Ambien is a brand name for the drug zolpidem, which is a sedative-hypnotic medication used to treat insomnia. It works by enhancing the activity of the neurotransmitter GABA in the brain, which helps to slow down activity in the brain and promote sleep. Ambien should be taken exactly as prescribed by a doctor, typically right before bedtime. It is important to follow the instructions carefully, as taking too much Ambien can lead to overdose, especially when combined with other medications or alcohol.