Speaking for myself irritability is tied to my mood, stabilizing my mood helped out. I haven't had zombie effect either. I'm prone to hypomania and it's more effective when depressive episodes are dominant, but not unipolar in nature. It means I have to be honest with the doc and report the hypomania so things can be adjusted accordingly. I take other stuff in conjunction and compared to depakote or tegratol the side effects have been nominal. I've been on it a year now.