I have known some people who were diagnosed with bipolar disorder in their thirties and forties, sometimes after a long period of suffering, and sometimes after a trial of an antidepressant tripped a manic episode. So it is possible.

I was originally diagnosed with depression and an anxiety disorder. My doctor told me that sometimes it is difficult to determine whether it's the combination of the two illnesses causing the extremes in mood (depression vs. insomnia and the frantic feeling that I must get something done) or if it in fact bipolar disorder. It's worth talking to your therapist or doctor about.

Good luck.

-apislily