Effects of Progressive Muscle Relaxation on Sleep Quality, Serotonin, and Melatonin in Hospitalized Cardiac Patients: A Randomized Controlled Trial

This study aimed to evaluate the effects of progressive muscle relaxation (PMR) on sleep quality and urinary 5-HIAA levels as an indicator of serotonin metabolism and urinary 6-HMS levels as an indicator of melatonin metabolism in hospitalized cardiac patients with sleep disturbances. This prospective, randomized, controlled trial included 60 patients diagnosed with heart failure or myocardial infarction. Patients in the intervention group received PMR in addition to routine care, whereas the control group received routine care alone. Sleep quality was assessed using the Richard-Campbell Sleep Scale (RCSS). Urinary concentrations of 5-HIAA and 6-HMS were measured as secondary outcomes. Data were analyzed using independent-samples t -tests, Mann-Whitney U tests, Wilcoxon signed-rank tests, and paired t -tests as appropriate, with statistical significance set at p < 0.05 . Baseline RCSS scores were comparable between the intervention and control groups (21.0 ± 3.5 vs. 21.5 ± 3.0, p > 0.05). Following the intervention, the PMR group demonstrated a marked improvement in sleep quality compared with the control group (73.5 ± 8.2 vs. 25.0 ± 7.3, p < 0.001). Urinary 5-HIAA concentrations increased significantly in the PMR group (23.2 ± 1.9 to 42.4 ± 1.5), whereas concentrations decreased significantly in the control group. Similarly, urinary 6-HMS concentrations increased significantly following PMR (27.0 ± 2.3 to 48.4 ± 5.1), with significant between-group and within-group differences ( p < 0.05). Progressive muscle relaxation significantly improved sleep quality and increased urinary concentrations of 5-HIAA and 6-HMS in patients with heart failure and myocardial infarction. These findings suggest that PMR may be an effective non-pharmacological nursing intervention for improving sleep and related neuroendocrine outcomes in hospitalized cardiac patients.