Early evening low alcohol intake also worsens sleepiness‐related driving impairment

Abstract

Following night-time sleep restriction, afternoon driving performance during the bi-circadian surge in afternoon sleepiness is markedly worsened by blood alcohol concentrations (BACs) well under most national driving limits. This study assessed how driving with this same sleep restriction and BACs (av 40 mg and 28 mg alcohol/100 ml blood at the beginning and end of drive, respectively) respond during the evening circadian rise in alertness. In a 2 x 2 (alcohol versus control drink [double blind] x normal night sleep versus sleep restricted), repeated-measures design, eight healthy young men drove for 2 h from 18:00 h, in a real-car simulator, on a monotonous, simulated highway. Driving impairment (lane drifting), subjective sleepiness and EEG measures of sleepiness were recorded. While sleep restriction alone produced significant impairments to evening driving and subjective sleepiness, alcohol alone did not. However, alcohol combined with sleep restriction significantly worsened all indices, although, this was less than that found for afternoon driving with identical interventions. Whereas low BACs may not affect driving in normally alert drivers in the early evening, the addition of moderate sleep restriction still produces a dangerous combination. Probably, there is no 'safe' level of alcohol intake for otherwise sleepy drivers, at any time of the day.

Alcohol and Sleep Restriction Combined Reduces Vigilant Attention, Whereas Sleep Restriction Alone Enhances Distractibility

“…46 Awareness of alcohol intake by study participants may exacerbate a speedaccuracy tradeoff for the combined condition. As our study was designed in a single blind manner comparable to previous studies, [53][54][55]63 we did not evaluate whether participants were aware of alcohol intake and were unable to elucidate whether this had a true effect in our study. We suspect this had minimal effect on our data outcomes however because we did not find uniformity of impairment across alcohol conditions, plus increased awareness and performance compensation is typically associated with higher doses of alcohol intake.…”

“…Previous studies have examined the combined effect of sleep restriction and alcohol using driving simulation and/or PVT measures. 10,[52][53][54][55][56]90 These tasks provide little insight into specific attentional mechanisms affected by the combination of these factors. For instance, driving taps into more global aspects of performance impairment, whereas the PVT examines vigilant attention.…”

“…[46][47][48] Although much data exist on the effect of sleep loss and alcohol on sustained and selective attention separately, studies examining the combined effects of sleep loss and alcohol remain largely focussed on sustained attention 50,51 or global aspects of driving impairment, such as lane departures. 9,50,[52][53][54][55][56] Clear increases in lane drifting (typical of sleep related crashes) and steering deviation have been reported during a 2-h simulated driving task in the afternoon 9,10,54 and evening 55 following a night of partial sleep restriction (between 4-5 h) when combined with alcohol within legal limits (0.05% BAC). These adverse driving outcomes have been largely attributed to changes in vigilance, drowsiness, and sleep onset/microsleep.…”

Survey of alcohol-related presentations to Australasian emergency departments

“…However, while blood alcohol levels up to 0.05 per cent may not significantly impair psychomotor performance, they invoke a level of drowsiness sufficient to impair performance and increase motor vehicle crash risk (Banks et al 2004;Barrett et al 2004;Barrett et al 2005). This is compounded if alcohol is combined with other drugs such as cannabis (Lamers & Ramaekers 2001;Kuypers et al 2006).…”

Direct Assessment of Alcohol Consumption in Mental State Using Brain Computer Interfaces and Grammatical Evolution

“…Alcohol consumption is related to impaired driving, even in low doses [3,4]. Moreover, driver authentication from brain waves can be integrated into a driver's authentication system [5,6] and thus BCI systems for road safety have been into consideration [7][8][9].…”