I think quite a bit of the trouble is that psychiatry is not a pure hard science. Even those in the hard sciences don't agree on everything of course, but in the soft sciences (or a mixture, which is seems psychiatry would be) all the more, as it's pretty much impossible to eliminate so many other variables when doing studies. There's so much subjectivity. Which kind of sucks, because it'd be great to have rock-solid answers to work with(!)

That said, I absolutely agree with the traditional definition of Mixed State. That both extremes are SIMULTANEOUS. It wasn't until I personally experienced it that I could truly understand. It was no short burst, but a sustained state. Words fail in describing the magnitude of its awfulness. The mere memory, which is but a pale reflection of it, makes me shudder.

The question of rapidity in switching is tricky. I (personally) think the official 4x of rapid is rather arbitrary, but I do think it points to a "rapid doesn't mean constant" understanding. Through my reading and observation, I'm frankly sceptical of ultra and ultradian being "genuinely" BP. I don't say that to invalidate or dismiss anyone's experience. It's just a complicated business that warrants more study, and that throwing everything under the BP umbrella isn't the answer, is ultimately a detriment to the term having meaning, and a disservice to all involved.

When I'm being tossed all over, I find it's usually my emotions, not my moods. But even IF it were my moods, I would NOT consider it a mixed state. It's kind of like trying to describe full-on serious depression to someone who thinks of depression as being very sad. When one has experienced both, they know they are different beasties. It's a linguistic shortfall and the dual casual use of the word only complicates things.

Not sure if that made any sense. Must go eat.