RESUMEN
An educational project in nursery schools was carried out with the aim to improve children's sleep. Its effectiveness was tested in terms of awareness of families and length of sleep of children. The method was a prevention trial based on the random division of classes of 3-year old into two groups (intervention group and control group) comprising children enrolled in nursery schools in the Rhône region (France) in 1992. The project, lasting 2 years, relied on physicians from the community (Maternal, Child Health Service and School Health Service), their role being to mobilise the teaching teams, distribute specific teaching tools and raise awareness of families to respect the sleep patterns of children, during routine medical examinations. The study was carried out in 140 nursery schools with 1,500 children in each group. The evaluation was based on the application of a logistical regression model taking potentially confounding factors into account, and an analysis in sub-groups in order to demonstrate the effectiveness of intervention on particularly exposed groups. The results show: 1) the feasibility of such an intervention among nursery school children on a large scale, 2) the effectiveness of the action, with a reduction of the risk of "poor knowledge" among parents (OR = 0.76), particularly in urban areas, and a reduction in the risk "short nights" in the sub-group of children who had " little sleep at 3 years" in low social class families (OR = 0.50).