Introduction. Several studies have shown high rates of sleepiness in the general population in the United States and Europe, but there is little data on sleepiness, associated sociodemographic factors, and its consequences in the French population. Method. A general population survey was conducted as part of National Sleep Day by the National Institute of Sleep and Vigilance (INSV) in 2011 among a representative sample of the adult population, with detailed characterization of work schedules, commute times, family structure, and socio-professional categories. The questionnaire was developed by sleep specialists and includes: 1) items to estimate total sleep time (TST) and reported associated sleep disorders; 2) an assessment of drowsiness using the Epworth Sleepiness Scale (ESS) and items regarding complaints of drowsiness, daytime episodes of falling asleep, and naps; 3) characteristics of drowsiness while driving and the countermeasures adopted. Results. 1,012 adults (51% women) aged 18 to 60 were surveyed. Among the respondents, 21% experience daytime sleepiness at least 3 times a week, even after a good night’s sleep; 11% feel sleepy every day; and 7% (15% of men) regularly fall asleep without being able to resist the drowsiness at least 3 times a week. For 4%, these episodes of falling asleep occur every day. Based on the ESS: 19% of the group can be considered drowsy (ESS > 10) and 3% severely drowsy (ESS > 16); 26% of participants report occasionally taking a nap, 9% nap at least 3 times a week, and 2% nap every day; 12% of drivers have had to stop driving at least once to sleep in the past 12 months; 3% of drivers report having fallen asleep at the wheel in the past 12 months. Factors significantly associated with drowsiness include daily commute time, night work and shift work, and certain reported sleep disorders (sleep apnea syndrome, restless legs syndrome, hypersomnia). Conclusion Drowsiness affects one in five French people and has severe consequences on the risk of falling asleep at the wheel. (R.A.)