Professor David Koh

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Occupational Health Conference Muscat, 11-13 Dec
2006
Shift Work
Professor David Koh MBBS, MSc, PhD, FFOM, FFOMI,
FFPH, FAMS Department of Community, Occupational
and Family Medicine Faculty of Medicine
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Shiftwork

• Done for hundreds of years
• Numbers increased tremendously since invention of
  the light bulb (Edison)
• 20-25 of all workers in developed countries do
  shiftwork
• Occupations
• transport, security, health care, essential
  services, continuous manufacturing processes

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Shiftwork
Any work outside normal 0800 hr to 1700 hr
regular hours

• Different types
• double day
• 3 shift systems
• split shifts
• day-and-night shifts
• permanent shifts
• irregular shifts
• 8 hour vs 12 hour shifts
• Forward vs Backward rotation
• F morning, afternoon, night
• B morning, night, afternoon

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Circadian Rhythm
Changes in body temperature, heart rate, blood
pressure, metabolism, respiration, hormonal
secretion, urine flow, absorption of drugs, etc.
Activities increase in daytime (ready for
action) and decrease at night (rest and
recuperation) Circadian system reset by
external synchronizers e.g. light/darkness,
mealtimes Good health requires synchronicity
between activity/rest cycle and human circadian
rhythm
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Circadian Rhythm in Body Temperature
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Effects of Shiftwork
Two things wrong with shiftwork - having to
work when supposed to sleep - having to sleep
when supposed to be awake For some people, this
can result in performance, health and social
effects
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Effect on Performance
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Health Effects
Short term disorientation, fatigue, health
problems Longer term heart, gastrointestinal,
sleep, psychological effects, effects on
pre-existing illnesses
Social Effects

• - Interactions with family and friends
• Lifestyle and community activities

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Health Effects

• Heart disease
• Some studies show an increased risk of heart
  disease among shiftworkers
• ? due to anxiety, sleep disturbance, lack of
  exercise, fatigue, potential for family conflict,
  diet, increased blood lipids, tobacco etc.

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Gastrointestinal disease

• Indigestion, heartburn, loss of appetite
• Poorer diet ? at night, loss of appetite may
  cause increased snacking on junk food instead of
  a well balanced meal
• Irregular meals, excess alcohol, caffeine, smoking

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Effects on Pre-existing Illness
e.g. Diabetes, Epilepsy, Peptic ulcers
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Sleep Disorders
Sleep quantity and quality affected, especially
with night work Daytime sleep not as deep or
refreshing Worse when room is not quiet, dark,
comfortable Sleep Quantity Night shift 4-6 hrs
sleep Day shift 7.5 hrs Evening shift 8.5
hrs Sleep Quality Day sleep less deep sleep
(stage 3-4) Rotating shift lt Permanent shift
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Alertness and Accidents

• - Fatigue affects alertness in many shiftworkers
• 80-90 of shiftworkers feel sleepy during
  night shift (? nap!)
• Some studies show increase (others do not) in
  accident rate
• Tendency for more severe / serious accidents
  to occur

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Exxon Valdez 12.04 a.m. 24/3/89
Tanker with 1.3 million barrels of Alaskan crude
Bhopal 12.15 a.m. Dec 3 1984
Chernobyl 1.23 a.m. April 26 1986
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Psychological Effects

• Shiftwork dislocates family life
• Interferes with social contacts

Less chance to participate in group activities
As a result, some shiftworkers are
irritable, moody, tired
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Social Effects
Interactions with family and friends - Depends
on age, marital status, children, hobbies,
personal interests Problems in establishing
regular routines in daily activities, planning
for family responsibilities and coping with
physical and mental fatigue
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• Participation in clubs, sports and other
  organized activities may be difficult
• Lack of regular social contact may cause feelings
  of isolation, loneliness

Lifestyles and Community Activities
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Shiftwork is Not Always Bad !

• Not all effects are negative, advantages
  include
• More off days or off time
• Fewer trips to from work, less time wasted
  in travel
• Shops, other amenities open during off work time
• Greater freedom to plan leisure
• More incentives, benefits

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Shiftworkers are a self-selected group
About 10 to 15 of workers cannot
tolerate shiftwork, and leave About 10 to
15 of workers enjoy working in shifts
Majority cope with shiftwork well
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Shift-friendly Workplaces
Scheduling and work environment Shift design
and scheduling e.g. longer rest pauses, forward
rotation Work environment - provision of
amenities e.g. transport, food - work environment
design e.g. lighting, first aid / health cover

Pre-employment screening pre-employment
screening may not be so useful, but a good
opportunity to educate advise
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Shiftworkers Should

• Be aware of alertness levels
• on different times of shift
• on different days of shift
• get enough sleep

Time of Night
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Is bad . . . .
Hours of Sleep on Prior Night
Successive Days of Reduced Sleep
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Effect of Light on Alertness Level
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Alertness
Triggers to Alertness sense of danger,
interest or opportunity muscular activity
time of day on circadian clock sleep bank
balance ingested nutrients and chemicals
environmental light environmental temperature /
humidity environmental sound environmental
aroma
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Sleep Hints
Nap 1-4 hrs before first night shift After the
last night shift, take a short sleep first, then
go to bed early that night Some people prefer
other sleep patterns see which best suits you
Nutrition
Regular eating patterns as far as
possible Balanced, varied meals are
important Timing of meals
Exercise
Physically fit people adapt to shiftwork better
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Medications

• Avoid excessive use of antacids, tranquilizers
  and sleeping tablets
• Check with family doctor or pharmacist if you
  take medication during working shifts
• Some drugs may cause drowsiness, some may
  have to be timed differently in order to
  account for absorption patterns and activity
  patterns

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Family
Solutions Must involve whole family Shift
workers must understand social implications of
shift work Social and family activities must be
arranged to accommodate the schedules of the
shift worker Use of time management strategies
and spending quality time
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Summary
Types of Shiftwork Circadian Rhythm Effects of
Shiftwork Health and Social Effects Shift-friendl
y Workplaces Scheduling Work environment Pre-emp
loyment screening What Shiftworkers can
do Alertness and Sleep Lifestyle Nutrition,
Exercise, Medications Family