Why are writers crazy? Lousy self-esteem, conflicted self-image, emotions running rampant, compulsory compromises, and self-medication via substance abuse are the latest theory.
Don't look at me. I once got into a tank with a killer whale to research some SF characters. Your life doesn't flash before your eyes, btw, your tombstone does: She was Dedicated to Her Work, and Looked Too Much Like a Seal When Wet.
If you're worried about your mental health, check out online resources like Cosmic Cherry, Psych Central, Queendom.com, and Tickle.