Z-drugs are a group of nonbenzodiazepine

Nonbenzodiazepine

The nonbenzodiazepines, also called benzodiazepine-like drugs, are a class of psychoactive drugs pharmacologically resembling the benzodiazepines, with similar benefits, side effects and risks, despite having dissimilar or entirely different chemical structures.-Classes:There are currently three...

 drugs with effects similar to benzodiazepines which are used in the treatment of insomnia

Insomnia

Insomnia is most often defined by an individual's report of sleeping difficulties. While the term is sometimes used in sleep literature to describe a disorder demonstrated by polysomnographic evidence of disturbed sleep, insomnia is often defined as a positive response to either of two questions:...

, and whose names mostly start with the letter "Z". Some Z drugs may have advantages over benzodiazepines. Benzodiazepines actually worsen sleep architecture

Sleep architecture

Sleep architecture describes the structure and pattern of sleep and encompasses several variables. Sleep quotas refer to the amount of time spent in REM and NREM sleep. Sleep duration is the total time spent asleep in a 24 hour period. The duration of a NREM-REM cycle is also an important aspect...

 whereas certain Z drugs such as zaleplon

Zaleplon

Zaleplon is a sedative/hypnotic, mainly used for insomnia. It is a nonbenzodiazepine hypnotic from the pyrazolopyrimidine class. In terms of adverse effects zaleplon appears to offer little improvement compared to both benzodiazepines and other non-benzodiazepine Z-drugs.Sonata is manufactured by...

 have less or no disruption of sleep architecture.

List of Z-drugs

• Zaleplon
  Zaleplon
  Zaleplon is a sedative/hypnotic, mainly used for insomnia. It is a nonbenzodiazepine hypnotic from the pyrazolopyrimidine class. In terms of adverse effects zaleplon appears to offer little improvement compared to both benzodiazepines and other non-benzodiazepine Z-drugs.Sonata is manufactured by...
  
   (Sonata)
• Zolpidem
  Zolpidem
  Zolpidem is a prescription medication used for the short-term treatment of insomnia, as well as some brain disorders. It is a short-acting nonbenzodiazepine hypnotic of the imidazopyridine class that potentiates gamma-aminobutyric acid , an inhibitory neurotransmitter, by binding to GABAA...
  
   (Ambien)
• Zopiclone
  Zopiclone
  Zopiclone is a non-benzodiazepine hypnotic agent used in the treatment of insomnia. In the United States, zopiclone is not commercially available, although its active stereoisomer, eszopiclone, is sold under the name Lunesta...
  
   (Imovane)
• Eszopiclone
  Eszopiclone
  Eszopiclone, marketed by Sepracor under the brand-name Lunesta, is a nonbenzodiazepine hypnotic used as a treatment for insomnia. Eszopiclone is the active dextrorotatory stereoisomer of zopiclone, and belongs to the class of drugs known as cyclopyrrolones.Eszopiclone is a short acting...
  
  (Lunesta)