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 (19–65 years; 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 maneuvers and lane deviations, respectively. Physiological drowsiness was defined by eye closures (Johns drowsiness scores) 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 (emergency brake) driving event occurring in the next 15 minutes (OR: 1.76–2.4, AUC > 0.81, p < 0.009), except “head dropping down”. Karolinska Sleepiness Scale (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 0.8), 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.
Methods: Sixteen shift workers (19–65 years; 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 maneuvers and lane deviations, respectively. Physiological drowsiness was defined by eye closures (Johns drowsiness scores) 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 (emergency brake) driving event occurring in the next 15 minutes (OR: 1.76–2.4, AUC > 0.81, p < 0.009), except “head dropping down”. Karolinska Sleepiness Scale (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 0.8), 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.
| Original language | English |
|---|---|
| Article number | zsad136 |
| Journal | Sleep |
| Early online date | 9 May 2023 |
| DOIs | |
| Publication status | E-pub ahead of print - 9 May 2023 |
Bibliographical note
Funding:This study was supported by a grant from the Institute of Breathing and Sleep Research (to M.E.H.); by Liberty Mutual Insurance; National Institutes of Health Award 5T32HL7901-14 (to M.L.L.); National Space Biomedical Research Institute Award PF03002 (to M.L.L.); Department of Homeland Security Federal Emergency Management Agency Assistance to Firefighter Grant EMW-2010-FP-00521 (to C.A.C.); National Heart, Lung and Blood Institute Cooperative Agreement U01-HL111478 (to C.A.C.); National Institute of Occupational Safety and Health Grant R01-OH0103001 (to C.A.C.); National Institute on Aging Grant R01-AG044416 (to C.A.C.); and an endowed professorship provided to Harvard Medical School by Cephalon, Inc. (to C.A.C.). The content of this article is solely the responsibility of the authors and does not necessarily represent the official views of the Federal Emergency Management Agency, Assistance to Firefighters Grant Program, National Institutes of Health, National Space Biomedical Research Institute, Institute of Breathing and Sleep, or Liberty Mutual Insurance Company. The federal sponsors did not have a role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; or preparation, review, or approval of the manuscript.
Keywords
- Drowsiness
- sleepiness
- subjective
- driving
- lane departure
- eye closure