Bipolar mixed states. What are they? Essentially, though many experts will quibble on the finer details, mixed states are depressive episodes that are "soldered to" manic behavior. The bipolar person will have high engery levels, racing thoughts, trouble sleeping, all elements of hypomania or full blown mania----yet instead of euphoria or grandiosity, the individual will be filled with negative emotions, typically expressed as irritability or even, in some instances, as extreme anger or even rage.
From "My Social Seciroty Disability SSI blog"