Bipolar disorder, sometimes called manic depression, is characterised by mood swings so severe that a person's relationships, occupation, and overall ability to function can be severely compromised.
The US National Institute of Mental Health says symptoms typically include episodes of extreme euphoria, followed by episodes of extreme sadness, depression or anger - but often with temperate periods in between. Other signs of bipolar disorder include insomnia or sleeping too much, drastic weight loss or gain, difficulty concentrating, anxiousness, and thoughts of suicide.
The disorder usually can be controlled with prescription medications - frequently lithium - that minimize the emotional swings. Treatments are most effective if they are taken continuously, not intermittently, the NIMH says.
A-Z of Bipolar disorder