Shift Work

The shift plan, rota or roster (esp. British) is the central component of a shift schedule in shift work. The schedule includes considerations of shift overlap, shift .
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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, 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. A shiftworker, particularly one who works nights, must function on a schedule that is not "natural".

Constantly changing schedules can:. 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. 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.


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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.

Many human physical functions follow a daily rhythm or a hour cycle. These cycles are called circadian rhythms. The word circadian comes from the Latin "circa dies" which means "about a day. These rhythmical processes are coordinated to allow for high activity during the day and low activity at night.

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For example, body temperature is highest during the afternoon and early evening 6: However, if the person is working at night, the body temperature does not have as much variation during a hour period as it would normally. The temperature rhythm and other body rhythms get out of sync: This disorientation can lead to feelings of fatigue and disorientation.

Kenny Chesney - Shiftwork (Duet with George Strait)

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.

Disruption of both the quality and quantity of the normal sleep is inevitable in shiftwork particularly where night work is involved. The daytime sleep is seldom as deep or as refreshing as sleep at night. The problem is greater if there is not a quiet, dark, comfortable place to sleep. Even when disturbances are removed, a worker who returns home in the morning may still find sleep impossible or less refreshing. This difficulty occurs because the circadian rhythms are no longer synchronized. Being constantly tired is a typical complaint of shift workers. 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.

Introduction

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.

Shift work and health

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. 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. Workers who require prescription drugs to control certain disorders should be aware that disruption of the circadian rhythm can interfere with the medical treatment of some diseases.

Check with your family physician if you take medication while working shifts. Your pharmacist may also be able to give you some additional information. If you get all your prescription drugs from the same pharmacy, the pharmacists can also advise you if one drug is likely to interact with another one you may be taking. 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. One study reported that night shift had the most incidents, followed by afternoon shifts least incidents in the morning shift.

More incidents are reported on the 4th successive night shift than the first night shift. The best solution to the problems of shiftwork would be to eliminate it but this is not often a practical possibility. Shiftwork is likely to continue to be a reality for a large percentage of Canadian workers. There are several approaches the organization can take to help reduce the effects of shiftwork.

Health effects of shift work and extended hours of work | Occupational & Environmental Medicine

There are also several important considerations for organizations. Optimizing the design of the shift schedule is the most effective way of reducing the health and safety problems. Satisfaction with a particular shift system is the result of a complicated balancing act that is the best compromise for personal, psychological, social and medical concerns.

The provision of certain facilities can help the shiftworker cope better. Educate employees on the potential health and safety effects of rotational shiftwork and what can be done to stop these effects.


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In particular, education in stress recognition and reduction techniques is helpful. People who work shifts face many problems that others do not recognize.

The difficulties stem from the change in eating, sleeping, and working patterns. The following guidelines can help people cope better. Add a badge to your website or intranet so your workers can quickly find answers to their health and safety questions. Although every effort is made to ensure the accuracy, currency and completeness of the information, CCOHS does not guarantee, warrant, represent or undertake that the information provided is correct, accurate or current. CCOHS is not liable for any loss, claim, or demand arising directly or indirectly from any use or reliance upon the information.

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Constantly changing schedules can: There are two basic levels where improvements can be made: The organizational level - primarily through the design of shift schedules, education and better facilities. The individual level - helping workers to get better sleep, a healthier diet, and the reduction of stress.

Six other wards, plus staff at the intervention wards who chose not to change schedules, served as controls. Cholesterol measures, as markers of the risk of heart disease, were taken before and six months after the change in shift schedules. For those whose new schedules reflected all four principles outlined above, there were favourable changes in the cholesterol measures relative to the control group.

Knauth and Hornberger outlined 20 recommendations to prevent or mitigate negative health outcomes of shift work, based on their assessment of the implications of existing research. However, Knauth and Hornberger noted that few studies have evaluated the effects of implementing such guidelines for shift workers, and that the studies that do exist show only limited effects. They suggested that the approach has to be tailored to the specific work context. In addition, there is evidence for gains from designing the shift system in a participatory way, with engagement of workers, unions, supervisors, etc.

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Researchers found beneficial effects from three types of interventions. There is a relatively large literature on possible connections between shift work and several aspects of worker health. In some of these areas, the research findings clearly point to an elevated risk of adverse health outcomes arising from shift work. In other areas, the research is less conclusive. Guidelines have been proposed—examples are given in the section on mitigating adverse effects—to counter health risks facing shift workers.

However, there appear to have been few studies of high quality that evaluate the effects of implementing such guidelines. These findings suggest that we still need more high quality studies to resolve some of the questions regarding the health effects of shift work, such as the possible link to heart disease and the possible role that hormone levels play in the connection between shift work and cancer risk.

In particular, we need more studies that distinguish the different types of shift work, that examine the relative impact of different lengths of time spent on a shift work schedule, and that explore the question of whether some individuals are more susceptible than others to negative effects of shift work.

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We also need more research on the impact of interventions designed to mitigate the adverse consequences of shift work on health. That will require partnerships between workplaces and researchers in testing the potential benefits associated with different interventions. Plain-language summaries Issue briefing. Shift work and health.

Long-term exposure to night shift work may elevate the risk of breast cancer. There are also findings pointing to an elevated risk of colorectal cancer. Some studies indicate an elevated risk of preterm delivery, gastrointestinal disorders and mental health problems among shift workers. Research findings regarding a causal link between shift work and heart disease are inconsistent. Shift workers, especially those working at night, face a higher risk of workplace injury than regular day workers.

Promising approaches to mitigate the adverse effects of shift work include restricting successive evening or night shifts to three shifts, limiting weekend work, moving from backward to forward shift rotation and using a participatory approach to the design of shift schedules. More research is needed to resolve some of the questions regarding the health effects of shift work, and to investigate the impact of interventions designed to mitigate the adverse consequences of shift work on health. Following the approach taken by Williams , one can identify the following categories of shift work: Overview of possible health effects Costa cited research findings that indicate that shift work particularly, night work can lead in the short term to sleep difficulties, digestive problems and anxiety.

In the rest of this Issue Briefing, we look at research findings regarding possible links between shift work and the following health problems that seem to be most commonly cited in the literature: Those most likely to be susceptible to health effects from shift work may be less likely to do such work. Those who develop health problems may drop out of a shift work schedule early. Shift workers could have worse health prior to beginning a shift schedule, associated with their typically lower socioeconomic status.

Shift work and sleep Numerous studies, including an early literature review on shift work and health by Rutenfranz et al. Workplace injury Folkard and Tucker reviewed the literature on the relationship between shift work and work safety. When such influences have been controlled for, the following trends emerged: The risk of incidents rises about 20 per cent from the first to the second hour of the night shift, but then falls steadily, except for an upward blip between 3 a. Incident rates increase on successive night shifts: There is a much smaller increase in incident rates over successive morning or day shifts.

The risk of an incident increases markedly after more than eight hours on duty: Cancer One hypothesis that has emerged in the literature is that working at night might increase the risk of cancer because of disrupted melatonin levels, which affects tumour growth. A Finnish study Pukkala, Auvinen and Wahlberg, reported a significantly higher incidence of breast cancer in female flight attendants who had been working in the airline industry for 15 years or more.

This study hypothesized that exposure to ionizing radiation was the cause, but others have pointed to the exposure to light at abnormal times as the possible source. Similar findings were reported in a study of female flight attendants in Iceland Rafnsson et al. A Norwegian study Tynes et al. However, these studies contained only a few controls for other possible causes of breast cancer.

Participants were asked in how many years they had worked on a rotating night shift and then were followed over the next 10 years to identify incident breast cancer. Those who reported cancer in or previously were excluded. Researchers controlled for a number of established breast cancer risk factors such as age, menopausal status, number of children, body mass index and family history of breast cancer.

Relative to those who had no history of night shift work, women who worked years on rotating night shifts had a risk of developing breast cancer that was eight per cent higher. For those working 30 or more years on night shifts, the risk was 36 per cent higher.

In a study of another cohort of nurses in the U. Pregnancy complications Bonzini, Coggon, and Palmer conducted a systematic review of the literature on the association between several possible pregnancy complications premature delivery; low birth weight; and pre-eclampsia and various working conditions, including shift work or night work, which were grouped together.

Gastrointestinal disorders Rutenfranz et al. Heart disease Rutenfranz et al. Kristensen concluded that shift workers have a 40 per cent higher risk of heart disease compared with regular day workers — that is, a relative risk of 1. They reported a wide range of findings, with a risk ranging from 60 per cent lower to per cent higher relative risks were 0. Most of the larger and more methodologically sound studies found a 40 per cent higher risk of cardiovascular disease among shift workers, but four relatively large studies found no association.

They found indirect evidence of a connection with heart disease: Psychological distress Jamal , drawing on a cross-sectional study of full-time workers in a Canadian city, noted that shift workers report significantly higher burnout, emotional exhaustion, job stress and psychosomatic health problems such as headaches, upset stomach, difficulty falling asleep than workers on a regular day schedule. Diabetes Suwazono et al. Through a participatory approach, agreements were made at the four wards to change the shift scheduling system so as to respect one or more of the following: Maximum of three or four consecutive night shifts followed by an extra day off all four wards.

More regular and predictable but somewhat less flexible schedules three wards. Going from three different shift types to two three wards. Increasing the number of weekends off two wards. Some of these recommendations are also found in the paper by Haus and Smolensky.

Increasing the speed of shift rotation was associated with improved sleep and reduced fatigue for example, from seven consecutive morning shifts to a maximum of three or four consecutive shifts of the same type. Changing from backward to forward rotation also led to improved sleep. However, Bambra et al. Conclusion There is a relatively large literature on possible connections between shift work and several aspects of worker health.

There is also some indication of sleep disruption for those who work shifts that begin in the early morning. The risk of workplace injury appears to be higher for afternoon shift work than on a morning shift, and higher still for night shifts. The risk of incidents is particularly high in the second hour of a night shift. While past review studies had concluded that there was evidence of a causal link between shift work and heart disease, the most recent review of this literature finds only limited evidence of this link.

Medical problems of shift-work. Industrial Medicine and Surgery. The health effects of reorganizing shift work. American Journal of Preventative Medicine. Bara AC, Arber S. Working shifts and mental health — findings from the British Household PanelSurvey Light during darkness, melatonin suppression and cancer progression.

Work environment of Danish shift and day workers. Intervention in shift scheduling and changes in biomarkers of heart disease in hospital wards. Shift work, risk factors and cardiovascular disease. Risk of prematurity, low birthweight and pre-eclampsia in relation to working hours and physical activities: Occupational and Environmental Medicine. Rotating night shift work and the risk of ischemic stroke. American Journal of Epidemiology. Sleep and autonomic nervous system changes — enhanced cardiac sympathetic modulations during sleep in permanent night shift nurses.

Shift work and occupational medicine: Nonstandard shift schedules and the risk of jobrelated injuries. Folkard S, Tucker P. Shift work, safety and productivity. Shift work and the risk of ischemic heart disease — a systematic review of the epidemiological evidence. The mediating role of work-to-family conflict in the relationship between shiftwork and depression. Haus E, Smolensky M. Biological clocks and shift work: Cancer Causes and Control. Burnout, stress and health of employees on non-standard work schedules: Blocking low-wavelength light prevents nocturnal melatonin suppression with no adverse effect in performance during simulated shift work.

Knauth P, Hornberger S. Preventive and compensatory measures for shift workers. Health disorders of shift workers. Increased risk of ischaemic heart disease in shift workers. Cardiovascular diseases and the work environment: