well, to most, it helps to remove ones thoughts from where you are at the present time. So it can help by giving a healthy escape, rather than falling to harmful things to take your mind off things. It can also help keep you in a more patient, and realistic, while still staying more positive. It is a lot like meditation in some ways, imagining yourself elsewhere, somewhere nice, comfortable, where you can simply relax. Imagining yourself in such a place can help you to relax in the here and now, in the midst of chaos.
I hope this helped!