Barbiturates and benzodiazepines are classes of psychoactive drugs classified as depressants. They share in common their ability to serve as agonists of the gamma-Aminobutyric acid (GABA) neurotransmitter system. When these drugs bind to their specific receptor sites on the GABA-gated chloride ($\text{Cl}^-$) channel, they open the chloride channel. This allows negatively-charged chloride ions ($\text{Cl}^-$) to enter the neuron's cell body, changing its charge in a negative direction and pushing the neuron away from firing. Because of this quieting effect on the brain, these types of drugs are often prescribed to treat both anxiety and insomnia.