Maintaining Safety and High Performance on Shiftwork, by Monk, 1996

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Maintaining Safety and High Performance on
Shiftwork, by Monk, 1996

• Presentation by Stacey Cooper

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Viewpoints On the Study of Shiftwork

• Focus on effectiveness and productivity.
• Safety and well-being of the shiftworker.
• Not all accidents can be attributed to human
  error social, organizational and technical
  problems interactions can create problems.

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2 X 2 Error Classification

• Error vs. failure.
• Danger to society vs. danger to self.

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Night and Day

• Circadian system
• Risks youngsters take
• Day noises wake the sleeping vampires
• Night workers less satisfied with time available
  for family and friends
• Social activities such as church or other daytime
  activities interfere with sleep cycle, resulting
  in more accidents

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5 Problem Areas

• Errors
• Sleep and excessive fatigue
• Moodiness, irritability and disruptiveness
• Absence
• Off-work accidents (mainly traffic)

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Solutions

• Elimination or reduction of nightshifts
• Selection of appropriate shiftworkers
• Education of shiftworkers
• Adoption of correct shift rotation shedules
• Improvement of the working environment

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Sleepiness, alterness and performance during a
laboratory simulation of an acute shift of the
wake-sleep cycle, by Porcu, et al.
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Sleepiness

• Reduction in sleep and sleepiness detrimental to
  performance
• Night shift workers show increases in EEG alpha
  and theta activity related to performance lapses
  and errors
• Sleep loss associated with nightshift work,
  usually 2-4 hours of stage 2 and REM

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Multiple Sleep Latency Test

• Assesses the ability to remain alert
• Sleep loss, time of day and time on task impact
  sustained night operations the most
• Fatigue

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Method

• 10 males, 23-56
• Maintenance of Wakefulness Test
• MSLT
• Questionnaire upon awakening, and only those who
  reported no sleep, medical or psychiatric
  disorders were included in the study, with
  reported normal rest-activity cycles.

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Other tests

• EEG
• Polygraph
• EOG
• EMG
• Digit Symbol Substitution Test (DSST)
• Deux Barrages Test (DBT)
• Letter Cancellation Task (LCT)

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Procedure

• Tests performed both at night and day, 4 times
  every 2 hours
• Data Analysis with ANOVA

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Results and Discussion

• Sleepiness, altertness and performance are
  affected differently by an acute shift of
  wake-sleep cycle
• Maintaining wakefulness more difficult at night
• Optimal amounts of sleep difficult to estimate
• Sleepability varies by individuals,
  multidimensional
• Acute shift of wake-sleep cycle affects on
  performance required to allocate a high attentive
  load for a continued time.

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Does Exogenous Melatonin Improve Day Sleep or
Night Alertness in Emergency Physicians Working
Night Shifts by Jorgensen and Witting
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The Perils of Rotating Shiftwork

• Shiftwork is taxing on the circadian system,
  causing health hazards which increase with age

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Melatonin

• Melatonin is a sleep-promoting hormone
• Produced during the day
• Light exposure at night decreases melatonin
  production
• Decreases with age
• Decrease associated with sleep disorders
• Melatonin maintains slow wave and REM phases of
  sleep
• Permanent night-shift workers shift their
  melatonin production but fast-rotating
  night-shift workers do not

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Aim and Design of Study

• Test the effects of melatonin on fast-rotating
  emergency physicians
• Subjects rated their subjective sleep quality and
  kept a sleep log
• Subjects given melatonin and placebo at
  different times
• Alertness measured with the Stanford Sleepiness
  Scale (SSS)
• Visual Analog Scale (VAS)
• Physical symptoms of side effects recorded

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Results and Discussion

• Of 18 subjects, 2 experienced side effects
• No significant benefit of melatonin, yet found a
  somewhat improved alertness at the end of a night
  shift (d.5)
• Light exposure at night more efficient in raising
  melatonin levels than supplement
• Media attention to melatonin out of proportion to
  the amount of scientific study

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Recovery From Work Shifts How Long Does it Take?

• By, Totterdell, et al.

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Questions

• How much time off is sufficient?
• What is the relationship between work and
  leisure?
• Is work alienating and does the alienation
  transfer to non working times?
• How much time after a stressor does one need to
  recover?
• How does fatigue affect performance?
• How does daily stress affect social behavior and
  physiological responses?

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The good, the bad, and the worked

• Return to sanity slowed by repetitive,
  uncontrollable work.
• Those with high mental workload show better
  adjustment.
• Vacations, good, overtime, bad.
• Shiftwork, especially at night is bad for your
  health and well-being.
• Free on the weekends, good, half-days and singles
  days off, bad.

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Theory

• Adaptive-cost theory adaptation to night work
  and back to daytime routine associated with
  higher costs.
• Proposed Hypotheses