Guest blog by Koos Meijer from KM Human Factors Engineering
Why do you lose the ability to fully concentrate after a few nights of poor sleep? Or why does a sleep debt of only two hours increase the risk to get involved in a car accident by 200%? Think about it, you spend almost one-third of your life on this planet asleep. But why? And how does it affect performance and process safety? In this blog, I will explain the neuroscience of how a lack of sleep affects cognitive performance, how this reduces the reliability of process safety, and how to deal with it from a barrier-based risk management perspective.
Reason 1 – A lack of sleep reduces the capacity of our brains’ neurons to communicate effectively
Neural processes form the basis of decision-making and are at the core of every safety-critical task. Poor sleep and fatigue directly impede this process by reducing the ability of your brains’ neurons to communicate effectively. When you are not able to get the required hours of high-quality sleep, the following two things will happen: First, chemicals and waste products remain accumulated in the brain and second, some regions of your brain will suffer from depleted energy supplies (e.g. glucose and glycogen).
To feel energized and refreshed, the brain needs to be fully cleaned and supplied with these sources of energy. The problem is that the brain, unlike the rest of your body, can only clean effectively during sleep, and especially during slow-wave (i.e. deep) sleep.
After a good night of sleep, your brains are cleaned from toxins and fully supplied with energy. As a result, neurons are more able to communicate effectively, leading to increased alertness, energy, concentration, and problem-solving abilities. A fatigued brain is a dirty brain and reliability for process safety.
Adenosine: the fatigue barometer of the brain
One crucial predictor of mental fatigue is the accumulation of the waste product called ‘adenosine’ in the brain. For this reason, I call it the fatigue barometer of the brain. After a good night of sleep, the level of adenosine in the brain is low. However, after a period of wakefulness and mental activity, adenosine levels rise, signaling the brain to sleep. Besides the inducing feelings of fatigue, adenosine modulates (i.e. attenuates) the synaptic activity of your brains’ neurons. The negative effect this can have is illustrated by multiple fatigue-related studies and most strikingly, by events such as the Chernobyl disaster and the explosion of the space shuttle Challenger.
Studies have shown that performance and vigilance after being awake for 17-19 hours tend to be equal or worse to the performance of individuals with an alcohol concentration of 0.05% in their blood (i.e. the drunk driving limit in Europe).
This neuroscientific perspective shows why long shifts can be dangerous and why high-quality rest is essential for optimal brain performance. When you sleep better, you have more energy, you’re more focused and your work and safety performance is better.
Reason 2 – A lack of quality sleep reduces the effectiveness of the ‘process safety part of the brain’
The prefrontal cortex, located at the frontal part of the brain (above your eyes), is ‘the process safety part’ of the brain and very sensitive to a lack of sleep. It is related to the so-called executive functions such as working memory, attention, communication, regulation of emotions and problem-solving skills.
“A lack of sleep induces adverse changes in our brain and reduces cognitive performance. It impairs attention, vigilance, working memory and other functions, such as long-term memory and decision-making. These are all safety-critical aspects of human performance and process safety, poor sleep and fatigue should, therefore, be prevented at all times.” SPE
When being in a state of high fatigue, the brain tends to switch to a more energy efficient way of processing information. As a result, it is inclined to switch from a conscious, analytical, rational, reflective and thoughtful – prefrontal cortex mode – of reasoning, to a more energy efficient way of processing information that produces automatic, pre-conscious, reactive, habitual and emotion-based actions.
The more energy efficient way of processing information paves the way for various types of cognitive biases and errors to occur.
Also very important: a sleep-deprived brain is less able to inhibit the amygdala (the so-called fear center of the brain), which consequently leads to the rise of stress hormones and general anxiety levels. Hence, it is important to remember that stress is not only a cause of sleeping poorly but also a consequence. Sleep improvement is an effective stress countermeasure.
Reason 3 – Fatigue and lack of sleep may lead to risk-taking
The prefrontal cortex, as explained above, also plays a crucial role in inhibiting certain behavioral impulsive acts and regions of the brain. Most sleep and fatigue research support the hypothesis that sleep deprivation increases many aspects of risk-taking, including simple impairments in attention and judgment, greater willingness to accept risk, and a tendency to focus on short-term rather than long-term consequences. These fatigue-related consequences have serious impacts on performance and process safety.
Reason 4 – A lack of sleep decreases motivation and effort
At many high-hazard organizations, the long work hours combined with sleep cycle disruptions due to shift work can lead to high fatigue levels. When the workforce is in a state of high fatigue, their ability to perform tasks that require additional energy is impaired and the ability of their brain to overcome the deficiencies caused by sleep loss is limited. This, in turn, can have a critical impact on overall health and safety.
Reason 5 – Fatigue increases the tendency to use heuristics when making risk-based decisions
Closely related to the abovementioned consequences of a lack of quality sleep is the increased tendency to use heuristics during work. Heuristics are simple, efficient rules which people often use to form judgments and to make decisions. They can be seen as mental shortcuts, rules of thumb, that usually involve focusing on one aspect of a complex problem and ignoring others. The good thing is that they are quick and, most of the time, sufficiently correct. However, when they are used to a situation that demands an effortful and analytical approach, they may lead to cognitive biases in judgments. These biases may contribute, in various ways, to suboptimal decision making.
As explained before, our fatigued brain has a natural tendency to use a more efficient, fast mode of thinking (e.g., pre-conscious, reactive, habitual, and emotion-based), which makes a person more inclined to the use of error-prone heuristics. In a safety-critical environment, heuristics can lead to mistakes in decision making, which will be discussed in the next section. Prevention of falling into these cognitive biases or traps demands effortful thoughts (and effective communication with colleagues), which is much easier in a well-rested state.
For high-hazard organizations, removing or at least mitigating these biases should be an important goal if you want to enhance process safety. Prevention of falling into these cognitive biases or traps demands effortful thoughts (and effective communication with colleagues), which is much easier in a well-rested state. Proactive fatigue countermeasures to improve sleep quality are crucial components of process safety.
Reason 6 – Fatigue leads to human error: slips, lapses, and mistakes
Slips can be thought of as actions not carried out as intended or planned (e.g. finger trouble when dialing a number on the phone or Freudian slips when saying something). One of the ways fatigue creates slips is the decrease in hand-eye coordination. In a study of Dawson and Reed, the effects of mental fatigue on hand-eye coordination were assessed compared to the effects of the use of alcohol. A striking finding was that:
Seventeen hours of sustained wakefulness was equivalent to the impaired performance of a person with a blood-alcohol concentration of 0,05%.
This is one of the reasons why slips are more likely to occur when the operator is not fully rested.
Lapses are missed actions and omissions. An example of a lapse is that somebody forgets to (re)buckle their safety harness while working at height. Primarily, lapses are caused by memory or attention failures. As shown above, fatigue has both impacts on memory and attention. It’s harder to remain vigilant with a sleep-deprived brain.
Mistakes are a specific type of error brought about by a faulty plan or intention. i.e. somebody did something believing it to be correct when it was, in fact, wrong, e.g. switching off the wrong alarm or using the incorrect type of fire extinguisher during a liquid fire at work.
Proactive fatigue management is an effective defense mechanism against mistakes and impulsive emotion-laden reactions that can put you and others at risk. Improving the quality of sleep of the workforce will also strengthen the analytical, and troubleshooting capabilities of the prefrontal cortex, which in turn is a critical safeguard against the risk of mistakes on the work floor.
Reason 7 – Fatigue makes it difficult to store new information and consolidate memories
Do you also experience problems remembering information during that boring meeting at work after a poor night of sleep? This is very common. The reason for this is that your ability to store new information into the brain (which is essentially the creation of new neural connections in the brain see point 1 and 2) is hindered by fatigue. As discussed before, this is likely to be caused by various consequences of fatigue, such as reduced focus, motivation, attention, and concentration caused by fatigue and increased sleep pressure. Firstly, this prevents new information to be stored in memory. Secondly, the lack of sleep prevents so-called memory consolidation (i.e. the strengthening of existing neural connections), which happens during sleep.
In sum, improved quality of sleep between shifts results in enhanced concentration and focus of the workforce during safety-critical tasks and training. Also, it results in better storage and recall of this safety-critical information.
How to deal with fatigue from a barrier based risk management perspective
Which safety barriers are not affected by mental fatigue? The answer to this question: None! Not even the hardware barriers? No, even the hardware barriers are designed, maintained, and in some cases operated by human operators. Fatigue on the work floor both increases the number of potential so-called ‘initiating events’ and increases the size and number of holes in the Swiss Cheese model of James Reason.
What does fatigue look like from a barrier based risk management perspective? Now that you know the effects of fatigue on humans and their performance, do you know how it impacts your business? Can you answer the 3 process safety questions when taking into account fatigue among the workforce?
- Do you understand what can go wrong?
- Do you know what your systems are to prevent this from happening?
- Do you have information to assure they are working effectively?
To help you understand the impact of fatigue on your business, CGE and I cordially invite you to attend the upcoming CGE Guest Webinar ‘Why fatigue affects process safety and how to deal with it’, on the 11th of December.
Join the webinar and learn how to deal with fatigue in your organization
During the ‘Why fatigue affects process safety and how to deal with it‘ webinar, we will discuss the following subjects:
- What is fatigue?
- What are the effects of fatigue on process safety?
- What is the impact of fatigue on safety barriers?
- Examples of fatigue bowties that help you answer the 3 questions
- What are preventive fatigue barriers/countermeasures
- What are mitigating fatigue barriers/countermeasures
About the author
In his career, Koos has already supported various organizations in getting insight into the effects of fatigue on their business and how to deal with them. Think of organizations in Defence, Oil & Gas, Healthcare, Consultancy, Law Firms, but also top sporters. Learn more about Koos in this 2-minute video.