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Understanding and minimizing the effects of shiftwork

(by Dr. Joti Samra, for Lifespeak)


About 30% of employed Canadians, approximately 3 million, work shift—non-standard work hours that cover a wide variety of work schedules. Shift work can consist of fixed shifts or shifts that rotate or change according to a set schedule.

About 30% of employed Canadians, approximately 3 million, work shift—non-standard work hours that cover a wide variety of work schedules. Shift work can consist of fixed shifts or shifts that rotate or change according to a set schedule. The length of shifts can vary between 8 to 12 hours. Shift work is critical to our economy due to our society’s need for around-the-clock provision of medical, transportation, and protection services. Shift work is also common in industrial work, mines, and in workplaces where technical processes cannot be interrupted without affecting the product and/or where expensive equipment is used more profitably when in constant operation.


Although shift work is a job requirement for many employees, there are a number of workers who choose shift work because it allows for more free time or enables their families to manage child care needs. Interest in the effects of shift work on people has grown because many experts have pointed to rotating or extended shifts for the “human error” connected with nuclear power plant incidents, air crashes, and other catastrophic incidents.


While shift work is essential to the economy and may be a necessary choice for some, researchers have found compelling evidence that working shift takes a physical and psychological toll on workers. Many workers find that shift work disrupts their family and personal life, limiting their ability to participate in leisure and family activities and making it difficult to find or maintain long-term relationships with a spouse. This fact is important because of the correlation between amounts and quality of social interaction and physical and mental health.


People who do shift work report fatigue as the most common health complaint. Dr. Joti Samra, Clinical Psychologist and Researcher and member of LifeSpeak’s Vancouver roster of expert speakers, points out that 1/3 of shift workers experience a severe clinical disturbance in their sleep in the form of shift work sleep disorder. Dr. Samra explains that this is a clinically recognized condition where a constant or recurrent pattern of sleep disruption results in insomnia or fatigue. Shift work has also been associated with cardiovascular disease, hypertension and gastrointestinal disorders, and for women, reproductive health problems and breast cancer. Researchers have identified three interrelated factors that contribute to the association of shift work and health issues:


  • Disruption of circadian rhythms, the body’s natural 24-hour clock – 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.
  • Adoption or worsening of unhealthy behavior – shift workers have been found to more likely be smokers, to drink heavily, to eat poorly and have weight issues.
  • Physiological impacts of stress – the physiological stress of sleep interruption stimulates the body to release higher levels of stress hormones which can lead to increased feelings of anxiety, depression, irritability and apathy, and decreased levels of concentration and focus. In fact, research has proven that over the long term, shift workers experience actual shrinkage in the brain glands (amygdala and hippocampus) that control focus, concentration, morals and values because cortisol (stress hormone) inhibits the production of chemicals responsible for these brain functions.


Since it is not a practical possibility to eliminate shift work, employers can implement some strategies to reduce the effects of shift work on employees. The Canadian Centre for Occupational Health and Safety recommends two 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.


The Canadian Centre for Occupational Health and Safety recommends several organizational strategies for reducing the effects of shift work.


  1. Shift Schedule Design: Optimizing the design of the shift schedule is the most effective way of reducing the health and safety problems. The length of a rotation period (the number of days on a shift before switching to the next shift) is a key consideration. The longer shift rotation (two weeks to a month) allows for a worker’s circadian rhythm to adjust. Conversely, rapid shift rotations (two to three days) can also be beneficial since it reduces disruption to the body rhythms because it minimizes the readjustment of circadian rhythms and provides for some social interaction each week. Other strategies include:
    • Shifting rotations forward from day to afternoon to night because circadian rhythms adjust better when moving ahead than back.
    • Considering the time at which a shift starts and finishes. Early morning shifts, starting at 5 or 6 a.m. are associated with shorter sleep and greater.
    • Providing a rest period of at least 24 hours after each set of night shifts. The more consecutive nights worked, the more rest time should be allowed before the next rotation occurs.
    • Using alternative forms of organizing work schedules—for example, extended work days of ten or twelve hours have been used. It has the advantage of fewer consecutive night shifts and longer blocks of time off. However, because additional fatigue from long work hours may also have adverse effects, the physical and mental load of the task should be considered when selecting the length of a work shift.
    • Providing time off at socially advantageous times like weekends whenever possible.
    • Informing shift workers of their work schedules well ahead of time so they and their families and friends can plan activities. Allow as much flexibility as possible for shift changes. Keep schedules as simple and predictable as possible.
  2. Facilities: The provision of certain facilities can help the shift worker cope better.
    • Give attention to the work environment. For example, good lighting and ventilation are important on all shifts. Do not widely separate workstations so that workers at night can remain in contact with one another.
    • Provide rest facilities where possible. Whenever a person must remain at work after a night shift to attend a meeting or a training session, providing rest facilities is advisable.
    • Provide good cafeteria services so a balanced diet can be maintained. The nutritional needs differ between day shifts and other shifts because of circadian rhythms.
    • Consider offering facilities for social activities with the needs of the shift worker in mind. Recreational opportunities are often minimal for workers on “non-day” shifts.
    • Consider access to quality day-care for shift workers’ children. Some strain on all family members would be alleviated.
  3. Education: Educate employees on the potential health and safety effects of rotational shift work and what can be done to stop these effects. In particular, education in stress recognition and reduction techniques is helpful.


By supporting employees through strategies that mitigate some of the very serious physical and mental health concerns brought on by shift work, organizations can lay the foundation for workers to address, on the individual level, the difficulties they face from the changes in eating, sleeping, and working patterns.




  1. “The Health of Canada’s Shift Workers” by Margot Shields, Canadian Social Trends, Statistics Canada-Catalogue No. 11-008, Summer 2003
  2. “Rotational Shift Work”, Canadian Centre for Occupational Health and Safety (


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