What is already known on this topic
Z drug hypnotics have short term benefits in the treatment of insomnia
Their effectiveness has been questioned because of publication bias reported in previous meta-analyses, and little is known about the
extent of the placebo response
What this study adds
Z drugs decreased subjective and polysomnographic sleep latency compared with placebo especially with larger doses and in younger
or female patients and regardless of type of drug
The drug effect and the placebo response were small and of questionable clinical importance, but the two together produced a reasonably
large clinical response
The FDA clinical trial data were free from publication bias but might have been subject to other forms of bias
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Accepted: 30 November 2012
Cite this as: BMJ 2012;345:e8343
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BMJ 2012;345:e8343 doi: 10.1136/bmj.e8343 (Published 17 December 2012) Page 6 of 13