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Fatigue and Shift Work

Fatigue has long been associated with Shift Work. That is because humans are diurnal creatures that are designed to live and work during daylight hours. Traditionally businesses respected this fact, however we are now entering the era of 24/7 living. Businesses have to move more and more away from the traditional 9-5 working towards around the clock work on seven days of the week.

Fatigue itself is an interesting subject; Fatigue obviously exists, we all recognise it and feel it on occasion, but it can’t be measured directly. There are occasions when we ‘feel tired’ or sleepy or exhausted and in general these are regarded as times when we are fatigued. When we are fatigued we are less alert and more prone to error. Fatigue affects how diligent we are, our reaction time, memory, focus, decision-making skills and can cause irritability. If we are fatigued while at work accidents will happen. These accidents can be very expensive to the company financially but also can result in the loss of human life and lead to environmental pollution. The financial cost of sleep-related accidents in the USA is estimated at $43-56 billion per year (1995). For the UK it is estimated that the financial cost of ‘sleepiness’ per year is £115-240 million (1995).

Shift work can contribute to fatigue because it limits the amount of sleep the worker can have. Working night shifts can cause workers to feel fatigued. This is because of our internal body clock, which inhibits sleep during the day. Therefore workers try to ‘kip’ in the afternoon and morning before and after the shift. This is not an effective way to sleep and hence the worker quickly becomes fatigued. Fatigue has also been shown to be cumulative therefore it is important to consider how many consecutive night shifts to use in a shift pattern.

When considering fatigue it is a good idea to understand the factors that affect fatigue and the impact that fatigue can have on the individual, company or society. There are many individual elements that contribute to fatigue, and by recognizing that some of the effects of fatigue also contribute to fatigue, we can try to draw up a visual representation of the causes and effects.

For instance, fatigue increases absences. If a person is fatigued and feels fatigued, then they are very likely to underperform when at work, which can be stressful when this under performance can lead to disciplinary action or worse still, could cause an error or accident. Hence a person may decide to take the day off work to recover and reports in sick. Whilst this may incur disciplinary action in itself on their return, they will be refreshed. By being absent, this usually throws more work onto the staff at work and the increase in physical or mental work increases their fatigue. Another contributor to fatigue is stress and if a fatigued person is at work and makes an error, this can increase their stress, causing them to overwork and these factors in turn increase the fatigue. Thus the effects of fatigue cause there to be a feedback loop that contributes to more fatigue.

The causes of fatigue can be grouped together, and it is often the case that a cause can be in several groups. Thus ‘lack of Sleep’ can be due to social pressures or an early shift start time or poor sleeping habits or all of these. This type of interaction creates a complicated picture, which we have illustrated in the form of a Fatigue Map.

Fatigue Map

To understand the Fatigue map you need to break it down into its separate lines. These lines are as follows:

Health Line (Red) (stress/heavy work/medication/health)

Personal Line (Yellow) (Personality/ Medication/Stress/ Overworked/ Fitness/ Age/ Diet/ Breaks on shift/ Body clock)

Sleep Line (Orange) (Body clock/ Poor sleeping habits/ Social pressure/ Shift length/ Shift start time/ Lack of sleep)

Shift Line (Green) (Number of consecutive shifts/Rotation of shifts/Breaks between shifts/Holidays/Start time/Lack of sleep/Shift length/Social pressure/Breaks on shifts/Diet)

Workload Line (Blue) (Workload/Underworked/Overworked/ Heavy work/ Mentally hard work/ Absenteeism)

Performance Line (Brown) (Overworked/Stress/Error/mistakes/Poor vigilance/ Poor memory/ Slow reaction times/ High Costs)

Company Line (Black) (Absenteeism/ Accidents/ High Costs)

Fatigue 3

The dotted pale blue line separates the Inputs to fatigue from the Impacts of fatigue. The circles denote factors, which interact with different lines. For instances “Absenteeism” interacts with the company line because it cost the company money and so the person who is absent has to be replaced. It also interacts with the workload line because absenteeism can increase the workload for the people still at work. Sometimes the factors can also interact with each other. For instance the “Start Time” of a shift will have a knock on effect to the persons sleep pattern causing “Lack of Sleep”.

An employer will have little or no control over most of the factors affecting a shift worker fatigue level. However they do have complete control over the Shift Line (Green). They can alter the breaks on the shift, change the start and finish times, alter the shift pattern to minimise fatigue. They also have some control over the Workload Line (Blue). They can monitor the workload and react to changes so that the shift workers are not over or underworked. By maintaining the correct staffing levels through a proper holiday management plan and absence arrangements the company can avoid unnecessary stress and not overwork anyone.

If you would like to find out more about Fatigue and Shift Work our ebook is available from Amazon for only £6.30.

If you would like to know about holiday and absence management we have a range of ebook available from Amazon and training courses available.

We provide our clients with tailor made shift patterns, as part of this service we highlight the best ways to minimise fatigue and apply a holidays and absence management plan.  Please contact us for more information.