Objective - Our aim is to evaluate sleep habits, sleep quality and influencing factors among preschool- and schoolchildren.Two questionnaires were recorded. Questionnaire 1 dealt with sleeping habits, breastfeeding and health behavior of preschool children and infant, and it contained the abbreviated version of the Children's Sleep Habits Questionnaire. Questionnaire 2 dealt with health behavior and the application of sleep hygiene rules, as well as it contained the Athens Insomnia Scale. Subjects - We assessed a total of 1063 questionnaires: 516 kindergarten children participated in our online survey across the country; 547 primary and secondary school students participated in the 2nd questionnaire survey in Szolnok.Parents' observation shows that the average nighttime sleeping time of kindergarten children is 10 hours 20 minutes on weekdays and 10 hours 36 minutes on weekends. The most popular sleeping habits in kindergarten age: teal reading (65.1%) and co-sleeping (42.8%). Parents of infants used breastfeeding (50.4%) and rocking (43.2%) most frequently before sleep. Co-sleeping has a positive influence on the length of lactation. Among the preschool sleeping habits we have proved a number of positive effects of teal reading, while watching television have negative effects. The sleep quality of school-age children according to the Athens Insomnia Scale is 6.11 points (SD: 4.11), 19% of the children are insomniac. Their sleep time is 7 hours 31 minutes on weekdays and 9 hours 30 minutes on weekends. The usage of good health behavior and sleep hygiene rules positively influence sleep quality and sleep duration.With our results, we would like to draw the attention of children and parents to the importance of sleeping and using sleep hygiene rules.