insomnia
"I've taken 12.5 mg Ambien CR on an off for 3 months now.  Within the last two weeks, it's been more like every day.  I was so groggy all day. Also, I'm not sure I slept... It was more like just being turned off rather than in a state of recuperative sleep.  I cut the pill in half last night and had only 4 hours of sleep, where I awakened twice.  I still feel more refreshed than ever, probably because this is the first time in weeks I don't have an ambien hangover.  It's a great medicine, but I'd like to ween myself off of it.  I suspect it's either causing depression, or is amplifying a depression I didn't know I had."