An old but interesting article and discussion related to your question: http://www.theatlantic.com/magazine/print/1969/12/how-your-cat-is-making-you-crazy/8873

An old but interesting article and discussion related to your question: http://www.theatlantic.com/magazine/print/1969/12/how-your-cat-is-making-you-crazy/8873/ http://www.theatlantic.com/magazine/print/1969/12/how-your-c... https://news.ycombinator.com/item?id=3573694 https://news.ycombinator.com/item?id=3573694 Articles somehow related to the subject: http://www.nature.com/news/the-tantalizing-links-between-gut-microbes-and-the-brain-1.18557 http://www.nature.com/news/the-tantalizing-links-between-gut... http://universityofcalifornia.edu/news/do-gut-bacteria-rule-our-minds http://universityofcalifornia.edu/news/do-gut-bacteria-rule-... http://www.scientificamerican.com/article/gut-second-brain/ http://www.scientificamerican.com/article/gut-second-brain/ http://www.theverge.com/2013/8/21/4595712/gut-feelings-the-future-of-psychiatry-may-be-inside-your-stomach http://www.theverge.com/2013/8/21/4595712/gut-feelings-the-f... http://newsroom.ucla.edu/portal/ucla/changing-gut-bacteria-through-245617.aspx http://newsroom.ucla.edu/portal/ucla/changing-gut-bacteria-t...