Feeling sleepy? stop driving—awareness of fall asleep crashes

Abstract

Study Objectives To examine whether drivers are aware of sleepiness and associated symptoms, and how subjective reports predict driving impairment and physiological drowsiness. Methods Sixteen shift workers (19-65y; 9 women) drove an instrumented vehicle for 2-hours on a closed-loop track after a night of sleep and a night of work. Subjective sleepiness/symptoms were rated every 15-minutes. Severe and moderate driving impairment was defined by emergency brake manoeuvres and lane deviations, respectively. Physiological drowsiness was defined by eye closures (Johns Drowsiness Scores, JDS) and EEG-based microsleep events. Results All subjective ratings increased post night-shift (p<0.001). No severe drive events occurred without noticeable symptoms beforehand. All subjective sleepiness ratings, and specific symptoms, predicted a severe driving event occurring in the next 15-minutes (OR: 1.76-2.4, AUC>0.81, p<0.009), except ‘head dropping down’. KSS, ocular symptoms, difficulty keeping to center of the road, and nodding off to sleep, were associated with a lane deviation in the next 15-minutes (OR: 1.17-1.24, p<0.029), although accuracy was only ‘fair’ (AUC 0.59-0.65). All sleepiness ratings predicted severe ocular-based drowsiness (OR: 1.30-2.81, p<0.001), with very good-to-excellent accuracy (AUC>0.8), while moderate ocular-based drowsiness was predicted with fair-to-good accuracy (AUC>0.62). KSS, likelihood of falling asleep, ocular symptoms and ‘nodding off’ predicted microsleep events, with fair-to-good accuracy (AUC 0.65-0.73). Conclusions Drivers are aware of sleepiness, and many self-reported sleepiness symptoms predicted subsequent driving impairment/physiological drowsiness. Drivers should self-assess a wide range of sleepiness symptoms and stop driving when these occur to reduce the escalating risk of road crashes due to drowsiness.

Subjective awareness of sleepiness while driving in younger and older adults

“…Despite this, as both KSS and LFA were strong predictors for early (lane deviations) and late (near crashes) impairment in both age groups, our data suggest that drivers should routinely ask themselves how sleepy they feel, and how likely they might fall asleep in the next few minutes, particularly during long drives and/or after driving following a night of insufficient sleep (Anderson et al, 2018; Hallvig et al, 2014). Our findings are consistent with previous simulated and naturalistic studies examining the predictive capacity of the KSS for lane deviations (Anderson et al, 2023; Anund et al, 2017; Hallvig et al, 2014; Philip et al, 2005; Williamson et al, 2014), and driving metrics indicating severe impairment, such as crash events (Ingre et al, 2006; Williamson et al, 2014) and emergency brake procedures (Anderson et al, 2023). Although these studies collectively cover a wide age range (18–60) within their samples, our study builds on these data by systematically examining the impact of age on the predictive value of subjective ratings on drowsy driving outcomes.…”

“…Finally, we included a wide range of subjective measures in our analyses. While the KSS is most used in driving studies examining the association between subjective and objective sleepiness (Alvaro et al, 2016; Cai et al, 2021; Filtness et al, 2012; Kosmadopoulos et al, 2017; Williamson et al, 2014), our study includes the LFA, which is highly predictive of near crash events in both older and younger adults, and the SSQ which has been shown in younger drivers to predict adverse driving outcomes in both simulator (Howard et al, 2014) and on‐road (Anderson et al, 2023) studies. Alongside the high face validity of the scales we used, and ease of understanding/accessibility for the majority of the driving population, our data suggest that the KSS, LFA, and SSQ may be useful for educational campaigns on a group level.…”

“…To address this, we recently examined the accuracy of subjective sleepiness and associated symptoms, in predicting both driving impairment and physiological signs of drowsiness using an on‐road track design. Here, (some indices of) subjective sleepiness predicted near crash events, lane deviations, long eye closures, and microsleep events in shift workers driving post‐night shift (Anderson et al, 2023).…”