There are some people living here in the United States with seasonal affective disorder, which is a form of bipolar disorder. Typically these folks suffer from depression only during autumn and winter, when there are fewer hours of daylight; and when spring and summer come, they are all high with near mania. Well, that's because it is actual mania. With guidance and medication from a professional, they ought to be able to keep the mood swings at bay.
Bipolar disorder involves both mania and depression. The depression part of the syndrome could be the mild type, like in dysthymia, but it mostly is of the severe form, sometimes lasting for a period of years. The manic part sometimes may not last as long, but it is no less destructive. And to think that people can be like this for years without ever realizing it should let you know just how bad the disorder is.
Various mental health professionals refer to clinical depression as regular in occurrence, although it is a mental disorder by its own right. However, harsher manifestations of the syndrome could manifest in other formats such as bipolar disorder. This one uses both depression and mania to achieve its purpose. So, you need to watch out for the symptoms of this condition before you can grade it with clinical depression.
Further facts about bipolar disorder can be accessed from the Internet where many websites, such as this, and medical directories have published articles that keep you informed of the latest information about the condition.