What Creates A Sense Of Emptiness?

What does it mean if you have episodes where you shut down and only think about certain things that are not normal thoughts? For instance for over 2 years, at least 10 times a day, I shut everything out for at least 5 minutes and think about violence. I don t even hate these thoughts, in fact I welcome them. Now I don t condone violence but I have urges to act. Although I don t and I know I never will. I would just like to know what these episodes mean.