Valerian for sleep: a systematic review and meta-analysis 2006 - "The available evidence suggests that valerian might improve sleep quality without producing side effects. Future studies should assess a range of doses of standardized preparations of valerian and include standard measures of sleep quality and safety." Valerian for sleep: a systematic review and meta-analysis 2010 - The AMED and MEDLINE databases were searched for primary sources of literature published between 1950 and 2009, using keywords: herbal medicine, medicinal plants, herbal, Valeriana officinalis, valerian, Humulus lupulus, hops, sleep, insomnia. Studies were included if they evaluated the efficacy of valerian or hops in improving primary insomnia in adults: sixteen studies met the inclusion criteria. Twelve of these found that the use of valerian, on its own, or in combination with hops, is associated with improvements in some sleep parameters (eg. sleep latency and quality of sleep). However, th...