Background: Patients in coronary care units (CCUs) are at risk of sleep deprivation. This study investigated the effects of ear plugs, eye masks and both together on the sleep quality of patients in a CCU. Materials and methods: This randomised-controlled trial was conducted on 90 patients in Imam Khomeini Hospital in Jiroft. Patients were randomly assigned to three groups: eye mask (group 1), ear plugs (group 2), and both together (group 3). Using the Verran and Snyder-Halpern Sleep Scale, perception of patients' sleep with and without intervention were evaluated. This tool consists of 16 items grouped into three main subscales: disturbance, effectiveness, and supplementation. Results: The mean length of time patients slept for was 6.34±1.2 hours. In group 1, the quality of sleep improved significantly in relation to disturbance and effectiveness. In group 2, all three subscales showed significant improvements. In group 3, which used the eye mask and ear plugs together, only the disturbance subscale showed significant improvement. Conclusion: The use of ear plugs and eye masks is an easy and cheap method of improving the quality of sleep in CCU patients. Nurses should consider these devices for reducing environmental factors that disturb the sleep of CCU patients.