In-vehicle fragrance administration as a countermeasure for driver fatigue

Dahlman, Anna Sjörs; Aust, Mikael Ljung; Mama, Yaniv; Hasson, Dan; Anund, Anna · 2024 · Crossref

DOI: 10.1016/j.aap.2023.107429

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Summary

This study investigates the efficacy of in-vehicle fragrance administration as a countermeasure for driver fatigue, specifically comparing fragrances with trigeminal components (which stimulate facial nerves and cause a tingling sensation) against pure olfactory fragrances. Driver fatigue contributes to 10–30% of fatal crashes, and while effective countermeasures like naps exist, they are intrusive. The research aims to determine if non-intrusive odor-based interventions can restore alertness and improve driving performance in severely fatigued individuals. The experiment utilized a driving simulator with 21 healthy, sleep-deprived night-shift workers. Participants performed a monotonous driving task twice in a cross-over, single-blind design: once exposed to a trigeminal fragrance (containing allyl isothiocyanate) and once to an olfactory fragrance (vanilla). Fragrance was administered via a nebulizer either when the participant fell asleep (defined as eye closure >3 seconds) or after 45 minutes if they remained awake. Data collection included subjective sleepiness ratings via the Karolinska Sleepiness Scale (KSS), driving performance metrics (line crossings, speed and lateral position variability), and physiological measures (heart rate, eye blink duration via EOG, and Psychomotor Vigilance Test results). Results indicated that fragrance administration significantly reduced subjective sleepiness and improved driving performance, evidenced by a significant decrease in line crossing frequency that lasted at least five minutes post-exposure. Objective physiological signs of sleepiness, specifically mean blink duration, decreased significantly immediately after fragrance exposure, though this effect lasted only one minute. However, there were no statistically significant differences between the trigeminal and olfactory fragrances regarding subjective sleepiness, driving performance, or most physiological markers. The trigeminal fragrance was perceived as significantly more unpleasant, though not significantly more alerting. Psychomotor Vigilance Test results showed slightly shorter reaction times after the trigeminal drive, but the difference was deemed unlikely to be practically relevant. The study concludes that in-vehicle fragrance administration can temporarily restore alertness and improve driving performance in fatigued drivers, with effects comparable to other common countermeasures like loud music. However, the benefits are short-lived, raising questions about whether such interventions are sufficient to maintain safety until a driver can make a safe stop. The lack of significant difference between trigeminal and olfactory stimuli suggests that while trigeminal components may be useful for waking drivers from actual sleep, they do not offer superior alerting effects for general fatigue mitigation compared to standard olfactory scents.

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Topics

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• drowsiness detection algorithms
• drowsiness
• truck driver fatigue
• time on task
• sleep deprivation
• circadian factors

Information type

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• Empirical Findings: physiological data
• Methodological Resource: tool software
• Theoretical Contribution: theory or model