I'm not sure this is unhealthy or not, but during a bad time I fell into the habit of crawling into my mind and constructing a "parallel universe" with my imagination. In this world, there was no exam stress, impending coursework deadlines, an empty social life etc. In fact, the new idyllic life in my mind was so much better I detached myself from the real one. I bunked college and became a recluse, staying at home the whole time. I turned more paranoid and cynical, convinced that all the teachers and students despised me. The more I avoided reality, the more paranoid I became of it and everyone, and so I avoided it some more. I think the only way I broke out of the loop was when my mum had the day off and the school rang, saying I hadn't been attending lessons all week. And then I burst into tears, which bewildered the two of us.
I guess it's more of a young INP thing, then specifically INTP.