A person with a bipolar disorder has experienced at least one episode of mania as well as episodes of depression. It's common to experience depressive episodes with low mood and low energy and manic or hypomanic episodes with elevated mood and high energy. A mood episode can last for hours, days, or even months.
Most people with bipolar disorder have mostly depressive episodes, although some have mostly manic or hypomanic episodes. It’s not always up or down; most people with bipolar have significant periods in between mood episodes where they experience euthymia, meaning they are neither depressed nor manic.
During a manic episode, individuals may have increased energy, grandiose feelings or beliefs, rapid thoughts, sleeplessness, and impulsive behavior. Depressive episodes are characterized by feelings of sadness and hopelessness, lack of energy, too much or too little sleep, and changes in appetite, among other symptoms. Manic and depressive episodes may be separated by periods of time where the person's mood is not affected. While bipolar illness is a mood disorder, some patients experience psychosis as a symptom.