When most of us hear the words bipolar or manic depression, we think of very high highs and very low lows. Additionally, we think that people with bipolar disorder simply go from one to the other, with no stop in between.
While severe cases can involve such features, most people don't careen from high to low and back again. Patients may be in state of mania or depression for a while, or they may be in between the two. They may even show signs of both simultaneously. Some people go months or even years with bipolar disorder in regression, only to have it rear its ugly head again. Some people cycle quickly between high and low, while others only experience a full-blown manic state once every few years.
Regardless of frequency, the intensity is highly variable as well. Many people with bipolar disorder have more mild highs and lows and cycle between these states.