IntroductionThis single-arm pilot study aimed to investigate the effects of a 1-month Xiao-Yao-San (XYS) treatment with on objective and subjective sleep parameters among insomnia patients with and without moderate-to-severe obstructive sleep apnea (OSA). MethodsThis single-arm pre-post study included fourteen participants (average age, 48.2±15.5 years). All participants received XYS (3 g × 3 times/day, after meals) for 28 days. Among them, 7 participants had an apnea-hypopnea index (AHI) ≥15 events/hour and were classified as having moderate-to-severe OSA, while 7 patients had an AHI <15 events/hour. Polysomnography was performed to evaluate the AHI, sleep stage, sleep efficiency, and sleep latency at the beginning and after 28 days of usage. Subjective questionnaires were also administered, including the Pittsburgh Sleep Quality Index (PSQI), Hospital Anxiety and Depression Scale (HADS-A and HADS-D), and Epworth Sleepiness Scale (ESS). The Wilcoxon test was used to compare the pre-treatment and post-treatment differences. ResultsOur 14 insomnia participants, with an average AHI of 21.2 events/hour at baseline, who were taking XYS, exhibited a statistically significant reduction in PSQI scores (reduction of -3.0; p=0.002) compared to the corresponding baseline values. The objective sleep evaluations did not show differences between participants with or without moderate-to-severe OSA after receiving XYS treatment. For subjective sleep parameters, only participants without moderate-to-severe OSA exhibited statistically significant improvements in sleep quality (PSQI score pretest/posttest: 10.0±3.5/7.0±3.5; p=0.012). ConclusionsXYS treatment may significantly improve sleep quality in participants without moderate-to-severe OSA. Further studies with larger sample sizes and longer durations are needed.