100 mg just makes sleepy. It's all consumed by histamine receptors, It's not stabilizing mood swings nor effecting to psychotic features. 200-400mg bonds also to serotonine receptors and effects mostly mood stabilizing. over 400 bonds also to dopamine receptors, which begins to have effect on more severe mental issues.

This is what i've been told and i have personal experience that this is pretty much how it works for me. I use occasionally 50-100 for insomnia. It has absolutely no other effects but knock me out. 200 mg prolong brings down hypomania and paranoid thoughts in couple of days. Zero effect to depression.

if it's prescribed for psychotic features i would recommend to ask if your doc might want to check your dosage.