It helps to learn techniques to calm the mind and at times, completely shut it off. I'd recommend a good book on meditation. This might sound like a cliche. But, it doesn't hurt to spend half an hour for a few days finishing this book and see if that changes anything for you. http://www.amazon.com/Mindfulness-practical-guide-peace-fran.... Or you could browse around for books on similar topic and find one that appeals you.

It is helping me reduce my stress levels.