Fatigue Biomarker Trial in Emergency Service Workers: Technical Report Prepared for the Victorian Department of Transport & Planning

Driver ‘fatigue’ remains a significant contributor to road trauma in Victoria, yet, unlike alcohol, there are currently no objective scientifically accepted methods that can detect fatigue, sleepiness and any associated impairment at, or near, the point of risk (i.e., the roadside). In the absence of such a method, it is difficult to establish fatigue-specific offences in road-safety legislation (e.g., driving while impaired by fatigue) or to implement other countermeasures that depend on a definitive biological standard. In Victoria, previous work under the Road Safety Strategy (2016–2020) investigated whether device technologies could screen for fatigue-related driving impairment at the roadside, but a reliable biological test for fatigue that could function at an evidentiary standard, has yet to be demonstrated.

Without a recognised evidentiary standard for fatigue, sleepiness or associated impairment, current approaches rely on proxies (e.g., time-on-task limits, self-reports, and behavioural screening) that vary in their sensitivity to the underlying physiological state (Thomas et al., 2021). Due to their subjectivity and low sensitivity, these approaches are unable to be translated into a clear legal threshold of impairment. Consequently, there is a limited capacity for regulators to define, enforce and deter fatigue related risk.

The Monash Fatigue Biomarker (Jeppe et al., 2024) is a promising blood-based metabolomic biomarker, with excellent predictive accuracy for sleep deprivation under tightly-controlled laboratory conditions.

Evidence for the biomarker was gathered under controlled laboratory conditions where participants were tested at multiple time points across 40 hours of sustained wakefulness, and a small set of five metabolites were identified that reliably predicted sleep deprivation at both the group and individual level. These five metabolites are collectively referred to as the Monash Fatigue Biomarker.

A validated blood-based biomarker, such as the Monash Fatigue Biomarker, would provide an objective biological measure that, with further validation, may serve as an evidentiary standard for fatigue assessment and provide the basis for an evidence-informed regulatory framework for driver fatigue in the future. Thus, the focus of this research was to evaluate the Monash Fatigue Biomarker in a real world context.

The specific aim of the research was to assess the efficacy of the Monash Fatigue Biomarker and optimising compounds in predicting objective measures of prior sleep duration (or conversely, time spent awake) in a real-world, shift-working population of emergency call-takers. The study aimed to answer the following research questions:

• Does the Monash Fatigue Biomarker correlate with independent objective and subjective measures of sleepiness, drowsiness, and fatigue-related impairment?
• Does the Monash Fatigue Biomarker accurately predict low levels of time since wake (TSW) outside of controlled laboratory conditions in shift workers operating in a real-world setting?
• Is the sensitivity of the Monash Fatigue Biomarker sufficient to predict shift type (day shift versus night shift)?