© 2004 American Thoracic Society doi: 10.1164/rccm.2408009
Sleepiness, Sleep Apnea, and DrivingStill Miles To Go Before We Safely SleepUniversity of Western Ontario London, Ontario, Canada Over the past 10 to 15 years, the problem of drowsy driving has received increasing attention. The U.S. National Highway Traffic Safety Administration estimates that each year, 100,000 police-reported crashes are the direct result of driver fatigue. Many researchers believe that these estimates are conservative (1), in part due to lack of awareness by many crash investigators of drowsiness (fatigue) as cause for many crashes and the lack of simple, reliable field measures of sleepiness (c.f. breathalyzer for alcohol levels), which could provide evidence for causality. Major causes of fatigue—and therefore risk factors for drowsy driving—including time of day (e.g., night or early morning), a long duration of wakefulness, inadequate sleep, prolonged work hours (not necessarily operating a motor vehicle), and disorders of excessive sleepiness (e.g., sleep apnea). Many, if not all, of these factors are part of daily life for many commercial vehicle drivers, so it is not surprising that these drivers may be at increased risk for drowsy driving. The study by Howard and coworkers in this issue of the Journal (pp. 1014–1021) (2), assesses the prevalence of excessive sleepiness, sleep-disordered breathing, and obesity among commercial vehicle drivers in Australia and further evaluates factors associated with increased accident risk. The study consisted of administration of questionnaires to 3,268 drivers from randomly selected truck yards and full polysomnography on a smaller number (244) of drivers. Relevant questions apart from those related to sleep apnea included work schedule, hours of sleep, medical conditions including medication use, and accidents in the preceding year. Even though this and other studies have used subjective accident reporting, this is more likely to lead to underestimation rather than overestimation of accident rates, which strengthens the overall results. This study complements the recent work of Pack and colleagues (3), which also examined prevalence of sleep apnea in commercial drivers. Of note, the prevalence of sleep apnea was very similar in both studies (15.8% in the study by Howard and coworkers versus 17.6% in the study by Pack and colleagues). Unlike a previous study (4) there was no relationship seen between severity of sleep apnea and accident risk in those undergoing polysomnography. However, several factors may account for this difference including smaller sample size, subjective versus objective accident records, and, as mentioned by the authors, the possibility of a survivor effect. In terms of sleep duration, the results clearly show that the less sleep obtained before driving, the more likely there is to be an accident. This is not a new finding, but it is a consistent finding now in many studies across several continents (5–9). There are two new findings from this study. The first is the increased accident risk in association with analgesic use (odds ratio 2.40) or antihistamine use (odds ratio 3.44). Although the number of drivers taking these medications was not high, it does highlight another potential risk factor for accidents for which the clinician should be aware. Due to the rigors of the job, musculoskeletal injury is common and the potential for increasing use of analgesics may exist. The second is in the use of a quality of life measure, the Functional Outcomes of Sleep Questionnaire (FOSQ), where impact of sleepiness is clearly an accident risk factor. Other studies have examined the relationship between the Epworth Sleepiness Scale (ESS) and accidents. Using both the ESS and specifically the FOSQ in this study, the sleepiest drivers had at least a twofold increase in accidents, supporting the previously recognized relationship between accident risk and chronic sleepiness. It is clear that the risk of accidents is greatest in those who are the sleepiest, whether this sleepiness is due to work hours, reduced sleep time, medication use, or sleep-disordered breathing. Yet, despite previous efforts at education, a great many drivers continue to drive while drowsy, as evidenced by the 2004 National Sleep Foundation Sleep in America poll (10). Thus clinicians, researchers, and educators must continue to highlight this message at every opportunity. Although this study should help clinicians identify commercial drivers who are at increased risk for accidents, it will not tell them which at-risk drivers will actually have a crash. More research is required before we can achieve this point. Given the high prevalence of sleep apnea in this population (2, 3), should we begin screening all commercial drivers? The answer to this is currently no, given the magnitude of the task and the available data suggesting that even when sleep apnea is present, up to two-thirds of patients may never have an accident (4, 11). A two-stage screening model recently reported (12) may be very good at excluding severe sleep apnea, but more data is needed to evaluate the role of sleep apnea as accident risk in commercial vehicle drivers before widespread screening can be recommended. We must remain committed to identifying and promptly correcting those risk factors for drowsy driving. Although prompt treatment of sleep apnea reduces crash risk (11), access to diagnosis and treatment is often lacking, as recently highlighted in the Journal (13). We are making important progress in the area of sleepiness and sleep apnea but, in the (paraphrased) words of Robert Frost, we still have miles to go before we safely sleep. FOOTNOTES Conflict of Interest Statement: C.F.P.G. does not have a financial relationship with a commercial entity that has an interest in the subject of this manuscript. REFERENCES
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