What causes dreams?

Dreams serve a purpose. They serve a specific function for our bodies and mind. While many dream analysts at the turn of the century focused on dream interpretations, dream experts of today focus on the scientific approach of what causes dreams. Dream Analyst and author Craig Webb says before we can look at what causes dreams, we must understand what dreams are to begin with. “Usually we define a dream as an experience remembered upon awakening that comes through nonphysical channels. Basically, it is an altered experience we have when we are sleeping and that we remember when we wake. However, there are lots of other variations on the definition. Some people define dreams as life goals and wishes for the future. This is another way we use the word.

According to the Freudian school, dreams are the result of subconscious thoughts and desires. The other extreme attributes dreams to random "noise" in the neurons without special meaning.
There is definitely value behind dreams nevertheless; nobody knows precisely, that causes them. The general theory - which they occur from subconscious thoughts from our daily thoughts and actions. It is true, things which we underline about the majority; apparently, take a priority in our dreams, though not always.

Reference: http://www.types-of-dreams.net/what-causes-dreams.html