Objectives: The inadequate quality and nature of sleep is a commonly reported problem among hospitalized patients. The purpose of this study is to examine the effects of progressive muscle relaxation training program on sleep quality, sleep state, pain and life quality of patients who underwent pulmonary resection. Methods: Our study was planned as a single blind prospective randomized controlled trial. The study was conducted on 26 patients who underwent surgery by using posterolateral thoracotomy method. Progressive muscle relaxation training were given to the training group with a therapist 2 times a day. Sleep quality, daytime sleeping, pain, and quality of life were respectively evaluated in the morning before the surgery and 1 week after the surgery by using Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, visual analogue scale and Euro Quality of Life-5D. Results: There is no significant difference between preoperative groups in the total The Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Euro Life Quality-5D, visual analogue scale scores (p>0.05). The intra-group change in the study group showed a significant deterioration in the Euro Life Quality-5D, visual analogue scale scores (p<0.05). There was a significant deterioration in total Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, EQ-5D, visual analogue scale scores in the control group (p<0.05). The intergroup analysis showed that patients in the study group had better The Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale and EQ-5D scores after treatment at 1 week (p<0.05). Conclusion: The inadequate quality and nature of sleep is a commonly reported problem among hospitalized patients. Different psychological indicators should be focused on to understand which psychological method is effective in improving postoperative outcomes. Psychological interventions are cheap and are welcomed by patients. Relaxation exercises are not a routinely applied method after pulmonary resection, however they are thought to make contributions to postoperative recovery. It should be tried to reduce the effects of the factors deteriorating sleep and patients who suffer from sleep problems should be identified on time. Progressive muscle relaxation exercises are a practice that improves sleep quality after pulmonary resection and is non-invasive, affordable, effective and easy to apply during the hospitalization period starting from the intensive care phase after surgery. Therefore, the healthcare team should involve such practices in treatment plan.