In a multicenter randomized placebo-controlled parallel-group study Half Frog Yoga Pose of 184 adults with mild insomnia Morin, Koetter, Bastien, Ware, & Wooten, Half Frog Yoga Pose 2005, the groups given valerian-hops or diphenhydramine showed modest improvements in subjective sleep parameters, most of which did not reach statistical significance.
The valerian-hops produced greater, but not statistically significant, reductions in sleep latency than diphenhydramine and placebo. Quality of life improved significantly in the valerian-hops group compared to placebo, suggesting that valerian-hops may be a useful adjunct for mild insomnia. No serious adverse events occurred and there were no residual symptoms.
Reports of dystonia and hepatitis from preparations containing a mixture of ingredients including valerian are difficult to interpret. Valerian tea and tablets have an unpleasant taste and odor. One advantage of valerian over other sedative/hypnotics is that there have been no cases of habituation or abuse and only one case of possible withdrawal symptoms. Valerian should be avoided in pregnancy.