Introduction: Sleep disorders are common in adolescence, as biological, psychological and social changes that arise during adolescence are associated with poor-quality sleep. Relaxation of muscles leads to peace of mind, prevents and neutralizes negative thoughts and emotions, and balances the effects of muscle strain increase on the body. This study aimed to determine the effects of progressive muscle relaxation on the sleep quality of pre-university students.

Methods: In this clinical trial, 46 pre-university students from public schools of Malayer city, Iran participated. Samples were systematic randomized into two groups of progressive muscle relaxation (test) and control. In the test group, progressive muscle relaxation programs were taught and they were asked to do this once a day for a month. The sleep quality of the samples was measured using "Pittsburgh Sleep Quality Index" at the beginning and end of the intervention. Data were analyzed using SPSS version 17 and Mann-Whitney and Wilcoxon tests were used.

Results: The mean score of sleep quality in the control group after one month showed a significant increase (P < 0.001) and the average score of sleep quality in the test group, after a month of PMR, had a significant reduction (P < 0.001). In addition, there was a significant difference in the sleep quality score between test and control groups (P < 0.001).

Conclusions: The findings of this study showed that the progressive muscle relaxation program enhanced the sleep quality in pre-university students.