Tehran University of Medical Sciences Journal of Sleep Sciences 2476-2938 1 4 2017 04 09 169 175 EN Samereh Eghtedar Department of Medical-Surgical, School of Nursing and Midwifery, Urmia University of Medical Sciences, Urmia, Iran Mina Nahamin Department of Medical-Surgical, School of Nursing and Midwifery, Tabriz University of Medical Sciences, Tabriz, Iran Robab Hassanzadeh Department of Midwifery, Bonab Branch, Islamic Azad University, Bonab, Iran Fateme-Sara Aparnak Department of Midwifery, Urmia Branch, Islamic Azad University, Urmia, Iran Elnaz Asghari Student Research Committee, School of Nursing and Midwifery, Tabriz University of Medical Sciences, Tabriz, Iran 2016 09 19 2017 01 21 Background and Objective: Breast cancer is the most common cancer among women. Many of the women with breast cancer suffer from sleep disorders. This study aimed to investigate the quality of sleep and its related issues in women with breast cancer referred to the Hematology and Oncology Research Center affiliated with Tabriz University of Medical Sciences, Tabriz, Iran. Materials and Methods: In this cross-sectional study, 103 women with breast cancer were chosen using the census method. Data were collected using the Pittsburgh Sleep Quality Index. Descriptive and analytic statistics and linear re-gression test were used for data analysis. Results: The mean age of the sample was 42.59 years [standard deviation (SD): 11.72 years] and the average length of diagnosis was 19.90 months (SD: 12.67 months). The mean score of sleep quality was 11.50 (SD: 3.71) in a range from 0 to 21. Except the history of mastectomy, age, smoking status, the remaining demographic data could predict 39.5% of the variance of sleep quality. Conclusion: The results of this study are a wakeup call for officials. To prevent the negative impact of poor quality of sleep, there is a need to design holistic and appropriate interventions. The findings provide valuable information with scheduling for these interventions. https://jss.tums.ac.ir/index.php/jss/article/view/46 https://jss.tums.ac.ir/index.php/jss/article/download/46/55