Your mind, if you allow it, "goes" to the future and sees the most probable events. Then it brings back to you the information. This sensed info depends a lot on your connection with the people (you will care to know about loved ones, like your son, and not about strangers) and also on your beliefs.

For example, if you don't want to be exposed to bad things in your life then your mind might block any future image/info that you might not like. or vice versa, it can bring only "bad" images, because the "dark" is being repressed during your awaked hours.

The best thing to do about such prophetic dreams is to breathe them in and release. Like in my dreams of the Japanese. When I woke up I took a deep breath, smiled to myself, remembered the feeling of ease when receiving that 5000$, and released the dream, didn't think about it, at all, until a few days later I won that 5000NIS.

The more you contemplate and process the dream, in your mind, the higher blockages you put in the natural flow of the reality.

I hope I answered your question.