Human factors: Fatigue
Why is fatigue important?
More than 3.5 million people are employed as shift workers in the UK. They work in a wide variety of industries including the emergency services, healthcare, the utilities, transport, manufacturing (including oil, gas & chemical industries), entertainment and retail. Poorly designed shift-working arrangements and long working hours that do not balance the demands of work with time for rest and recovery can result in fatigue, accidents, injuries and ill health.
Fatigue refers to the issues that arise from excessive working time or poorly designed shift patterns. It is generally considered to be a decline in mental and/or physical performance that results from prolonged exertion, sleep loss and/or disruption of the internal clock. It is also related to workload, in that workers are more easily fatigued if their work is machine-paced, complex or monotonous.
Fatigue results in slower reactions, reduced ability to process information, memory lapses, absent-mindedness, decreased awareness, lack of attention, underestimation of risk, reduced coordination etc. Fatigue can lead to errors and accidents, ill-health and injury, and reduced productivity. It is often a root cause of major accidents eg Herald of Free Enterprise, Chernobyl, Texas City, Clapham Junction, Challenger and Exxon Valdez.
Fatigue has also been implicated in 20% of accidents on major roads and is said to cost the UK £115 - £240 million per year in terms of work accidents alone.
Key principles in fatigue
- Fatigue needs to be managed, like any other hazard.
- It is important not to underestimate the risks of fatigue. For example, the incidence of accidents and injuries has been found to be higher on night shifts, after a succession of shifts, when shifts are long and when there are inadequate breaks.
- The legal duty is on employers to manage risks from fatigue, irrespective of any individual's willingness to work extra hours or preference for certain shift patterns for social reasons. Compliance with the Working Time Regulations alone is insufficient to manage the risks of fatigue.
- Changes to working hours need to be risk assessed. The key considerations should be the principles contained in HSE's guidance. Risk assessment may include the use of tools such as HSE's 'fatigue risk index'.
- Employees should be consulted on working hours and shift patterns. However, note that employees may prefer certain shift patterns that are unhealthy and likely to cause fatigue.
- Develop a policy that specifically addresses and sets limits on working hours, overtime and shift-swapping, and which guards against fatigue.
- Implement the policy and make arrangements to monitor and enforce it. This may include developing a robust system of recording working hours, overtime, shift-swapping and on-call working.
- Problems with overtime and shift-swapping may indicate inadequate resource allocation and staffing levels.
- There are many different shift work-schedules and each schedule has different features. This sheer diversity of work and workplaces means that there is no single optimal shift system that suits everyone. However, a planned and systematic approach to assessing and managing the risks of shift work can improve the health and safety of workers.
- There are a number of key risk factors in shift schedule design, which must be considered when assessing and managing the risks of shift work. These are the workload, the work activity, shift timing and duration, direction of rotation and the number and length of breaks during and between shifts. Other features of the workplace environment such as the physical environment, management issues and employee welfare can also contribute to the risks associated with shift work.
- Sleep disturbances can lead to a 'sleep debt' and fatigue. Night workers are particularly at risk of fatigue because their day sleep is often lighter, shorter and more easily disturbed because of daytime noise and a natural reluctance to sleep during daylight.
More information on fatigue
- Extract from inspectors human factors toolkit – Managing fatigue risks
Contains questions for checking your management of fatigue.
- Managing shift work: Health and Safety Guidance HSG 256
Aimed at employers, safety representatives, trade union officials, employees, regulators and other stakeholders. This guidance explains employers' legal duties to assess risks associated with shift work and aims to improve understanding of shift work and its impact on health and safety. It includes good practice guidelines on how to reduce the risks and practical advice on how employers, safety representatives and employees can reduce the negative impact of shift work (see Hints and tips for shift-workers).
- Reducing error and influencing
Contains a good summary of key fatigue issues
- The development of a fatigue / risk index for shiftworkers
This report describes the work carried out to revise and update the HSE Fatigue Index (FI). Also included is an Excel spreadsheet calculator for assessing shift patterns.
- Managing rail staff fatigue guidance (ORR)
Although written for the rail industry, the principles contained in this guidance are transferable to other safety critical industries.
- Guidance for managing shiftwork and fatigue offshore
This information sheet provides advice on good practice approaches to shift working in the offshore industry. While it is intended to be used in conjunction with HSE's generic guidance on shift work this document provides specific advice relating to working practices in the UK offshore sector
- Effect of shift schedule on offshore shiftworkers' circadian rhythms and health
This research measured changes in circadian phase, sleep parameters, metabolic and hormonal markers of cardiovascular disease during different offshore shift schedules. It provides advice as to the most appropriate schedules to operate and strategies for improving tolerance to shiftwork schedules.