Lunesta, commonly known as eszopiclone, is a prescription drug primarily used to treat insomnia, a sleep disorder characterized by difficulty falling or staying asleep. It is a non-benzodiazepine sedative and hypnotic that acts on the central nervous system by enhancing the activity of gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter in the brain. This results in a calming effect that promotes sleep.