Prescription sleep aid Ambien is a medication used to treat insomnia. It works by slowing down the activity of the brain, allowing the user to fall asleep faster and stay asleep longer. Ambien is a brand name for the generic drug zolpidem, which is available in both immediate-release and extended-release forms. It is typically taken just before bedtime and should not be taken with alcohol or other sedatives. Ambien can cause side effects such as dizziness, drowsiness, and headaches.