Bipolar disorder is a condition in which people go back and forth between periods of a very good or irritable mood and depression. The "mood swings" between mania and depression can be very quick.
This is an information post with my personal opinions added.
Fact 1: People with bipolar disorder type 1 have had at least one manic episode and periods of major depression.
In the past, bipolar disorder type 1 was called manic depression.
Opinion: Yes, My family member has had at least 1 manic episode of major depression.
Fact 2: People with bipolar disorder type 2 have never had full mania. Instead they experience periods of high energy levels and impulsiveness that are not as extreme as mania (called hypomania). These periods alternate with episodes of depression.
Opinion: True, The highs and lows of Bipolar are 'out of nowhere'. You have to watch your words carefully around patients diagnosed with it. You never know what mood they are in and you never know what they are going to say or do next.
Fact 3: A mild form of bipolar disorder called cyclothymia involves less severe mood swings. People with this form alternate between hypomania and mild depression. People with bipolar disorder type II or cyclothymia may be wrongly diagnosed as having depression.
Opinion: This is saying that people that are diagnosed with cyclothymia are USUALLY misdiagnosed as having depression. This does NOT mean that cyclothymia patients can NOT have depression, it is simply saying that most cyclothymia patients don't suffer from depression.
Want to read more?
The link: http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001924/