Bipolar disorder, also known as manic-depressive illness, is a brain disorder that causes unusual shifts in mood, energy, activity levels, and the ability to carry out day-to-day tasks. People with bipolar disorder experience periods of unusually intense emotion, changes in sleep patterns and activity levels, and unusual behaviours. These distinct periods are called mood episodes. Mood episodes are drastically different from the moods and behaviours that are typical for the person. Extreme changes in energy, activity, and sleep go along with mood episodes.
Bipolar disorder can be present even when mood swings are less extreme. For example, some people with bipolar disorder experience hypomania, a less severe form of mania. During a hypomanic episode, an individual may feel very good, be highly productive, and function well. The person may not feel that anything is wrong, but family and friends may recognize the mood swings and/or changes in activity levels as possible bipolar disorder. Without proper treatment, people with hypomania may develop severe mania or depression. A person with mania needs hospitalisation for rapid control of symptoms and mood stabilisers for maintenance.