A poor night’s sleep, some bad shift patterns, it’s all manageable when you’re at work, isn’t it?
Sleep is one of the most important factors in reaction time, concentration and the ability to make good decisions. Lack of sleep is also linked to ill-health and mental health issues. As a result, the effect of poor sleep and fatigue in an occupational environment can have serious effects on risk and well-being
What is fatigue?
Fatigue can be defined as:
“a physiological state of reduced mental or physical performance capability resulting from sleep loss or extended wakefulness, circadian phase, or workload (mental and/or physical activity).”
Occupational fatigue arises from issues that arise from excessive working time or poorly defined shift patterns. It affects workers through a variety of physiological and cognitive factors including:
- Slower reaction times
- Reduced ability to process information
- Memory lapses
- Absent-mindedness
- Decreased awareness
- Lack of attention
- Reduced co-ordination
- Underestimation of risk
- Poor communication
- Irritability
All these factors increase the risk of errors, accidents, injury and productivity. These risks are present for both safety-critical and non-safety critical industries. Fatigue has been attributed as a root cause for some major accidents, with three of the most devastating disasters in recent history being linked to sleep deprivation and fatigue.
Disasters caused by fatigue
Challenger Space Shuttle
The NASA space shuttle Challenger disintegrated in a huge explosion 73 seconds after launch. The disaster killed all seven crew.
The programme was reported to be under huge time pressures. This meant that managers and staff were working very long hours leading up to the mission in order to rectify faults that plagued the mission. The night before take off very little sleep was had, with some managers getting only 2 hours and starting duty at 1am on launch day.
In a review, poor judgement and human error were reported as causes of the disaster, brought about by severe sleep deprivation.
Chernobyl Nuclear Reactor
An explosion a reactor at the nuclear power plant caused the immediate death of 30 people and sent radiation across all of Eastern Europe. The WHO predicts that up to 4000 deaths will be attributable to the effects.
Investigators found that fatigue, due to 13-hour shifts, was a leading contributor to the human error that led to the explosion in addition to the flawed reactor design.
Exxon Valdez Oil Tanker
The Exxon Valdez was a huge oil tanker that struck a reef east of Anchorage, Alaska. The disaster is considered one of the most environmentally devastating oil spills of all time, costing around $2bn to clean up the 10.8m gallons of oil and causing damage to flora and fauna across over 2000 kms of shoreline.
The vessel moved out of its shipping lane to avoid ice but failed to return. It is speculated that the crew member’s inability to return the vessel to the lane was caused by fatigue. It was reported that in the previous 16 hours, they had “only one cat nap”.
Clapham Rail Disaster
During the morning rush hour, three busy commuter trains were involved in a horrific collision killing 35 people and injuring 500. One of the trains ran head-on into the rear of a second stationary train. This impact caused the second train to veer across the tracks into a third oncoming train.
The subsequent inquiry exposed serious shortcomings in the installation, commission and maintenance of signalling equipment, attributed to long hours and fatigue among maintenance staff working on safety-critical systems.
The role of Sleep
The message is clear:
a sleep deprived workforce is a dangerous workforce
With fatigue being implicated in so many errors, it is vital that appropriate levels of importance are placed in the fatigue risk management and sleeping. It needs to be managed like any other hazard and not consider “just part of the role.”
Fatigue increases cumulatively as a result of increasing sleep debt. Over a long term, sleep debt can affect concentration levels and health. Night workers are particularly at risk of fatigue because their day sleep is often shorter and more disturbed. The only way to repay sleep debt is with good quality sleep.