Introduction - Sleep plays a crucial role in adolescents’ health and development. It is universally recommended that adolescents get enough sleep, particularly during the school year. However, age-specific sleep guidelines are based more on tradition than on reference values from the general population. The aim of this study was to gain a better understanding of the actual sleep patterns of French adolescents. Method - Data from 9,251 students aged 11 to 15 recruited to participate in the French survey of the international Health Behaviour in School-aged Children (HBSC) study were analyzed; 50.7% of respondents were boys. An estimate of total sleep time (TST) reported for days with school the following day (TSTAC), as well as for days without school the following day (TSTSC), was calculated based on 8 specific items. Subjects whose TSTAC was 2 hours were classified as "short sleepers." Results - A significant decrease in TSTAC was observed between the ages of 11 and 15, for both TSTAC (9 h 26 min vs. 7 h 55 min; p