I had periods like that, too. In my cases, I think it was either or a combination of the two. I know depression can cause that numb feeling. That is even a known possible symptom. But medication sedation and/or cognitive impairment doesn't help.

I felt perfectly clear headed at times on meds I later blamed for numb feelings and obviously numb on them. That convinced me that meds weren't 100% to blame.

I do think that some meds' antimanic features can over do it. I know sometimes lowering doses does good, but some people go too far and go off such meds completely without trying others.