Barbiturates, including amobarbital (Amytal), pentobarbital (Nembutal), phenobarbital (Luminal), and secobarbital (Seconal), are central nervous system depressants. They are commonly used for anesthesia and are prescribed to treat seizures. At one time, they also commonly treated insomnia or anxiety on a short-term basis. But because of overdose dangers, benzodiazepines have largely replaced barbiturates for those purposes.