In the manic “high” state, people experience different combinations of the following: elated or euphoric mood… irritable mood… a decreased need for sleep, grandiosity… increased talkativeness, racing thoughts or jumping from one idea to another, an increase in activity or energy levels, changes in thinking, attention, and perception, and impulsive, reckless behavior. These episodes alternate with intervals in which a person becomes depressed, sad, blue, or “down in the dumps,” loses interest in things he or she ordinarily enjoys, loses weight or appetite, feels guilty and bad about him- or herself, has trouble concentrating or making decisions, and often feels like committing suicide.
Episodes of either mania or depression can last anywhere from days to months. Some people… don’t experience manias and depressions in alternating fashion. Instead, they experience them simultaneously, in what we call mixed episodes…
– The Bipolar Disorder Survival Guide
Good summary of the disorder in general. A few notes: I often have mixed episodes when off my medications or not exercising and keeping busy, and they’re exhausting. During mania, one can often experience grandiosity to the point where delusions and paranoia and anxiety seem rational — I also speak from experience here. There is a strain of bipolar called rapid cycling in which a person experiences different mood swings in rapid succession over a series of days — I have this, and it makes the disorder both better and worse in equal measure.