The role of sleep-disordered breathing, daytime sleepiness, and impaired performance in motor vehicle crashes-a case control study.

STUDY OBJECTIVE: To examine levels of sleep-disordered breathing, daytime sleepiness, and impaired performance in 60 motor vehicle crash drivers and 60 controls matched for age, gender, and body mass index.

MEASUREMENTS AND RESULTS: All participants underwent polysomnography and daytime function assessments. Cases reported significantly higher levels of driver sleepiness (% sleepiness: mean +/- SD; cases: 26 +/- 17%; controls: 16 +/- 12%; p = 0.003) and demonstrated slower reaction times on a sustained attention task ( p = 0.02). There was a trend for more objective sleepiness in cases (maintenance of wakefulness test: cases: 17 +/- 4 minutes; controls: 18 +/- 3 minutes, p = 0.06) despite no differences in general subjective sleepiness (Epworth score: cases: 8 +/- 4; controls: 8 +/- 4; p = 0.93). There were no significant differences in polysomnography measures between groups (apneas + hypopneas per hour slept: cases: 8 +/- 9; controls: 9 +/- 16; p = 0.89; arousals per hour slept: cases: 18 +/- 8; controls: 21 +/- 12; p = 0.11).

CONCLUSION: Crash drivers demonstrated significantly more driver sleepiness, slower reaction times and a trend for greater objective sleepiness compared with well-matched controls. However, the findings in crash drivers were independent of medical causes of sleep fragmentation, with both cases and controls showing moderate levels of unrecognized mild sleep-disordered breathing. Crash prevention strategies should focus on increasing personal awareness of the risks of sleepiness behind the wheel in all individuals.