Report on shiftwork, health and aging 2018

I have been asked to comment on shiftwork, specifically nightshift work for aging physicians at SJRH.


The following information has been gathered from emergency medicine and occupational medicine sources in North America, mainly from Canada, as well as a brief research project completed at SJRH.


There is no exact, commonly recognized age at which someone is considered an older worker. Some studies have focused on people older than 55, while other studies examined those 45 years or older.



Statistics Canada (2011) states that “Nearly one person in four in the labour force projected to be 55 or more: The aging of the baby boomers, which is largely behind the projected decline in the overall participation rate, has had a major impact on the aging of the labour force. Between 2001 and 2009, the proportion of people in the labour force aged 55 and over rose from 10% to 17%, an increase of 7 percentage points in nine years. The first baby boomers reached the age of 55 in 2001. This increase is projected to continue from 2010 to 2021, when the succeeding cohorts of baby boomers in turn reach 55. By 2021, according to three of the five scenarios, nearly one person in four in the labour force (roughly 24%) could be 55 years of age or over, the highest proportion on record.”


Our bodies change as we age. People reach full physical maturity or development at around the age of 25 years. Then after a period of relative stability, our bodies begin to show signs of aging. Most of these changes are first noticed at ages 40 or 50, but changes can occur (or start) as early as 20 or 25. These changes include:

  • Maximum muscular strength and range of joint movement: In general, people lose 15 to 20% of their strength from the ages of 20 to 60. However, every person is different and there is a large range between individuals. However, most jobs do not require a person to use all their strength. Older employees may be able to perform the same tasks as a younger worker, but they may be working closer to their maximum level. The musculoskeletal system weakens over time, resulting in a decreased capacity for load-bearing work. Keep in mind that, for example, highly repetitive motions — doing the same thing, over and over again — can cause physical problems at any age.

    As we age, the body loses some ‘range of motion’ and flexibility. People may be used to certain range of movements at one task or workstation. Being less flexible or able to reach could cause problems in some unpredictable situations that require unusual movements.

  • Cardiovascular and respiratory systems: The ability of the heart, lungs and circulatory system to carry oxygen decreases. Between the age of 30 and 65, the functional breathing capacity can reduce by 40%. These changes can affect the ability to do extended heavy physical labour, reduce the body’s ability to adjust to hot and cold conditions.
  • Regulation of posture and balance: In general people may find it harder to maintain good posture and balance. When seated or standing still, this may not be a problem. However, accidents that happen because someone loses their balance do happen more often with age. Work that requires precise adjustments, strong muscular effort (including lifting and carrying), joint movements at extreme angles, or those done on a slippery or unstable surface, will be affected by poorer posture. Unexpected bumps or shocks may cause a more serious problem than with a younger worker.
  • Sleep Regulation: As we age, our body is not able to regulate sleep as well as it used to. How long a person sleeps, and how well they sleep, can additionally be disrupted by changing work hours or by light and noise. The impact on employees is especially a concern for older shift or night workers. They might need more recovery time between shifts or extended workdays. Use of shift rotations that are the least disruptive to sleep patterns are preferred.
  • Thermoregulation (Body Temperature): Our bodies are less able to maintain internal temperatures as well as less able to adjust to changes in external temperature or due to physical activity. This change means that older workers may find heat or cold more difficult to deal with than when they were younger. It also means that if they are doing hard manual labour, they may get overheated more easily.
  • Vision: Vision changes with age. We will notice we cannot see or read from certain distances as well as we used to. This reduction in the “amplitude of accommodation” (the ability to see or adjust focus in certain distance ranges) is normally corrected with prescription glasses. Changes also occur in the peripheral visual field (how well you can see in the areas to the side of you, that you’re not directly looking at), visual acuity (how exact, clear, and “unfuzzy” things appear), depth perception (how far away things seem), and resistance to glare, and light transmission. These changes are normally not noticed by a person unless there is poor lighting or there are sources of glare. Someone might also notice that they can’t see as well when they’re reading something when text size is small, or when there is poor contrast between the text and the background. Brighter lighting (that is suitable for the task) and well laid-out documents which avoid small print are important.
  • Auditory (Hearing): Hearing also changes. We may not be able to hear as well at higher frequencies (high pitch sounds). Most often, this change is noticed as the inability to listen to a particular voice or sound in a noisy environment. As well, people who work with a lot of background or noise may have difficulty hearing verbal instructions.


  • Changes in mental capacityalso occur as a person ages. Older people may not think as quickly and clearly as they once did. Also, it may take longer to learn new skills. Much of the research on cognitive functioning (how people think and how quickly they do it) has been done in laboratory settings. As a result, there is information available on how individuals score on specific tests or tasks. However, there has been little testing to see how these results apply in the “real world”. In particular, at work people naturally develop different habits to match or suit their learning and working styles.
  • Generally speaking, fluid intelligence (such as inductive reasoning, selective attention, ‘dual-task’ activities, and information processing) declines with age, while verbal tasks and vocabulary (talking and expressing themselves) remain constant or improve. Tasks that depend on short-term memory usually take longer. Older workers tend to use experience and expertise when working and may find it hard to work with complex or confusing stimuli. This means they might find it hard to do tasks in which they have to do (or think) a lot of different things quickly or at one time. They may also find it tricky to work in a busy environment where lots is going on. They may be less able to focus attention only on information relevant to the task at hand, especially in “new” situations. This means that there may be so much going on in new situations that they aren’t sure what to prioritize, what to pay attention to, and what to ignore.
  • Training requirements may be different for older workers. Since learning is based on previous experience, training may need to be more “practically” based. New skills need to be explained in a way that fits into what they already know. Justification and the logic behind the information — why you’re doing what you’re doing — are more important. Training may take longer than with younger workers. There may also be a need for more assistance or practice. However, several studies show that there may not be a difference in how well someone works once the learning curve has been reached.


From: Projected trends to 2031 for the Canadian labour force. Statistics Canada, 2011

Many studies are looking at the effects older workers have on the workforce. They are also looking at the effects different types of work have on older workers’ bodies, and how to keep them safe and free of injury.

Some studies noted that older workers work slower and can’t easily make quick decisions. However, this change is balanced because older workers often tend to be more accurate in their work and make more correct decisions than faster, younger co-workers.



The term “rotational shiftwork” covers a wide variety of work schedules and implies that shifts rotate or change according to a set schedule. These shifts can be either continuous, running 24 hours per day, 7 days per week, or semi-continuous, running 2 or 3 shifts per day with or without weekends. Workers take turns working on all shifts that are part of a particular system.

Workers on fixed night shifts and workers on rotational shiftwork schedules have much in common due to the constantly changing schedules, night work and potential disruption to family and social lives.

The length of a shift can vary between 8 and 12 hours.

Shiftwork is a reality for about 25 percent of the North American working population. Interest in the effects of shiftwork on people has developed because many experts have blamed rotating shifts for the “human error” connected with nuclear power plant incidents, air crashes, medical error, and other catastrophic accidents.

The overall prevalence of shift work is similar for women and men. However, there are gender differences in shift work patterns by sector of employment. Many more women than men work in the health care sector, while many more men than women work in manufacturing.

Many workers find that shiftwork disrupts their family and personal life and leads to health problems including chronic fatigue and gastrointestinal disorders. On the other hand, some workers prefer shiftwork because it usually allows for more free time.


Circadian disruption:

Many human physical functions follow a daily rhythm or a 24-hour cycle. These cycles are called circadian rhythms. The word circadian comes from the Latin “circa dies” which means “about a day.” Sleeping, waking, digestion, secretion of adrenalin, body temperature, blood pressure, pulse and many other important aspects of body functions and human behaviour are regulated by this 24-hour cycle. These rhythmical processes are coordinated to allow for high activity during the day and low activity at night.

Normally, the body uses cues from its processes and from the environment such as clock time, social activities, the light/dark cycle, and meal times to keep the various rhythms on track. For example, body temperature is highest during the afternoon and early evening (6:00 p.m.) and lowest in the early morning (4:00 a.m. or just before sunrise). However, if the person is working at night, the body temperature does not have as much variation during a 24-hour period as it would normally. The temperature rhythm and other body rhythms get out of sync: these rhythms also get out of phase with the person’s activity pattern. This disorientation can lead to feelings of fatigue and disorientation. “Jet lag” is a term often used to describe these feelings.

Some rhythms adapt in two to three days while others change only after longer periods. People adapt to new schedules at different rates as do the different rhythms. Total reversal of circadian rhythms may never occur because on days off most people go back to a “normal” day schedule. Frequent changes in schedule and disruption to circadian rhythms can lead to chronic fatigue and other health problems.



A shiftworker, particularly one who works nights, must function on a schedule that is not “natural”. Constantly changing schedules can:

  • upset one’s circadian rhythm (24-hour body cycle),
  • cause sleep deprivation and disorders of the gastrointestinal and cardiovascular systems,
  • make existing disorders worse, and
  • disrupt family and social life.

The International Agency for Research on Cancer (IARC) has concluded that “shiftwork that involves circadian disruption” is considered a Group 2A carcinogen and “probably carcinogenic to humans.” Group 2A means that this conclusion was based on “limited evidence of carcinogenicity in humans and sufficient evidence of carcinogenicity in experimental animals”. IARC based their conclusion on studies on long-term night workers who have shown a higher risk of breast cancer than women who do not work at night. These studies have involved mainly nurses and flight attendants. These results are consistent with animal studies that have shown that constant light, dim light at night, or simulated chronic jet lag can increase tumour development.

The exact causes of this association are still not known. These results may be explained by the disruption of the circadian system that is caused by exposure to light at night. This exposure can alter sleep-activity patterns, suppress melatonin production, and disregulate genes involved in tumour development. Among the many different patterns of shiftwork, those that include nightwork are most disruptive to the circadian system.

(From: IARC 2007. Press Release N°180. IARC Monographs Programme finds cancer hazards associated with shiftwork, painting and firefighting.)



Gastrointestinal and digestive problems such as indigestion, heartburn, stomachache and loss of appetite are more common among rotating shiftworkers and night workers than among day workers. It is less clear if more serious conditions such as peptic ulcers are more common in shiftworkers. The irregular work, sleep and eating schedules are not helpful for the proper care of ulcers.

Given the irregularity in type and timing of meals, it is not surprising that the night worker is more likely to have a poorer diet. At night, the loss of appetite often leads to increased snacking on “junk” food rather than eating a full, well-balanced meal. Feelings of fatigue may encourage the consumption of beverages with caffeine (coffee, cola) to help the worker stay awake.



Shiftwork is not absolutely associated with cardiovascular disease. However, heart rate and blood pressure have been shown to follow a circadian rhythm. Life-style can directly affect an individual’s health. Therefore, it is very important that a shiftworker follows exercise programs to maintain an adequate level of fitness. It is also very important not to smoke, to have good dietary habits and to participate in leisure activities.

A study of Swedish men with a history of heart attack showed they were significantly more likely to have been shiftworkers than those men without a history of heart attack. Another study showed that the modification of shift rotation schedules by changing the direction of rotation of shifts to a forward direction (for example, days -> afternoons -> nights) can significantly decrease the levels of several coronary risk factors, e.g., triglycerides, glucose, and urinary excretion of catecholamines (chemicals like adrenalin that occur naturally in the body).



Working irregular shifts have been associated in some studies with preterm birth, and low birth weight. No conclusions can be made based on the studies available, and more studies are being conducted.


Family and Social Impact

Compared with people who work straight days, shiftworkers report more interference to their family lives, especially the time available to spend with spouses and children. This fact is very important since the amount and quality of social interaction is related to physical and mental health. Individuals who cannot establish regular routines in their daily activities have difficulties planning for family responsibilities and coping with physical and mental fatigue as effectively as non-shiftworkers. Participation in clubs, sports and other organized activities is very difficult since they are usually geared to the normal day schedule. The lack of regular social contact can lead to feelings of loneliness and isolation. In addition, quality child care facilities aimed at meeting the needs of shiftworkers is almost nonexistent.



The Institute for Work and Health (IWH) reports that there is strong evidence that night, evening, rotating and irregular shifts are associated with in increased risk of occupational injury. This risk is associated with worker fatigue, and less supervision and co-worker support during non-daytime shifts. There is an increased risk of post-shift motor vehicle collisions.

One study reported that night shift had the most incidents, followed by afternoon shifts (least incidents in the morning shift). The risk of an incident was 20% more during the first to second hour of a night shift, as well as a small raise between 3 and 4 am. More incidents are reported on the 4th successive night shift than the first night shift.


Emergency Medicine

The percentage of working doctors 65 and older climbed from 13 percent in 1975 to 18 percent in 2004 and is expected to rise even higher as the impending wave of baby boomers reach 65, according to the American Medical Association. We all know that emergency medicine is a young man’s sport. EM had the joint highest rate of burnout at 55% among all specialties in 2016.


In the September 2006, Annals of Surgery, a study was published that found for three complicated surgeries, including heart bypasses, surgeons older than 60 had higher death rates. This was especially true if the surgeons did not do a large volume of cases, as many surgeons reduce their caseloads as they age.

A February 2005 study in the Annals of Internal Medicine suggested a similar correlation, albeit with a slightly different reasoning. The study stated that heart attack patients were 10 percent more likely to die in the care of a doctor 20 years out of medical school compared with a recent graduate. According to the study, mortality rates did not depend on the physicians’ age as much as on the number of years since medical school.


While these studies paint a rather bleak picture for aging in medicine, a recent Emergency Physicians Monthly survey found that EPs recognize an array of advantages to working with older physicians. Among the responses, readers credited their older colleagues with calmness, efficiency, fewer arguments, the ability to work with fewer resources and use fewer consultants, better technical skills, finesse and grace.


“Many older physicians were the pioneers in emergency medicine and propelled the specialty forward,” wrote one respondent. “This is a group of highly motivated individuals who did not just put in their shift and leave. The presence of the senior physician is often a deterrent to the on-call staff from eating the young emergency physician alive. It is the friction of the road that fine tunes the machine.”


Yet, at the Saint John Regional Hospital, we have no full time clinical emergency physicians over the age of 60 years (there are several in peripheral EDs and Urgent care who also work at SJRH). What happens to old EPs? In the current system, the rotating shifts, high stress, and life-and-death decisions eventually take their toll. Little by little, physicians lose the physical and mental ability required to make efficient and proper decisions under these stressors. Many opt to leave the specialty, either completely or by going part time.


Our local research program has looked at the following 2 issues:

First, do coping mechanisms affect burnout rates in emergency care workers? We found that task-oriented coping (i.e. doing something about stress) was associated with decreased risk of burnout, while emotion-oriented coping (i.e. complaining, feeling sorry for yourself, etc.) was associated with increased risk of burnout.

We also looked at ways EPs “did something” about night shifts and asked if increasing age affected Emergency Physician willingness to work night shifts?


Knowing that there is established evidence of the physiological toll of night shifts on older workers, we wished to assess if such pressures translated into actions by older emergency physicians resulting in them working fewer night shifts in a tertiary urban emergency department.

Unless excluded from nights for medical reasons, or having requested more night shifts by personal preference, all EPs are allocated a proportional number of nights according to the total number of weekly shifts they work. Night shifts are paid at a preferential rate (20% higher hourly rate than day and evening shifts). Shifts can be traded by mutual agreement. EPs may choose to work full time (more than 3 shifts per week) or part time.


We compared choices to work full or part time, mean number of night shifts worked, and scheduled versus actual night shifts worked for a group of 23 EPs, 12 of whom were classified as younger (under 40 years) and 11 who were classified as older (over 40 years). One outlier who worked night shifts preferentially and who accounted for around one third of all night shifts was excluded from the analysis of night shifts.


Even without a formal night shift policy in place, we found that that older EPs were more likely to work part time clinical emergency shifts supplemented by other clinical, administrative and academic work and work fewer night shifts annually.  There was also a trend towards older EPs relinquishing their night shifts in this tertiary level ED.


So what do we do with EPs when they pass 50 years? Do we cast them aside or restrict them to urgent care centers and non-acute patients? Are they still capable of the full duties of any emergency medicine specialist? What are the options?


First of all, we need to acknowledge, and ensure NBMS acknowledges, that emergency medicine is not like family practice. We cannot slow down, limit our practice, eliminate call and after-hours work and peter out some time in our 80s. Some can become administrators, teachers, researchers, but for the rest, just cutting back on shifts, could negatively affect their abilities.


However, according to the EPM poll, many physicians want to create more viable options for aging physicians. 93% of respondents said that emergency medicine groups should offer alternatives for aging physicians. 61% of respondents said that older physicians should be offered the alternative of doing fewer or no night shifts or working less hours overall. 87% agreed that these benefits should affect pay. This did not seem to be an issue with older physicians as most were more financially established. Only 13% and 8% respectively, said older physicians should be limited to less acuity or only work when accompanied by another physician. The age recommended for attaining these alternatives ranged from 52 to 70, median being 55.


And what about competency? Most of any age can answer questions correctly during a standard day time shift. How does age affect the ability to answer questions correctly when being bombarded with multiple questions at a time, at 4 am, after changing your sleep cycle, in an uncontrolled noisy environment? How does age affect the ability to do procedures that require fine motor skills in this same environment?

Answers to these questions do not only rely on age but also on the individual’s motivation and health. Someone who exercises regularly, studies daily and without health problems is going to be more competent than a sedentary, 2 pack/day smoker with peripheral vascular disease, who sits around reading journal articles all day!


EM is a physical as well as a mental specialty. Running from room to room, constantly changing sleep cycles, while performing procedures that require fine motor skills and rapid decision making is physical. Cognitive ability relies on adequate cerebral circulation.



Shifts should be scheduled and paid at a rate to allow flexibility and facilitate trading of night shifts to reflect the number of ageing EPs in the department.


Innovative options such as weighted pay rates, splitting night shifts, designating antisocial shifts (such as weekend late evenings) in lieu of night shifts, should be considered.


Older physicians should be permitted to work less hours to facilitate part time work, with respective decreases in income.

Options for urgent care work should be available and paid appropriately with respect to training and experience.


Offering these alternatives will attract and retain the more experienced and efficient physicians.


Older physicians should be given opportunities to teach, take on administration and research, while developing these skills for younger EPs to ensure that they have these opportunities in the future.


All physicians need to practice the same health recommendations we ask of our patients.


All physicians need to study and keep current.


Employers have a legal responsibility to accommodate medical limitations for all physicians, which are likely to be more frequent with increased age.





Projected trends to 2031 for the Canadian labour force


IARC Monographs Programme finds cancer hazards associated with shiftwork, painting and firefighting


Waljee JF, Greenfield LJ, Dimick JB, Birkmeyer JD. Surgeon age and operative mortality in the United States. Annals of surgery. 2006 Sep;244(3):353.


Choudhry NK, Fletcher RH, Soumerai SB. Systematic review: the relationship between clinical experience and quality of health care. Annals of Internal medicine. 2005 Feb 15;142(4):260-73.


Carter MW, Lapierre SD. Scheduling emergency room physicians. Health care management science. 2001 Dec 1;4(4):347-60.


Atkinson P, Vaillancourt C, Talbot J, Howlett MK. Does increasing age effect Emergency Physican willingness to work night shifts?CJEM 2014;16(Supp 1):s50


Howlett M, Doody K, Murray J, LeBlanc-Duchin D, Fraser J, Atkinson PR. Burnout in emergency department healthcare professionals is associated with coping style: a cross-sectional survey. Emerg Med J. 2015 Sep 1;32(9):722-7.

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