Zopiclone (Rhovane, Imovane) 7.5 mg tablets, sold as Imovane and Zimovane in Europe and Canada, and as the eszopiclone analogue Lunesta in the United States, is a novel hypnotic agent used in the treatment of insomnia. Zopiclone is a controlled substance in the United States, Canada and some European countries and may be illegal to possess without a prescription. It is not a benzodiazepine (with which it shares a number of characteristics and effects), but a cyclopyrrolone derivative, belonging to a novel chemical class which is structurally unrelated to existing hypnotics. Zopiclone is known colloquially as a ‘Z drug’, Other Z drugs include zaleplon (Sonata) and zolpidem (Ambien and AmbienCR) and were thought in initial studies to be less addictive and less habit forming than benzodiazepines.