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It could absolutely be the medication. I don't know how long you've been on them, but it will take your body some time to adjust. Abilify is an anti-psychotic that is used for mood stabilization. It works well in leveling out Bipolar Disorder, but unfortunately it comes with a lot of the usual side effects of other anti-psychotic medications including fatigue, drowsiness, dizziness, headaches, etc. Cogentin is less likely to have the side effects of mental slowing or emotional dulling. So my guess is that it might be the Abilify in particular.
Another thing to think about is that it could be your Bipolar cycling out of a manic phase. When mania is present there is a high level of productivity, concentration, and an increased feeling of mental sharpness. When cycling out of the manic phase it can feel like you're unnaturally slow or groggy - but this might just be natural and normal.
Either way I think it depends on the timing. If you just began the meds, I'd give your body some time to adjust. It takes a while for everything to come into balance. In time you should begin to liven up again. However, if you've been on them for some time, you might want to talk to your physician about decreasing the dosage a bit.
I hope this helps - please feel free to ask further questions!
Good luck to you,