Accident · Behaviour based safety (BBS) · Health and Safety Regulations · Health and Wellbeing · Human Factors · Occupational Health and Safety · Risk Assessment · Workplace environment

Managing Workplace Fatigue

It is estimated that fatigue in the workplace costs the UK economy between £155 and £240 million each year – in direct workplace accident costs alone.

A general term often used to describe a wide variety of conditions, fatigue is generally accepted as ‘feeling very tired/weary/sleepy due to insufficient rest or sleep, prolonged work periods (mental or physical), or extended periods of anxiety/stress’.

Fatigue can further be categorised as acute (usually reversed by sleep/relaxation) or chronic (constant, severe state of tiredness that is not relieved by rest). Boring or repetitive tasks can adversely affect fatigue levels.

According to the Health and Safety Laboratory (HSL), inappropriate arrangements for shift-work, extended working but failing to balance job requirements together with necessary rest and recovery time, can all lead to fatigue, accidents, injuries and ill health in the workplace.

Stress is a difficult issue for employers to manage. Part of the reason for that is due to the fact that different people exhibit signs of stress in different ways.
Fatigue can result from excessive working time or poorly-designed shift patterns, but can also be related to workload – especially with machine-paced, complex or monotonous tasks.

Fatigue has been revealed as the root cause of many significant accidents including the Clapham Junction rail disaster, Chernobyl, the Texas City oil refinery explosion, the Exxon Valdez oil spill and the loss of the Challenger space shuttle and is further implicated in a huge 20% of road traffic accidents – on major roads. (HSL)

Nowadays, employers have a duty to take all practicable steps to ensure that employees are safe at work, and fatigue is a workplace hazard that needs to be managed. Businesses in all sectors need to address workplace fatigue to prevent the health and safety risks that can arise, safeguard employees, improve productivity levels and protect the bottom-line.

More on fatigue and why it affects your business

Generally considered to be a decline in mental and/or physical performance, fatigue results from prolonged exertion, sleep loss and/or disruption caused to a person’s ‘body clock’.

Results of workforce fatigue:

  • Reduced attention
  • Slower reactions
  • Lack of coordination
  • Decreased awareness
  • Underestimation of risk
  • Memory lapses/absent-mindedness
  • Reduced ability to process information

Causes of fatigue in the workplace

clock-1673583__340Fatigue can result from excessive working time or ill-designed shift patterns, but can also be related to workload – especially with machine-paced, complex or monotonous tasks.

Under the Working Time Regulations (1998), employers have a duty to offer a health assessment to those who work at night. While the employee is not obliged to accept the offer (or fill in a health questionnaire), employers must offer it.

Vigilance for signs of fatigue and associated health effects in workers is a basic requirement for companies operating extended shifts and shift work – especially in roles which necessitate good judgement, quick reactions/decisions and safety-critical roles. All levels of the hierarchy need to be educated about the risks of working long hours and dealing with associated fatigue. Including ways of avoiding adverse outcomes and errors, and signs and symptoms of health issues. A longer working day has a potential to contribute to human error and workplace accidents.


Research has shown that some working patterns can result in less fatigue than others and employing more favourable patterns which allow for sufficient recovery time, helps to balance the needs of both worker and workplace.

Benefits of managing fatigue:

  • Increased employee motivation levels
  • Increased productivity
  • Healthier shift patterns
  • Assurance of compliance with relevant health and safety regulations
  • Reduced likelihood of (fatigue-induced) human error leading to accidents
  • Optimised alertness and decision making
  • Staff buy-in to managing fatigue (on and offline)

In the UK, more than 3.5 million people are employed in a wide variety of shift work across industries including healthcare, emergency services, utilities, transport, manufacturing, entertainment and retail.

The Royal College of Nursing on shift work sets out how shift work affects the occupational health of workers (especially health workers) – although the guidance is useful for protecting and enhancing the health of shift workers in industry generally.

Circadian rhythms – humans follow an “internal” or “biological clock” cycle of sleep, wakefulness and alertness. It is the brain that sets the pattern, although these “circadian” rhythms are influenced by external cues such as the sun setting and rising. Most cycles are 23 to 25 hours long and there are natural dips or periods when workers feel tired or less alert (even amongst those well-rested).

Health and safety – many negative health aspects are associated with shift work, including an increase in accidents while on the job, reduced duration and quality of sleep, fatigue, and being less alert when performing duties (Smith et al, 1998; van der Hulst, 2003), where the worker may feel decreased reaction times and poorer performance (Scott et al, 2006). Shift work has also been recently implicated in breast cancer.

Measuring sleepiness – as fatigue levels vary from person to person, measuring fatigue is not easy. It is also difficult to isolate the actual effect of fatigue on accident and injury rates. Research studies have shown however that when workers have slept for less than five hours before work or when workers have been awake for more than 16 hours, their chance of making mistakes at work is significantly elevated. Further reports reveal that most accidents occur when people are most likely to want sleep, ie between midnight and 6 am, and between 1 pm and 3 pm.

What can employers do to raise alertness levels?

cyber-security-1923446__340Levels of fatigue increase with poor lighting, limited visual acuity (for example due to weather), high temperatures, loud noises, high comfort, tasks that must be sustained for long periods of time and tasks that are long, repetitive, difficult, boring or monotonous.

Workplaces can help by providing environments that work to avoid those situations highlighted above with tasks offering varied interest and changing over the course of the shift. In the case of extended hours or overtime, further consideration should be made for commute times and time for meal preparation, socialising and eating. Consider offering onsite accommodation; prepared meals for workers; and/or facilities where employees can take a nap before driving home.

Further ergonomic recommendations arising from shift work include:

  • Minimising permanent night shifts
  • Minimising sequence of night shifts – only 2-4 shifts back-to-back
  • Consider shorter night shifts
  • Avoidance of quick changeovers
  • Planning rotas with free weekends
  • Avoiding too long sequences of work
  • Rotating forward (clockwise rotation – morning/evenings/nights)
  • Avoidance of early starts

Measuring Fatigue in the Workplace

The Fatigue Risk Index – The Health and Safety Executive (HSE) has developed and refined a method of assessing the risk inherent in fatigue levels associated with work patterns for safety critical workers. The methodology involved the calculation of a ‘Fatigue Index’ and it was intended that the index could be used to provide an assessment of changes in work patterns and for comparing different shift schedules and can also be used to identify a particular shift (within a schedule), which may be of concern.

The FRI can be a useful tool in risk assessment, although shift work planners should always start by considering the guidelines in Managing shift work: Health and Safety Guidance (HSG 256). This includes background information on health and safety risks associated with shift work and fatigue, UK legal duties and practical guidance on how to reduce the associated risks. The outputs of FRI calculations should be considered together with feedback from staff.

The development of the Fatigue Index (FI) was born from a requirement to assess the risks from fatigue associated with rotating shift patterns and the particular requirement to provide guidance in support of the Railway (Safety Critical Work) Regulations.

The initial Fatigue Index included six factors associated with the development of fatigue:

  • Length of the shift
  • Interval between shifts
  • Number of rest days
  • Quality of the rest breaks
  • Variability of shifts
  • Time of day

Each of the six factors was scored independently. The composite score was then used to provide an overall index of fatigue. Since its’ development in 1999, the FI has been widely used by the rail sector and it is now being increasingly used in other areas e.g. by the police and by the nuclear and chemical industries.

When more recent information relating to fatigue and shift work has become available (including the development of cumulative fatigue, the impact of breaks, time of day and shift length, to the time required to recover from a sequence of duties), the HSE modified its’ calculation.

Recent (chronic fatigue) studies of the impact of chronic sleep reduction, over a period of one to two weeks, have offered a deeper insight into fatigue accumulation over a period of several days and recovery patterns. Further data relating to time of day, and in particular to early starts, has become available which has established the trend in alertness levels inherent in duties starting at different times during the day and there is more information available on the impact of time of day on sleep duration.

Access the Fatigue Risk Calculator here

Epworth sleepiness scale – An eight-point questionnaire providing a measurement of general daytime sleepiness, the Epworth sleepiness scale (ESS) is assessed by an individual employee rating their usual chances of dozing or falling asleep in eight different situations.

The Health and Safety Laboratory ‘human reliability team’ has worked over many years to develop a comprehensive understanding of the issues surrounding fatigue and is at the forefront of scientific knowledge and thinking in this area. The team further provides expert assistance to businesses and regulators, as the many interacting factors that can contribute to fatigue make this a challenging risk to manage without informed guidance.

The team at HSL offers consultancy services to help organisations to manage fatigue risk, quantifying the demands leading to increased fatigue risk and allows businesses to optimise assessments when using HSE’s Fatigue Risk Index. HSL also works at an industry level, with trade associations and/or regulators to understand sector-specific issues.



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