The 4th century BC Daoist philosopher Zhuang Zhou told a story that attest to the power of dreams:
“Once upon a time, I dreamt I was a butterfly, fluttering hither and thither, to all intents and purposes a butterfly. I was conscious only of my happiness as a butterfly, unaware that I was myself. Soon I awaked, and there I was, veritably myself again. Now I do not know whether I was then a man dreaming I was a butterfly, or whether I am now a butterfly, dreaming I am a man.”
Dreams are so real at times that they make us question the reality of waking consciousness.
These notes will only cover the perception states in dreams, not the meaning of dreams or why we dream.
Characteristics of dreaming
The human brain has been called “the Most Complex Object in the Universe” containing between 80 and 100 billion neurons. So, altering the state (sleep) of such a complex system is not simple. Sleep is just another state of consciousness. When you sleep, your senses remain active at some level (depending on the sleep stage). Consider how you might talk around someone who is asleep without disturbing them, until you call their name.
Dreams are rich, sensorimotor hallucinations, usually with a narrative framework. We perceive them as a conscious experience, we see, hear, touch and interact with things in a dream. But we usually aren’t aware that we are in an altered state of consciousness, we are not introspective during our dreams, we do not question their bizarre events. The one detachment between experiencing and not questioning dreams may be the result of decreased activity of the prefrontal cortex during sleep (the area of the brain responsible for logic and planning).
There’s some disagreement over whether everything we perceive during a dream is actually perceived or not. Our eyes are shut, but we still feel, still hear the outside world, so it’s possible dreams are part normal brain activity, part true perception, and partly a result of sensory deprivation, an attempt to construct something when little or no sensory input is available.
The Stages of Sleep
There are four stages of sleep (some include drowsiness and say five states) NREM-1, NREM-2, NREM-3, and REM (Rapid Eye Movement), NREM is Non rapid eye movement. Dreams are strongly associated with REM state (the state most like wakefulness), but not completely, NREM3 is the when night terrors happen. REM episodes lengthen as sleep periods progress.
During REM our motor cortex is active but the brainstem blocks that activity. This state is sometimes paralleled with “defensive immobilization.” The brain releases melatonin from the pineal gland (a pea-sized conical mass of tissue behind the third ventricle of the brain) which basically paralyzes/relaxes all movement except the eyes. This type of paralysis is a defensive mechanism to keep us from acting out our dreams (note, sleepwalking does not occur in REM).
The ability to report dreams follows a series of interesting patterns:
- When people are woken from REM sleep, they usually report vivid dreams.
- People tend to under-report how often and how much they dream -all healthy people dream although some claim they do not – REM studies proves this point.
- The increase in the ability to recall dreams appears related the intensity in the vividness of dream.
- Individuals exhibiting more low frequency theta waves in the frontal lobes are more likely to remember their dreams.
- In the early phases of deep (non-REM) sleep vivid hallucinations are often reported that are short and more thought like than regular dreams.
- Dreams are best remembered when they are written down, told, or rethought just after waking.
- Remembering dreams is usually limited to the short period just before waking, and some psychologist even believe that narratives of our dreams are constructed just moments after we wake (in an attempt to make sense of random perceptions).
- Night Terrors (dream perceptions of terror where no events are usually remembered) usually occur in children and are relatively easy to time (occurring during the first NREM-3 stage) and prevent by waking up the individual just before NREM-3.
- A small minority of people say that they dream only in black and white.
Vivid and emotionally intense dreams have been associate with activity in the amygdala (which had a primary role in the processing and memory of emotional reactions) and the hippocampus (which is important for memory functions).
Dreams are generally visual in nature of dreams and reflect a person’s memories and experiences, but can take on exaggerated and fantastic forms. Blind people have dreams based on auditory, touch, smell and taste perception instead of visual dreams.
Unusual dream types
False awakening: a vivid dream about awakening from sleep (while still asleep) and moving about or performing normal activates. False awakenings are sometimes layered with a dream within a dream.
Lucid dreams: any dream during which the dreamer knows they are dreaming. The dreamer may have some control over their actions or the characters in the dream. Lucid dreams tend to happen during the last REM state of the night. Sometimes control of Lucid dreams can be extensive. American theoretical physicist Richard Feynman reported in his book Surely You’re Joking, Mr. Feynman! that he taught himself how to induce a lucid dream at will.
Sleep paralysis: a parasomnia resulting from dysfunctional overlap (improper synchronization) of the REM and waking stages of sleep. It usually characterizes itself when an individual is waking but is still unable to move their body as a result of REM induced paralysis. Sleep paralysis can be quite terrifying because (1) if the individual is conscious they may fear that they are paralyzed for life or dying (2) if they are not completely conscious they may associate the event with some supernatural abduction (incubus or succubus demons), experience body image distortion, alien abduction, out-of-body experiences, or see human-like shadows. Because sleep paralysis is so vivid and unusual, those suffering from it are often reluctant to report the event.
Culture and Dreams
Some elements in dreams may come out of cultural background. We know that different cultures report variations on the most common types of dreams and that some cultures value dreams more, and as a result individuals in those cultures may remember their dreams better. As a point of reference, I have a friend one who tried to keep a dream diary (waking each morning to write her dreams out). She had to stop after about a week because she kept remember more and more and by the seventh day was writing pages each morning.
None unless sometime in the future we learn how to combine dream states with virtual reality.
- The Science Behind Dreaming
- To Sleep, Perchance to Dream – Crash Course Psychology #9
- Dream States: A Peek into Consciousness
- Sleep paralysis
- Dream argument
- False awakening
- Lucid dreams
- Dream Diary
- The Dream In Other Cultures