Governmental agencies do not systematically investigate the presence o
f daytime sleepiness as a determinant of driving accidents. We surveye
d automobile drivers traveling on summer vacations and driving long di
stances on a European highway. We evaluated their subjective daytime s
leepiness while driving and any sleep deprivation just prior to depart
ure. Five-hundred sixty-seven automobile drivers (mean age 37.7 +/- 11
years) were interviewed at a roadside rest-stop. Questions covered th
e sleep/wake schedule during the year, sleep habits, and the presence
of symptoms frequently associated with sleep-disordered breathing. Sle
ep behavior just prior to departure was compared to the usual sleep sc
hedule during the year. Fifty percent of the responders had a sleep re
striction just prior to departure (mean -203 minutes) compared to usua
l total sleep time during the year; 10% had no nocturnal sleep prior t
o departure. Drivers younger than 30 years were significantly more acu
tely sleep deprived than other drivers. Economic migrants (subjects wi
th low economic status) also experienced significant acute sleep restr
iction.