Bipolar disorder is a mental disorder characterized by periods of depression and abnormally elevated moods. If the elevated mood is severe or associated with psychosis it is called mania if it is less severe it is called hypomania. During mania an individual behaves or feels abnormally energetic, happy or irritable. Individuals often make impulsive decisions with little regard for the consequences. There is usually a reduced need for sleep during manic phases. During periods of depression individuals may experience crying, a negative outlook on life and poor eye contact with others.