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Figure 1

Meta-analysis of 6 studies reporting dichotomous outcomes for sleep quality (sleep improved or not). The dichotomous outcome (improved sleep or not) is presented as the relative risk for reporting improved sleep in the valerian group. Risk ratios greater than one indicate a benefit in the valerian group. Point estimates are represented by diamonds (with first author names) for individual studies and by squares for the summary estimates. Vertical lines represent 95% confidence intervals [CIs].

Figure 2

Funnel plot of studies reporting a dichotomous outcome of sleep quality. The funnel plot shows the relationship between study size (as measured by standard error, with larger standard errors indicating smaller studies) and study outcome (as measured by relative risk). The visual inspection of the graph suggests an absence of small negative studies (low relative risk, bottom left), which is supported by the statistical test for publication bias, Kendall’s tau (P = .03). The points are labeled with the first author name.


Insomnia affects approximately one-third of the adult population and contributes to increased rates of absenteeism, health care use, and social disability. Extracts of the roots of valerian (Valeriana officinalis) are widely used for inducing sleep and improving sleep quality. A systematic review of randomized, placebo-controlled trials of valerian for improving sleep quality is presented. An extensive literature search identified 16 eligible studies examining a total of 1093 patients. Most studies had significant methodologic problems, and the valerian doses, preparations, and length of treatment varied considerably. A dichotomous outcome of sleep quality (improved or not) was reported by 6 studies and showed a statistically significant benefit (relative risk of improved sleep = 1.8, 95% confidence interval, 1.2-2.9), but there was evidence of publication bias in this summary measure. 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.

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This work was supported by Grant Number 1 K08 ATO1338-01 (Dr Bent) from the National Center for Complementary and Alternative Medicine.


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