Effectiveness of Lesser Known Herbal Sedatives for Insomnia: A Systematic Review and Meta-Analysis

Abstract Background Insomnia is a major public health problem affecting an estimated 852 million adults worldwide. Current pharmacological treatments, including benzodiazepines and Z-drugs, carry serious risks of dependency, cognitive impairment, and adverse events. These limitations have driven growing interest in complementary and alternative therapies, particularly herbal sedatives, which are perceived as natural and safer. However, evidence on their safety and efficacy remains insufficient and patchy. Objective: This review evaluated the effectiveness of lesser known herbal sedatives for insomnia. Methods The protocol was registered with PROSPERO (CRD420251101795). Eligibility was defined using the PICO framework: Population: adults aged [≥]18 years with insomnia; Interventions: Passiflora incarnata, Hawthorn, Melissa officinalis, Chamomile, Viola odorata, Nelumbo nucifera, Rhodiola rosea, and Eschscholtzia californica. Comparators: placebo or usual care; Primary and Secondary Outcomes: sleep quality (Pittsburgh Sleep Quality Index, Insomnia Severity Index, Epworth Sleepiness Scale), sleep duration, and sleep latency. Databases and registers were searched from January 2005 to July 2025. Randomized controlled trials, nonrandomized controlled trials, clinical trials, and observational studies were included. Five reviewers independently screened studies. Data extraction used a structured Excel spreadsheet. Risk of bias was assessed using RoB 2.0 for randomized trials and ROBINS-I V2 for nonrandomized studies. Random-effects meta-analyses (DerSimonian and Laird) were conducted in RevMan. Narrative synthesis followed SWiM guidelines. Results From 1,294 records, 32 studies met eligibility criteria. Meta-analysis of 23 RCTs demonstrated a statistically significant pooled effect favouring herbal sedatives (SMD -0.77, 95% CI -1.14 to -0.40, p=0.0001), with substantial heterogeneity (I square=92%). Subgroup analysis showed larger effects for chamomile (SMD -1.06) and Melissa officinalis (SMD -0.66). Most RCTs had high overall risk of bias; nonrandomized studies predominantly had critical risk of bias. Conclusions This systematic review provides preliminary evidence that several herbal sedatives, particularly chamomile and Melissa officinalis, may improve insomnia-related outcomes. However, methodological weaknesses, high risk of bias, and substantial heterogeneity limit evidence strength. Future research requires standardized extracts, large multicentre RCTs, and extended follow-up.