Shiftwork by MikeJenny


									                 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
Done for hundreds of years
Numbers increased tremendously since invention of
the light bulb (Edison)
20-25% of all workers in developed countries do
transport, security, health care, essential services,
continuous manufacturing processes
  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
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
Circadian Rhythm in Body Temperature
   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
Effect on Performance
  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
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.
Gastrointestinal disease

Indigestion, heartburn, loss of

-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
Effects on Pre-existing Illness

e.g. Diabetes, Epilepsy, Peptic ulcers
  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 < Permanent shift
  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
          Exxon Valdez – 12.04 a.m. 24/3/89

          Tanker with 1.3 million barrels of Alaskan crude

Chernobyl – 1.23 a.m.       Bhopal – 12.15 a.m.
April 26 1986               Dec 3 1984
 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
  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
Lifestyles and Community Activities
-Participation in clubs, sports and other
organized activities may be difficult

-Lack of regular social contact may
cause feelings of isolation, loneliness
       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
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
 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
 Shiftworkers Should :
Be aware of alertness levels
-on different times of shift
-on different days of shift
-get enough sleep

                  Time of Night
                                                Is bad . . . .

Hours of Sleep on Prior Night   Successive Days of Reduced Sleep
Effect of Light on
 Alertness Level
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
 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

Regular eating patterns as far as possible
Balanced, varied meals are important
Timing of meals

 Physically fit people adapt to shiftwork better
- 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
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
Types of Shiftwork
Circadian Rhythm
Effects of Shiftwork
Health and Social Effects
Shift-friendly Workplaces
Scheduling & Work environment
Pre-employment screening
What Shiftworkers can do
Alertness and Sleep
Lifestyle: Nutrition, Exercise,

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