What I'm led to believe is that I have a hyper-active brain. That means that I can't stop thinking, & in some cases, I tend to over-think things, especially with those that shouldn't concern me. The worst part is, if there's nothing else to keep my brain occupied, that's when it starts having those cravings.
One of my friends on Skype told me this not too long ago, & with that, I also know that it's also the thing that makes it hard for me to relax without outside influences, such as candy or video games. Lastly, it makes it hard for me to fall asleep without said outside influences as well.