 What is shiftwork?
 Shiftwork in Canada
 Why there is a need for shiftwork
 Health and safety concerns of shiftwork
 Circadian Rhythm
 Optimal shift scheduling
 Shift work systems
 Strategies for dealing with shiftwork
A shift worker is anyone who follows a work schedule
that is outside of the typical "9 to 5" business day
National Sleep Foundation
Shiftwork differs from a “normal” work day in two ways:
Work is performed regularly during times other than morning
and afternoon
2) At a given workplace, more than one shift is worked during the
24-hour day
A shift often lasts 8 hours but may be shorter or longer
 Approximately 25% of the North American working
population work shiftwork
CCOHS stat
Shiftwork in Canada
 In 2005, the General Social Survey conducted by
Statistics Canada found that 28% of employed
Canadians (4.1 million workers) were shift workers
 82% worked full time (>30 hrs/week)
Shiftwork in Canada
 In 2005, women accounted for only 37% of full time
shift workers, but made up 69% of part time shift
 Men made up 57% of the total number of workers who
do shift work (all full- and part-time)
Shiftwork in Canada
 In 2005, rotating shifts and irregular schedules were
the most common types of shift work, accounting for
2.3 million full-time workers
 Even though these are considered among the most
difficult shifts because the body cannot properly adjust
to the sleep pattern changes, rotating child care is
difficult to find and health effects can be profound
Types of Shiftwork in Canada
Shiftwork is not new!
 Deliveries were made in ancient Rome at night in order to
relieve street congestion
 Bakers habitually work through the late night hours
 Soldiers and firefighters have always been accustomed to
night shifts
 With industrialization came long working days with teams
of workers relaying each other to maintain blast furnaces,
rolling mills, glassworks, and other workplaces where
continuous operations were required
Who works shiftwork
Traditionally: shift work was required to provide vital services and emergency cover at
all hours of the day and night and also to maintain long-term industrial processes
Today: Shiftwork is found in financial and retail services where employees deliver
services around the clock , supermarkets, newsroom and banks, call centres
Why the need for shiftwork?
 The need for "around the- clock" workers has
increased dramatically in industry during recent years
 This reliance may be attributed to three main sources,
namely technological, economic and social
 Economically: utilization of equipment/resources
If equipment is available 168 h per week and used for only 8h a
day for 5 days a week gives only 24% utilization
 Socially: convenience (24-hour shopping, restaurants,
Why is shiftwork a problem?
The problems associated with shiftwork fall under three
1) Economic: people tend to dislike shiftwork which
may require extra pay for workers
2) Social: many workers feel that shiftwork disrupts
their personal and family life
3) Health and Safety: Rotating shifts have been
blamed for the “human error” involved with nuclear
power plants incidents, airplane accidents, and other
catastrophic accidents
Individual health factors
The Interaction Between Personal
Factors and Shiftwork
“Some of the most serious and persistent problems shift workers face are frequent sleep
disturbance and associated excessive sleepiness, which can lead to poor concentration,
absenteeism, accidents, errors, injuries, and fatalities. The issue becomes more
alarming when you consider that shift workers are often employed in the most
dangerous of jobs, such as firefighting, emergency medical services, law enforcement
and security”
- National Sleep Foundation
Individual Health and Shiftwork
Frequently changing work
schedules can lead to:
Shiftwork may also be
independent predictor of
 Increased risk of insomnia
 Increased body mass
 Chronic fatigue
 Increased body mass index
 Anxiety and depression
 Prevalence of obesity
 Cardiovascular and
 Waist-to-hip ratio
gastrointestinal problems
 Impaired reproduction in
 Circadian rhythm
Atkinson et al. (2008)
Fatigue Symptoms
 Sleepiness
 Irritability
 Increased
susceptibility to illness
 Depression
 Reduced alertness,
concentration and
 Lack of motivation
 Headaches
 Giddiness
 Loss of appetite and
digestive problems
Personal Factors
 Many functions of the human body have long been
recognized to exhibit periodic variations
 Of concern are those fluctuations which occur on a
daily basis called circadian rhythms
 Among those body functions which show diurnal
 Sleep
 Readiness to work
 autonomic processes
 heart rate
 body temperature
 Blood pressure
Circadian Rhythms
Circadian Rhythms
 Circadian comes from the Latin word “circa dies”
which means “about a day.”
 Many human physical functions follow these daily
rhythms or 24-25 hour cycles
 Sleeping, walking, digestion, secretion of adrenalin,
body temperature, blood pressure, pulse, other body
 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
Circadian Rhythms
 Involvement in shiftwork, in particular night work,
results in a disruption of these inherent rhythms.
 These phase shifts occur slowly over a considerable
 Some people can start to adapt after 2-3 days while some
take much longer.
 Adjustment on “days off” does not happen because
most individuals go back to normal day schedules
Circadian Rhythms
• Circadian rhythm phase shifts induced by shiftwork
can have significant effects on the worker in terms of:
performance efficiency
sleep patterns
family and social life
Shiftwork Disorder
 Shift work sleep disorder is a circadian rhythm sleep
 The main complaint for people with shift work sleep
disorder is excessive sleepiness. Other symptoms
 Insomnia
 Disrupted sleep schedules
 Reduced performance
 Difficulties with personal relationships
 Irritability/depressed mood
Circadian Type
 There are 2 broad classifications of personality
associated with circadian type which are differentiated
between the “morning larks” and the “night owls”:
1)Morning types (M-types) aka larks:
 Have early bedtimes & wake times and
are more alert in the morning hours
2)Evening types (E-types) aka owls:
 Are more aroused later at night and
experience difficulty waking up early
Circadian Type & Shiftwork
 M-types have been found to be less tolerant of night
shift for 3 reasons:
They find it extremely hard to stay awake at night, or
to sleep late in the morning (standard night worker behaviors)
2. They appear to be more susceptible to environmental
zeitgebers (time cues)
When M-types are isolated from all time cues, they exhibit
"free-running" circadian rhythms with an approximate length
of 24.3 hours in comparison to E-types who tend to have slower
rhythms of approximately 25.5 hours
Circadian Type & Shiftwork
 Night work is best suited to those individuals with a
longer running period as this leads to a phase delay in
behaviour (i.e.- a later bedtime)
 It has been questioned whether morningness-
eveningness is a stable, genetically determined trait, or
simply a reflection of a recently developed habit
 Example: An M-type individual could temporarily
acquire E-type characteristics, but may revert back to
their morningness tendency at a later stage
Shift Scheduling
What is the most optimal shift
1) There is no “golden” schedule that fits every
operation’s needs
2) The schedules that perform the best:
balances operational requirements, employee
preferences and lifestyle issues, and takes into account
the human factors considerations that influence safety
and employee performance
3) The best schedules can only be achieved by involving
the employees in the shift schedule selection process
Why involve employees in shiftwork
 Through education, participatory design, and group
implementation of employee involvement in schedule
design/redesign financial and performance benefits
increase substantially compared to schedules decided by
management alone
 Resulting in:
 Better employee morale and satisfaction with scheduling
 Lower absenteeism and turnover
 Increased operational efficiency
 Improved daytime sleep quality
 Decreased physical and
psychological circadian
General Notes on Scheduling
 An early morning start (before 7:00am) for the
morning shift should be avoided
 Shifts should rotate forward:
 The schedule should be simple and predictable –
people want to plan their lives!
Shift Systems
Four Important Questions Regarding
the Features of Shift Systems
Does a shift extend into hours that would be
normally be spent asleep?
2. Is the shift worked throughout the entire seven-day
week, or does it include days of rest, such as a free
3. Into how many shifts are the daily work hours
divided? Are there two, three, or more shifts per day?
4. Do the shift crews rotate or do they work the same
shifts permanently?
 Kogi (1985)
Other Important Features of Shift
 The starting and ending time of a shift
 The number of workdays in each week
 The hours of work in each week
 The number of shift teams
 The number of free days per week or per rotation cycle
 The number of consecutive days on the same shift,
which may be a fixed or variable number
 The schedule by which an individual works or has a
free day or days
Types of Shift Systems
 Rotational shiftwork
 Rapidly rotating shift systems
 weekly/monthly rotating systems
 Permanent night shift systems
Rotational Shiftwork
 Shifts rotate or change according to a set schedule
 Shifts can be continuous (24/7) or semi-continuous (2-
3 shifts/day without weekends)
 Workers take turns working all of the shifts in the
Rapidly Rotating Systems
 Switches once or twice during a week
 Found to cause the least disturbance to the
endogenous body clock
Weekly/Monthly Rotating Systems
 Changes every week or every month
• Provide for both the physical and social needs of
the worker
 A forward direction (morning-afternoon/eveningnight) is preferred for shift rotation
• Means minimum disturbance of diurnal rhythms
Weekly/Monthly Rotating Systems
 Weekly rotating shifts are generally regarded as
being the worst system
• Because disruptions to the circadian rhythms lead
to a cumulative sleep debt
• These systems tend to be the most commonly used
(employment equity)
Permanent Night Shift System
 An acceptable level of circadian rhythm
adjustment can normally be achieved with this
shift system
 This nocturnal orientation may in turn improve
sleep and performance
 Permanent night shifts are preferred when safety is
Permanent Night Shift System
 Family units appear to prefer permanent night
work as it facilitates the organization of domestic
 Some individuals working this shift feel socially
Extended Workdays
 One further variable to consider in terms of the
design of shift systems is that of the length of the
 Some suggest a shift should not exceed 8 hours
(except where the work is low in physical and
mental demands) while others recommended that
extended work periods of 9 to 12 hours may be
Advantages of twelve hour shifts
Management Perspective
 Increased productivity,
reduced errors
Increased continuity and
Reduced adaptation time
Higher project completion
Reduced absenteeism
Lower attrition and turnover
Improved morale
“Dedicated” employees
Employee Perspective
More days off
Longer/better breaks
Few consecutive days worked
Less commuting required
Twice as many weekends off
Improved family & social life
Improved Morale
More home study time
More frequent “recovery” days
Better use of vacation time
Better utilization of personal time
Elimination of double
 Elimination of evening shifts
Disadvantages of 12 Hour Shifts
Employee Perspective
Management Perspective
 Harder to sustain vigilance
 Potential comprise in alertness
and performance
 Increased exposure to work
related stress
Diminished communication or
personal interaction
Unequal distribution of work
Increased risk of getting “out of
Increased “moonlighting”
Increased ergonomic risk
More difficult absence coverage
Difficulties of change
Limited social time during work days
Sleep schedule inflexibility
Irregular pay weeks
Concerns of older workers
Reduced tolerance of long commutes
Difficult to schedule meetings
Decreased tolerance to physically
demanding jobs
Pay loss when day is missed
Driver fatigue
Fast-rotating 12-hour schedules
Longer hours away from home in
Increased percentage of night shifts
Summary of Features for 8 and 12Hour Shift Schedule
Strategies for Improving Problems
Associated with Shiftwork
 Most obvious solution?
 There are two basic levels where improvements can be
1) The organizational level - primarily through the
design of shift schedules, education and better
2) The individual level - helping workers to get better
sleep, a healthier diet, and the reduction of stress.
Organizational Approaches
 Talk to employees to see shift preferences
 Consider time at which shift starts/ends
 Provide time off during socially advantages times
 Let employees know schedules well in advance
 Allow some flexibility for staff to switch shifts but
make sure people aren’t double-shifting
 Provide same facilities & support for all shifts
Organizational Approaches
 Educate employees on how to cope with shiftwork
 Consider exposure limits, breaks required
 Consider different lengths for shifts
 Keep schedule regular and predictable
 Keep long shifts and overtime to a minimum
 Plan for some weekends or holidays off
Good Practice Guidelines for the
Work Environment
 Adequate lighting & proper heating
 Same facilities available for each shift
 Access to healthy meals
 Encourage interaction between employees
 Keep in contact about employees about their
 Encourage exercise
 Encourage breaks when sleepy
Individual Approaches
 Pay attention to food/nutrition
 Exercise
 Figure out how to optimize sleep time
 Get information on shiftwork health risks
 Have a social life
 Seek advice from doctor if you have health
 Take more frequent breaks when fatigued
Individual Approaches
 Talk to family and friends about sleep schedule
 Restrict or avoid caffeine, cigarettes and alcohol
 Avoid long commutes when sleepy
 Use co-workers to keep you awake on the job
 Talk to co-workers for tips on how to cope
 Don’t leave the boring tasks for the end of the shift
when most fatigued
 Try not to alter sleep schedule too much on “days
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