Fatigue at Work. Dr Alan Black. Consultant in Occupational Medicine

Transcription

1 Fatigue at Work Dr Alan Black Consultant in Occupational Medicine

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3 Learning Points The main factors that cause fatigue How fatigue affects an individual How to avoid or reduce fatigue The risks associated with coping with fatigue How to create an affective system for managing fatigue Comparing shift patterns and identification of when risks are highest Good practice shift rota design

4 Fatigue* Fatigue is the decline in mental and/or physical performance that results from prolonged exertion, lack of quality sleep or disruption of the internal body clock. The degree to which a worker is prone to fatigue is also related to workload. For example, work that requires constant attention, is machine paced, complex or monotonous will increase the risk of fatigue.

5 Fatigue* Fatigue is the decline in mental and/or physical performance that results from prolonged exertion, lack of quality sleep or disruption of the internal body clock. The degree to which a worker is prone to fatigue is also related to workload. For example, work that requires constant attention, is machine paced, complex or monotonous will increase the risk of fatigue. *Health & Safety Executive

6 Fatigue A vague and imprecise term A normal emotional and physiological consequence of work A subjective symptom Distinct from weakness or excessive drowsiness Does not automatically denote ill health Can be pleasant, but usually regarded as unpleasant tiredness, weariness or exhaustion Can affect mental performance

7 Neurasthenia* The simplest form of neurasthenia is that which is often met with towards the end of a years work. The patient is mentally and physically overdone, work becomes an effort, there is lack of concentration, and mere trifles are magnified out of all proportion to their importance. Neurasthenia may thus be so slight an affliction as to be cured by the usual annual holiday. On the other hand, it may develop into a serious affection shading off into melancholia or hypochondriasis. *The Complete Family Doctor cira 1920

8 Disasters Attributed to Fatigue Chernobyl Exxon Valdez Challenger Clapham Junction Bhopal pesticide plant

9 The Physiology of Circadian Rhythms Few physiological parameters are constant, but rather show a rhythm throughout 24 hours Body regulated by internal clock (supra-chiasmatic nucleus -SCN), running 25 hour day SCN influenced by external environmental cues, esp. light through melatonin (Zeitgebers) Growth hormone, melatonin, cortisol peak at night Cardiac output, blood pressure, core temperature peak during the day

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11 Adverse health affects of working shifts Workers who have poor tolerance of night work tend to leave it healthy worker effect Gastro-intestinal disease Mechanism of action unknown role of use of coffee, smoking, alcohol? Glucose metabolised less readily at night Cardiovascular disease Cancer Endometrial Non-Hodgkin s lymphoma Prostate Breast females working over 30 years on nights

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13 Pregnancy and Shift Work No significant differences until late pregnancy (last trimester) No automatic ban but total working hours should not exceed 40 / week Should avoid prolonged standing Insufficient evidence to insist on worker stopping nights

14 Identify at Risk workers young workers older workers new and expectant mothers workers with pre-existing health conditions workers taking time-dependent medication such as insulin sub-contractors On call workers, having to work through from a full days work

15 Key Risk Factors Workload Work activity Shift timing and duration Direction of rotation Number and length of breaks during and between shifts

16 Good Practice for Shift Design (1) Night shifts Restrict number of night shifts to 4 maximum if possible. Allow at least 2 days off following night shift. Avoid keeping workers on permanent night shifts.

17 Good Practice for Shift Design (2) Early starts Move early shift starts before 6am forward (e.g. 7am not 6am start). Limit the number of successive early starts ie before 7am (to 4 maximum if possible) Shifts involving an early start should be shorter in length to counter the impact of fatigue later in the shift.

18 Good Practice for Shift Design (3) Shift length If 12-hour shifts worked then no overtime worked in addition. Avoid long working hours (more than 50 hours per week). If 8/10 hour shifts then no more than 4/2 hours additional overtime to be worked. Restrict back to backs with 8 hour shifts and avoid entirely with 12 hour shifts.

19 Good Practice for Shift Design (4) Rest periods Allow minimum of 12 hours between shifts and avoid quick return of 8 hours if possible. (Rest period between shifts should permit sufficient time for commuting, meals and sleep.) Plan some weekends off, advisably at least every 3 weeks.

20 Good Practice for Shift Design (5) Rotation Rotate shifts quickly (e.g. every 2-3 days) Avoid rotating shifts every 1-2 weeks. Use forward rotation (morning/afternoon/night) for preference.

21 Good Practice for Shift Design (6) Social Considerations Arrange start/finish times of the shift to be convenient for public transport, social and domestic activities. Consider travelling time of workforce. Allow some individual choice where possible to accommodate larks/owls and family commitments. Keep the timing of shifts regular and predicable but also allow employees to have some flexibility to choose their own work schedule.

22 Managing Fatigue Key Principles (1) Fatigue needs to be managed Higher risk of accidents and injuries Legal duty on employer to manage risk reliance on Working Time Directive alone is insufficient Needs to be risk assessed HSEs Fatigue Risk Index Consult employees Develop policy that sets limits on overtime, shift swapping and working hours

23 Managing Fatigue Key Principles (2) Implement, monitor and enforce Problems with shift swapping / overtime may be due to inadequate staffing levels No single optimal shift pattern that suits everyone owls v. larks Sleep disturbance can lead to sleep debt

24 Assessment Tools HSE s Fatigue and Risk Index Tool The Epworth Sleepiness Scale Johns M W A new method for measuring daytime sleepiness: The Epworth sleepiness scale Sleep (6) The Standard ShiftworkIndex A battery of questionnaires for assessing shift-related problems Work and Stress (1), 4-30 Swedish Occupational Fatigue Inventory A Perceived Quality of Fatigue during Different Occupational Tasks. Development of a Questionnaire International Journal of Industrial Ergonomics (2)

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26 Questions?