Cyclothymic disorder, also called cyclothymia, is a type of mood disorder where people experience numerous periods of mood "highs" and "lows" that are unrelated to life circumstances. The mood instability - mild elation or mild depression - is related to bipolar disorder (which was formerly known as manic depression) and is in fact considered to be a milder form of bipolar disorder.
Though less severe, cyclothymia can have great impact on a person's life, where unexpected and extreme mood changes disrupt the ability to function normally.
Both men and women are equally likely to suffer from cyclothymia, affecting up to 1% of the population. Cyclothymic disorder generally starts appearing during young adulthood, though it may also first occur at a later age.