Lemon Verbena (Aloysia citrodora) and Insomnia / sleeplessness: evidence and sources

Ethnopharmacological relevance Aloysia citrodora Paláu (Lippia citriodora Kunth), commonly known as "lemon verbena" is a medicinal plant native to South America, North Africa, and South of Europe which is used by native people for several indications such as diarrhea, flatulence, insomnia, and rheumatism. Aim of the review Despite the wide biological activities of lemon verbena, there is no current review summarizing medicinal properties of the plant; thus, this paper aims to discuss current state of the art regarding the phytochemistry, pharmacology, and therapeutic applications of A. citrodora considering in vitro, in vivo, and clinical studies. Materials and methods Electronic databases including PubMed, Scifinder, Cochrane library, Scopus, and Science direct were searched with the scientific name of the plant and its synonyms, as well as the common name. All studies on the ethnobotany, phytochemistry, pharmacology, and clinical application of the plant until October 2017 were included in this review. Results Despite the few number of studies on the ethnopharmacology of the plant, A. citrodora is widely assessed regarding its phytochemistry and biological activities. Neral and geranial are the main ingredients of the essential oil; whereas verbascoside is the most significant component of the extract. Biological activities such as antioxidant, anxiolytic, neuroprotective, anticancer, anesthetic, antimicrobial, and sedative effects are proved in cell cultures, as well as animal studies. Conclusions Several pharmacological activities have been reported for A. citrodora; however, the plant is not fully assessed regarding its safety and efficacy in human. Future well-designed human studies are essential to confirm the therapeutic benefits of this plant in clinical settings.

Seventy-one healthy subjects with sleep disturbances participated in a randomized, double-blind controlled trial in which dietary supplementation with an extract of Aloysia citrodora (lemon verbena) ( n = 33) or placebo ( n = 38) was administered for 90 days. There were between-group differences in favor of the experimental group in the visual analogue scale (VAS) for sleep quality (6.5 ± 1.6 vs. 5.5 ± 2.1, p = 0.021) as well as in the overall score (5.8 ± 2.4, p = 0.008) and scores for sleep latency (1.6 ± 1.0 vs. 1.9 ± 0.7, p = 0.027) and sleep efficiency (84.5 ± 12.8 vs. 79.8 ± 13.6, p = 0.023) in the Pittsburgh Sleep Quality Index (PSQI). Sleep-related variables (latency, efficiency, wakefulness after sleep onset, awakenings) assessed by actigraphy also showed better scores in the experimental group ( p = 0.001). Plasma nocturnal melatonin levels also increased significantly in the experimental group (199.7 ± 135.3 vs. 174.7 ± 115.4 pg/mL, p = 0.048). Changes in anthropometric parameters and physical activity levels were not found. In summary, a dietary supplement of lemon verbena administered for 3 months was associated with a significant improvement in sleep quality as compared with placebo in a population of healthy subjects with sleep problems.

Aloysia citriodora (A. citriodora) has a long history of traditional use for sedation and treatment of insomnia in different societies. This study was carried out to assess the efficacy of A. citriodora in patients with insomnia. One hundred patients were randomly divided into two groups of A. citriodora (total essential oil 1.66 mg/10 ml and total amount of flavonoid in terms of quercetin 3.22 mg/10 ml of the syrup) and placebo. They were advised to use 10 cc of the syrups; an hour before the bedtime for a period of 4 weeks. Participants were assessed using Pittsburgh Sleep Quality Index (PSQI) and Insomnia Severity Index (ISI) questionnaires at the baseline and then 2 and 4 weeks after the enrollment. Mean scores of global PSQI and its four components including sleep latency, habitual sleep efficiency, daytime dysfunction, and subjective sleep quality and also ISI score in the A. citriodora group improved significantly after 4 weeks of treatment when compared with the placebo group (p < 0.001, for all of them). Also, improvement of global score of PSQI and ISI was observed in the intervention group as compared with the placebo group, 2 weeks after the enrollment (p < 0.001). The results of this study showed that oral intake of A. citriodora can be suggested as a complementary treatment for patients with insomnia.