"This is interesting. What's the evidence?"

http://www.madinamerica.com/2011/11/anxiety/

The actual book (Anatomy of an Epidemic) explains it better, but those are just some quick links. They're also vastly more addictive than heroin. While the worst of heroin withdrawals are over in less than a week, benzo withdrawals can literally last over a year, with people unable to sleep and in severe pain that entire time:

http://en.wikipedia.org/wiki/Benzodiazepine_withdrawal_syndr...