Bipolar disorder is an illness that affects thoughts, feelings, perceptions and behaviours - even how a person feels physically. It's probably caused by electrical and chemical elements in the brain not functioning properly, and is usually found in people whose families have a history of one or more mental illnesses.

While we're at it, let's be clear about something: a "mental illness" is one that affects the mind, not one that's all in the mind.

Most often, a person with manic-depression experiences moods that shift from high to low and back again in varying degrees of severity. The two poles of bipolar disorder are mania and depression. This is the least complicated form of the illness.

Depression might be identified by:

* Refusing to get out of bed for days on end
* Sleeping much more than usual
* Being tired all the time but unable to sleep
* Having bouts of uncontrollable crying
* Becoming entirely uninterested in things you once enjoyed
* Paying no attention to daily responsibilities
* Feeling hopeless, helpless or worthless for a sustained period of time
* Becoming unable to make simple decisions
* Wanting to die

Mania might include:

* Feeling like you can do anything, even something unsafe or illegal
* Needing very little sleep, yet never feeling tired
* Dressing flamboyantly, spending money extravagantly, living recklessly
* Having increased sexual desires, perhaps even indulging in risky sexual behaviours
* Experiencing hallucinations or delusions
* Feeling filled with energy

Some people think that they are just "over their depression" when they become manic, and don't realize this exaggerated state is part of the illness - part of bipolar disorder. A person who has depression and mania is said to have Bipolar I.

In addition to Bipolar Disorder I, the American system of diagnosing this disorder also includes Bipolar Disorder II, which involves symptoms of hypomania instead of full-blown mania.

Hypomania - a less extreme form of manic episode - could include:

* Having utter confidence in yourself
* Being able to focus well on projects
* Feeling extra creative or innovative
* Being able to brush off problems that would paralyse you during depression
* Feeling "on top of the world" but without going over the top.

Hypomania does not include hallucinations or delusions, but a hypomanic person still might exhibit some reckless or inappropriate behaviour. A person who has moods of depression and hypomania is said to have Bipolar II.