This report, prepared for the National Commission on Sleep Disorders Research, explores the economic implications of sleepiness in relation to accidents. In Part One, I describe the frequency of accidents in the United States and explain a method for estimating the economic cost of these of accidents. Accidents are the fourth leading cause of mortality in the United States, and motor-vehicle accidents represent 51% of total deaths caused by accidents. The method used for calculating the cost of accidents is called "the human capital approach". It is based on the principle that "one person produces a sum of output during his/her life-time, which can be approximated by his/her earnings". It is necessary to understand that this estimate of human value is not intended to reduce human beings to a sum of earnings during his/her lifetime. It does, however, serve as a useful indicator in making decisions regarding public health policy for the country. The results of the total cost of accidents and the relative costs for work-related, home-based and public accidents in 1988 are discussed. In Part Two, I explore the role sleepiness plays in contributing to the total number of accidents. The difficulty of researching this subject is compounded by the fact that reports of rates of accidents related to sleepiness differ significantly from author to author. This is true both for drivers with sleep disorders and those without. We have calculated two different rates for estimating the number of motor-vehicle accidents caused by sleepiness.(ABSTRACT TRUNCATED AT 250 WORDS)