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.
