my husband is also in his forties and it took a serious manic episode this past summer to come to the conclusion that he is bipolar. we now believe that he has always had a mild form of it called cyclothmia (hope I spelled that right) that was just part of who he was and we lived with his ups and downs, never thinking it was a condition. but after a severe amount of stress in our lives he he became hopelessly depressed which in turn became a full blown manic episode. We are still in the beginning stages of all of this so a lot is speculation and following the clues like a mystery. Left on his own my husband would never have figured this out as he wasn't recognizing what was going on...do you have someone close to you who can point out your behavior that you might not even be aware of? Sometimes it really takes someone you trust to tell you the obvious.