Sleep disorders in children are common. Sleep plays an important role in children's development and sleep disorders can have a substantial impact on their quality of life. Indeed, sleep is crucial for physical growth, behavior, and emotional development and it is also closely related to cognitive functioning, learning and attention, and therefore to school performance. In the present study sleep habits were investigated in 173 school-age children by using the Children's Sleep Habits Questionnaire (CSHQ). Results show that children attending the third elementary grade had higher CSHQ total score, indicating sleep problems, as compared to other classes. Moreover, an inverse correlation was observed between sleep disturbance and school performance (p?<?0.05), meaning that children with sleep problems also have a lower performance at school. Our findings imply that sleep disorders could negatively impact school performance.