I don't mean to detract from the good posts about lithium, (different meds work for different people!), but I did have a negative experience with it and I just want to throw it out there just in case.
I took lithrobid for about a year. I started noticing at one point that at night, I would be between waking and sleeping and then my body would seize up and I wouldn't be able to move. My mind became fully awake at that point and I could hear voices laughing, but I still couldn't move. It was very scary and my doctor took me off of lithrobid immediately. It hasn't happened since.
Good luck, and I hope the lithium works out for you...just watch out for any side effects.