Objective: The purpose of this article is to present a brief review of the effects of excessive sleepiness on driving performance, and to emphasize the importance of the subject. Methods: Bibliographic review of national and international literature, including original articles and official publications from the American Thoracic Society and the American Sleep Apnea Association. Results: There is growing evidence that excessive sleepiness may be an important factor related to the occurrence of motor vehicle accidents. Difficulties regarding the identification of sleepiness as a preceding factor related to motor vehicle crashes are discussed on the text. There are many causes for excessive sleepiness. Fortunately most of them are easy to recognize and have specific treatment. Conclusions: A better understanding of the problem is fundamental to promote a better approach for patients with excessive sleepiness and perhaps encourage the discussion about the current motor vehicle legislation and the physicians' legal obligations.

Keywords: sleepiness; motor vehicle accidents