Fatigue at Work Dr Alan Black - - PowerPoint PPT Presentation

Fatigue at Work

Dr Alan Black

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

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

• r monotonous will increase the risk of

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.”

Fatigue*

*Health & Safety Executive

Fatigue

• A vague and imprecise term
• A normal emotional and physiological consequence
• f 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

Neurasthenia*

“The simplest form of neurasthenia is that which is

• ften 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

• f 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

Disasters Attributed to Fatigue

• Chernobyl
• Exxon Valdez
• Challenger
• Clapham Junction
• Bhopal pesticide plant

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

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

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

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

Key Risk Factors

• Workload
• Work activity
• Shift timing and duration
• Direction of rotation
• Number and length of breaks during and

between shifts

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.

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.

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.

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.

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.

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.

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

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

Assessment Tools

• HSE’s Fatigue and Risk Index Tool

– www.hse.gov.uk/research/rrpdf/rr446cal.xls

• The Epworth Sleepiness Scale

– Johns M W ‘A new method for measuring daytime sleepiness: The Epworth sleepiness scale’ Sleep 1991 14 (6) 540-545

• The Standard Shiftwork Index

– A battery of questionnaires for assessing shift-related problems’ Work and Stress 1995 9 (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 1997 20 (2) 121-135

Questions?