Why Do We Dream?

The explanation for dreams are mixed and are open to interpretation. In terms of physiology they are defined as the mind's response to sleep, while others interpret them as coded messages from the subconscious and as having deeper or prophetic meaning for the future. It is believed that virtually humans dream at a similar rate, while some animals do not dream at all. Some scientists believe that dreams are caused by the buildup of long term memory, triggered by electrical sensations in the brain during sleep. They are also connected to the REM movement in sleep, which is used as an indicator of dreaming. Others suggest that dreams are the brain's reaction to sensory input, and represent a combination of the different parts of the brain attempting to synthesize information that is not commonly noticed when a person is awake. However, it is difficult to attain a fully biological understanding of dreams, as their meaning and cause resides largely in the uncharted territory of the mind, which can only be analyzed through theoretical readings rather than surgery.

We dream because life sucks and you want to have your own place do what ever you say.

It is mostly based in the subconscious mind, when you are sleeping but it can also mean a precognition, a symbol to future events, a forewarning for terrible events to happen