Tehran University of Medical Sciences Journal of Sleep Sciences 2476-2938 1 3 2016 12 06 125 130 EN Mahmood Vakili Department of Community Medicine, School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Mozhgan Modaressi Department of Community Medicine, School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Maasomah Rezvani School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Arezoo Aghakoochak Health Monitoring Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran 2016 02 21 2016 05 30 Background and Objective: Poor sleep, poor quality of sleep and sleepiness are among the common problems as-sociated with learning, memory and educational performance in children and adolescents. Considering the lack of pre-vious literature in this field, especially in the city of Yazd, Iran, a number of high-school students of the city participat-ed in a study to assess sleep problems and influencing factors. Materials and Methods: In this cross-sectional study, 740 high-school students in Yazd were selected using multi-stage cluster random sampling method. The data were collected using Pittsburg Sleep Quality Index (PSQI), reliability and validity of which had been proved (with Cronbach’s alpha of 0.8). After encoding questionnaires, correlation and chi-square tests were used to evaluate the impact of corresponding factors on sleep quality via SPSS software. Results: Of 740 students, 39% had sleep disturbances that had significant relationship with variables of gender, field of study, father's occupation, and father's education. Mean PSQI score did not have significant relationship with varia-bles of mother's education, body mass index (BMI), students’ birth, and mother's job. Furthermore, 16.7% of students were unsatisfied with their sleep pattern, while 3.5%, 58.7%, and 21.1% were very unsatisfied, satisfied, and very satis-fied, respectively. Conclusion: Teenagers’ sleep may be affected by different factors such as sex, field of study, father's occupation, and father's education. Change in environmental and family condition could improve sleep disturbances, educational, and occupational performance. https://jss.tums.ac.ir/index.php/jss/article/view/20 https://jss.tums.ac.ir/index.php/jss/article/download/20/37