This is a very good question and one you should also mention to your wife. For some people ECT can trigger (hypo)mania though I understand it's quite rare.

While I've never been triggered (as I see it), I do find that the lethargy dissipates. In the last few days before my maintenance treatments I tend to sink into a mild depression. Your description of waiting for the day to be over is apt. After the ECT, though, I am back where we're supposed to be, engaged, ambitious, energetic in a normal capacity.