Sleep apnoea and driving risk

Obstructive sleep apnoea syndrome (OSAS) represents the most common organic cause of excessive daytime sleepiness. It has a prevalence of at least 1±4% according to different epidemiological studies, and depending on the diagnostic criteria used [1±4]. The prevalence of OSAS is highest among males in the 40±59 yr age group, being ~4±8% [4]. There is considerable evidence that sleepiness is a major contributing factor to road traffic accidents, and furthermore, that road accidents are far more frequent in patients with OSAS than in the general population [5±9]. However, the media and relevant authorities have concentrated on excessive speed and alcohol consumption as potential causes of accidents, and have paid insufficient attention to date on driver sleepiness as a potential cause for accidents. Now that the public is very aware of the accident risk related to speed and alcohol, it seems timely that proper attention be given to the accident risk related to driver sleepiness. Studies of motorway accidents have indicated that 20± 25% appear to be due to drivers falling asleep at the wheel [10], and are particularly likely to occur in the early morning or mid afternoon. Accidents associated with the driver falling asleep tend to be particularly serious because of the lack of reaction of the sleepy driver to the impending collision. Furthermore, sleepy drivers report a high incidence of near-misses on the road while driving, which suggests that they have an awareness of the driving risks related to sleepiness short of being involved in an actual collision. Data are now available from several North American studies [11, 12] in addition to others from Israel [13] and Finland [14] supporting sleepiness as a significant risk factor for road accidents. A recent questionnaire survey by MAYCOCK [15] of 9,000 male drivers in the UK revealed that 29% admitted to having felt close to falling asleep while driving in the previous year, the probability of which depended on a number of factors including Epworth sleepiness scores (ESS), age, motorway driving, and annual mileage. A history of snoring every night increased the likelihood of an accident by 30%. There is also evidence that occupations such as long-haul truck driving are particularly associated with a risk of sleepiness while driving [16], and an increased risk of accidents, particularly when there is evidence of associated OSAS [7]. These findings may not be surprising given the relative sedentary and monotonous nature of this occupation …