We hypothesized that impaired performance on driving simulation and EEG defined attention lapses are greater in obstructive sleep apnea patients than in the normal population. Participants completed a 60-minute driving simulation with continuous EEG monitoring. Sleep apnea patients demonstrated increased lane position variability, crashes, and attention lapses throughout the task. Attention lapses appeared to underlie the poorer driving performance. Because sleepiness can occur in other populations, e.g. shift workers and on call physicians, these results support the need for the development of countermeasures, highway safety education programs, and the recognition and treatment of sleep disorders.