Ambien creates both a physical addiction and a psychological one. Plus, you shouldn't go cold-turkey off Ambien. Is it possible for you to wean yourself down, maybe try taking half of that dose for 10 days, then half of a half for 10, etc?
Otherwise I would suggest you simply tell your doc you want off the stuff, and see if they can help you with a step-down program. That or you can go to a NA meeting, if you're into that kind of thing.
The problem with addictions to sleeping pills is that you forget how to fall asleep on your own, and insomnia is a bitch of a withdrawal symptom ....
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