Does your brain race? I suspect it does!
Nature evolves a creature like us, gives us a super-sized, experimental brain, and tries out thinking. What a fascinating capacity with which to aid or burden a creature!
Since the goal of nature is not to evolve perfection but rather to evolve functionality within a context, you would naturally expect an immense, wild and flawed capacity like thinking to come with some set of profound repercussions and challenges.
That is indeed what we see—and its own sort of proof that we are not designed but rather have evolved into existence.
Not knowing what else to do to solve our problems or to make sense of life, we set our brain racing off, whether or not it has good brakes, whether or not it is equal to the task, and whether or not the task is reasonable. The smarter we are, the more likely it is that we will use our brain in these ways and the more painful pressure we are likely to produce.
Phenomena like insomnia, manias, obsessions are addictions are much more understandable—and natural, if you will—the second we realize that we have come equipped with a racing brain and no off switch. So much is explained by that lack of an off switch!
What to do? I have many suggestions for you in Why Smart People Hurt. Take a look!