In the 1950s, chemists searching for drugs to reduce anxiety came up with benzodiazepines. The best known of these is Valiumİ (diazepam). All have a calming effect, without much drowsiness. Benzodiazepines inhibit the activity of neurones in the brain, especially in the parts that deal with emotions. Like barbiturates, they work by increasing the activity of a naturally occurring neurotransmitter, gamma-aminobutyric acid (GABA).