A person with a bipolar disorder has experienced at least one episode of mania as well as episodes of depression. 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.