Bipolar disorder can appear similar to depression and is often misdiagnosed as such. This is partially because hypomanic episodes are very difficult to distinguish from normal moods, and you don't normally go to a doctor because you're happy. The real harm of this misdiagnosis is that treatment for depression worsens bipolar disorder - while appearing a partially effective cure for depression, as it kicks you into a high mood before you crash again. http://en.wikipedia.org/wiki/Hypomania http://en.wikipedia.org/wiki/Mania I wish I could break them down, but I don't know how they're experienced by others. For me, before being diagnosed as bipolar, I felt many times that the depression had lifted and was so disappointed when it came crashing back. So, have you had weeks- or months-long breaks from depression, just to have it come back with a vengeance? Have you found unexpected happiness when you expected misery? Keep a mood journal for a while, recording a morning and afternoon mood on a scale of 1 (suicidal) to 10 (ecstatic) every day, see what happens. If you think you might be bipolar, talk to a psychiatrist and try to get proper treatment.