Sleep, sleepiness and motor vehicle accidents: a national survey

Objective: To assess the role of sleep-related factors, ethnicity and socio-economic deprivation in self-reported motor vehicle accidents while driving, after controlling for gender, age and driving exposure. Methods: Mail survey to a random electoral roll sample of 10,000 people aged 30-60 years, stratified by age decades and ethnicity (71% response rate). The analytical sample included 5,534 current drivers (21.6% Maori men, 21.2% Maori women, 30% non-Maori men, 27.2% non-Maori women). Results: Multiple logistic regression analyses revealed the following independent risk factors for accident involvement while driving (last three years): being younger; higher average weekly driving hours; never/rarely getting enough sleep (OR=1.26, 95% CI 1.06-1.49); reporting any chance of dozing in a car while stopped in traffic (Epworth Sleepiness Scale question 8, OR=1.52, 95% CI 1.15-2.02); and among women, being non-Maori. Total Epworth score was not significantly related to reported accident involvement. Conclusions: Chronic sleep restriction, and any likelihood of dozing off at the wheel of a motor vehicle, were significant independent predictors of self-reported involvement in all types of motor vehicle accidents, not only those identified as fatigue-related. The Epworth Sleepiness Scale alone is not a reliable clinical tool for identifying individuals at higher risk of crashes. Implications: Factors relating to chronic sleepiness were as important as established demographic risk factors for self-reported motor vehicle accident involvement among 30-60 year-old drivers. The findings reinforce the need for multi-faceted campaigns to reduce sleepy driving.