Can we say that a disease is contagious if patients who die from it, in the act of dying, cause the deaths of others? In Wisconsin (USA), a group of 602 civil servants, ranging from 30 to 60 years of age, were evaluated. Among those, 24% of the males and 9% of the females were diagnosed with sleep-disordered breathing, defined as five or more attacks of apnea or hypopnea per hour of sleep. In a subgroup of that sample, 4% of the males and 2% of the females presented sleep-disordered breathing together with the main symptom of sleep disturbance (excessive daytime sleepiness), which provided the elements for the diagnosis of obstructive sleep apneahypopnea syndrome (OSAHS). (1) The prevalence of OSAHS increases with age. (2) Although it is known that patients diagnosed with OSAHS are from two (3) to eight times (4) more likely to become involved in traffic accidents, the effect that sleepiness-related accidents have on the mortality of patients with OSAHS and of the population in general still cannot be directly measured. Data from the Ministry of Health reveal that traffic accidents are a male phenomenon. Of all licensed drivers in Brazil, 73% are male; among all victims of traffic fatalities, 82% are male. Coincidentally, OSAHS is also a male phenomenon. Such a coincidence may further the understanding of and search for a solution to this problem. Every year, 30,000 people die on the streets and roads of Brazil. Accidents caused by falling asleep at the wheel can only be correctly identified if the drivers involved admit the fact. (5) Dozing off for less than two minutes can go unnoticed. (6) After having had an accident, a driver might deny having fallen asleep due to inability to identify such microsleep episodes or due to fear of reporting having fallen asleep to the authorities. The suspicion that a driver has fallen asleep is strengthened if the vehicle went off the road or collided with another vehicle without leaving any brake marks on the pavement. Authorities in Kentucky (USA) have identified falling asleep or fatigue as the cause of 13% of all fatal truck collisions and 4% of all nonfatal truck collisions. (7) During a three- to four-second