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. 2020 Jun 22;20(1):980.
doi: 10.1186/s12889-020-09095-5.

The impact of sleep deprivation and alcohol on driving: a comparative study

Joanna Lowrie  1 , Helen Brownlow  2
Affiliations

The impact of sleep deprivation and alcohol on driving: a comparative study

Joanna Lowrie et al. BMC Public Health. .

Abstract

Background: There is concern about the detrimental effects of shift-workers' increasing working hours particularly when driving sleep deprived. The approach to measuring the magnitude of driving impairment caused by sleep deprivation was by comparing it to alcohol. The study compared driving performance after 24-h of wakefulness to performance with a BrAC of just over 22 μg/100mls of breath which is equal to 50 mg of alcohol per 100mls of blood (Scottish drink-drive limit). The effectiveness of coffee as a countermeasure for driver fatigue and the association between subjective impairment and actual performance was also investigated.

Methods: A study of 30 participants (11 male and 19 female; mean age 21) was conducted. Subjects were tested under three conditions: fully rested, sleep deprived, and alcohol intoxicated - BrAC mean [SD] 25.95 μg [2.78]. Under each condition, subjects were tested before and after coffee ingestion. This involved driving simulation (Lane Change Task and Reaction Test) and subjective Likert scales (Karolinska Sleepiness Scale and driver impairment scale). Outcome measures included lane tracking adaptive mean deviation, reaction time, and subjective sleepiness and impairment ratings.

Results: Compared to alcohol, sleep deprived mean reaction times were slower (2.86 s vs. 2.34 s) and lateral control of the vehicle was reduced (lane tracking adaptive mean deviation: 0.5 vs. 0.3). Coffee did not produce an improvement when sleep deprived, and instead, performance deteriorated. Females were less impaired following sleep deprivation than males. Following prolonged wakefulness, the correlation between subjective impairment and actual performance was significant.

Conclusions: It was concluded that sleep deprivation has a greater impact on driving performance than a BrAC of 22 μg/100mls of breath, as measured by driving simulation. Coffee is not an effective countermeasure for sleep deprived driving and drivers' ability to judge this impairment is suggested to be limited.

Keywords: Alcohol; Caffeine; Coffee; Driving; Road traffic accident; Sleep deprivation.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Outcome measure results across all experimental conditions. 1. Lane Tracking Adaptive Mean Deviation (MDLT): Score increases with impairment. 2. Braking Reaction Time (BRT): Score increases with impairment. 3. Lane Change Reaction Time (LCRT): Score increases with impairment. 4. Karolinska Sleepiness Scale (KSS): Score increases with perceived level of sleepiness. 5. Subjective Impairment (SI): Score increases with perceived confidence in driving
Fig. 2
Fig. 2
Lane Change Task – extract of Participant 7’s performance when fully rested. The green line illustrates the normative model and the red line illustrates the actual path taken by the driver
Fig. 3
Fig. 3
Lane Change Task – extract of Participant 7’s performance following sleep deprivation. Note the slower reaction time response after signage and the larger deviation from the normative path. Just before the 3rd sign the image demonstrates the driver veering off the road after having fallen asleep at the wheel. The greater the difference between the two paths, the greater the driving impairment and thus the higher the MDLT
Fig. 4
Fig. 4
Combined simulated driving scores (RT and LCT) with SEM across the three conditions. (Score increases with driving impairment)
See this image and copyright information in PMC

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