Publication

EVALUATION OF A FRAGRANCE SYSTEM - Final Report

Driver fatigue is a major cause of car accidents, and the prevention of fatigue is a major goal in the automotive industry. To reach the goal of zero traffic-accident fatalities, developing innovative solutions to prevent fatigue is a key objective. Solutions for fatigue countermeasures during driving have not yet reached a satisfactory level for effectiveness and safety. The most effective ones, such as taking a break and napping, are highly intrusive in the sense that they require you to stop the vehicle or shift drivers. In the current study, the possibility of using odors to counter driver fatigue has been explored.
In this proof-of-concept study, the aim was to investigate if a fragrance system incorporating trigeminal components can have an alerting effect on sleepy drivers. The goal of the project was to provide enough evidence to determine whether the alerting fragrance is effective enough to justify further development and integration of the product into vehicles. The fragrance was tested on 21 healthy but sleep-deprived individuals while they performed a driving task in a simulator. We investigated whether the fragrance system had a measurable effect on subjective sleepiness, objective signs of fatigue and driving performance and attention.
Each participant performed a monotonous driving task twice. An alerting fragrance or an inactive substance was administered during these driving tasks using a cross-over single-blind design. Hence, each participant performed one drive with active fragrance and the other with an inactive treatment. The order of active/inactive fragrance was randomized between participants, and the participants were not informed about the type of fragrance they received. Self-reported sleepiness was assessed using the Karolinska Sleepiness Scale (KSS) every 5 min during the driving task. Speed variability, lateral position variability and line crossing frequency (the vehicle crossing the lane demarcation line) were logged for each drive to measure driving performance. For the analyses, data were aggregated in one-minute segments around the point in time when the fragrance was administrated (five segments before and ten after). Physiological assessments; heart rate measurements (ECG), eye blinks (EOG), and brain activity (EEG) were performed during each drive to investigate potential arousing effects of the fragrance and to track objective signs of sleepiness. A Psychomotor Vigilance Test (PVT) was used to capture attention and cognitive performance before and after the drives.
Subjective sleepiness decreased after fragrance administration, irrespective of whether the fragrance had the active alerting substance or not. However, the effect was no longer significant after controlling for sleepiness at the start of the drive. Mean blink duration, which was used as an objective measure of sleepiness, decreased after fragrance administration, as did the frequency of line crossings. The effect was similar for active and inactive fragrance. In summary, fragrance administration in general had a small but significant effect on some but not all of the included measures typically connected to risk in driver fatigue.
The results for the fragrance administration as such are in line with the effects found for fatigue countermeasures like bright light and caffeine. These types of countermeasures might buy the driver some time, in the sense that driving performance might be restored for a short while. Whether this is sufficient to support driving performance until the driver can make a safe stop or not in real traffic remains a topic for future studies. Based on the results of this study, a more large-scale study using the active fragrance studied here in an operational setting is not justified. It is possible that a different dose or strength of the active fragrance could have given a stronger or longer lasting effect on driver sleepiness and performance. Another avenue for further research is to investigate whether longer duration or repeated administration of fragrance has a stronger effect.

Author(s)
Anna Sjörs Dahlman, Mikael Ljung Aust, Dan Hasson, My Weidel, Yaniv Mama
Research area
Road user behaviour
Publication type
Project report
Year of publication
2022