Night Shift and the Risk of Early Death

Working while the rest of the world is sleeping may increase the risk of cancer, heart disease, sleep disorder, mental health....
Sleep isn’t just a time to rest and give your body and brain a break. It’s a critical biological function that restores and replenishes important body systems. Night shift workers deprive the body of sleep and this can lead to exposure to so many health risks.

Several studies show how detrimental night shift jobs can be.

In a study published in the American Journal of Preventive Medicine, scientists led by Dr. Eva Schernhammer, an epidemiologist at Brigham and Women’s Hospital, studied 74,862 nurses enrolled in the Nurses’ Health Study since 1976. The nurses were an ideal group for studying the effects of rotating night shifts on the body, since RNs tend to have changing night shift obligations over an average month rather than set schedules.

After 22 years, researchers found that the women who worked on rotating night shifts for more than five years were up to 11% more likely to have died early compared to those who never worked these shifts. In fact, those working for more than 15 years on rotating night shifts had a 38% higher risk of dying from heart disease than nurses who only worked during the day. Surprisingly, rotating night shifts were also linked to a 25% higher risk of dying from lung cancer and 33% greater risk of colon cancer death.

Why does the body react when sleep cycles change?

 Previous studies showed that too little sleep or the kind that’s disrupted can alter melatonin levels so that the body never powers down and slips into restorative mode, a time when much-needed repairs are made to cells and tissues and supplies of nutrients are replenished to the body. Without this period of rest, important processes such as inflammation, fat and sugar metabolism and immune functions get out of balance, creating fertile ground for heart disease or cancer. The growing number of studies connecting shift work with unhealthy outcomes led the World Health Organization to classify shift work as a probable carcinogen in 2007.

 

Cicardian Rhythms

 One of the most important physiological problems associated with shift work and the night shift in particular, is that working, eating, and sleeping phases are changed.

Mammals have a natural rhythmicity to many bodily functions and these circadian rhythms exist in humans, with many operating on a 24 hour cycle. Such free running cycles, which include body temperature, respiratory rate, urinary excretion, cell division, and hormone production, can be modulated by exogenous factors such as light-dark cycle, social climate, and of course, work schedules.

For example, under normal living conditions, body temperature peaks in the late afternoon with its lowest point occurring in the early hours of the morning. Under experimental conditions, it is possible to reverse this cycle but rotating shift workers usually only succeed in flattening the curves. Body temperature records are often used as a surrogate measure of disruption of circadian rhythm, but it is probably too simplistic to link this measure directly to performance

Family and Social Life

Workers who engage in shift work or who work long hours can experience considerable disruption of family and social activities as many of these rhythms of the general population are oriented around the day. Saturday and Sunday work, for example, can preclude involvement in sporting events or religious activities. Shift work can thus lead to social marginalisation.

Family and marital responsibilities can be severely disrupted by shift work or long hours. Childcare, housework, shopping, and leaving a partner alone at night can all lead to marital strain and family dysfunction. On the positive side, for those shift workers who like relatively solitary leisure pursuits or who abhor the crowds often find that shift scheduling provides them with greater opportunities to do what they want to do in their non-working time

Mental Health

Studies show that shift orders are usually stressed and sometimes have psychiatric problems.

Cardiovascular Disorders

The effect of overtime or long hours of work has been less extensively investigated. One mortality study from California showed increased rates of arteriosclerotic heart disease for male occupational groups in increasing proportions of the population who worked more than 48 hours a week.

The 48 hour week cut off was an arbitrary one with information taken from censuses, and the study has not been replicated. The publicity surrounding the Japanese phenomenon of Karoshi (sudden vascular death) and overwork is relevant here but the published studies are little more than case series and thus lack epidemiological rigor.

Gastrointestinal Disorders

 Many shift workers complain of digestive disorders, which may be a reflection on the poor quality of catering on some shifts. Night workers seem to have the most complaints of dyspepsia, heartburn, abdominal pains, and flatulence. The data in these studies are not particularly robust. It is necessary to realise that psychosomatic disorders are common in the general population and to recognise the influence of several other factors including Helicobactor pylori, infection, family history, and lifestyle. 

Reproductive Effects

Reproductive effects include disruption of the menstrual cycle, increased risk of spontaneous abortion and low birth weight.
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Working graveyard shifts forces the body to operate against its circadian rhythm and this can lead to Shift Work Sleep Disorder which can cause depression, anxiety, substance abuse and other mood disorders.  
Someone still has get that job done. Policemen, firefighters, physicians, night guards and others have to do the job. Make health your priority.  

Credits: time.com/, oem.bmj.com