Eszopiclone, sold under the brand name Lunesta among others, is a medication used in the treatment of insomnia. Evidence supports some benefits up to six months. The degree of effectiveness, however, is slight. It is taken by mouth. Lunesta (eszopiclone) is a sedative, also called a hypnotic. It affects chemicals in your brain that may be unbalanced in people with sleep problems (insomnia). Lunesta is used to treat insomnia. Lunesta causes relaxation to help you fall asleep and stay asleep.