Having googled postical symptoms, I see what you mean. Judging from the wikipedia page I do have many of those symptoms. I had personally attributed this inability to think clearly to the exhaustion of this long episode. The intrusive and racing thoughts I had attributed to anxiety, and this urge to change my whole life I thought was me "externalizing" my depression. I typically tend to associate mixed episodes with increased energy and irritability/aggression in addition to the above symptoms and depression. I don't have increased energy right now (more like the opposite, although I do have insomnia), and irritability kind of comes and goes. I still don't know which explanation is true, but it's definitely an interesting different perspective, so thank you for that.

This whole thing did start out as a "normal" (typical for me) mixed episode way at the start of this year, but I thought it had morphed into depression. But maybe this is what a mixed episode feels like after all your energy is gone and you're all worn out, I don't know. The confusion, inability to think clearly, and memory problems that I experience, among other things, are interesting considering your theory that bipolar episodes are like seizures.