Ambien is a sedative used to treat the Ambien For insomnia treat. The short-term release tablet will help you sleep immediately when you first go to bed. The extended-release form, Ambien CR, has two layers. The first will dissolve quickly to help you sleep immediately, and the second layer will keep you asleep till morning. Ambien works by boosting GABA activity, a neurotransmitter in the brain. The neurotransmitter serves as a messenger between the neurons.