Despite their beneficial therapeutic effects, benzodiazepines and barbiturates have the potential for misuse and should be used only as prescribed. The use of non-benzodiazepine sleep aids, or z-drugs, is less well-studied, but certain indicators have raised concern about their misuse potential as well.
During the first few days of taking a depressant, a person usually feels sleepy and uncoordinated, but as the body becomes accustomed to the effects of the drug and tolerance develops, these side effects begin to disappear.
If one uses these drugs long-term, he or she may need larger doses to achieve the therapeutic effects. Continued use can also lead to dependence and withdrawal when use is abruptly reduced or stopped (see Understanding Dependence, Addiction, and Tolerance).