Objective: The physical and psychological changesexperienced during adolescence can change the sleep pattern. However,unconsciously use of internet by adolescents can lead to some problems onsleeping habits. The aim of this study was to investigate the relationshipbetween sleep habits and internet use and changing sleep-wake schedule inadolescents. Method: Across-sectional study was conducted. The participants were 1498 secondaryschool students aged 10-14. Sleep habits and internet use and changingsleep-wake schedule were assessed using a questionnaire which was by preparedthrough by the researchers.Results:Nearly half ofthe students had sleep problems and the most common sleep problem was difficultyon fall asleep (43.5%).  Almost all ofadolescents were used internet and they mostly were spent 1.5-2 hours ininternet. It was determined to delay timing of sleep due to use of internet23.6% of adolescents who used internet and majority of their families (73.9%)had complaints about the negative effects of internet use on sleep. Adolescents’sleep problems were found to be associated with delaying the timing of sleepdue to internet use (p<0.05). Also, adolescents’ internet use was associatedwith fall asleep duration (p< 0.005). Conclusion:Internet usecreates various problems in adolescents’ fall asleep duration and sleep hourswhen it is used without family control and in a long duration.