One of the reasons why it is problematic to talk about depression, mania and hypomania is that those words may mean many different things.
For instance, bipolar and unipolar depression are called the same, but they are not the same. In most cases, unipolar depression is caused by past events, and dealt with using anti-depressants and therapy. In fact, therapy is the better solution of dealing with unipolar depression, as it offers a possibility of removing the trigger that’s been hidden deep inside for years, sometimes decades. Anti-depressants deal with the symptoms, and are sometimes absolutely necessary because a person in deep depression is unlikely to respond to therapy (or to anything at all).