You close your eyes and start climbing...higher and higher. Step by step the terrain gets steeper. You climb until gravity takes its toll and you fall—down, down, down. Landing with a start, your head is on your pillow and your eyes are wide open. Your heart is pounding and your body is breaking out in cold sweat. It was a dream—just a dream.
Why do we get chased by frightful critters, fall off cliffs or act in wonderfully weird ways when we dream? Why does our brain produce these colourful movies night after night?
Even though we sometimes don’t remember, we all have dreams.
Dreaming is defined as our subjective experience while we sleep, and multiple theories try to make sense of why we dream. Some researchers assume that dreaming plays an important role in processing and reinforcing what we have learned throughout the day. The idea is that our brain is storing new impressions, combining past experiences with new experiences and linking concepts through emotions while we dream. While a sleeper is engaged in processing subjects, the creativity of dreams possibly helps with finding solutions to problems. Another theory explains that dreaming prepares us for situations and helps us practice skills we might need later on.
Everyone dreams. Even small children experience intense dreams, characterized by the observation of Rapid-Eye-Movement (REM) during sleep. The brain is most active during REM phases, compared to non-REM sleep or deep sleep. During this stage, our eyes dart around behind closed lids with rapid and random movement. REM sleep is responsible for 20%–25% (90–120 minutes) of a total night’s slumber. Dreaming appears to be most pictorial and intense during the REM sleep phase.
Between our waking state and REM sleep, two major differences are noticeable in the brain:
- The amygdala, an almond-shaped set of neurons in the brain's medial temporal lobe that processes emotions, is more active during REM.
- Neurons of the pre-frontal cortex fire less often (which might explain how some dreams appear bizarre, as the pre-frontal cortex is responsible for strategic planning and decision-making).
Researchers also assume that we learn to deal with anxiety through nightmares. If you were in a dangerous or stressful situation during the day, you might dream about it at night to reinforce the lessons learned, which can help you to avoid such situations in the future and increase your chances of survival. Similar to when you are awake, when creating dreams, every part of your brain is responsive. Even the motor cortex is active during our dream state, but transmission of information to your muscles is blocked by your brainstem to prevent your body from moving.
Even unconscious or comatose people dream and report incredible recollections. Some patients report flying through a tunnel into a bright light, feeling weightless and in harmony with the world. These accounts of personal experience in people who've come close to clinical death are referred to as near-death experiences. When unconscious, the brain releases endorphins to inhibit the transmission of pain signals to ease distress and these endogenous drugs may produce a feeling of euphoria in unconscious patients when dreaming. Other patients experience being removed from their own body and watching themselves from the outside. The parietal cortex creates a self-image, telling us that we belong in the body we are in, if this brain region is damaged by lack of oxygen or injury, self-awareness will shift when body and mind split and one believes to be outside of one’s body.
Dreaming—it’s a pretty mind blowing experience.
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