Browsing by Subject "Sleep deprivation"

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    The Effect of Sleep Deprivation on Driving Performance
    (University of Minnesota Center for Transportation Studies, 2009-01) Bloomfield, John; Harder, Kathleen A.; Chihak, Benjamin J.
    Each of twenty commercial motor vehicle (CMV) drivers participated in a single twenty-hour experimental session, during which they were continuously kept awake, but were allowed to ingest caffeine and use tobacco as they would in real-world conditions. Each participant drove in a fixed-base advanced driving simulator for approximately one hour on four occasions (at 9:00 am, 3:00 pm, 9:00 pm, and 3:00 am). The 59.5-mile (95.8-km) test route was designed with overpasses and intersections and changes in speed limits—to make the driving experience more like real-word driving. After the fourth drive, the participants were driven to the University of Minnesota’s General Clinical Research Center, where they slept for eight hours. The main result was that the steering performance of CMV drivers was impaired when they stayed awake for an extended period: There was a considerable increase in steering instability between the morning drive, at 9:00 am, and the nighttime drive, at 3:00 pm—an increase likely to have been produced by sleep deprivation. [Other results were: (1) stopping behavior improved throughout the session—suggesting practice effects; (2) after the fourth drive, there was less reduction in the participants’ pupil size—but, since there was no difference in pupil size before the fourth drive, there was no evidence to suggest that pupil size reductions could be used to predict sleep deprivation; (3) data from other visual performance tests showed no effect of time of day; and, (4) results obtained from reaction time tests did not show decrements in performance—instead there may have been practice effects.]
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    Validating an Objective Roadside Tool to Assess Driver Fatigue
    (Center for Transportation Studies, University of Minnesota, 2020-05) Morris, Nichole L.; Craig, Curtis M.; Iber, Conrad; Schwieters, Katelyn R.
    Fatigue has a known influence on negatively affecting driving safety (e.g., increased micro-sleeping, falling asleep at the wheel, and lane drifting) but has been difficult to detect and identify. As such, an objective and reliable roadside tool to detect driver fatigue is needed. The purpose of this project was to validate a series of assessment tests, including but not limited to the Critical Flicker Frequency (CFF), Brief Psychomotor Vigilance Test (PVT-B), and Trail Making Test, to determine their ability to reliably measure level of alertness or fatigue as an objective tool to assess driver fatigue. A large sample fatigue study was conducted to identify the rate and public acceptance of drowsy driving and establish normative data sets for select fatigue assessment measures among the general Minnesota population. Following that, a 30-hour sleep deprivation study assessed driving performance and fatigue under alert to extreme fatigue conditions. Results from the large sample fatigue study demonstrated a positive relationship between CFF threshold, age, gender, and elapsed sleep measures. Results from the sleep deprivation study showed prolonged wakefulness influenced driving performance (i.e., sleepiness at the wheel) and the relationship between impaired driving and cognitive test performance. A cognitive composite measure of the PVT-B and Trail Making Test predicted fatigue-related driving outcome variables, suggesting that these tests could be useful for further development and assessment of roadside measurement fatigue.