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...
To claim that the Z drugs are "vastly more addictive than heroin" is, frankly, ridiculous.
Rebound insomnia is nasty; and the Z drugs should be treated with respect; and sleep hygiene should be tried first; but it's stupid to scare people with nonsense like "addictive as heroin".
I'd be interested to see the evidence for "terrible for you".
Hypnotics just make you sleep - they don't treat the cause of the insomnia. (For some people they're great at kicking you back into a routine.) There's evidence that long term use can create rebound insomnia.
Here's a guide for general public stating the need for using the meds short term:-
(http://www.nice.org.uk/nicemedia/pdf/TA077publicinfoenglish....)
Here's a slightly more technical document with links to the evidence that they used:
(http://www.nice.org.uk/nicemedia/pdf/TA077fullguidance.pdf)
Here's a guide aimed at clinicians with many links to good evidence:
It is a collection of statistical methods based on interpretation of available data, usually from public health records.
Anyone who complains that it doesn't prove anything outright has no idea of what it is, how it works or what it tries to achieve.