Clinical depression is split into two categories: unipolar and bipolar. Bipolar depression involves periods of extreme sadness (depressive episodes), but also periods of elevated mood or hyperactivity (manic episodes). Signs and symptoms of the depressive phase of bipolar disorder include persistent feelings of sadness, anxiety, guilt, anger, isolation, or hopelessness; disturbances in sleep and appetite; fatigue and loss of interest in usually enjoyable activities; lack of motivation; and morbid suicidal ideation.
Mania is generally characterised by a distinct period of elevated, expansive, or irritable mood state. People commonly experience an increase in energy and a decreased need for sleep. Judgement may become impaired; sufferers may go on spending sprees or engage in behaviour that is quite abnormal for them. People may feel out of control or unstoppable and have grandiose or delusional ideas. Individuals who experience manic episodes also commonly experience depressive episodes or symptoms, or mixed episodes in which features of both mania and depression are present at the same time. These episodes are usually separated by periods of "normal" mood, but in some individuals, depression and mania may rapidly alternate, known as rapid cycling. Extreme manic episodes can sometimes lead to psychotic symptoms such as delusions and hallucinations. The cycles of the disorder may last for days, weeks or months. Depression is a very treatable illness using therapy and/or medication.