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Shiftworking
Working Hours
Shiftwork
Human Behaviour
Biopsychosocial model
Mental Distress
Dr. Craig Jackson
Senior Lecturer in Health Psychology
BCU
“Peoples’ health should be
no worse at the end of a
working day than it was at the
start”
M.J. Harrington
(1997)
“People who work sitting
down get paid more than
people who work standing
up”
Ogden Nash
(1902 - 1971)
Core Occupational Diseases (EU)
Chemical
Inorganic
Chemical
Organic
Biological
Physical
Dusts
Physical
Others
Cadmium
CS5
Zoonoses
Asbestos
Radiation
Chromium
Benzene
Hepatitis
Silica(te)
NIHL
Mercury
Chlorine
TB
Mesothelioma
Cataract
Manganese
Aromatics
Vibration
Nickel
P.aromatics
Dermatitis
Lead
Isocyanates
21st Century Workplaces
• Global companies and operations
• Leaner & Meaner managers
• Gender issues
• Disability issues
• Migrant issues
• Longer & less fixed working hours
• Shorter contracts
• Dirty jobs out-sourced
Regulation of working hours
1800 – 1900
12 hour days & 6 day weeks
Thomas Paine 1737 - 1809
Age of Reason
Rights of Man
Annie Besant 1847 – 1933
Reformist movement
Fabian Society
Secular Society
“Fruits of philosophy”
“The Link”
“White slavery in London”
1889
Humanitarian concerns influenced change
48 hour week + regular rest = increased productivity
Regulation of working hours
1900 – 1970
progressive reduction in working hours
traditional work patterns
1970 
working hours increase
shiftwork increases
irregular hours increase
24 hour processing
technology
unpaid extended hours
flexible working
annualised hours
Regulation of working hours
Linear Assumption of workers and productivity
units
reality
units
assumption
time
time
Pieter Bruegel 1563
Wembley Stadium
326.5 Million pounds – Multiplex 2002
730 Million pounds
British Library
32 Million pounds – estimate
511 Million pounds – 10 yrs late
Scottish Assembly
37 Million pounds – estimate
431 Million Pounds – 3 yrs late
PaddyPower .com
Fatigue
Stress
Pilot Fatigue
“Nodding off”
Uncontrolled spontaneous episodes of sleep
Can last seconds or minutes
Disengages from reality and becomes unresponsive
Fail to respond to outside information
Aircraft cruising at 450 knots on glide path can travel nearly
730 feet during a one-second lapse.
123 feet
Near Misses and Hits
Regulation of working hours
Environmental effects upon Performance
Disturbed concentration
Impaired memory
Impaired decision making
Mood changes
Sleep disturbance
Increased risk taking
Paying Attention!
Coping with Extreme Hours
European directive on working time
Organisation of work
Min. daily rest period of 11 consecutive hours per 24 hours
1 rest break where working day > 6 hours
Min. uninterrupted rest period of 35 hours per 7 day period
Max. of 48 work per week
Min. 4 weeks paid annual leave
European directive on working time
Night work
Mean 8 hours work in any 24 hour period
Free health assessment before assignment and at regular intervals
Transfer to day work when suffering health problems connected
with night work
Night work and shifts
Protection appropriate to the nature of the night work
Prevention and protection services on parity with day workers
Take account of principles adapting work to the workers
Derogations
Certain jobs
junior docs
Certain industries
press
media
utility provision
Circumstances
where rests are not practicable
Does not apply to:
health checks
provision of health and safety facilities
Nearly 900 extra consultants will be needed by 2010
compensate for a reduction in doctors’ hours due to EWTD
BMJ 2002;325:855
Shiftwork
Any work regularly undertaken outside “normal” working hours
Normal working hours = 07:00 – 18:00
Nights
Early am
Evening
Fixed
Rotating
Eight hour
Twelve hour
Effects
Circadian disruption
Sleep loss
Fatigue
Social disruption
Circadian Rhythms
Body Temp
Pulse
Urinary excretion
Blood pressure
Hormonal changes
Mental Performance
Physical Performance
Physiologically determined
Socially modified & Externally cued
Circadian Rhythms
Adjustment to shiftworking
Aprrox. 7 days to adjust to shift
External cues hamper adjustment
Nightworking sometimes never achieves adjustment
Slow rotating shifts
partial adjustment
continual adjustment
continual disrhythmia state
Rapid rotating shifts
no adjustment
Adjustment to shiftworking
stress
strain
Phase-shifting of
waking and
sleeping hours
Impaired
performance
Impaired health
Disturbed
relationships
modifying
factors
organisational
effects
> Absenteeism
> Accidents
> Labour turnover
< Productivity
Individual
characteristics
Job-related factors
Environment
Domestic
Colquhoun & Rutenfranz 1980
Cardiovascular problems associated with shiftwork
Increased Ischemic Heart Disease (IHD)
Knutsson et al. 1986, 1988
Increased risk of IHD and Myocardial Infarction (MI)
Akerstedt et al. 1986
Increased risk of Coronary V related disorders – Permanent Nightworkers
Teiger 1984
Some studies show NO increased risk
Bursey 1990
Chan et al. 1987, 1993
Kobayashi et al. 1992
Cardiovascular problems of shiftwork
Liu & Tanaka 2002 – Japanese working men study
260 cases
445 controls
Working Hours, Sleeping Hours and Acute MI
Working hours related to:
increased risk in year prior to AMI
increased risk in month prior to AMI
x2 increase in risk for overtime (>61 hours)
x2-3 increase in risk for <5 hours sleep
x2-3 increase for lack of sleep (2 or more days with <5 hours sleep)
lack of sleep & few days off in recent past show > odds than those in past
Overtime work and lack of sleep may be related to AMI
Gastrointestinal disorders and shiftwork
Indigestion
(Chan et al. 1987)
(Poole et al. 1992)
Reflux
Peptic Ulceration
(Waterhouse et al. 1992)
Related to:
irregular hours
circadian dysrhythmia
poor catering facilities
inequality in GP access
Gastrointestinal disorders and shiftwork
Irritable Bowel Syndrome (IBS)
13-52% new referrals to GI (Walker et al. 1990)
Some occupations have > G.I than others (Cucino & Sonnenburg, 2001)
IBD < in manual workers and farmers
IBD > in sedentary workers
Assoc. with occupation difficult to prove
• shift workers seen as greatest risk of IBS
• especially nightworkers
• night workers present in GI more than day workers
Access / Availability reasons ?
Research fails to answer:
genuine aspects ?
psychosocial aspects of workers ?
effects of shiftwork lifestyle ?
Mental health problems and shiftwork
Increased stress
Alcohol consumption
Neuroticism
Review by Cole et al. 1990 OM
Sources of performance impairment
Day sleepers
Endogenous factors
Cortisol >
Temp. >
Exogenous factors
Daylight
Noise
Societal bias
Endogenous factors
Melatonin >
Temp. <
Exogenous factors
Darkness
Societal bias
Night wakers
Current evidence
Performance impairments more likely:
on nightshift
vs.
morning or evening
on advancing shifts
vs.
delaying shifts
on rapid rotating shifts vs.
slower rotation
on irregular shifts
regular shifts
vs.
at changeover periods
in older shiftworkers
where work is stressful
Inconsistencies:
12 hour shifts
Sex
Performance effects – methodological considerations
Task
monotony
cognitive skills
Measures
speed
accuracy
efficiency
Individual aspects
motivation
perceived importance
age
ability
health
activity
Situation / context
supervision
morale
distractions
12 hour shifts
Williamson et al. 1994
Australia
8hr vs. 12hr rotating
computer operators
psych health improved
reduced tiredness
Duchon et al. 1994
Canada
8hr vs. 12hr rotating
miners
improved sleep
improved performance
Chan & Gan
Singapore
8hr vs. 12hr rotating
electronic workers
no health differences
some headaches
Groups prone to negative effects
Over 50’s
Morning types
Long sleepers
Personality types
Heavy domestic commitments
Multiple jobs
Some physical conditions
Psychiatric problems
Employee Selection Issues ?
Pre-employment counselling ?
Standard Shiftwork Index (SSI) Barton et al. 1995
Questionnaires
Work Context + Shift System
Health
Well-being
Individual Differences
Normative Data
Training & Education
Survey current work schedule
Analyse data
health effects
performance
safety
quality of life
Identify problem area(s)
Recommend schedule changes
Shiftworker education
Asses & review
information & awareness
coping methods education
lifestyle changes info
Intervention strategies
Organisation
Slow / fast rotation (task considerations)
Start times
Rest breaks
Expert systems
Environmental Modification
Bright lights
Mood lights
Temp. compensation
Workload
Facilities
Evaluate process
Evaluate outcome
Health Surveillance
Do what?
How often?
Individual Adjustment
Pharmacological help
Behavioural
sleep management, diet, exercise, counselling
Overtime working
Extension of normal workday
Extension beyond 8 hours (08:00 / 09:00 - 16:00 / 17:00)
Non-paid is still overtime
Increasing in UK
especially managerial & professional groups
1990 UK had twice as many more employees on >48 hrs than any other EU
countries
More common in males
Percentage of employees working less
than 16 and more than 48 hours a week
Overtime working
(Europe 1990)
Percentage of European employees working <16 hrs per week, and > 48 hrs
per week, 1990
20
<16
>48
% 10
0
B
DK
F
If graph was males only?
G GR NL IRL
I
LU
P
E
UK AV
0
ILO
Rep.
Czech
Czech
Republic
Turkey
Turkey
S. Korea
South
Korea
Iceland
Iceland
Swiss
Switzerland
Mexico
Mexico
Hungary
Hungary
USE
United States
Canada
Canada
Japan
Japan
Ireland
Ireland
UK
Britain
Australia
Australia
Portugal
Portugal
Greece
Greece
Italy
Italy
Spain
Spain
Denmark
Denmark
France
France
Germany
Germany
Norway
Norway
Sweden
Sweden
Austria
Austria
Belgium
Belgium
Finland
Finland
Netherlands
Netherlands
Employees working more than 40 hours a
week - % of labour force, 1996
Employers >40hrs per week as % of labour force, 1996
100
Male
Female
80
60
40
20
Source: ILO
Potential effects
cardiovascular
mental health
Stress
immune system
gastrointestinal
musculoskeletal
social effects
Fatigue
Exposure
performance impairment
safety problems
over-exposure
Cardiovascular disorders and overtime
Increased Risk
> 60hrs
> 48hrs
Night school students
50 – 60 hrs
Overtime (females only)
No increased Risk
>10 hrs overtime / week
“Overtime”
BP & Serum Chol.
Karoshi
Range of CVIs 65%> if 60hrs / wk
1980
Mental Health
1985
SITES WITH MASS
PSYCHOGENIC
ILLNESS (USA)
KIBBUTZIM
(ISRAEL)
?
No. of
symptoms

>8
hrs/
day
< 50
Smoking

Burnout
X
Psychiatric
Status (Crown
Crisp)
Stimulant
use/ Sleep
disturbance
Exhaustion/
Insomnia

1987
MUSIC THERAPISTS
(USA)
1990
BUS DRIVERS (UK)
?
1991
COACH DRIVERS
(AUSTRALIA)
30-70
1992
FEMALE HOSPITAL
STAFF (USA)
32-19
1994
FACTORY WORKERS
(JAPAN)
?
Psychiatric
State (GHQ)

1995
ACCOUNTANT (UK)
?
Psychiatric
Status (GHQ)

1991 1995
MANAGERIAL STAFF
(USA/JAPAN)
? 50 55
Stress (OSI)

1991 1995
CLERICAL STAFF
(USA/JAPAN)
ACADEMICS
?
Stress (OSI)

50
Stress (SACL)
X
1996


Health & Well-being:
Methodological Issues
Mostly Cross-sectional studies
Direction of any association ?
Lag
Healthy worker / Survivor Effects
Response Rates
Control Groups
Exposure Assessment
Outcome Measures
Performance Effects:
Accidents
General Data Analyses suggests:
Rise in accident rates after 9hrs work
Cognitive (simulation) studies suggests errors increase after 8 hrs work
HOWEVER
Shift change from 8 to 12 hrs
Safety record stays same
Attitudes ?
Safety culture increased ?
Schedule org ?
Nature of work ?
Existing Gaps in Research
Irregular Hours
Increased concomitant exposure to other hazards
Reproductive effects
Family / Social influences
Behavioural Effects
Effect Modifiers
Intervention procedures
Further Reading
Cooper, C.L., and Sutherland, V.J: Job Stress, Mental Health and Accidents
among Offshore Workers in Oil and Gas extraction Industries. Journal of
Occupational Medicine (1987) 29.
Gann, M., Corpe, U., and Wilson, I. (1990) The Application of a Short Anxiety
and Depression Questionnaire to Oil Industry Staff. Journal of the Society of
Occupational Medicine 40:
Glazner, L.K. Shift Work and its effects on fire fighters and nurses.
Occupational Health & Safety, July 1992
Hanecke, K., Tiedemann, S., Nachreiner, F., and Grzech-Sukalo, H: Accident
risk as a function of hour at work and time of day as determined from accident
data and exposure models for the German working population. Scandinavian
Journal of Work, Environment and Health (1998) 24(3).
Further Reading
Harrington, J.M., Shiftwork and health: a critical review of the literature.
London, The Stationary Office, 1978.
Harrington, JM. (2001) Health effects of shift work and extended hours of work.
Occup Environ Med 58: 68-72.
Jackson,C.A. (2002) Working hours and shifts in the petrochemical and gas
industries: a review. Croner’s Occupational Hygiene 34: 13-17.
Jackson,C.A., Spurgeon,A. and DeJong.G Mental Health of expatriate oil
workers on extended twelve hour shifts in a desert-based oil field. Society of
Petroleum Engineers. SPE 61016.
Lees, R., and Laundry, B.R. Comparison of reported workplace morbidity in 8hour and 12-hour shifts in one plant. Journal of the Society of Occupational
Medicine (1989) 39.
Further Reading
Lodden, T., The Effect on the Health and Safety of Older Offshore Personnel Long Shifts and Working Night Shift. Society of Petroleum Engineers. SPE
60996.
Parkes, K.R.: Sleep patterns, Shift work, and Individual Differences: A
Comparison of Onshore and Offshore Control-Room Operators. Ergonomics
(1994) 37(5).
Rosa, R.R: Performance, alertness, and sleep after 3.5 years of 12 hour shifts:
a follow-up study. Work and Stress (1991) 5(2).
Spurgeon A, Harrington JM, Cooper CL. (1997) Health and safety problems
associated with long working hours: a review of the current position. Occup
Environ Med; 54:367-375.