = Reid | first2 =K | title=Fatigue, alcohol and performance impairment|journal=Nature|year=1997|issue=6639|pages=235 |bibcode=1997Natur.388..235D |volume=388 |doi=10.1038/40775 | pmid=9230429| s2cid = 4424846 |doi-access=free }}</ref>  Much of the effect of acute sleep deprivation can be countered by [[nap]]ping, with longer naps giving more benefit than shorter naps.<ref>{{cite journal | last1 = Mollicone | first1 = DJ | last2 = Van Dongen | first2 = HPA | last3 = Dinges | first3 = DF | year = 2007| title = Optimizing sleep/wake schedules in space: Sleep during chronic nocturnal sleep restriction with and without diurnal naps | journal = Acta Astronautica | volume = 60 | issue = 4–7| pages = 354–361 | doi = 10.1016/j.actaastro.2006.09.022 | bibcode = 2007AcAau..60..354M }}</ref>  Some industries, specifically the fire service, have traditionally allowed workers to sleep while on duty, between calls for service.  In one study of EMS providers, 24-hour shifts were not associated with a higher frequency of negative safety outcomes when compared to shorter shifts.<ref name=Patterson>{{cite journal |author1=Patterson PD |author2=Weaver MD |author3=Frank RC |author4=Warner CW |author5=Martin-Gill C |author6=Guyette FX |author7=Fairbanks RJ |author8=Hubble MW |author9=Songer TJ |author10=Calloway CW |author11=Kelsey SF |author12=Hostler D |title=Association Between Poor Sleep, Fatigue, and Safety Outcomes in Emergency Medical Services Providers|journal=Prehospital Emergency Care|year=2012|volume=16|issue=1 |pages=86–97|doi=10.3109/10903127.2011.616261|pmid=22023164 |pmc=3228875}}</ref>
* Chronic sleep deficit occurs when a worker sleeps for fewer hours than is necessary over multiple days or weeks.  The loss of two hours of nightly sleep for a week causes an impairment similar to those seen after 24 hours of wakefulness.  After two weeks of such deficit, the lapses in performance are similar to those seen after 48 hours of continual wakefulness.<ref>{{cite journal |author=Van Dongen HP, Maislin G, Mullington JM, DingesDF|title=The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation|journal=Sleep|year=2003|issue=26|pages=117–126}}</ref>  The number of shifts worked in a month by EMS providers was positively correlated with the frequency of reported errors and adverse events.<ref name=Patterson />