RESUMO
Valerian is one of the most used herbal agents (phytotherapeutics) to manage sleep disturbances, in particular, sleep-onset difficulties in young adults. However, the evidence based on primary studies and systematic reviews that supports its use in this domain is weak or inconclusive. In the current study, an umbrella review was performed on the efficacy of valerian for sleep disturbances with a focus on insomnia. As such, only systematic reviews (with or without meta-analysis) were considered for this study. Systematic searches in PubMed, Web of Science, Scopus, Cochrane Database of Systematic Reviews, PROSPERO and CNKI databases retrieved 70 records. Only 8 articles were considered eligible for qualitative analysis. Overall, data suggested that valerian has a good safety profile, however, the results showed no evidence of efficacy for the treatment of insomnia. Moreover, valerian appears to be effective concerning subjective improvement of sleep quality, although its effectiveness has not been demonstrated with quantitative or objective measurements. Despite its widespread use and prescription by general practitioners, psychiatrists and other professionals, valerian does not have empirical support for insomnia. Further studies, in particular high quality randomized controlled trials, are highly recommended since there are scarce studies and the existing ones are quite heterogeneous and with low methodological quality. The implications of our findings for clinical practice are critically discussed.