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Work
Schedules > Rotational Shiftwork
 What is the definition of "rotational
shiftwork"?
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.
The definition of rotational shiftwork in this document does not
include fixed shifts like straight nights, straight afternoons or straight
days and, generally, fixed shifts are not discussed here. However, we
should remember that workers on fixed night shifts and those on rotational
shiftwork have much in common due to the constantly changing schedules,
night work and possible disruption to family and social lives.
Also, the length of a shift can vary between 8 and 12 hours. Specific
concerns about the extended workdays (10-12 hour shifts) is discussed in
the Extended
Workday document.
 Why study the effects of shiftwork?
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.
Alternating day, night and afternoon shifts are common in industrial
work, mines, hospitals, as well as food, health, and transportation
services. Shiftwork is also common 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.
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.
Are there adverse health and safety effects
to working shifts?
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.
Scientific studies throughout the world have shown that shiftwork, by
its very nature, is a major factor in the health and safety of workers.
What are the effects on circadian
rhythms?
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 - see
Table 1). 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.
What are the changes in sleep patterns?
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.
What are the gastrointestinal disorders
associated with shiftwork?
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. Certainly 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.
What are the cardiovascular disorders
associated with shiftworkers?
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).
Can shiftwork aggravate existing
conditions?
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.
What are the effects on family and social
life?
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.
What are the safety concerns associated
with working shifts?
The causes of accidents are very complicated. Usually, no single factor
can be identified as having "caused" an accident. The disturbance of
circadian rhythms can affect concentration, motivation, and reaction time,
particularly at night. This combination can result in an increased risk of
accident and injury.
However, there is disagreement about whether shiftworkers have a
greater risk of injury. Studies can be found to show that shiftworkers'
accident rates are less, the same, or more than day workers. Part of the
difficulty with the research is that work conditions are not always the
same on different shifts. For example, the amount of supervision, the
nature of the workload, the backup systems available, and so on all can
vary from shift to shift: these factors can make comparisons inaccurate.
Nonetheless, lack of sleep heightens the decline in performance
normally experienced at certain times of the day. When deprived of sleep,
a worker is not fully aware that his or her performance has deteriorated.
Research has shown that the optimum mental performance level for workers
occurs between 2 and 4 p.m. and maximum general awareness is between 1 and
7 p.m. Performance levels are lowest between 3:30 and 5:30 a.m.
What are some strategies for
improvement?
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 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.
What are some organizational
approaches?
There are several approaches the organization can take to help reduce
the effects of shiftwork. There are also several important considerations
for organizations.
Shift Schedule Design: 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.
- Consider the length of the rotation period (the number of days on
any one shift before switching to the next shift). The optimum length of
the rotation period has been disputed. The most common system has a
rotation period of one week, with five to seven consecutive night
shifts. However, since it generally takes at least seven days for
adjustment of the circadian rhythms, it is argued that just as
adjustment starts to occur, it is time to rotate to the next shift. Some
schedule designers feel that a longer shift rotation should be arranged
so that the worker spends from two weeks to one month on the same shift
that would allow circadian rhythms to adjust. A problem occurs when the
worker reverts to a "normal" day/night schedule on days off, thus,
possibly cancelling any adaptation. Also, longer periods of social
isolation may result.
Others suggest a rapid shift rotation where different shifts are worked
every two to three days. This system may reduce disruption to body rhythms
because the readjustment of circadian rhythms is minimized. It also
provides time for some social interaction each week.
Individual differences and preferences, in the end, play the most
important role. Based on scientific information, there is no way to
determine which is the best length of rotation period.
- Consider the direction of rotation of shifts. It is recommended that
shifts rotate forward from day to afternoon to night because circadian
rhythms adjust better when moving ahead than back.
- Consider the time at which a shift starts and finishes. Early
morning shifts are associated with shorter sleep and greater fatigue. It
is advisable to avoid shift start times as early as 5 or 6 a.m. The
social customs and desires of the specific work force should be
considered as well as the availability of public transportation. The
safety on the streets, in terms of crime and violence, is another
consideration.
- Provide 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.
- Consider 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, the 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 workshift. Exposure to
chemical or physical agents should also be considered when selecting a
shift system.
- Provide time off at "socially advantageous" times like weekends
whenever possible.
- Start a special shift system if production demands result in
extended periods of overtime work.
- Inform shiftworkers 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.
Facilities: The provision of certain facilities can
help the shiftworker 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. When a night worker is
"on call" and must remain in the building, it is advantageous for this
person to be well rested rather than tired and bored.
- 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 shiftworker in mind. Recreational opportunities are often minimal
for workers on "non-day" shifts.
- Consider access to quality day-care for shiftworkers' children. Some
strain on all family members would be alleviated.
Education: Educate employees on the potential health
and safety effects of rotational shiftwork and what can be done to stop
these effects. In particular, education in stress recognition and
reduction techniques is helpful.
What can the individual do to cope with
shiftwork?
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.
Guidelines for Diet and Eating Patterns
- Maintain regular eating patterns as much as possible. Balanced,
varied meals are very important. Keep family meal times the same even
though the work routine constantly changes. Family meals may need to be
altered in content to suit the shiftworker.
- Time meals carefully. Afternoon workers should have the main meal in
the middle of the day instead of the middle of the work shift. Night
workers should eat lightly throughout the shift and have a moderate
breakfast. This way they should not get too hungry while sleeping during
the day and digestive discomfort should be minimal.
- Pay careful attention to the type of food eaten. Drink lots of water
and eat the usual balance of vegetables, fruit, lean meat, poultry,
fish, dairy products, grains and bread. Eat crackers and fruit instead
of pop and candy bars during work breaks. Reduce the intake of salt,
caffeine, and alcohol. Avoid greasy foods, particularly at night.
- Avoid excessive use of antacids, tranquilizers and sleeping pills.
It is healthier to watch what and when you eat, and use relaxation
techniques to aid sleep.
- Relax during meals and allow time for digestion.
Sleep
- Sleep on a set schedule to help establish a routine and to make
sleep during the day easier. Some people may prefer to get a full period
of rest just before the next work shift (as it is with "normal day"
work). Try different patterns of work and sleep to see which is best for
you.
- Make sure that family and friends are aware of and considerate of
the worker's sleep hours and needs. Ensure that the shiftworker has a
comfortable, dark, quiet place to sleep during the day. Air
conditioning, a telephone answering machine, and good blinds on windows
are recommended.
- Make time for quiet relaxation before bed to help get better sleep.
Learn how to relax using muscle relaxation, breathing techniques and so
on. Use mental imagery to block out unpleasant thoughts. If you still do
not fall asleep after an hour, read a book or listen to quiet music on
the radio for a while. If sleep still does not come, reschedule sleeping
hours for later in the day. Limit commitments later in the day to allow
for napping.
Other Important Considerations
- Pay attention to general physical fitness and good health habits.
- Find out about and understand the potential health and safety
effects of shiftwork.
- Learn how to recognize and reduce stress through physical fitness,
relaxation techniques and so on.
- Take leisure seriously.
Document last updated on April 20,
1998
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