Study designs of evaluations included in the review
Only randomised, placebo-controlled double-blind trials were eligible for inclusion in the review.
Specific interventions included in the review
The trials needed to examine valerian (Valeriana oficinalis). Three trials considered the cumulative effects of valerian administered over consecutive days, whilst six measured acute responses to single doses. The doses ranged from 60 to 1,215 mg/day.
Participants included in the review
No inclusion criteria were stated in terms of the participants. The participants included chronically ill patients in geriatric hospitals for whom difficulty in sleeping was one of a number of complaints, elderly female poor sleepers, patients with non-organic insomnia who were not suffering from depression, mild insomnia sufferers and volunteers without documented sleep problems.
Outcomes assessed in the review
To be eligible, the trials needed to have measured the effect of valerian preparations on sleep. The outcomes measured in the trials included sleep latency and quality, total sleep time and the amount of rapid eye movement (REM) sleep. Where found, adverse events were also highlighted.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.