ESZOPICLONE belongs to a group of medicines called 'sedative-hypnotics,' primarily used to treat sleep problems or insomnia. Insomnia is defined as a sleep disorder which makes it difficult to fall asleep or stay asleep.  ESZOPICLONE works by increasing the chemical substance in the brain called gamma-aminobutyric acid (GABA). GABA is an amino acid that works as a neurotransmitter (a chemical messenger that transmits the message from one nerve cell to another nerve cell, muscle cell, or gland cell) in the central nervous system.