Drowsiness and sleeping at the wheel are now identified as the reasons behind fatal crashes and highway accidents caused by occupational drivers. For many years, fatigue has been associated to risk of accidents but the causes of this symptom were unclear. Extensive or nocturnal driving was associated to accidents but few reports differentiated fatigue from sleepiness. In the early nineties, epidemiological data started investigating sleepiness and sleep deprivation as cause of accidents. Sleepiness at the wheel, sleep restriction and nocturnal driving have been incriminated in 20% of traffic accidents. Drugs affecting the central nervous system (i.e., narcotic analgesics, antihistamine drugs), nocturnal breathing disorders and narcolepsy have been also associated with an increasing risk of accidents. Treatments improving daytime vigilance (i.e., nasal Continuous Positive Airway Pressure) reduce significantly the risk of traffic accidents for a reasonable economical cost. Sleep disorders among occupational drivers need to be systematically investigated. Chronic daytime sleepiness is still under diagnosed and sleep disorders (i.e. obstructive sleep apnea syndrome) are not enough explored and treated in this exposed population of sedentary males. Drivers education and work schedules integrating notions of sleep hygiene as well as promotion of sleep medicine could significantly improve road safety.