The healing power of video games
polygon.com
polygon.com
The basics of the theory are that our brains haven't really evolved to truly tell the difference from what we are seeing on the screen and what we are seeing in real life. So, you can guide a soldier through a really violent battle scene in a video game, with things exploding and people shooting at them, and their brain can eventually "rewire" itself to not be afraid of these things because no harm is happening to the actual person. It's fascinating stuff.
[edit]
Here's one reference but there are loads more:
https://intro2psych.wordpress.com/2008/11/26/can-video-games...