if you have insomnia, agitation, low mood, etc., that makes misusing your psych drugs more appealing. with the benzodiazepines, it could also mean that you've developed tolerance and/or have an issue with anxiety between doses.

lots of people abuse stimulants, btw. that's why they're in the Schedule II of the DEA classification...high potential for dependence, addiction, etc. Its definitely not just you.