feeling tired?
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Shiftwork and Fatigue
Fatigue is a loss of alertness which
eventually ends in sleep
Once, a pilot crashed after 16 hours on duty
because he read an altimeter incorrectly.
He had been flying safely for 15 hours, and
suddenly he couldn't read an altimeter?
This is hard to believe. That's fatigue.
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Fatigue is a serious issue
• Fatigued operators can cause accidents, (eg
Three Mile Island, Bhopal, Space Shuttle
Challenger, Exxon Valdez and Chernobyl)
• USA – cost of sleep-related accidents estimated
to be between $43 - $56 billion
• UK – annual cost of work accidents caused by
sleepiness estimated to be £115 – 240 million
• 25% of fatal truck crashes are due to fatigue
• 7% of motor vehicle accidents may be attributed
to fatigue, a figure that rises to 15% for motorway
accidents
• pilot fatigue is implicated in upwards of 20% of
near-accidents in aviation
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The Sleep Quiz
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I’m safe at work so it doesn’t
matter if I’m sleepy?
False…being sleepy can cause:
• slower reaction time
• impaired judgements and decision making
• decline in attention
• decreased alertness
• increased moodiness and aggressive behaviour
• difficulty in remembering things
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I can tell when I’m going to fall
asleep
False….
• People do not know how sleepy they
are
• The more tired you become, the less
able you are to make a good judgement
about your ability to remain awake
• Being awake for 18 hours is as great a
risk as driving drunk
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Signs of tiredness
The signs include:
• not feeling refreshed after sleep
• difficulty keeping your eyes open and
focussed
• greater tendency to fall asleep while at work
• more frequent naps during leisure hours
• lots of yawning
• extended sleep during days off
• increased errors and loss of concentration at
work
• feeling irritable, restless and impatient
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Lack of sleep is the only cause
of fatigue...
False… but it is the only cure
Causes of fatigue include:
• Workload
• Social factors
• Individual factors – e.g., age, diet,
fitness etc
• Shift work
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The older you get, the fewer
hours of sleep you need
False
• Sleep needs remain unchanged throughout
adulthood
• Older people wake more frequently through
the night
• Shift work becomes harder with age (40–50
yrs)
• Ability to cope with ‘early starts’ may improve
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Most people need 8 hours of
sleep to function at their best
True
• 7 – 8 hours is recognised as an average and normal
need
• Less than this and you build up a sleep debt
• Sleep comprises several stages which must follow a
certain pattern if you are to feel fully rested and alert
– Stage 1 and 2: transitional phase between waking and
sleeping
– Stage 3 and 4: deep sleep
– Rapid Eye Movement (REM) sleep
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If I sleep a lot now, I won’t
need to sleep much later
False
• Sleep is not like money – you can’t save
it up and you can’t borrow it
• While napping is an effective means of
managing alertness it is not a substitute
for regular sleep
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Everyone has a “biological
clock”
True
• We have evolved own internal body clock /
circadian rhythm
• It controls a number of internal rhythms, eg,
sleep/wake cycle, body temperature
• It is this body clock that makes us feel
sleepier and less alert when we try and work
at times normally reserved for sleep
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The human body can adjust to
nightshift work
False
• Our body clock programmes us to feel most
sleepy when it is dark
• Eating meals at times normally reserved for
sleep means they are less well digested
• On night shifts you tend to get less sleep and
it is of a poorer quality (e.g., after one week of
night shifts, workers had lost the equivalent of
one night’s sleep)
• Successive night shifts, eg, 4, result in an
increase in accident risk
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Features of shiftwork
that lead to fatigue
• Timing of shifts (earlies, lates and
nights)
• Duration of shifts
• Rotation of shifts
• Rest and recovery periods
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Early Starts
• Associated with a reduction in duration of
sleep
• Sleep periods prior to early start are on
average 3 hours shorter
• Difficult to compensate with earlier bedtime:
– Social pressures
– ‘Forbidden zone’
– Fear of not waking up early
• Successive early starts – cumulative sleep
deficit
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Snoring is not harmful as long
as it does not disturb sleep
False
• Chronic snoring may indicate sleep
apnoea, a sleep disorder
• Other common sleep disorders are:
– Insomnia
– Restless leg syndrome
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Drinking coffee cures
drowsiness
False…
• Caffeine has a short term effect
• Caffeine should be used carefully as it will
disrupt sleep
• Other measures such as opening windows
and putting on the radio are not effective
• The only cure for drowsiness is to get some
sleep
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Conclusions
• Being tired impact on our performance
and increases the risks of an accident
• The amount and quality of sleep are
important factors in ensuring you wake
up feeling fully rested
• Shift work makes us more prone to
fatigue because it makes us work
against out natural circadian rhythms
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Coping with Shiftwork
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Sleep Strategies
•
•
•
•
•
Managing your work time
Use naps to improve alertness
Create a good sleep environment
Establish a regular pre-sleep routine
Establish a regular bedtime and wake-up
schedule
• Manage your caffeine intake
• Other advice:
– Avoid alcohol
– Take regular exercise
– Manage your diet
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Managing Your Work Time
• There are different tips for managing fatigue
depending on your shift pattern and the type
of shift you have just finished.
• Example: managing night shifts
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–
–
–
Go to bed as soon as you get home
Have an afternoon nap
Avoid exposure to daylight
Eat 3 regular meal with “lunch” during your night
shift
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Creating a good sleep
environment
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•
•
•
Quiet
Dark
Warm/cool
Comfortable bed that you associate with
sleep
• Fresh air
• Free from interruptions
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Pre-sleep routine
• You can learn that it is time to relax and
go to sleep
• Establish a pre-sleep routine to provide
specific cues:
– Reading
– Listening to music
– Getting dressed for bed
• Only get into bed when your tired
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Napping – Not to be used
whilst at work
• Limit naps to about 30 – 45 minutes including
the time it takes to fall asleep
• Naps of 15 – 20 mins are most restorative
• Give yourself time to get over sleep inertia
• There is no minimum time period for effective
napping
• Improved alertness may last for several hours
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Caffeine
• It is a stimulant so it can keep you
awake but it can also disrupt sleep
• Use caffeine in moderation and when it
is most needed
• Avoid it for several hours before sleep
• Don’t quit “cold turkey”, cut back
gradually
• How much caffeine is okay?
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