Shift Work and Your Health

Rotating 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.

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