[codev]

Zopiclone can be habit forming and has an associated increase risk of road traffic accidents like most hypnotics - wikipedia is a good start for the risks.

I think melatonin is a better drug for correcting problems with sleep cycles which can include jet lag, changes in season and the like but there's plenty you can do help your sleep quality without drugs.

Here's a great article (about Huntington's disease but applies to everyone - it really helped me) based on a published paper in Experimental Neurology:

http://en.hdbuzz.net/120