Xanax causes extreme dependence. Xanax is a form of benzodiazepine. Benzodiazepines are a class of drugs used to help people who suffer from anxiety and insomnia. This group of drugs is the depressants of the central nervous system. This means that they slow down the action of the nervous system. In addition, benzodiazepines are used to treat seizures and relieve the symptoms of alcohol withdrawal syndrome. This class of drugs is the most widely used of all psychoactive substances. Xanax acts quickly, causing a calming effect, but is also one of the most frequent drugs misused. When taken with other central nervous system depressants, it can be deadly.