Gamma-aminobutyric acid, or GABA, is a neurotransmitter that sends chemical messages through the brain and the nervous system, and is involved in regulating communication between brain cells, according to the Cleveland Clinic.The role of GABA is to inhibit or reduce the activity of the neurons or nerve cells.GABA plays an important role in behavior, cognition, and the body’s response to stress, research has shown.Research also suggests that GABA helps to control fear and anxiety when neurons become overexcited, notes McGill University.Lower-than-normal levels of GABA in the brain have been linked to schizophrenia, depression, anxiety, and sleep disorders, as the Cleveland Clinic notes.GABA ReceptorsGABA receptors on nerve cells receive the chemical messages that help to inhibit or reduce nerve impulses.Prescription medications called benzodiazepines bind to and then enhance GABA expression, mimicking GABA’s natural calming effects, according to research.Diazepam (Valium) and lorazepam (Ativan) are among the most widely prescribed benzodiazepinesfor insomnia and anxiety disorders. They slow down the body’s central nervous system and cause sleepiness.Benzodiazepines should be used only as prescribed. Taking too much can lead to shallow breathing, clammy skin, dilated pupils, weak pulse, coma, and death.Medications used to treat insomnia, including zolpidem (Ambien) and eszopiclone (Lunesta), work by improving the ability of GABA to bind to GABA receptors in the brain, per the Cleveland Clinic.GABA SupplementsGABA supplements, taken alone or in combination with other ingredients, are marketed widely for use in treating depression, anxiety, and insomnia.While a few small studies have suggested that GABA supplements may help to lower anxiety levels, the Cleveland Clinic notes that more scientific evidence is needed to support these overall claims.GABA supplements may increase levels of the chemical circulating in the blood, but there is little evidence to suggest that circulating GABA can pass through the blood-brain barrier and increase GABA levels in the brain.Talk to your doctor or a qualified healthcare professional before taking GABA supplements (or any other supplements).