Dear Editor,We read the research of Diogo von Gaevernitz Lima et al. 1 with great interest. Their study found higher rates of poor sleep quality among medical students who used a computer and a mobile phone during the night and before going to sleep, and among dentistry students who longer time of computer use before going to sleep [sic]. They believed that the use of a mobile phone and a computer can influence poor sleep quality among medical and dentistry students during the night and immediately before going to sleep. In my opinion, it is necessary to investigate and analyze to reach conclusions.First, the authors surveyed respondents who use a mobile phone and a computer over the past month. These data relied on the personal subjective impression to fill in and the real situation is quite different, especially the time of use of the mobile phone in 24 hours. The data should be recorded by pre-installed software. In addition, the author fails to analyze the reasons for using computers and mobile phones. Possibly medical and dentistry students study or play using computers and mobile phones. If high academic pressure leads to losing sleep 2 , so it is not related to the use of computers and mobile phones. The author should pay attention to the importance of this problem.There are several risk factors for poor sleep quality among medical and dentistry students. If you want to know whether the use of computers and mobile phones influences sleep quality, several factors need to be eliminated, such as academic pressure, student work, domestic violence 3 , and possibly other factors that contribute to poor sleep quality among medical and dentistry student. Therefore, it is evident that further research needs to be done to prove the influence of the use of computers and mobile phones on poor sleep quality.