They are used to treat insomnia.
Sleeping pills, including the z-drugs, have been associated with an increased risk of death. 
There are three primary groups of Z-drugs:
They are categorized as nonbenzodiazepines. All of these groups are believed to modulate benzodiazepine specific subunit sites, as specific agonists of the GABAA receptors. It is thought that the primary mode of action utilized by Z-drugs is selective, and carries a high affinity for the a1 hypnotic-inducing site on the benzodiazepine subunit within the GABAA receptor.
Z-drugs emerged in the last years of the 1980s and early 1990s, with zopiclone (Imovane) approved by the British National Health Service as early as 1989, quickly followed by Sanofi with zolpidem (Ambien). By 1999, King Pharmaceuticals had finalized approval with the American Food and Drug Administration (FDA) to market zaleplon (Sonata, Starnoc) across the US. In 2005, the FDA approved eszopiclone (Lunesta) the (S)-enantiomer of zopiclone. That same year, 2005, the FDA finalized approval for Ambien CR, or extended-release zolpidem. Most recently, in 2012 the FDA approved Intermezzo, which still utilizes zolpidem as its active ingredient, but is marketed for middle-of-the-night insomnia, available in doses only half of the strength of immediate-release Ambien to avoid residual next-day sedation.
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- Treves, N; Perlman, A; Kolenberg Geron, L; Asaly, A; Matok, I (1 March 2018). "Z-drugs and risk for falls and fractures in older adults-a systematic review and meta-analysis". Age and Ageing. 47 (2): 201–208. doi:10.1093/ageing/afx167. PMID 29077902.
- Kripke, DF (February 2016). "Mortality Risk of Hypnotics: Strengths and Limits of Evidence". Drug safety. 39 (2): 93–107. doi:10.1007/s40264-015-0362-0. PMID 26563222.
- Barbera J, Shapiro C (2005). "Benefit-risk assessment of zaleplon in the treatment of insomnia". Drug Saf. 28 (4): 301–18. doi:10.2165/00002018-200528040-00003. PMID 15783240.
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