Can anti-anxiety drugs cause sedation if used long term?

Yes: Benzodiazepines such as klonopin, ativan, valium, and xanax (alprazolam) can all cause sedation anytime they are used. Dose adjustments and monitoring are very important. When used long-term and consistently, they can produce physical habituation and dependence. This is one reason ssri and other less habit-forming medications are safer (plus effective) when anxiety is chronic.