What kind of behaviors in a child would get diagnosed as bipolar disorder?

Multiple Problems. Bipolar disorder in children usually includes high levels of hyperactivity along with severe problems related to the mood. There may be dramatic and inpredictable mood swings, or there may be a mixture of depression with irritability or euphoria occurring within short periods of time. Impulsivity is frequently present with severe behavior problems. Temper outbursts and aggression may occur.
Random mood changes. You could have a very happy, friendly, talkative, well groomed and social child and all of a sudden, without a noticeable reason, this same person could become more insecure, lonely, more attached to his parents, dressed more carelessly, quiet. It is not unusual during their depressive time to be more concerned about their health. They might start visiting more often their school nurse.