If you sat down and thought about getting into a fight with somebody, and really focus on the details of the fight, what happens? Or even focus on an argument you had in the past where you now try to think of something you could have done or said differently. You get a physiological response, right?
So imagine what happens when you're researching fatal diseases, that you don't actually have. Do you think your subconscious is capable of being pragmatic about your conscious behavorial decision?*
*trick question, it's not.