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

Each dream, including nightmares contains images from our day-to-day life. Sigmund Freud states that each thing we dream has a symbolic meaning which lead to the fulfilment of our subconscious wishes.

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.

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

To increase the performance on some certain tasks, sleep is good, but dreaming while sleeping is better.