How Risky Is Driving While Sleepy?
Harry E. Davis II , MD, FACP
Salva MAQ, Barbot F, Hartley S, Sauvagnac R, et al. Sleep disorders, sleepiness, and near-miss accidents among long-distance highway drivers in the summertime. Sleep Med. 2014;15:23-26.
Salva et al1 describe the concern about traffic accident–related morbidity and mortality in France that has led to road-safety campaigns. These campaigns have been focused on reduction of factors known to affect driving performance, such as excessive speed and the use of alcohol and other substances known to affect driving performance. Efforts to address sleepiness and driver fatigue have included the creation of billboards and rest areas to reduce the monotony of long drives and encourage drivers to obtain enough sleep, to rest before long trips, and to start trips during the day. While this has been associated with a gradual decrease of nearly 50% in the number of automobile accidents from 2001 to 2011, the reported 3,970 road deaths in 2011 prompted the researchers to investigate factors associated with sleepiness and accident risk.
The study was designed to evaluate these factors by surveying drivers on high-volume travel days in July 2011 at a highway tollbooth near Tours, France. Drivers were stopped at random by highway patrol officers and invited to participate in an anonymous questionnaire survey. The survey was administered by trained investigators independent of the law-enforcement services and required a maximum of 15 minutes. Drivers participated on a strictly volunteer basis. During the study period, 322,369 cars went through the tollbooths. About 1% of the drivers were invited to participate in the study and 80% of those invited (3051) agreed. Data recorded included sex, age, weight, height, marital status, occupation driving habits, and use of alcohol, cigarettes, coffee, and other caffeinated beverages and medications. Sleep-specific data included the estimated sleep needs and total sleep time in the past 24 hours as well as the usual sleep time during the workweek and on weekends. Acute sleep debt was calculated as the mean sleep time per workweek night minus the sleep time in the past 24 hours. In addition, information on subjects’ sleepiness and sleep complaints was obtained using recognized sleep-evaluation instruments. The interviewers then determined if the drivers had experienced severe sleepiness during the current trip, leading to a near-miss sleepy accident (NMSA), an NMSA in the past year, or a sleepiness-related accident in the past year.
The mean age of the study participants was 46 ± 13 years; 75% of the drivers were men. The total driving distance for the current trip was 330 km ± 226 km. The data suggested that July is a major time for vacation in France. Of the 3051 participants in the study, almost 85% of the drivers were on vacation. A key finding of the study was that 2.9% of drivers reported at least 1 NMSA during a long trip in the summertime.
Analysis revealed 4 factors associated with NMSA: NMSA in the past year (odds ratio [OR], 3.4; 95% confidence interval [CI], 1.7-6.4), nonrestorative sleep in the past 3 months (OR, 1.9; 95% CI, 1.0-3.6), snoring in the past 3 months (OR, 2.0; 95% CI, 1.1-3.7), and sleepiness during the interview (OR, 1.4; 95% CI, 1.2-1.6). Drivers who reported an NMSA during the current trip had a 2.6-fold increase in sleep-related accidents in the past year compared with drivers without a current NMSA. However, the risk for NMSA was not affected by the time of departure, duration of driving, or total sleep time in the 24 hours before the interview. The authors suggest that this may be related to the fact that the majority of the drivers were on vacation plus the possible success of road-safety campaigns in raising awareness about the risks associated with sleepiness at the wheel. However, they express concern about the possible contribution of organic sleep disorders such as obstructive sleep apnea (OSA) syndrome to driving risk. The authors conclude that raising awareness about the risks of chronic sleepiness while driving remains a major challenge for road safety campaigns. They also call for studies of sleep-related breathing disorders, an area not addressed in the current study.