Researchers in Hong Kong have carried out a systematic review of twenty randomised controlled trials investigating the effects of acupuncture on insomnia. The majority of trials concluded that traditional acupuncture was significantly more effective for helping insomnia, than benzodiazepines, the mean effective rates being 91% and 75% respectively.
The authors point out methodological shortcomings in the studies reviewed and cite the need now for large scale, high-quality trials. (Traditional Needle Acupuncture Treatment for Insomnia: A Systematic Review of Randomised Controlled Trials. Sleep Med 2009 March 18. Epub ahead of print)