Effects of Nature Sounds on Sleep Quality among Patients Hospitalized in Coronary Care Units: A Randomized Controlled Clinical Trial

Background: Sleep disorders are a source of stress for patients hospitalized in coronary care units (CCUs). Objective: The aim of this study was to investigate the effects of nature sounds on sleep quality among patients in CCUs. Methods: This randomized controlled trial was conducted on 93 patients hospitalized in the CCUs of three teaching hospitals in Tehran, Iran. Patients were randomly allocated into three groups, namely, nature sounds, silence, and control groups. Patients in the nature sounds group listened to nature sounds for 30 min in two consecutive nights while their counterparts in the silence group only wore mute headphones. Patients in the control group neither listened to nature sounds nor wore headphones. The Richards–Campbell sleep questionnaire was used for the evaluation of the patients’ sleep quality two days before and during the intervention. The mean scores of sleep quality at the first two and the last two nights, respectively, were considered as the pretest and the posttest sleep quality. Cohen’s d, one‑way analysis of variance, paired‑sample t, Chi‑square, Fisher’s exact, and the Scheffe post hoc tests were used to analyze the data. Results: Posttest‑pretest mean differences of the sleep depth, the number of awakenings, and the returning to sleep domains of sleep quality in the control group were significantly less than nature sounds group (P < 0.001). Moreover, the posttest‑pretest mean differences of the total sleep quality and its sleep latency and subjective sleep quality domains in the control group were significantly lower than both the nature sounds and the silence groups (P < 0.001). On the other hand, none of the differences between the nature sounds and the silence groups were statistically significant (P > 0.05). Conclusion: Both nature sounds and silence can significantly improve sleep quality among patients in CCUs. Nurses can use these strategies to improve the sleep quality of a patient in these units.