Short of sleep spells D A N G E R for drivers & operators

Short of sleep, fatigued … just a two-second lapse in concentration can result in a horrific accident, on the road, in the plantation or in the yard. Seven to nine hours a night is required for a proper sleep, and is especially important for truck drivers and operators of heavy equipment.

By Carl van Loggerenberg
Society has generally been apathetic towards sleep and the need to have enough sleep. This has been ascribed to the historic failure of science to explain why we need it. Sleep has remained one of the last great biological mysteries. Astonishing, but until recently doctors and scientists could not give a consistent or complete answer as to why we sleep. (Walker, 2017)

The question “Why do we sleep?” is simplistic, and implies that there is one single function connected to sleep. However, contemporary research has revealed that we sleep for a wide range of benefits that serve both our brains and our bodies. There does not seem to be any major organ within the body, or process within the brain, that is not optimally enhanced by sleep. The opposite also holds true, if we do not get enough sleep there are detrimental impairments to our organs as well as our brain function. In the context of operators and drivers, the most concerning negative effect of not enough sleep is fatigue. More critically fatigue in the workplace.

Fatigue can be described as an acute or ongoing state of tiredness that affects employee performance, safety and health. Fatigue is associated with health and safety risks in the workplace as it affects the physical and mental capacities required for the performance of work and is associated with increased workplace incidents. Through the build-up of sleep debt, it can result in errors of judgement that may lead to injury or death. Work-related fatigue affects not only the employee’s health and safety, but the health and safety of others as well. The longer term health effects of fatigue are less well known, but prolonged sleep loss from chronic sleep deprivation due to long periods of night and morning shift work has been associated with increased rates of gastrointestinal and cardiovascular illness - and even death.

There are three types of fatigue: transient, cumulative, and circadian. Transient fatigue is acute fatigue brought on by extreme sleep restriction or extended hours awake over one or two days. Cumulative fatigue is fatigue caused be repeated mild sleep restriction or extended hours awake across a number of days. Circadian fatigue is manifested when our sleep patterns are disrupted. (Worksafe, 2004)

What causes fatigue?
Fatigue can be caused by:
• mentally or physically demanding work (high and low demands)
• long periods of time awake
• inadequate amount or quality of sleep
• inadequate rest breaks
• disruption of circadian rhythms (that is, working when we would normally be asleep or sleeping when we would normally be awake)
• environmental stresses (e.g. heat, noise and vibration)
• work scheduling and payment systems that provide incentives to work longer and harder than may be safe.

How to recognise fatigue
Workplace fatigue can be difficult to spot, but look out for the following:
• feeling drowsy/relaxed
• feeling tired or sleepy, or not feeling refreshed after sleep
• blurred vision
• increased irritability
• finding it difficult to keep your eyes open
• taking more frequent naps during leisure hours, or falling asleep at work
• finding it hard to concentrate and/or making more mistakes than usual
• excessive head nodding or yawning
• increased absenteeism
• repeatedly moving off track while driving vehicles and plant
• near-misses.

Advantages of managing fatigue
Managing workplace fatigue can:
• reduce workplace incidents and work-related claims
• reduce absenteeism and staff turnover
• reduce damage to plant and equipment, and associated costs
• improve work quality, performance and productivity.

There are many ways in which lack of sufficient sleep can kill us. Some will manifest over time; others are immediate. One brain function that is adversely affected by even the smallest dose of sleep deprivation, is concentration. Research shows that someone dies in a traffic accident every hour in the United States due to fatigue related error!

Drowsy driving accidents can be ascribed to two main causes. Firstly, there are people completely falling asleep at the wheel. This happens infrequently, and requires a person to be acutely sleep deprived; having gone without sleep for 20 hours or more. The second, more common cause is a lapse in concentration, called ‘microsleep’. The duration is only a few seconds during which time the eyelids will be either partially or fully closed. These microsleeps are usually suffered by people who are chronically sleep restricted, which is defined as getting less than seven hours of sleep a night on a routine basis.(Walker, 20017)

During a microsleep our brains become blind to the outside world for a brief moment - not just visual perception, but all aspects of perception. Even more scary is the fact that most of the time we are unaware that we are ‘microsleeping’! What is of concern is that our decisive control motor actions, such as those necessary for operating a steering wheel or a brake pedal, will momentarily cease. The consequence is that we don’t need to fall asleep for 10 to 15 seconds to die while driving. Two seconds will do it! Consider a two second ‘microsleep’ at 60 kph, a modest angle of drift can result in your vehicle transitioning entirely from one lane to the next. This includes into oncoming traffic. Should this happen at 90 kph, it may be the last microsleep you will ever have.

Research in Australia has shown that people who had been awake for 19 hours were as cognitively impaired as those that were legally drunk (0.8 percent blood alcohol). Figure 1 shows how catastrophic drowsy driving is when it comes to vehicle accidents. The key result shown in Figure 1, reveals how catastrophic drowsy driving is in the context of vehicle accidents. Operating on less than 5 hours of sleep, your risk of having a vehicle accident increases by four times. Driving with 4 hours sleep or less increases the probability of being involved in a vehicle accident 11.5 times.

Figure 1: The relationship between sleep loss and increase of crash risk.

Of interest to note is that the relationship between decreasing hours of sleep and increasing mortality risk of a vehicle accident is not linear, but it mushrooms exponentially. Each hour of sleep lost vastly amplifies the crash likelihood, instead of incrementally pushing it up.

With the onset of the festive season and the associated festivities, perhaps now is the time to remind operators, drivers and ourselves about the importance of sleeping the required 7-9 hours a night.


Walker, M. (2017). Why We Sleep. United States of America: Simon & Schuster.

Worksafe Victoria. (2004). Fatigue Management Guidelines for the Forestry Industry. Retrieved October 10, 2017 from the World Wide Web