This article (abstract) compares “Mixed Depression” (major depression + some manic/hypomanic symptoms) with “Dysphoric/Mixed Hypomania” (major depression + full hypomania; as close as you can get to a DSM-defined mixed state (full mania + full depression) and still be bipolar-II. They looked at a lot of bpII outpatients who presented for depression treatment, and also asked a separate bunch of bpII people who weren’t having symptoms at the time to remember what hypomania was like. (Weird study design, but there’s probably a reason for it – maybe just that most people don’t come in complaining of regular hypomania.)
Seventeen percent of people had full-blown hypomania along with their depression, and 66% had mixed depression – that’s a *lot* of mixed states in people who are coming in for depression, not for mixed states.
More specifics at the link. I’m at martial arts camp all this week, and am going to try very hard to keep up with regular content, but may have to just dump some links back in there. After this week, I have no school or work for two weeks, and there will be extra-spiffy stuff then.