The British Medical Journal has published the results of a meta-analysis that aimed to assess the effectiveness of non-benzodiazepine hypnotics (otherwise known as Z drugs) in treatment of adult insomnia.
The analysis included data from 13 studies submitted to the Food and Drugs Administration that involved 4,378 participants in 65 separate drug-placebo comparisons. The main outcomes assessed were polysomnographic and subjective sleep latency. Secondary outcomes including measures such as total sleep time, number of awakenings and sleep quality were also assessed but data for these were not available in all studies.
The study found a statistically significant but small reduction in polysomnographic sleep latency (−0.36, 95% CI −0.57 to −0.16) and subjective sleep latency (−0.33, 95% CI −0.62 to −0.04). Non-benzodiazepine hypnotics reduced sleep latency by 22 minutes (-11 to -33 minutes) compared to placebo. It was noted that the placebo response could account for approximately half of the drug response. No significant effects were found in any secondary outcomes but the population sizes were inadequate to allow conclusions to be drawn.
The authors note some limitations in their analysis including the omission of small studies from the analysis, variable entry criteria and primary outcomes in the studies and that all studies were industry sponsored. Industry sponsorship enhances outcomes but it is also noted that unpublished data were also included in this analysis.
The authors conclude that, "Z drugs improve objective and subjective sleep latency compared with placebo" but the "size of this effect is small and needs to be balanced with concerns about adverse effects, tolerance, and potential addiction".
Action: Clinicians should be aware of this analysis. A NICE Technology Appraisal from 2004 recommends consideration of non-medicine treatments with short term drug treatment for severe insomnia that is interfering with normal daily life.