Shift Work and Your Health

overworked-workerRotating shifts causes difficulties because it works in opposition to the body’s normal circadian rhythms, the most influential being the sleep/wake cycle.  There is also the matter of social isolation that comes from working when everybody else is asleep, and vice-versa.  One of the complications of changing shifts is the incidence of gastrointestinal upset.  Shift workers have a notoriously high occurrence of ulcers, based partly on disruption of sleep patterns and partly on the activation of H. pylori infection if it is at all present and waiting for the opportunity to strike.  (Pietroiusti, 2006)  (Segawa, 1987)  Chronic fatigue, untimely sleepiness, and even failure to fall asleep are some other physical interruptions caused by shift work.  Among the worst social perturbations is divorce, an element that hits some jobs more than others, law enforcement being a prime example.

Canada’s Institute for Work and Health delved into this topic and found that night work is associated with an increase in breast cancer among women who work rotating shifts for long durations.  (IWH, 2010)  The etiology of breast cancer is mostly uncertain, but about one fourth its incidences can be attributed to genetic factors.  At least a little blame has been put on light at night and its effect on melatonin, the hormone produced by the pineal gland that communicates information about light to different parts of the body in order to regulate biologic rhythms.  When the eye’s pupil detects changes in brightness—night—it sends the sleep message to the brain by way of melatonin.  When this activity gets stymied, melatonin is not able to exert its anti-cancer character, and the risk of breast cancer is elevated after a prolonged time. (Schernhammer, 2001)   (Hansen, 2001)   Melatonin is a popular sleep aid, especially for those experiencing jet lag, but few have associated it with anti-cancer function.  (Knower, 2012)  An interesting realization in this circumstance is the body’s inability to manufacture vitamin D from exposure to natural light, raising the question of the appropriateness of supplementation.  (Shao, 2012)  Among researchers’ quests is the determination of the actual concentrations of vitamin D in women who have survived breast cancer and whether or not insufficiency is prevalent among sufferers, survivors, and healthy controls.  (Trukova, 2012)  (Blask, 2009)

Little is known about sleep taken at night, and even less about sleep taken during the day, when years of natural law dictate otherwise.  Nobody really knows how much sleep is necessary for optimal health.  But there is evidence that long sleepers and very short sleepers have increased mortality.  (Ferrie, 2007)  The first part of sleep lasts about fifteen minutes, and is labeled as Stage 1.  If you are awakened from this stage, you may even deny having been asleep.  Stage 2 occupies about half of sleep time, yet is the least understood part.  Being deprived of this stage results in almost total sleep loss because this is the part from which other stages develop.  This, by the way, is the stage affected by medications and sleep aids.  Stages 3 and 4 are combined into the slow-wave-sleep stage, differing only by the number of delta waves measureable by an EEG.  Contrasted to Stage 2, this is the one common to most persons, and is the one compensated after long periods of sleep deprivation.  This is the one needed for body repair and the activity of growth hormone(s).  Rapid eye movement (REM) sleep is the best known stage and throughout its duration the body is virtually paralyzed and loses its ability to regulate heat.  Dreams, which are deemed necessary to psychological well-being, occur here.  REM, dominating the late stages of sleep episodes, is strongly influenced by circadian rhythm.   Daytime sleep is normally one or two hours shorter than night time sleep.  REM, therefore, is shortened.  This adds to the alertness problems of the night shift.

A modern concern about shift work is increased risk of type 2 diabetes and the metabolic syndrome, compounded by the possible elevation of cardiovascular jeopardy.  This affects women more than men, but the combination of obesity, high triglycerides, and low HDL cholesterol is common to both.  (Karlsson, 2001)  Years of rotating night shift work are associated with weight gain that comes from failed attempts to eat right and from limited time for exercise.  And to think that all this is precipitated by disturbed circadian periodicity.  Eating on the run and mindless snacking are more common among night workers than their daytime counterparts.  Even if day and night workers had the same major CVD factors, the night workers admit to increased job strain and greater at-work physical exertion, both of which contribute to the altered parameters that incite metabolic syndrome.  (Esquirol, 2009)  In Japan, where the work ethic is ubiquitously strong, different work schedules have been associated with a rise in the incidence of diabetes.  (Morikawa, 2005)  (Suwazono, 2006)  Over the long term, changes are evident not only in daily glucose levels, but also in glycosylated hemoglobin (HbA1c), which measures glucose over an extended time.  (Suwazono, 2009)

Workplace cafeterias commonly close at night.  Workers are then left to their own culinary devices, and that often translates to unhealthy eating habits by virtue of convenience and time constraints.  A healthy work force is a boon to productivity and accident prevention, areas in which companies can demonstrate an interest that supersedes complaining about the opposite.  If a company is reactive, it can get you to the First-Aid station or to the HR person for failure to perform.  By being proactive, it can prevent both while saving money on bandages and the expense of training a replacement.

If there is a best-case scenario for shift work, scheduling a rotation that lasts at least six weeks seems to work by affording enough time to adapt one’s circadian dance to the situation.  There are those who prefer steady nights, but that breed is rare.  If we think adapting to factory work schedules is tough, we should look at those who work in the emergency room.  At least some of us have a scapegoat for tight trousers.

References

Blask DE.
Melatonin, sleep disturbance and cancer risk.
Sleep Med Rev. 2009 Aug;13(4):257-64. Epub 2008 Dec 17.

Costa G.
Shift work and breast cancer. 
G Ital Med Lav Ergon. 2010 Oct-Dec;32(4):454-7.

Esquirol Y, Bongard V, Mabile L, Jonnier B, Soulat JM, Perret B.
Shift work and metabolic syndrome: respective impacts of job strain, physical activity, and dietary rhythms.
Chronobiol Int. 2009 Apr;26(3):544-59.

Ferrie JE, Shipley MJ, Cappuccio FP, Brunner E, Miller MA, Kumari M, Marmot MG.
A prospective study of change in sleep duration: associations with mortality in the Whitehall II cohort.
Sleep. 2007 Dec;30(12):1659-66.

Ha M, Park J.
Shiftwork and metabolic risk factors of cardiovascular disease.
J Occup Health. 2005 Mar;47(2):89-95.

Hansen J.
Light at night, shiftwork, and breast cancer risk.
J Natl Cancer Inst. 2001 Oct 17;93(20):1513-5.

Institute for Work and Health (IWH)
Scientific Symposium, Toronto, 12 April, 2010
Scientific Symposium on the Health Effects of Shift Work
http://www.iwh.on.ca/shift-work-symposium

Karlsson B, Knutsson A, Lindahl B.
Is there an association between shift work and having a metabolic syndrome? Results from a population based study of 27,485 people.
Occup Environ Med. 2001 Nov;58(11):747-52.

Knower KC, To SQ, Takagi K, Miki Y, Sasano H, Simpson ER, Clyne CD.
Melatonin suppresses aromatase expression and activity in breast cancer associated fibroblasts.
Breast Cancer Res Treat. 2012 Jan 12.

Kroenke CH, Spiegelman D, Manson J, Schernhammer ES, Colditz GA, Kawachi I.
Work characteristics and incidence of type 2 diabetes in women.
Am J Epidemiol. 2007 Jan 15;165(2):175-83.

Morikawa Y, Nakagawa H, Miura K, Soyama Y, Ishizaki M, Kido T, Naruse Y, Suwazono Y, Nogawa K
Shift work and the risk of diabetes mellitus among Japanese male factory workers.
Scand J Work Environ Health. 2005 Jun;31(3):179-83.

Paul A. Schulte, PhD, Gregory R. Wagner, MD, Aleck Ostry, PhD, et al
Work, Obesity, and Occupational Safety and Health
American Journal of Public Health. Mar 2007; 97:3, 428-436

Pietroiusti A, Forlini A, Magrini A, Galante A, Coppeta L, Gemma G, Romeo E, Bergamaschi A.
Shift work increases the frequency of duodenal ulcer in H pylori infected workers.
Occup Environ Med. 2006 Nov;63(11):773-5.

Prasai MJ, George JT, Scott EM.
Molecular clocks, type 2 diabetes and cardiovascular disease.
Diab Vasc Dis Res. 2008 Jun;5(2):89-95.

Schernhammer ES, Laden F, Speizer FE, Willett WC, Hunter DJ, Kawachi I, Colditz GA.
Rotating night shifts and risk of breast cancer in women participating in the nurses’ health study.
J Natl Cancer Inst. 2001 Oct 17;93(20):1563-8.

Scott AJ.
Shift work and health.
Prim Care. 2000 Dec;27(4):1057-79.

Segawa K, Nakazawa S, Tsukamoto Y, Kurita Y, Goto H, Fukui A, Takano K.
Peptic ulcer is prevalent among shift workers.
Dig Dis Sci. 1987 May;32(5):449-53.

Shao T, Klein P, Grossbard ML.
Vitamin D and Breast Cancer.
Oncologist. 2012 Jan 10.

Suwazono Y, Sakata K, Okubo Y, Harada H, Oishi M, Kobayashi E, Uetani M, Kido T, Nogawa K.
Long-term longitudinal study on the relationship between alternating shift work and the onset of diabetes mellitus in male Japanese workers.
J Occup Environ Med. 2006 May;48(5):455-61.

Suwazono Y, Dochi M, Oishi M, Tanaka K, Kobayashi E, Sakata K.
Shiftwork and impaired glucose metabolism: a 14-year cohort study on 7104 male workers.
Chronobiol Int. 2009 Jul;26(5):926-41.

Trukova KP, Grutsch J, Lammersfeld C, Liepa G.
Prevalence of Vitamin D Insufficiency Among Breast Cancer Survivors.
Nutr Clin Pract. 2012 Jan 6.

*These statements have not been evaluated by the FDA.
These products are not intended to treat, diagnose, cure, or prevent any disease.

Print Friendly, PDF & Email