ACCIDENTS RELATED TO SLEEPINESS - REVIEW OF MEDICAL CAUSES AND PREVENTION WITH SPECIAL REFERENCE TO SWITZERLAND

Sleepiness is a major cause of traffic accidents. Our purpose was to r eview determinants of accidents related to sleepiness and measures to prevent them. We performed a systematic literature review on the topic and studied official accident statistics and legislation regarding me dical driving ability in Switzerland. In 1997, 79178 road traffic acci dents, each causing bodily injury or property damage in excess of 500 Swiss francs, occurred in Switzerland. According to official statistic s, sleepiness accounted for only 1% of identified causes. However, sci entific studies performed in other countries suggest that sleepiness i s a contributing factor in up to 30% of traffic accidents. Causes of h ypersomnolence are sleep restriction, sleep disturbance by external en vironmental factors, inappropriate sleep hygiene, and sleep disorders. Several reports suggest an increased crash rate in patients with obst ructive sleep apnoea syndrome. At our clinic, every sixth sleep apnoea patient reports sleepiness-related driving problems which resulted in traffic accidents in one third of them. Long monotonous motorway driv es, late night, early morning and late afternoon hours are associated with an increased crash rate. Drivers with excessive sleepiness should not drive until the cause of hypersomnolence is determined and treate d appropriately. Medical assessment of driving ability in patients wit h sleep disorders involves a specific history including standardised q uestionnaires, sleep studies and vigilance tests. Swiss legislation au thorises physicians to report sleepy drivers to the authorities if the y are thought to represent an accident risk for themselves or others. We conclude that sleepiness is a common but under-recognised cause of traffic accidents. Enhancing awareness of the problem in the public, e arly recognition and treatment of sleep disorders, and counselling of drivers with excessive sleepiness may contribute to prevention.