Sleep disorders are common among the general population and can generate health problems such as insomnia and anxiety. In addition to standard drugs and psychological interventions, there are different complementary plant-based therapies used to treat insomnia and anxiety. This review aimed to find and examine the most recent research on the use of herbal medicines for treating anxiety and insomnia as compiled from clinical trials, as well as to assess the safety and efficacy of these medicines and to elucidate their possible mechanisms of action. The process entailed a search of PubMed, Scopus, and the Cochrane Library databases from 2010 to 2020. The search terms included “sleep disorder”, “insomnia”, “sedative”, “hypnotic”, “anxiety”, “anxiolytic”, and “clinical trial”, combined with the search terms “herbs” and “medicinal plants”, in addition to individual herbal medicines by both their common and scientific names. This updated review, which focuses mainly on
clinical trials, includes research on 23 medicinal plants and their combinations. Essential oils and their associations have also been reviewed. The efficacy of medicinal plants depends on treatment duration, types of study subjects, administration route, and treatment method. More clinical trials with an adequate, standardized design are necessary, as are more preclinical studies to continue studying the mechanisms of action. As a result of our work, we can conclude that the 3 plants with the most potential are valerian, passionflower, and ashwagandha, with the combination of valerian with hops and passionflower giving the best results in the clinical tests.