The Herbal Medicine Suanzaoren (Ziziphi Spinosae Semen) for Sleep Quality Improvements: A Systematic Review and Meta-analysis

BACKGROUND: Sleep disturbances are common and bothersome among cancer and noncancer populations. Suanzaoren (Ziziphi Spinosae Semen) is commonly used to improve sleep, yet its efficacy and safety are unclear. METHODS: We systematically searched PubMed, Cochrane Library, and EMBASE from inception through October 5, 2021, to identify randomized trials of Suanzaoren. We included randomized trials comparing Suanzaoren to placebo, medications, cognitive behavioral therapy (CBT), or usual care for improving sleep outcomes in cancer and noncancer patients with insomnia or sleep disturbance. We performed a risk of bias analysis following Cochrane guidelines. Depending on heterogeneity, we pooled studies with similar comparators using fixed- and random-effects models. RESULTS: We included participants with insomnia disorder (N = 785) or sleep disturbance (N = 120) from 9 trials. Compared with placebo, Suanzaoren led to significant subjective sleep quality improvements in participants with insomnia and patients with sleep disturbance combined (standard mean difference −0.58, 95% CI −1.04, −0.11; P < .01); Compared with benzodiazepines or CBT, Suanzaoren was associated with a significant decrease in insomnia severity (mean difference −2.68 points, 95% CI −5.50, −0.22; P = .03) at 4 weeks in the general population and cancer patients. The long-term effects of Suanzaoren were mixed among trials. Suanzaoren did not increase the incidence of major adverse events. The placebo-controlled studies had a low risk of bias. CONCLUSION: Suanzaoren is associated with short-term patient-reported sleep quality improvements among individuals with insomnia or sleep disturbance. Due to the small sample size and variable study quality, the clinical benefits and harms of Suanzaoren, particularly in the long term, should be further assessed in a sufficiently powered randomized trial. REGISTRATION: PROSPERO CRD42021281943