Put simply, tolerance may develop for most in as little as 2-4 weeks after a person has taken benzodiazepine as the body and brain attempt to overcome or work around the drug’s effects (also known as neuroadaptations). The tolerance or “tolerance withdrawal” phenomenon is often how patients initially discover that their benzodiazepine is no working as well as it did the first time they used it and feel they need to up-dose their medication. Beyond anxiety, tolerance also develops to the anticonvulsant effects of benzodiazepines making them generally unsuitable for long-term control of epilepsy.
The original dose of the drug will be progressively less effective and a higher dose is required to obtain the original effect. This has often led doctors to increase the dosage in their prescriptions or to add another benzodiazepine so that some patients end up taking two benzodiazepines at once.
Tolerance to the hypnotic effects develops rapidly and sleep recordings have shown that sleep patterns, including deep sleep (slow wave sleep) and dreaming (which are initially suppressed by benzodiazepines), return to pre-treatment levels after a few weeks of regular benzodiazepine use. Similarly, daytime users of the drugs for anxiety no longer feel sleepy after a few days.