Shift work explained

Shift work is an employment practice designed to keep a service or production line operational at all times. The practice typically sees the day divided into shifts, set periods of time during which different groups of workers perform their duties. The term "shift work" includes both long-term night shifts and work schedules in which employees change or rotate shifts.[1] [2] [3]

In medicine and epidemiology, shift work is considered a risk factor for some health problems in some individuals, as disruption to circadian rhythms may increase the probability of developing cardiovascular disease, cognitive impairment, diabetes, altered body composition[4] and obesity, among other conditions.[5] [6]

History

The shift work system in modern industrial manufacturing originated in the late 18th century.

In 1867 Karl Marx wrote on the shift work system in Capital, Volume 1:

Capitalist production therefore drives, by its inherent nature, towards the appropriation of labour throughout the whole of the 24 hours in the day. But since it is physically impossible to exploit the same individual labour-power constantly, during the night as well as the day, capital has to overcome this physical obstacle. An alternation becomes necessary, between the labour-powers used up by day and those used up by night ... It is well known that this shift-system, this alternation of two sets of workers, predominated in the full-blooded springtime of the English cotton industry, and that at the present time it still flourishes, among other places, in the cotton-spinning factories of the Moscow gubernia. This 24-hour process of production exists today as a system in many of the as yet 'free' branches of industry in Great Britain, in the blast-furnaces, forges, rolling mills and other metallurgical establishments of England, Wales and Scotland.[7]

The Cromford Mill, starting from 1772, ran day and night with two twelve-hour shifts.

Health effects

See main article: Shift work sleep disorder. Shift work increases the risk for the development of many disorders. Shift work sleep disorder is a circadian rhythm sleep disorder characterized by insomnia, excessive sleepiness, or both. Shift work is considered essential for the diagnosis. The risk of diabetes mellitus type 2 is increased in shift workers, especially men. People working rotating shifts are more vulnerable than others.[8]

Women whose work involves night shifts have a 48% increased risk of developing breast cancer.[9] [10] 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. The WHO's International Agency for Research on Cancer listed "shift work that involves circadian disruption" as probably carcinogenic.[11] [12] Shift work may also increase the risk of other types of cancer.[13] 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.[14] [15] 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.[16]

Shift work also increases the risk of developing cluster headaches,[17] heart attacks,[18] fatigue, stress, sexual dysfunction,[19] depression,[20] dementia, obesity, metabolic disorders, gastrointestinal disorders, musculoskeletal disorders, and reproductive disorders.Shift work also can worsen chronic diseases, including sleep disorders, digestive diseases, heart disease, hypertension, epilepsy, mental disorders, substance abuse, asthma, and any health conditions that are treated with medications affected by the circadian cycle. Artificial lighting may additionally contribute to disturbed homeostasis.[21] Shift work may also increase a person's risk of smoking.

The health consequences of shift work may depend on chronotype, that is, being a day person or a 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.[22] Nighttime workers sleep an average of one–four hours less than daytime workers.[23]

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.[24]

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,

Notes and References

  1. Web site: Shift work, Definition(s) of . 2014-09-25 . Sloan Work . Family Research, Boston College . amp .
  2. Web site: Shift work and health. Institute for Work & Health, Ontario, Canada. 2010. 2018-08-05. ...employment with anything other than a regular daytime work schedule.
  3. Web site: Biological Rhythms: Implications for the Worker. 1991. U.S. Congress Office of Technology Assessment.
  4. 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
  5. Delezie J . Challet E . Interactions between metabolism and circadian clocks: reciprocal disturbances. . Ann N Y Acad Sci . 2011 . 1243 . 1. 30–46 . 22211891 . 10.1111/j.1749-6632.2011.06246.x . 2011NYASA1243...30D . 43621902 .
  6. Scheer FA . Hilton MF . Mantzoros CS . Shea SA . Adverse metabolic and cardiovascular consequences of circadian misalignment. . Proc Natl Acad Sci U S A . 2009 . 106 . 11 . 4453–8 . 19255424 . 10.1073/pnas.0808180106 . 2657421 . 2009PNAS..106.4453S . free .
  7. Marx, Karl. "The Working Day" Capital: Volume 1, 1867.
  8. Yong. Gan. Shift work and diabetes mellitus: a meta-analysis of observational studies. Occupational and Environmental Medicine. 2014. 10.1136/oemed-2014-102150. 25030030. 11 August 2014. 72. 1. 72–78. free.
  9. News: Running on Empty: Fatigue and Healthcare Professionals. Caruso. Claire C.. August 2, 2012. NIOSH: Workplace Safety and Health. Medscape and NIOSH.
  10. Megdal . S. P. . Kroenke . C. H. . Laden . F. . Pukkala . E. . Schernhammer . E. S. . Night work and breast cancer risk: A systematic review and meta-analysis . 10.1016/j.ejca.2005.05.010 . European Journal of Cancer . 41 . 13 . 2023–2032 . 2005 . 16084719 .
  11. http://www.iarc.fr/ENG/Press_Releases/pr180a.html IARC Press release No. 180
  12. Web site: The health of night shift workers . 2007-11-30 . WNPR, Connecticut Public Radio . Connecticut Public Radio, WNPR.
  13. Parent . M. -E. . El-Zein . M. . Rousseau . M. -C. . Pintos . J. . Siemiatycki . J. . Night Work and the Risk of Cancer Among Men . 10.1093/aje/kws318 . American Journal of Epidemiology . 176 . 9 . 751–759 . 2012 . 23035019 . free .
  14. Women who work nights are 9% more likely to have an early menopause. 2019-03-01. Human Reproduction. 34. 3. 539–548. 10.1093/humrep/dey390. 30753548. Stock. D.. Knight. J. A.. Raboud. J.. Cotterchio. M.. Strohmaier. S.. Willett. W.. Eliassen. A. H.. Rosner. B.. Hankinson. S. E.. Schernhammer. E.. 7210710. free.
  15. Stock. D.. Hankinson. S. E.. Rosner. B.. Eliassen. A. H.. Willett. W.. Strohmaier. S.. Cotterchio. M.. Raboud. J.. Knight. J. A.. Schernhammer. E.. 2019-03-01. Rotating night shift work and menopausal age. Human Reproduction. en. 34. 3. 539–548. 10.1093/humrep/dey390. 30753548. 7210710. 0268-1161. free.
  16. Web site: Why Working The Night Shift Has Major Health Consequences. 2015-01-06. HuffPost. en. 2019-03-09.
  17. Beck . E. . Sieber . W. J. . Trejo . R. . Management of cluster headache . American Family Physician . 71 . 4 . 717–724 . 2005 . 15742909.
  18. Vyas MV . Garg AX . Iansavichus AV . Costella J . Donner A . Laugsand LE . Janszky I . Mrkobrada M . Parraga G . Hackam DG . Shift work and vascular events: systematic review and meta-analysis. British Medical Journal (Clinical Research Edition). 345. e4800. July 2012. 22835925. 3406223. 10.1136/bmj.e4800.
  19. Fido A . Ghali A . Detrimental effects of variable work shifts on quality of sleep, general health and work performance. Med Princ Pract . 2008. 17 . 6 . 453–7. Abstract . 10.1159/000151566. 18836273 . free .
  20. Slanger . Tracy E . Gross . J. Valérie . Pinger . Andreas . Morfeld . Peter . Bellinger . Miriam . Duhme . Anna-Lena . Reichardt Ortega . Rosalinde Amancay . Costa . Giovanni . Driscoll . Tim R . Foster . Russell G . Fritschi . Lin . Sallinen . Mikael . Liira . Juha . Erren . Thomas C . Person-directed, non-pharmacological interventions for sleepiness at work and sleep disturbances caused by shift work . Cochrane Database of Systematic Reviews . 8 . CD010641 . 23 August 2016 . 2016 . 10.1002/14651858.CD010641.pub2 . 27549931 . 8406755 .
  21. Navara . Kristen J. . Nelson . Randy J. . The dark side of light at night: physiological, epidemiological, and ecological consequences . Journal of Pineal Research . October 2007 . 43 . 3 . 215–224 . 10.1111/j.1600-079X.2007.00473.x . 17803517 . free .
  22. Adan . Ana . Archer . Simon N. . Hidalgo . Maria Paz . Di Milia . Lee . Natale . Vincenzo . Randler . Christoph . Circadian Typology: A Comprehensive Review . Chronobiology International . 24 September 2012 . 29 . 9 . 1153–1175 . 10.3109/07420528.2012.719971 . 23004349 . 7565248 .
  23. Book: 10.1016/B978-1-4377-1703-7.10029-5 . Shift Work Disorder . Teri J. . Barkoukis . Jean K. . Matheson . Richard . Ferber . Karl . Doghramji . Therapy in Sleep Medicine . limited . 378–389 . 2012 . Ftouni . Suzanne . Sletten . Tracey L. . Barger . Laura K. . Lockley . Steven W. . Rajaratnam . Shantha M.W. . 978-1-4377-1703-7 .
  24. Book: Fatigue and Shift Work (Tools And Techniques) eBook: Dr Angela Moore, Alec Jezewski: Amazon.co.uk: Kindle Store. 9 September 2014. 3 February 2016.

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