An internet-based randomized, placebo-controlled trial of kava and valerian for anxiety and insomnia

Medicine (Baltimore). 2005 Jul;84(4):197-207. doi: 10.1097/


The herbal extracts kava and valerian are the leading dietary supplements used in the self-management of anxiety and insomnia, respectively. There is limited evidence to support their effectiveness for these common symptoms. The Internet has been used to a limited extent for research, but it is not known whether randomized controlled trials can be conducted entirely using Internet technology. We performed a randomized, double-blind, placebo-controlled trial using a novel Internet-based design to determine if kava is effective for reducing anxiety and if valerian is effective for improving sleep quality. E-mail recruitment letters and banner advertisements on websites were used to recruit a large pool of interested participants (1551) from 45 states over an 8-week period. Participants were first asked to read study information, complete an online informed consent process, and undergo electronic identity verification. In order to be eligible for the study, participants were required to have 1) anxiety as documented by scores of at least 0.5 standard deviations above the mean on the State-Trait Anxiety Inventory State subtest (STAI-State) on 2 separate occasions, and 2) insomnia, defined as a "problem getting to sleep or staying asleep over the past 2 weeks." We randomly assigned 391 eligible participants to 1 of the following 3 groups, and mailed 28 days' supply: kava with valerian placebo (n = 121), valerian with kava placebo (n = 135), or double placebo (n = 135). The primary outcome measures were changes from baseline in anxiety (STAI-State questionnaire) and insomnia (Insomnia Severity Index [ISI]) compared with placebo. Participants receiving placebo had a 14.4 point decrease in anxiety symptoms on the STAI-State score and an 8.3 point decrease in insomnia symptoms on the ISI. Those receiving kava had similar reductions in STAI-State score (2.7 point greater reduction in placebo compared with kava; 95% confidence interval [CI], -0.8 to +6.2). Those receiving valerian and placebo had similar improvements in sleep (0.4 point greater reduction in the placebo than the valerian group; 95% CI, -1.3 to +2.1). Results were similar when limited to the 83% of participants who adhered to study compounds for all 4 weeks. Neither kava nor valerian relieved anxiety or insomnia more than placebo. This trial demonstrates the feasibility of conducting randomized, blinded trials entirely via the Internet.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anxiety / classification
  • Anxiety / drug therapy*
  • Capsules
  • Double-Blind Method
  • Feasibility Studies
  • Female
  • Follow-Up Studies
  • Humans
  • Internet*
  • Kava* / adverse effects
  • Male
  • Patient Compliance
  • Phytotherapy*
  • Placebos
  • Plant Extracts / administration & dosage
  • Plant Extracts / adverse effects
  • Plant Extracts / therapeutic use*
  • Reproducibility of Results
  • Research Design*
  • Safety
  • Sleep Initiation and Maintenance Disorders / classification
  • Sleep Initiation and Maintenance Disorders / drug therapy*
  • Treatment Outcome
  • Valerian* / adverse effects


  • Capsules
  • Placebos
  • Plant Extracts