Sheffield, S3 7HQ

Working Long Hours

HSL/2003/02

Project Leader: Johanna Beswick MScAuthor(s): Joanne White MSc, Johanna Beswick

Science Group: Human Factors

Crown copyright 2003

CONTENTS

1 Background, method and scope of review ............................................................................ 1 1.1 Aims and objectives ...................................................................................................... 1 1.2 Methodology ................................................................................................................. 1 1.3 Scope of review............................................................................................................. 2

2 Introduction ........................................................................................................................... 3 2.1 Working time directive.................................................................................................. 3 2.2 What are long working hours? ...................................................................................... 3 2.3 Prevalence of long working hours................................................................................. 4 2.4 How could long working hours affect health and safety? ............................................. 5

3 Limitations of the research base............................................................................................ 6 3.1 Causation....................................................................................................................... 6 3.2 Sample issues ................................................................................................................ 6 3.3 Self report issues ........................................................................................................... 7 3.4 Possible biases............................................................................................................... 8 3.5 Conceptual ambiguity ................................................................................................... 8 3.6 Mediating variables ....................................................................................................... 9 3.7 Conclusions ................................................................................................................. 10

4 Fatigue................................................................................................................................. 11 4.1 Summary ..................................................................................................................... 11 4.2 What is fatigue?........................................................................................................... 11 4.3 The Effects of long hours on levels of fatigue ............................................................ 13 4.4 Why do long hours lead to fatigue?............................................................................. 14 4.5 Conclusion................................................................................................................... 15

5 Psychological health and stress ........................................................................................... 16 5.1 Summary ..................................................................................................................... 16 5.2 Definitions................................................................................................................... 16 5.3 Evidence for mental health effects (including stress) from general reviews............... 16 5.4 Mechanisms involved and mediating factors .............................................................. 18 5.5 Conclusion................................................................................................................... 19

6 Physical health .................................................................................................................... 20 6.1 Summary ..................................................................................................................... 20 6.2 Cardiovascular disorder............................................................................................... 20 6.3 Mechanisms involved.................................................................................................. 21 6.4 Other physical health effects ....................................................................................... 22 6.5 Conclusion................................................................................................................... 22

7 Safety and Accidents........................................................................................................... 24 7.1 Summary ..................................................................................................................... 24 7.2 Accidents..................................................................................................................... 24 7.3 Conclusion................................................................................................................... 26

8 Performance ........................................................................................................................ 27 8.1 Summary ..................................................................................................................... 27 8.2 Performance effects..................................................................................................... 27 8.3 Mechanisms involved.................................................................................................. 29 8.4 Conclusion................................................................................................................... 30

9 Work-Life balance............................................................................................................... 31 9.1 Summary ..................................................................................................................... 31 9.2 Definition of Work-Life Balance (WLB).................................................................... 31 9.3 The effects of working long hours on Work-life balance............................................ 32 9.4 The effects of WLB practices that manipulate working hours.................................... 33 9.5 Conclusion................................................................................................................... 34

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10 Conclusions and recommendations................................................................................. 35 10.1 The research base ........................................................................................................ 35 10.2 Main conclusions from the literature........................................................................... 36 10.3 Areas where research is lacking .................................................................................. 37 10.4 Recommendations ....................................................................................................... 38

11 References ....................................................................................................................... 39 12 Appendix 1 Summary table of key studies................................................................... 48

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EXECUTIVE SUMMARY

The Health and Safety Laboratory (HSL) was asked by the Health and Safety Executive (HSE) to review the literature on the relationship between long working hours and fatigue, health and safety and work-life balance outcomes. The review will contribute to the HSEs and the Health and Safety Commissions understanding of the effects of long working hours, rather than shiftwork, on health and safety. The following areas are covered:

Description of the Working Time Directive introduced to reduce working hours; Description of the prevalence of long working hours in the UK and the rest of the

world; Overview of the effects of long working hours on fatigue, health and safety outcomes

and work-life balance; Discussion of the mediating factors that influence the effects of long working hours and

the limitations of the research base. Main conclusions The literature suggests that there is an association between working long hours and fatigue. Evidence from the literature on accidents and performance also suggests that long hours are related to fatigue. There is some evidence that working long hours can lead to stress or mental ill health, although this is somewhat equivocal. The way an individual thinks about their job and the amount of control they have over their job will mediate this relationship. There is sufficient evidence for us to be concerned about the potentially negative effects of working long hours on physical health. The strongest evidence probably concerns the links with cardiovascular disorder. This evidence stems mostly from Japanese men. The evidence is not conclusive with regard to the impact of long hours on safety and accidents. However, there does seem to be cause for concern, particularly within the driving occupations where most of the research has been carried out. The evidence is not conclusive with regard to the performance effects of working long hours. There is strong evidence that people perceive that working long hours leads to poor work-life balance. Control over when an individual works is very important in the extent to which working long hours will impact on home and family life. Whilst researchers have associated working long hours with various effects, the relationships are complex and are mediated by the following factors