The Efficacy of V. odorata Extract in the Treatment of Insomnia: A Systematic Review and Meta-Analysis

Aim: This systematic review and meta-analysis was performed to assess the effect of Viola odorata (V. odorata) extract in the treatment of insomnia. Methods: PubMed, EMBASE, and Cochrane Library databases, as well as references of related articles, were searched. Finally, four articles with five clinical trials including 224 patients were included in the analysis. Results: The obtained results indicated a greater improvement in total PSQI scores (MD,-4.67; P = 0.0002), subjective sleep quality score (MD,-0.91; P = 0.003), sleep duration score (MD,-0.77; P < 0.00001), and ISI score (MD,-6.30; P = 0.009) in the Viola extract group compared with the placebo group. However, the Viola extract group did not significantly differ in sleep latency (MD,-0.85; P = 0.08), habitual sleep efficiency (MD,-0.61; P = 0.21), sleep disturbances (MD,-0.36; P = 0.11), and daytime dysfunction (MD,-0.94; P = 0.12) from the placebo group. Conclusions: Viola extract supplement led to a greater improvement in total PSQI scores, subjective sleep quality score, sleep duration score, and ISI score compared with the placebo group of patients with chronic insomnia.