The Maintenance of Wakefulness Test and driving simulator performance

Adelaide Institute for Sleep Health, Repatriation General Hospital-Daw Park, Australia.
Sleep (Impact Factor: 4.59). 12/2005; 28(11):1381-5.
Source: PubMed


It has been suggested that the Maintenance of Wakefulness Test (MWT) may be clinically useful to assess fitness to drive, yet little is known about the actual relationship between sleep latency and driving performance. This study examined the ability of 2 MWT trials to predict driving-simulator performance in healthy individuals.
Twenty healthy volunteers (mean age 22.8 years; 9 men).
The MWT and driving-simulator performance were examined under 2 conditions-partial sleep deprivation and a combination of partial sleep deprivation and alcohol consumption. Each subject was studied a week apart, with the order randomly assigned. Subjects completed a nighttime 70-minute AusEd driving simulation task and two 40-minute MWT trials, 1 before (MWT1) and 1 after (MWT2) the driving task. In the sleep-deprived condition, the MWT1 sleep latency was inversely correlated with braking reaction time. During the partial sleep deprivation and alcohol condition, the number of microsleeps during the driving task, steering deviation, braking reaction time, and crashes all negatively correlated with the MWT1 sleep latency. Additionally, construction of a receiver-operator characteristic curve revealed that MWT1 sleep latency in the partial sleep deprivation plus alcohol condition significantly discriminated subjects who had a crash from those who did not.
These results indicate that sleep latency on the MWT is a reasonable predictor of driving simulator performance in sleepy, alcohol-impaired, normal subjects. Further research is needed to examine the relationship between daytime MWT results and driving simulator performance in sleepy patients (eg, those with obstructive sleep apnea) and in experimentally sleep-deprived normal subjects.

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    • "Lane deviation, defined as movement (in centimetres) of the car from the median position of the left hand side of the road, variation in speed (outside the prescribed speed zone 60–80 kph), braking reaction time (ms) and mean number of crashes (off road events, collisions with slow moving trucks, or stopping events >10 s) were used as outcome measures. This simulated driving task is sensitive to performance changes due to sleep deprivation (Desai et al., 2006), circadian rhythms (Banks et al., 2005), sleep disorders (Desai et al., 2006) and alcohol (Howard et al., 2007; Vakulin et al., 2007). "
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    ABSTRACT: Driving is a complex task, which can be broken down into specific cognitive processes. In order to determine which components contribute to drowsy driving impairments, the current study examined simulated driving and neurocognitive performance after one night of sleep deprivation. Nineteen professional drivers (age 45.3±9.1) underwent two experimental sessions in randomised order: one after normal sleep and one after 27h total sleep deprivation. A simulated driving task (AusEd), the psychomotor vigilance test (PVT), and neurocognitive tasks selected from the Cognitive Drug Research computerised neurocognitive assessment battery (simple and choice RT, Stroop Task, Digit Symbol Substitution Task, and Digit Vigilance Task) were administered at 10:00h in both sessions. Mixed-effects ANOVAs were performed to examine the effect of sleep deprivation versus normal sleep on performance measures. To determine if any neurocognitive tests predicted driving performance (lane position variability, speed variability, braking RT), neurocognitive measures that were significantly affected by sleep deprivation were then added as a covariate to the ANOVAs for driving performance. Simulated driving performance and neurocognitive measures of vigilance and reaction time were impaired after sleep deprivation (p<0.05), whereas tasks examining processing speed and executive functioning were not significantly affected by sleep loss. PVT performance significantly predicted specific aspects of simulated driving performance. Thus, psychomotor vigilance impairment may be a key cognitive component of driving impairment when sleep deprived. The generalisability of this finding to real-world driving remains to be investigated.
    Accident; analysis and prevention 06/2012; 50. DOI:10.1016/j.aap.2012.05.020 · 1.65 Impact Factor
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    • "It has been shown that sleep restriction combined with extended wakefulness strongly affected simulated driving performance in healthy young drivers (Philip et al., 2005b). Another study (Banks et al., 2005) compared MWT with performance on a driving simulator in healthy sleep-deprived volunteers and found the first evidence of the predictive value of objective measure of sleepiness for simulated performance. A study (Sagaspe et al., 2008), set up in real driving condition, was the first to use a dose–response design of duration of driving (2, 4 and 8 h of nocturnal driving) while controlling the effects of prior waking time and time of day. "
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    ABSTRACT: To compare the impact of extended wakefulness (i.e., sleepiness) and prolonged driving (i.e., fatigue) at the wheel in simulated versus real-life driving conditions. Participants drove on an INRETS-MSIS SIM2 simulator in a research laboratory or an open French highway during 3 nocturnal driving sessions. A dose-response design of duration of nocturnal driving was used: a 2 h short driving session (3-5 AM), a 4 h intermediate driving session (1-5 AM) and an 8 h long driving session (9 PM-5 AM). Two groups of healthy male drivers (20 for simulated driving and 14 drivers for real driving; mean age±SD=22.3±1.6 years), free of sleep disorders. Number of inappropriate line crossings, self-rated fatigue and sleepiness were recorded in the last hour of driving sessions to control the effects of prior waking time and time of day. Compared to the daytime reference session, both simulated and real driving performance were affected by a short nocturnal driving session (P<.05 and P<.001, respectively). Extension of nocturnal driving duration affected simulated performance nonlinearly and more severely than that of real driving (P<.001). Compared to the daytime reference session, short nocturnal simulated and real driving sessions increased self-perceived fatigue and sleepiness. Real and simulated driving conditions had an identical impact on fatigue and sleepiness during extended periods of nocturnal driving. In healthy subjects, the INRETS-MSIS SIM2 simulator appropriately measures driving impairment in terms of inappropriate line crossings related to extended wakefulness but has limitations to measure the impact of extended driving on drivers' performance.
    Accident; analysis and prevention 03/2012; 45:677-82. DOI:10.1016/j.aap.2011.09.046 · 1.65 Impact Factor
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    • "These MWT conditions are admittedly more passive than an average driving situation, and it is thus unclear to what extent MWT results can be extrapolated to driving situations [14]. Subjects might fall asleep more easily under the MWT conditions, but in real-life situations the risk of falling asleep might be higher in general because of the longer exposure times. "
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    ABSTRACT: To test whether subjects spontaneously signal sleepiness before falling asleep under monotonous conditions. Twenty-eight healthy students were deprived of sleep for one night and then underwent a "maintenance-of-wakefulness test" (MWT) consisting of four 40-min trials. They were told to give a signal as soon as they felt sleepy and to try to stay awake as long as possible. In a first series of tests, the subjects were given no reward (nr); in a second series, monetary rewards (wr) were given both for an accurate perception of sleepiness and for staying awake longer. Seventeen of the 28 subjects (60.7%) did not signal sleepiness before a sleep fragment occurred in at least one of the four MWT trials. Women were more reliably aware of sleepiness than men in the nr trials (p=.02), while the men's performance improved in the wr trials (p<.02), becoming equivalent to the women's performance. Our results cast doubt on the general assumption that one cannot fall asleep without feeling sleepy first. If similar results can be obtained in monotonous driving or working situations, this will imply that accidents caused by sleepiness or by falling asleep cannot necessarily be attributed to an individual's negligence.
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