Two separate groups consisting of both long-haul (N=184) and short-haul (N=133) truck drivers were surveyed to examine the frequency of driver sleepiness-related problems at work during the previous three months and to assess the incidence of sleep apnea syndrome symptoms. We also aimed to identify factors likely to predict self-reported difficulties in staying alert in work driving, dozing off (sometimes referred to as microsleeps) at the wheel and near misses. The responses suggest that for approximately 13% of the long-haul drivers the mean driving time per shift exceeded the EEC regulation. About 40% of the long-haul drivers and 21% of the short-haul drivers reported having problems in staying alert on at least 20% of their drives. Over 20% of the long-haul drivers also reported having dozed off at least twice while driving. Near misses due to dozing off had occurred in 17% of these drivers. Factors indicating sleep apnea syndrome occurred in only about 4% of the long-haul drivers and in only two short-haul drivers. Work and individual related factors as well as factors indicating sleep apnea syndrome contributed only slightly to predicting driver sleepiness-related problems. This suggests that driver sleepiness-related problems tend to be shared by many of the professional drivers, rather than being a "specific" and permanent problem for a smaller portion of drivers. However, difficulties in sleep patterns, such as having difficulty falling asleep, were infrequent.