ObjectivesSleep is one of the basic elements which affects the growth and development and mental health of the child. The aim of this study was to determine the relationship between sleep habits and mental health in elementary school children in Nahavand/Iran.MethodsIn this correlation study, 240 children aged 6-11 years old were selected by cluster random sampling from schools of Nahavand city in Iran, 2017. Data were collected through questionnaires included demographic information, children’s sleep habits (CSHQ) and children sickness indications (CSI-4). Questionnaires were completed by one of parents as self-report. The data were analyzed using Pearson’s correlation and regression analysis.ResultsBased on results, Trouble in sleeping was reported by 36% and mental health disorders by 24.5% of elementary schools children. The regression analysis showed sleep habits had significant associations with the mental health score. In other words, improper sleep habits were associated with higher scores of illness symptoms of mental health that are indicative of poor mental health.DiscussionSleep disorder is one of the problems of elementary schools children, which related to their mental health. Sleep health training for parents and trainers in schools can help to improve the mental health of children by reforming proper sleep habits.