Tehran University of Medical Sciences Journal of Sleep Sciences 2476-2938 5 2 2020 12 09 168 168 Mahsa Shojaie Occupational Sleep Research Center, Baharloo Hospital, Tehran University of Medical Sciences, Tehran, Iran 2020 06 20 2020 08 02 I read with great interest the article entitled “Comparative investigation of sleep problems in opioid-dependent and normal subjects” by Madanifard et al. (1). I am grateful to authors for studying this important problem. https://jss.tums.ac.ir/index.php/jss/article/view/168