It is often stated that fatigue impacts decision-making. In the new Safe Work Australia Model Code of Practice for “Managing the Risk of Fatigue at Work” [1] for example, it states that fatigue can impact “mental and cognitive abilities like decision making and concentration”, and can also reduce judgment. To provide a high-profile example, fatigue from sleep loss and its impact on judgement is often cited as a critical factor contributing to the Space Shuttle Challenger Accident, as “key managers obtained only minimal sleep the night before the teleconference” [2], where it was discussed whether or not the launch should go ahead.
While simply stating that fatigue impairs decision-making may satisfy some, there are further questions that are worthwhile asking. Exactly how does fatigue impact decision-making? Exactly which aspects of decision-making are affected by fatigue? The reality is that the current scientific understanding of this is far from clear. Until recently, one of the only consensuses reached in this space is that fatigue from sleep loss usually results in riskier decision making.
Even then, this generalisation didn’t always hold; some studies, such as those using the scientifically valid decision-making paradigm, the “Balloon Analog Risk Task” or “BART”, found that fatigue from sleep loss resulted in less risk being taken [3, 4]. Indeed, some of my experimental work from my PhD research suggested that, in specific tasks, sleep loss-induced fatigue may result in both simpler and safer decision-making [5]. From the outside looking in, trying to understand how sleep loss-induced fatigue impacts decision-making could feel like you are looking at a “black box”.
In August 2025, this box was opened. Jeryl Lim and colleagues at Monash University and the University of Arizona published “The impact of sleep loss on decision making: Opening the cognitive black box” in the prestigious scientific journal Sleep Medicine Reviews [6].
While a five-point summary does this review no favours, some key findings of the review (outside of recommendations for how to better explore the relationships between sleep loss-induced fatigue and decision-making in the future) are as follows:
- The relationship between sleep loss and risk propensity is not crystal clear.
- Some researchers suggest that “delay discounting” (we may think of this as “delayed gratification”) is poorer following sleep loss; however, the current data on this is mixed.
- Sleep loss-induced fatigue leads people to favour less effortful decisions and tasks. Basically, when people have lost sleep, they try to take the “easy way out” and require greater motivating factors to engage in certain activities or make choices that require more cognitive effort.
- A small sample of experiments suggests that when people lose sleep, they tend to rely more on heuristics, or “rules of thumb,” in their decision-making, rather than truly appreciating and responding to specific situations. This is again likely done to reduce the cognitive effort used.
- Sleep loss appears to reduce one’s ability to use information learnt instantly to inform decisions, and adjust their strategy when circumstances change.
So, what may this mean for your workforce? How is sleep loss-induced fatigue likely to impact the judgment of your leaders? What about your workers in an operation centre or control room; how may a few nights of poor sleep change the decisions they make? Some possibilities, guided by the current best scientific evidence, are discussed below:
- Tired team members are more likely to take shortcuts or not follow procedures to the letter. While this does increase risk, team members will not do this because it is risky, but rather because it may simply require less effort.
- Individuals may require more motivation to make certain decisions or complete specific tasks. While the fear of a mechanical fault leaving one stranded on a long commute in a remote area is usually enough to motivate a team member to complete a pre-start checklist, for an excessively fatigued team member, it may simply not be enough.
- A tired investment banker may identify a pattern in a stock of interest that, as a “rule of thumb”, suggests they should buy. The tired banker simply follows their “rule of thumb” and buys, rather than digging a little deeper to find other signals that suggest buying the stock is not a good idea.
- A tired operator not adapting to the fact that a new piece of equipment (for example, a larger drill rod on an offshore rig) may need to be used differently or require additional or more rigorous controls.
Don’t let fatigued decision-making impact your organisation’s safety, productivity, or cost. At Melius Consulting, we use scientifically validated mathematical modelling to identify periods within work schedules with high inherent fatigue risk. We also provide comprehensive Fatigue Risk Management (FRM) assessments that help identify periods of fatigue risk and safeguard your operation from fatigued decision-making during these periods. Additionally, we offer tailored sleep health optimisation programs that help improve the judgment of everyone in your workplace. Getting in touch with us is a good decision!
For more information on our services, please contact info@meliusconsulting.com.au or check out what we offer here.
References
1. Safe Work Australia, Code of Practice: Managing the risk of fatigue at work. 2025, Safe Work Australia. p. 1-62. https://www.safeworkaustralia.gov.au/doc/model-code-practice-managing-risk-fatigue-work
2. Rogers, W.P., et al., Presidential commission on the space shuttle Challenger accident. 1986: Washington, DC.
3. Killgore, W.D.S., Effects of sleep deprivation and morningness-eveningness traits on risk-taking. Psychological Reports, 2007. 100(2): p. 613-626. DOI: https://doi.org/10.2466/pr0.100.2.613-626.
4. Killgore, W.D.S., et al., Restoration of Risk-Propensity During Sleep Deprivation: Caffeine, Dextroamphetamine, and Modafinil. Aviation, Space, and Environmental Medicine, 2008. 79(9): p. 867-874. DOI: https://doi.org/10.3357/ASEM.2259.2008.
5. Smithies, T.D., An Empirical Investigation into the Effects of Sleep Loss on Esports Performance, in Physical Education and Sport Sciences. 2023, University of Limerick: https://doi.org/10.34961/researchrepository-ul.25102469.
6. Lim, J.Y.L., et al., The impact of sleep loss on decision making: Opening the cognitive black box. Sleep Medicine Reviews, 2025. 82: p. 102114. DOI: https://doi.org/10.1016/j.smrv.2025.102114.