Why do we dream? - Amy Adkins

During REM sleeping, the neocortex reviews the neural connections and dumbs the unnecessary ones.

Without this process, which results in dreams, the brain could be overrun by useless connections.

The Continual Activation Theory proposes that the dreams result from your brain's need to constantly consolidate the long-term memories.

So, when the external input drops bellow a certain level, the brain starts generating data from your memory, resulting into dreams. This is like a screensaver for your brain, so it won't shutdown completely.

Dreams involving dangerous situations are very common and the Primitive Instinct Rehearsal Theory holds that the content of a dream is significant to its purpose.

Whatever you are running from a lion or fighting with a ninja, these dreams help you practice your fight or flight instincts. Also, not everytime these dreams have to be nightmares. Sometimes we can rehearse our reproductive instinct as well.

• Stress neurotransmitters in the brain are much less active during the REM stage of sleep even during dreams of traumatic experiences.
• This made some scientists to think that one purpose of dreaming is to take the edge off painful experiences to allow for psychological healing.
• People with certain mood disorders and PTSD often have difficulty sleeping, leading some scientists to believe that lack of dreaming may be a contributing factor to their illness.

Not being limited to the rules of conventional logic, the mind can create infinite scenarios to help you find solutions that you wouldn't think conscious.

This is how August Kekule discovered the structure benzene molecule. Also, this is might be why is better to take a decision after you've slept on it.