insomnia
"Used it for one night, had nightmares all night, restless, tense, weird taste in my mouth....YIKES.

Longer story:  Used Ambien for almost a year then needed something to last all night.  Had to try Lunesta before insurance would cover Ambien CR.  Tried it for one night and it really was that bad.  I was so happy to see it was time to wake up in the morning so it would stop."