insomnia
"I've tried several options, over the counter, homeopathic, and prescription in a quest to deal with transient insomnia which typically triggers a worsened depressive mood (kind of a negative feedback loop). Ambien was one of the first I tried. It works very quickly, has very little hangover, but did not always KEEP me asleep. I usually wake around 4. 

The bad: tolerance, "sleepwalking," waking up in my roommates bed with no memory of how I got there. Be cautious, if you live with other people let them know you're suffering from insomnia and that you are taking this medicine. My roommates reported me seeming completely coherent while sleepwalking%u2014 it can be more problematic than mere "sleepwalking.""