Simple answer to this one, we had very bad experiences underlining why we should not.
Scary Mommy http://www.scarymommy.com/mom-brain-makes-us-tired/?utm_source=FBOnsite
Scary Mommy makes a point that we are all struggling with similar type fear and insecurities so why don't we just share. I noticed that the people she mentions are trusted others. Too often people assume that each person can trust the same people in their lives as they do. I remember a friend gushing that she just wished her mother was there so they could share that precious moment. I looked at her kind of blankly because that wish never entered my head. However, I relate very well to the squirrel cage image of thoughts racing through my head and round and round they go.
I think this is why I enjoy nattering with my sister so much, we can spout off any thing that comes in our head and the other person will listen or if we are way off the mark help each other consider other possibilities. We are kind to each other. Open to your twists, turns and frustrations. Sometimes we just listen so the other person can get their thoughts of our head. We treat each other with respect so in that atmosphere of shared camaraderie we can share. I believe that this type of sharing is health and blesses both our lives. This however does not work for everyone.
I know other people that if I actually told them the tip of the iceberg of the off-the-wall thoughts or strange imaginings racing through my mind they would call a crisis team to come and lock me up. Racing thought, hyper-vigilance, and anxiety leave me tired. I don't know if I have ever felted rested.