Volume27, IssueS1 Special Issue: Abstracts of the 24th Congress of the European Sleep Research Society, 25–28 September 2018, Basel, Switzerland ; Human behaviour diferences are determined by factors such as the circadian phase preference. Adults have been well examined concerning performance variation during the work schedules depending on chronotype. However there is a serious gap on research of children respecting the evaluation and understanding of their sleep patterns, specifically referring the chronotype variability. The main goal was to validate the Children's Chronotype Questionnaire (CCTQ, Werner, LeBourgeois, Geiger et al., 2009) for French language and to identify chronotype and specific sleep habits differences of young children of Luxembourgish schools, according to age and different school schedules.