Elsevier

Sleep Medicine

Volume 1, Issue 2, 1 April 2000, Pages 91-99
Sleep Medicine

Original article
Valerian for insomnia: a systematic review of randomized clinical trials

https://doi.org/10.1016/S1389-9457(99)00015-5Get rights and content

Abstract

Objective: To systematically review the evidence for the effects of the herb valerian (Valeriana officinalis) on insomnia, based on randomized, placebo-controlled, double-blind trials.

Background: Valerian has long been advocated and used for promoting sleep but until quite recently evidence was solely anecdotal. However, during the last two decades a number of clinical trials have been conducted.

Materials and methods: Systematic literature searches were performed to locate randomized, placebo-controlled, double-blind trials measuring the effect of valerian monopreparations on sleep in human participants. Data were extracted in a standardized manner and methodological quality was assessed by the Jadad score.

Results: Nine trials were located meeting the selection criteria. The findings of the studies were contradictory and there was great inconsistency between trials in terms of patients, experimental design and procedures and methodological quality.

Conclusion: The evidence for valerian as a treatment for insomnia is inconclusive. There is a need for rigorous trials to determine its efficacy.

Introduction

Insomnia is defined as a condition of unsatisfactory quality and inadequate quantity of sleep and is characterized by difficulty initiating or maintaining sleep and early final wakening [1]. This can have adverse effects on daily functioning due to fatigue, poor concentration and memory problems [2]. Effective pharmacologic treatments include short and long-acting benzodiazepines, although many of these are associated with adverse effects, daytime sedation (hangover) and dependence with continued use [3]. Fatal overdoses are possible if taken in combination with other drugs but are rare [4]. More modern drugs such as zolpidem, zopiclone and zaleplon avoid some of the adverse effects of benzodiazepines by selective binding to receptor sites [5].

Valerian (Valeriana officinalis) is a herb that has long been advocated for promoting sleep [6]. In most countries it is marketed as an over-the-counter product for this purpose, with considerable success. Sales of valerian preparations in the US totalled $8 million between July 1997 and 1998 [7]. However, until fairly recently, clinical evidence of its value in improving sleep was almost entirely based on observational studies and anecdotal reports. A number of controlled clinical trials have been conducted during the past two decades investigating the effects of valerian on human sleep. This review aimed to summarize the evidence from all randomized, placebo-controlled, double-blind trials.

Section snippets

Materials and methods

Computerized literature searches were performed on the following databases: Medline, Embase, Biosis, The Cochrane Library, Current Contents (all from their inception to May 1999) using the search terms valerian, Valeriana officinalis, insomnia*, sleep* to identify all published articles on the subject. The reference lists of these papers were scanned for further relevant publications. Furthermore, manufacturers of valerian products and other experts working in the field were contacted and asked

Results

The search located 19 trials on valerian. Ten were excluded: four used combined preparations [9], [10], [11], [12], three were not randomized [13], [14], [15], and three did not measure sleep-related parameters [16], [17], [18]. Nine trials (reported in eight papers), therefore, met our criteria for inclusion in the systematic review. These trials are summarized in Table 1, Table 3 and described below. The first three studies examined the cumulative effects of valerian administered over

Discussion

Evaluating the efficacy of valerian for improving sleep based on randomized, placebo-controlled trials is a difficult task because of the conflicting findings and inconsistencies between studies. Nine randomized, double-blind, placebo-controlled trials meeting the inclusion criteria were found by the search. Although efforts were made to locate all available studies, it is possible that some trials were not unearthed. Since there is a tendency for negative trials to remain unpublished [27],

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