Lecture 7 - Fatigue and Shiftwork Flashcards
what can cause fatigue
- > physical exertion
- > physical discomfor
- > lack of energy
- > lack of motivation
- > sleepiness
what is the goal of reducing fatigue at work
we try and reduce fatigure to…
- > maintain/increase productivity
- > have “optimal” stress
when to use Spitzer’s vs Murrell’s model of rest hour allowance (recovery time required per shift)
Spitzers Model
- > if M (net metabolic cost; kcal/min) is 4<M<8
Murrell’s model
- > M>8
rest hour allowance formula variables
R% = percent of working time allowed for rest-recovery and light duty (added to work time for total shift)
Rt = minutes of recovery time required per shift
M = net metabolic cost of activity (Kcal/min)
T = total shift time
S = requirement of a standard task, Murrell estimates this to be 5kcal/min
general characteristics of shift work
- > affects around 25% of north america
- > rotating shifts have been blamed for human error
- > needed/common in workplaces where technical processes cannot be interrupted without affecting the product
safety concerns of shiftwork
- > causes of accidents
- > disturbance of circadian rhythms can affect concentration, motivation, and reaction time
- > combination can result in an increased risk of accident and injury
- > disagreement about whether shift workers have a greater risk of injury
- > lack of sleep heightens the decline in performance normally experienced at certain times of the day
what time of day produces optimum mental performance levels for workers
research shows that it’s between 2pm - 4m and maximal general awareness is between 1pm - 7pm
what physiological systems can shift work unfavourably affect
- > physical, mental and social wellbing
- > perturbing the psychophysical homeostasis
- > decreasing vigilance and performance
- > hampering family and social relations
shift work differs according to…
- > # of crews who alternate during the working day
- > duration of the work shift
- > extent of night work
- > work on + week-end (time off)
- > type (fast, intermediate, low)
- > direction (CW, CCW) of rotation
- > length of shift cycle
- > time of start/end of shifts
5 overarching factors that you must consider when designing a shift schedule
- > working hours
- > working conditions
- > family and living conditions
- > social conditions
- > individual
constantly changing one’s schedule can…
- > upset one’s circadian rhythm
- > cause sleep deprivation and disorders of the gastrointestinal and cardiovascular systems
- > make existing disorders worse
- > disrupt family and social life
the negative effects of prolonged work hours and sleep deprivation depend on…
- > type of task performed
- > motivation of worker
- > timing (wakefulness and sleepiness appear in cycles)
in which aspects of performance is affected by sleep loss
- > reaction time (failure to response or false response)
- > slowed cognition
- > diminished memory
how do we recover from sleep deprivation
- > a full nights sleep, undisturbed, probably lasting several hours longer than usual, restores performance efficiency almost fully
- > 1-2hr naps
- > “lapses”, “gaps”, “microsleeps”
direction of shift rotation
forward
- > to not disrupt circadian rhythym
