[sgillen]

The author does pay some lip service to this:

>>(Often in these case studies the euphoria is punctuated by irritability, but not sadness or depressed mood.) Now, most of the examples we know of these prolonged euphoric states are undesirable. They often come with reckless or harmful behavior, delusions, and cognitive impairment.

But I agree, I think most of the manic episodes described should probably be called euphoric hypomania.