The road to danger: the comparative risks of driving while sleepy.

Objectives/hypothesis: A large sector of the population of the United States has sleep deprivation directly leading to excessive daytime sleepiness. The prevalence of excessive daytime sleepiness in this population ranges from 0.3% to 13.3%. The consequences of even 1 to 2 hours of sleep loss nightly may result in decrements in daytime functions resulting in human error, accidents, and catastrophic events. The magnitude of risks in the workplace or on the highways resulting from sleepiness is not fully understood or appreciated by the general population. Hence, to more clearly emphasize the magnitude of these risks, we question whether mild sleep deprivation may have the same effect as alcohol on reaction times and driving performance.

Study Design: Nonrandomized prospective cohort investigation.

Methods: Sixteen healthy matched adult subjects (50% women) were stratified into two groups, sleep deprived and alcohol challenged. The sleep-deprived group was further subdivided into acute (one night without sleep) and chronic (2 h less sleep nightly for 7 d) sleep deprivation. Each group underwent baseline reaction time testing and then drove on a closed course set up to test performance. Seven days later, the group repeated this sequence after either sleep deprivation or alcohol intake.

Results: There were no significant between-group differences (sleep deprivation or alcohol challenged) in the changes before and after intervention for all 11 reaction time test metrics. Moreover, with few exceptions, the magnitude of change was nearly identical in the two groups, despite a mean blood alcohol concentration of 0.089 g/dL in the alcohol-challenged group. On-track driving performances were similar (P =.724) when change scores (hits and errors) between groups were compared (baseline minus final driving trial).

Conclusion: This comparative model suggests that the potential risks of driving while sleepy are at least as dangerous as the risks of driving illegally under the influence of alcohol.