Dream interpretations dates back to 3000-4000 B.C. were they were documented in clay tablets.  It is said that people in primal societies were unable to distinguish between the dream world and reality. They not only saw the dream world as an extension of reality, but the dream realm was a more powerful world. 

One sleep cycle comprises of four stages and last for about 90-120  minutes. Dreams can occur in any of the four stages of sleep but the most vivid and memorable dreams occur in the last stage of sleep (also commonly referred to as REM sleep). The sleep cycle repeats itself about an average of four to five times per night, but may repeat as many as seven times. Thus, you can see how a person can have several different dreams in one night. Most people, however, only remember dreams that occur closer toward the morning when they are about  to get up. But just because you can't remember those dreams does not mean that  they never happened. Some people swear on the fact that they simply do not dream when in reality, they just don't remember their dreams.

In the world of dreams the structure and rules of reality do not apply.  A dream unifies the body, mind, and spirit. It provides you with insight into yourself and a means for self-exploration. In understanding your dreams, you will have a better understanding and discovery of your true self.

Realize that your dreams are unique. No other individual can have your background, your emotions, or your experiences. Every dream is connected with your own "reality". Thus, in interpreting your dreams, it is important to draw from your personal life and experiences.

Dream Dictionary