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Driver Sleepiness
  • An Introduction to Sleep
  • Sleep Disorders
  • Driver Sleepiness
  • Sleep Disorders and Accidents





    Sleep is an essential part of life. Insufficient or non-restorative sleep has detrimental consequences for health, work performance, mood and motivation. Excessive daytime sleepiness (EDS) is manifest in a population not experiencing deep restorative sleep. EDS may be the consequence of short or long-term sleep deprivation common in shift-workers or busy truck drivers who drive long, monotonous routes and face deadlines. Regardless of its cause, EDS has potentially serious consequences for these individuals as the risk of having a road accident is dramatically increased.

    Road traffic injuries in developing countries particularly affect the productive (working) age group (15-44 years) and children. (A developing country is defined as a country that has an annual per capita gross national product (GNP) less than US$9361 (£6456), based on 1998 figures from the World Bank. Most low and middle income countries fall into this category.) Globally, in 1998, 51% of fatalities and 59% of disability adjusted life years lost due to road traffic injuries occurred in the productive age group. Fatality rates among children are especially high in developing countries, as shown in fig 2. In 1998 the fatality rate for children aged 0-4 years was 29.5 per 100 000 population in South East Asia and low income countries of the western Pacific region, compared with 4.5 deaths per 100 000 population in high income countries. For older children, aged 5-14 years, the fatality rate was 28.1 per 100 000 population in Africa compared with 4.8 for North America, western Pacific countries, and high income countries in Europe.

    Sleepiness in drivers is known to be an important factor contributing to motor vehicle accidents and injuries. Published estimates of the contribution of sleepiness to accidents vary considerably. In the United States 6% of all vehicle accidents are thought to be sleep related, in the UK 20%, in France the figure is 10% and in Australia it is 33%. In a survey, conducted in South Africa, 25% of truck drivers admitted to being involved in an accident as a result of sleepiness and up to 37% of all road fatalities may be attributable to driver sleepiness.

    South Africa has one of the highest road accident death rates in the world! The number of fatalities on South African roads has risen from 7260 in 1998 to more than 10,000 in 2004 i.e. 10 Times the number of Deaths compared to the UK! Applying data from the USA, UK and SA and other countries, we can predict that driver sleepiness was a factor in about 4000 of these fatalities. Of these 4000 sleep-related fatalities, about a 1000 are directly related to Driver Fatigue and Sleepiness.

    Factors associated with Sleep Related Vehicle Accidents (SRVA)
    The Institute for Traffic Management and Research in New York has identified the following five factors as the essential factors contributing to long-haul drivers falling asleep at the wheel:
    1. Driving Schedule -driving performance among truck drivers declined with an irregular schedule, more than 8 hrs of driving for regular schedules, and more than 5 h of driving for irregular schedules;
    2. The time of day is predictive of sleepiness-related driving among truck drivers -The US-Canadian Driver Fatigue and Alertness Study found that the strongest and most consistent factor influencing driver fatigue and alertness was time of day, rather than time on task or cumulative number of trips;
    3. The quantity and quality of sleep - a person’s tendency to fall asleep during normal waking hours is increased and psychomotor performance declines with fewer hours of sleep and successive days of restricted sleep;
    4. The Presence of Obstructive Sleep Apnoea (OSA) A condition of interruptions or pauses in breathing whilst asleep – signs of this disorder include obesity, snoring, sleep interrupted by intermittent gasping for breath, and excessive daytime sleepiness.

    Groups at high risk of causing Fatal SRVA’s:

  • Young Drivers
  • Commercial Drivers / Shift Workers
  • Drivers who consume Alcohol and/or Drugs
  • Drivers with Sleep Disorders particularly OSA
  • Drivers with other Medical Disorders