from Health Action October 2012

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Occupational
f'fazards
of Shift
Workers
K Mahalakshmi Sangeetha
ork efficiency and output are very much
dependent
on thehealthandphysicalfitness
of an individual.Provisionof nutritionally
adequate
dietstbr uorkersis appreciatecl
not onlv as
an importantlbrnard stepin socialprilctlcebut al:tr
for increasing
industnaieftlciencr'.
Today,many peoplevien shift *ork as drirrns
society's
response
to challenges
oftheneedtor constanr
growth and prosperity.The past few decadeshave
witnessedatremendous
growthin thepopulationof shift
workers, especiallyin the developedand highly
industrialized
countries.
Hazards
of nightshiftwork
Researches
showthat shift work, in particularnight
work, canhavenegativeeffecton health, safetyand
well-being of workers which includes both short and
long-term.
Circadiun Rhl,thmis defined as the oscillationsin
the biochemical,physiological,psychologicaland
behavioural
functionsof anorganismwith aperiodicity
of 24 hrs. There is sufticient evidenceto prove that
rotational shift work affects human health and
performanceb1'disturbingcircadianrhythmscausing
numerousalterationsin human behavioursand
physiology.(Deetc'on
untl Arendt, Igg4)
A modernhumanbodl'contains
ancient
genetic
codes.
These codeswere programmedas our ancestors
synchronized
their activitiesto dayli-eht.
darkness
and
seasons
of theyear.The level of light enterin-s
theeve
triggershormoneshift andtherebythe body then sets
itsbiologicalclock. Thisclockactslike achoreographer
of an intricate dance.But shifi work disruptsthis
complex danceas the switch to night work triggers
changes
in bodily rhythms.The changed
rhythmsstart
to adjustto thenew cuesbut theyadjustslowly andat
different rates.(Totterdellet al., 1998).
Shift work may aggravatecertainmedical disorders
relatedto circadianrhythm disruption,psychosocia
tres and/orsleepdeprivation.
The Tablebelowlists
conditron:thatmar be eracerbated
or ag_eravated
by
rrregular
schedules
and/ornisht nork and arethus
potential
conrraindications
for shifiu ork.
Table
Potential Contraindications for Shift work
Continuouswork in the night may lead to chronic
partial sleepdeprivation.In additionto performance
Condition Examples/Considerations
Gastrointestinal
disorders
Pepticulcer disease,gastritis,
irritable bowel syndrome
Diabetes
mellitus
Potentialdisruption of dietaryand
pharmacological
controldueto ,
irregulartiming of mealsand I
medicationdosing i
Epilepsy Increasedfrequency of seizure
episodesdueto sleepdeprivation
Cardiovascular
disease
Additional risk factorsfor
cardiovasculardisease
Psychiatric
disorders
Increasedsusceptibilityfor
depression
Sleepdisorders Circadianrhythm disruptionof
sleep/wakecycle and poor
daytimeenvironmentalconditions
for sleeping
Reproductive
dysfunction
Potentialadditionalrisk factor for
pretermbirth, low birth-weight
andspontaneous
abortion
flealth Action. October2012
t 4

2. decrements.
chronicsleep
deprivation
mayleadto many
otherclinicai complications.
The association
between
shiftu ork andsleepdisruptionresultsin adverse
medical
andp:1chological
consequences.
Chronobiologicalobservations
have raisedconcern
thatshiftworkersmaybeatincreased
risk of developing
affectivemooddisorderssuchasirritability,fatigue,poor
sleep,apathy,poor appetite,and psychosomatic
complaints.In addition,changesin mood havebeen
shown to be associatedwith irregularity of sleep
patterns,
andwith sleepdeprivation{Boivinetal.,1997:
Healy and Waterhouse,
199I )
Accordingto Johnni(2000), thelevel of cortisol, a
hormonethatstimulatestheheartrate,digestivesystem,
breathing and other functions during the day did not
adjustto help night shift workers stayalert.
Severallab studiesconfirm that sleepdisturbances
altertheregulationof severalhormoneswhich include
cortisol,,prolactinandgrowthhormonein night workers
and also studieshaveshownthat working nights and
beingoncallarenotonlyrelated
toincreased
adrenaline
release
, but alsoto reducedlevelsof testosterone(-/o/zn
Axelsson,2003
)
Peoplewho work in rotationshiftshavesigniflcantlv
lower levels of serotonin: a ltorntorte and
neurotransmitter
in thecentralnervoussvstembeliered
to play animportantrole in there_eulation
of impulses
responding
to emotionalandbehavioural
changes.
This
resultsin cumulativefeaturescharacterizing
"non-
entrainedsyndrome" which includes fatigue, mood
changes,erratic behaviour, irritability, decreased
attention,loss of memory and concentration.
poor
decision-making,fading of judgment and decreased
productivity.
Althoughthereason
isnotclearlyunderstood,
working
nights also appearto riaseperson'srisk of ischemic
heart disease.This may be linked to an elevationof
triglyceridesin night shift workers.(Grossman,1998).
It is documentedthat dietary intake is lower during
night shiftsthanduringmorningandaftemoonshift.The
redistribution of food intake from diurnal eating to
nocturnaleatingis relatedto serumtotal cholesterol,
LDL cholesteroland HDL cholesterolwhich might
increasethe risk of CVD. (Lennernaset.al., 1994)
Gastrointestinaldysfunctionis common in shift
workers.Gastrointestinal
complaintsincludingdiarrhea,
constipation,
excessflatulence,abdominalpain, hearl
burn etc are2 to 3 times more frequent amount shift
n'orkers. (Leanne 1999). The etiology of
gastrointestinaldisordersin shift workers probably
involvedietaryandlifestylefactorsaswell ascircadian
disruption.In additionto eatingat unusualtimes,shift
workers may alter their diet due to lack of eating
facilitiesavailableduring the night shift. Circadian
rhythm disruptionalso contributesto gastrointestinal
dysfunction.
(Steenland
utrcl
Fine,1996: Tepas
19901
While somestudieshavenot found an increased
incidence
of pepticulcerdisease
(PUD)in shiftworkers,
themajority'of studies,
addressing
this outcome,have.
Relevantfactorsapplicableto shift workers include:
sleeplossanddisruption,psychosocial
stress,
skipping
meals,and delayedgastricemptying.(Levensteirt
et
al.,1999).
Mamelleetal.(1984)studied
therelationship
between
occupationalfatiguefactorsandrisk of prematurebirth.
McDonald and co-workersfound an association
betweenrotating shiftwork and an increasedrisk of
spontaneous
aborlion.Thefew studies
whichhavebeen
publishedstudyingtimetopregnancy
raisethepossibility
that shift work and long hours of work may reduce
fecundity,particularly of the femalepartner.
The findings suggest
that night time exposure
to light
mayelevate
breast
cancer
riskby suppressing
production
of melatonin.
a brain hormonethat is madeduring
darkrre::and thatnormallr peaksat nis.ht.
(Mercola.
2(t0I t
Short-termeffectsof shitl work include disturbed
sleep,fatigue,stress,
irritability,psychosomatic
illness,
family problemsand accidents.Long-terme.ffects
of
shift work are increasedrisk of gastrointestinal,
cardiovascular,
psychoneuroticdiseasesand women
shift workers experienceadverseeffects on their
hormonalandreproductive
functionsandlamily roles.
Theterm
'shift
workmaladaptation
syndrome
(SMS)'
hasbeenusedto describethe typical constellationof
signs and symptoms seenin shiftwork-intolerant
workers.In SMS, the symptomsarepronouncedand
insteadworsenwith continuedexposureto shiftwork.
The longer the worker stayson shiftwork,the worse
thesymptoms
become,andeventually,
theworkermay
be fired, quit hisjob, or be involvedin an accident.
A
worker with SMS is likely to get into a vicious cycle
dueto thelackofrecognitionandunderstanding
ofthe
problemby himself/herselfand/orby othersnotfamiliar
with thecondition.Inability to adjustfamily/sociallife
to the work scheduleand poor scheduledesignmay
significantly contributeto the degreeof intolerance.
(Coleman,l9B9)
HealthActiona October
2012 l 5

3. Counter
measures
Sleep Strategies
Thespecificshiftwork schedule
designis asignificant
variable affecting the degree of sleep difficulties
experiencedbyindividual shiftworkers' Knauth,(I99n
has provided detailed practical recommendationsfor
achievingchronobiologicallysound shift schedule
systems.Within the constraintsof the shift schedule'
individuatworkerscanapplychronobiological
principles
to determine
thebesttime for sleeping'
After doingthe
night shift,goingto bedassoonaspossibleafterarriving
homewill usuallymaximizesleeplength'Workersoften
benefit from taking a nap for about 2 hours, in the
eveningbefore beginning a run of night shifts' Other
recommendations
for rotatingwork schedules
havebeen
addressed
by Monk andFolkard(1992)'Applying "Sleep
Hygiene," techniques (regular procedures and
behavioralruleswhich enhance
theability to fall asleep
andstayasleep)initially developedto helppatientswith
primary insomnia. is also recommended for
shiftworkers.
Recommendations
for a good sleep hygiene
programme have recently been summarizedby
boghramil and Fredman (1999)' Environmental
considerationsto decreasesleepdisruptions,include:
sound-proofing the bedroom from day-time noise;
eliminating sunlight with appropriateroom darken
shades,
curtains,or shutters;
andhavingair-conditioning
availablefor warm daytime temperatures'Eye shades
and/orearplugs may be useful.The phoneshouldnot
ring into thebedroomduring the scheduledsleeptime'
The shift worker's daytimesleepshouldbeasprotected
from intemrption asthe normal night time sleephours
are for the rest of societY.
Diet and Exercise
Caffeineshouldnot be ingestedcloserthanaround5
hoursbeforebedtime.Shiftworkersareadvisedto limit
thedoseto around300milligramsof caffeineperday'and
to avoidcaffeineduringthelasthalfofthe eveningshift
or night shift,sincetheworker'sbedtimewill comesoon
aftergettinghome.Fruitjuice is agoodalternativedrink
for the secondhalf of the shift.
Good dietary habits and exerciseare recommended
for all workers for preventivehealth reasons'These
recommendations,
of course,apply to shiftworkers as
well as regular day workers. Basedon the research
discussedabove,concerningCVD and shiftwork' it is
even more important for shiftworkers to follow
preventivehealthrecommendations
for reducingtherisk
of .oronuty heart disease.Additional dietary
precautionsfor shiftworkers include avoiding heavy'
gr"u.y or otherwisedifficult to digestmealsbeforebed
ti-" t. duringthenight shift.(Levenstein
et al', 1999)
Physicalfitnesstraining has been demonstrated
in
shiftworkersto reducegeneralfatigueand sleepiness
at work. increasesleep duration somewhat,and
decreasemusculoskeletal
symptoms'As regards
exercisefor shiftworkers moderatephysical exercise
is preferredoverintensivetraining' Exerciseshouldbe
done a few hours before the main sleepperiod' For
morning or day shifts, the best exercisetime is after
the shifi. After night shifts,theexerciseshouldbe done
before an evening nap. (Harma, 1996)'
FamilySuPPorUEducation
In orderfor individualcopingstrategies
tobeeffective'
familiesmustbe involved.In addition,theshiftworker
must rememberthe toll that the shiftwork schedules
may take on the rest of the family' The provision of
educationalmaterialsfor both theworker andfamily is
essential
for successful
copingwith shiftwork schedules
Severalpublicationswhich review strategies
for
increasingworker and family toleranceof shiftwork
schedules
are availableto assistemployeesand their
familiesin copingwith shiftwotk'(lttmber I 994)'
Creatingahealthywork environmentis beneficialfor
bothemployersandemployees'
It is very importantto
educateemployeesabout measures
to cope with the
varied work scheduleor else may show long-term
imbalancesandcomplicationson health'l
(AssistantProfessor Department of Foods and Nutrition' RVS
College ofArts and Science,Sulur Coimbatore' Theauthol
acknov'letlges
varioussourceswhich are availableon request
l (
HealthActlono October2012