By MHDavari MD What is shift work Shift work is defined as work outside of the normal daylight hours from about 7am until 6 pm Midnight Midnight Noon What is Shift Work One speaks of shift work if two or more persons or teams of persons work in sequence at the same work pla ID: 531302
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Slide1Slide2
Shift Work
By
M.H.Davari M.DSlide3
What is shift work?
Shift work is defined as work outside of
the normal daylight hours from about 7am
until 6 pm
Midnight
Midnight
NoonSlide4
What is Shift Work?
One
speaks of shift work if two or more persons , or teams of persons , work in sequence at the same work place.
Often
, each worker s shift repeats, in same pattern , over a number of days.Slide5Slide6
Production process > 8 hours or continuous
Expensive machinery that must be used continuously to be profitableSlide7
7
How many workers work
shift work in North America?
13 – 16
% of total work force work some shift work
Total
of
shift workers estimated to be
24 -25
million
5-6 % work evening shifts
4-5% work permanent night
shift
4-5 % work rotating shiftsSlide8
Why can shift work be difficult?
That is, they are biologically programmed to
sleep during the day and be awake at night. e.g. owls, bats, raccoons
Some
animals
are what
scientists
call
NOCTURNAL
8
DIURNAL
Humans
are what scientists call
That is, we are biologically
programmed to sleep at night
and be awake during the day.Slide9
How does the body work
Internal Biological Clock
(Circadian rhythm)
External stimulantsSlide10
Circadian
RhythmDifferent body functions vary during the 24 hour dayMetabolism is greatest in the afternoon to evening
Most people most alert
10 PM-8 AM
and most sleepy
2-4
AM
The body has a natural cycle of 25 hours
External factors synchronize us to a 24 hour day
The internal clock is located in the
suprachiasmatic
hypothalmusSlide11
The
Suprachiasmatic
NucleusSlide12
Circadian body rhythms
Hormone and gastric
secretionsBody tempreture
Bronchial reactivity
Blood Pressure
Sexual arousal
Anxiety
Metabolic
Rate
Short term
memory
Work performanceSlide13
Biochemistry and Circadian RhythmsSlide14
External clues “
Zeitgebers
”Light/Dark cycle
Timing of meals
Social interactions
Actual time clockSlide15
In 1879
Thomas Edison invented
the light bulb. Slide16
This forever changed our ability to work
at night, but not our biological programming
to sleep at night. Slide17
The 4 Hazards of
Shiftwork
1.
Increased risk of errors & accidents
in the work and out of the work
2 Insufficient daytime sleep leads
to
increased fatigue & sleepiness
3. Increase in health problems
4. Increase in social and domestic
problemsSlide18
Fatigue
affects alertness in many
shiftworkers 80-90 % of shiftworkers feel sleepy during night shift (?% nap!)
Studies
show
increase
in accident
rate
Tendency for more
severe
/ serious accidents to occur
Alertness and Accidents Slide19
Fatigue Related Accidents
Midnight
MidnightNoon
NumbersSlide20
Meter Reading Errors
Midnight
MidnightNoon
NumbersSlide21
Fully Alert
Midnight
Midnight
Noon
Relative Alertness
Biological Rhythms
DrowsySlide22
Drowsy
15
10
5
12
15
18
21
00
03
06
09
12
Exxon
Valdez
00:15
Full Alertness
Time of Day & Major Accidents
Bhopal
01:00
Chernobyl
01:23
Three Mile
Island
04:00
Midnight
Noon
NoonSlide23
Exxon Valdez
Disaster
Cleanup cost: $2 BillionExxon Fined: $5 BillionEnvironmental damage: ?$ Slide24
Health Hazards
Short effects:
sleep disturbancePoor concentration Decrease alertnessDecrease safetyProlonged exposure to chemical and biological substances and other hazardsSlide25
Long effects:
GI problemReproductive effectsCancer
Exacerbation of Sleep disorders Asthma Diabetes mellitus Coronary Artery Disease Slide26
GI Dis.
75% of night workers vs. 20% of day workers
ComplaintsLoss of appetite
Constipation
Dyspepsia
Heart burn
Abdominal pain
Flatulence
Many problems may not show up until years later
Reasons
Poor food quality
More caffeine
More alcohol
More tobacco
Drugs used to keep awakeSlide27
Cardiovascular problems
Increased incidence of
ischemic diseaseMay
be
related to:
disturbance of circadian
blood pressure
and
pulse
rate
Substance abuse
more likely in shift
workers
Elevated triglyceride levels in phase advance workersSlide28
Hypertension
Shift workers were found to have approximately
25% greater chance of developing hypertension than non shift workersSlide29
Cancer
At least three nights per month for 15 or more years may increase the risk of
Colorectal cancer in women 35%Shorter durations also have increased risk
Due to the suppression of melatonin production with nocturnal light exposure. Melatonin has
anti-
neoplastic
properties
Breast Cancer ,
Attributed to inhibition of melatonin production by light exposure during the nightSlide30
Cognitive
AbilityRecent studies have found deterioration in cognitive ability in shift workers vs. non shift workers.
This increases with duration of exposure
The effect seems to diminish 4 years after discontinuationSlide31
Medical evaluation:
History:
CAD
GI
dx
Sleep
dx
Epilepsy
diabetes
Asthma
Difficulty in night visionSlide32
Psychological
Shift workers demonstrate:
More
depression
and
despondency
More likely to use psychotropic
drugs
or require
hospitalization
Will have magnification of
underlying depression or bipolar disorders
Circadian
rhythm
disturbance may be a
cause
for depressionSlide33
Social Impact
Increases
Divorce
Family violence
Social Isolation
Sexual dysfunction
May affect women more than menSlide34
Impaired logical reasoning and decision-making
Impaired vigilance and attention
Slowed mental operationsLoss of situational awarenessSlowed reaction time
Short
cuts
Fatigue Effects on PerformanceSlide35
Major Fatigue Factors
Time of Day
: between midnight and 6 AM
Cumulative Sleep Debt:
Acute Sleep Debt:
More than 17 hours since the last
sleep period
Continuous Hours Awake:
Less than eight hours in last 24 hrs.
More than eight hours accumulation.Slide36
Shift work type:
Fixed pattern
Night
Evening
Rotating pattern
Clockwise (morning- evening- night)
Rapid (less than 4 days)
slow (more than 4 days)
Counter
clockwise
(night-evening- morning)
Rapid
slow Slide37
Oscillating shift work
Split shift workRelief Shift workSlide38
Quickly rotating shift system
:
Minimize sleep deprivation (Fischer et al., 1997)Minimize circadian rhythm disruption
(
Knauth
1993, 1995)
Improve social
contacts
(
Knauth 1993, 1995) Improve alertness and well-being
(Williamson & Sanderson 1986, Phillips et al., 1991)
Clockwise rotation
:
Better tolerated by the
shift workers,Improve
production & well-being
(Czeisler
et al
., 1982
)
Improve sleep quality
(
Folkard
1993
)
Reduce physical, social and psychological problems
(
Landén
1981)Slide39
Shift work
Maladaptation15-20% of workersSigns & symptoms:Sleep dis.Fatigue
Behavioral dis.GI dis.Sedative drugs usageSlide40
Shift work
Maladaptation:Age > 50Morning typeSecond job or heavy house workLong sleep time
Fixed & regular sleep patternHx sleep dis.Hx GI dis.Hx cardiovascular dis.Asthma,DM,EpilepsySlide41
How to keep worker alert?
High illumination
level
Breaks
Naps
Occasional
stirring
music
Stretching or light exercise
Social interaction
Snacks & caffeinated beverages
FDA recommended use
Modafinil
(
Provigil
)
for shift work sleep disorderSlide42
Suitable Shift systems
:Daily work: not be more than 8 hr.Number of night or evening shifts: as small as possible.A full day of free time follow every night shift
Contain consecutive work-free days, preferably including the weekend Clockwise rotationRapid Shorter shift ( < 8hr) : heavy manual workLonger shift (12hr) : light jobSlide43
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