I just looked at the pi sheet, and the target dose for bipolar depression is 300 mg, where it should be less sedating than lower doses (the crazymeds.us
wiki says above 200 mg is the cutoff for that one). 400-800 mg for mania. It's off label to use risperidone for the depressive side of bipolar, but if anything, you'd want to increase it, not decrease it. A Seroquel increase is probably a better thing to try first. And side effects often decrease after a couple of weeks.