Cognitive dysfunction in children with sleep-disordered breathing.

Two daily school periods are mandatory in Brazil owing to a shortage of academic facilities, which can decrease cognitive performance, especially in children with sleep-disordered breathing. This study aimed to verify the influence of starting time to school on cognition, comparing children with sleep disorders and normal children. Cognition was assessed in 79 children with sleep-disordered breathing, 468 children with nonrespiratory sleep disorders, and 633 normal control children. We analyzed total sleep time, starting time to school (morning or afternoon), and grades. First grade morning students with sleep-disordered breathing had 8.04 higher odds for cognitive dysfunction than normal children. For children with sleep-disordered breathing, second and third grade morning students had higher odds for cognitive dysfunction than those who studied in the afternoon (3.69 and 4.07). Fourth grade morning students had 8.27 higher odds for cognitive dysfunction than first grade children. In conclusion, sleep-disordered breathing, grades, and starting time to school interact to affect cognition in Brazilian children.