Science

What is a dream?

today2019.06.03. 5

Background
Need to give a speech? Too bad you left your pants at home. Taking a trans-continental flight? You’ll be rushing to pack in the morning and hopelessly lost trying to find your gate. Sometimes it feels like dreams are our brain simulating Murphy’s Law.
There are many theories about why we dream, from the mundane—to remove the cognitive waste from our brains—to the supernatural—to reconnect us with our past lives or receive prophetic visions. Historically it was a philosophical question, but during the early 1900s, recordings of brain activity during sleep brought it into the field of neuroscience.²
A dream is a sensory-motor hallucination experienced during sleep. Dreams often follow a narrative structure with setting, characters and plot described through one or more senses. Most dreamers experience sight, motion, and sound, while very few experience touch, smell, taste, temperature, or pain.⁶’¹⁴ While some do sleep like the dead, real sensations can also become a part of a dream.⁵

Scientifically, what is a dream?

​Dreams occur primarily during the last stage of sleep, called REM (rapid eye movement) sleep. It is named for an increase in eye movement, and is significant because there is more brain activity as compared to deep sleep. If a dream is a movie, then the thalamus is the producer, coordinating the rest, the limbic system is the animator, providing emotional color, and the cortex works overtime as the writers, the cast, and the creative director. These, together with the hippocampus for memory material and medial pre-frontal cortex for character depth, work to fabricate wild stories for your dreaming pleasure. Additionally, the hypothalamus, the internal everything-o-meter, keeps you breathing, heart-beating, and mostly motionless.⁶’⁷

Why don’t we know we’re dreaming?

​Some dreams are ordinary and realistic, but even the most unlikely of events fail to perturb the sleeping brain. Being zombified is overlooked as easily as failures in basic physics. Friends, family, and even your own identity can be completely falsified without consequence. This inability to recognize the unreality of dreams is attributed to a decrease in activity in the prefrontal cortex, responsible for executive control and abstract thinking.¹’⁶’⁷ In dreams, we tend not to ask that age-old question: why am I here? Instead, we take that lottery money and fly like an eagle, superman, or one of those fish from Mario.

The exception is lucid dreams, on which the 2010 science fiction film Inception is based. Lucid dreaming is the state of being aware that you are dreaming while dreaming.⁹ This is often imperfectly accompanied by access to waking memories and higher-level reasoning abilities.

Initially considered fanciful imagination, lucid dreams became scientifically recognized in the lab experiments of psychologist Keith Hearne. He found that a sleeping subject could become aware and signal that awareness through a pre-determined pattern of eye movements without waking.³ Since then, lucid dreaming has been successfully replicated by many researchers.¹’⁴’⁸’¹¹’¹²’¹³

On the physiological level, a lucid dream is distinguishable from regular sleep by a higher level of interconnectivity and activity within the brain, especially in the normally quiet prefrontal cortex and the temporoparietal junction, which links emotions to events and is associated with awareness, morality, and decision making.²’⁷’¹² Other studies have demonstrated that the state can be induced by stimulating high frequency activity in the frontal lobe though electrodes¹³ and through external sensory stimuli, such as sounds and lights.⁴’⁵’¹⁰

For those without a lab and an experimenter

​Many lucid dreamers have nightmares to thank as the catalyst for their ability to lucid dream, but fortunately it is not necessary to be terrified to become conscious in a dream. There are many different methods that are perfectly safe to try at home.

Having a healthy and regular sleep cycle, avoiding mind-altering drugs, and giving waking attention to dreams is generally considered a good starting point. The most common methods begin with keeping a dream diary, as recording your dreams every morning makes it easier to remember them. Additionally, waking without an alarm clock has been found to improve dream recall. Most lucidity techniques involve self-reflection and self-suggestion in order to rewrite your brain’s concept of dreams. Other common tricks include observing differences in reality and dreams through physical and mental reality checks, visualizing a lucid dream, and using phone apps that create nonintrusive visual or auditory cues to prompt your brain to recognize that you are dreaming while you are asleep.Although lucidity can be enjoyed without it, dream control, the ability to change your dreams while dreaming, is a useful skill that improves the dreaming experience. Lucid dreamers may tell you that knowing nothing is real makes everything possible, however this sometime lucid dreamer humbly suggests that it is easier to convince your brain that something false is true, for example flying or magic, and focus on that. As with any skill, lucid dreaming and dream control can be improved with practice.

Warning: Examining too closely the characteristics of the dream state may precipitate an individual or a collective strike by the different brain areas, resulting in loss of sensory imagery, motor ability, and even sleep. This is most easily solved by returning to sleep naturally, but it is also possible to reconstruct the lost dream and return to it.

​Why try lucid dreaming?

Lucid dreamers tell exciting stories of surreally vivid sights and sounds, fantastical events, and feelings of ecstasy. The onset of awareness can be likened to the switching on of a light: one moment everything is dark and hazy and confusing, the people are strangers dressed as friends, and the location a mystery. The next everything is bright and colorful and alive and gravity ceases to apply. However, lucid dreams can be as tragically mundane as any other dream.

The possibilities of lucid dreams border on science fiction. Have you ever noticed that your skills improve after sleep? When you move in a dream, that motion is created by the same neural activation as in real life, strengthening the same neural pathways.⁴ Because of their higher level of awareness, lucid dreamers are frequently able to choose what they do and what they dream about, practicing life skills, facing fears, exercising creativity, and solving problems. This requires some measure of dream control.

For more information on specific techniques and studies, consult the references below. Do not attempt lucid dreaming if you suffer somnambulism or other sleep disorders without consulting a certified sleep medical professional.


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References

  1. Baird, B., Castelnovo, A., Gosseries, O., Tononi, G. (2018). Frequent lucid dreaming associated with increased functional connectivity between frontopolar cortex and temporoparietal association areas. Sci Rep 8: 17798. 10.1038/s41598-018-36190-w
  2. Gottesmann, C. (2009). Discovery of the dreaming sleep stage: A recollection. Sleep 32(1) 15-16. PMC2625318
  3. Hearne, K.M.T (1978). Lucid Dreams: An electro-physiological and psychological study. The University of Liverpool.
  4. LaBerge S. (1990). Lucid Dreaming: Psychophysiological Studies of Consciousness during REM Sleep. Sleep and Cognition. 109-126
  5. Nielsen, T.A. (1993). Changes in the kinesthetic content of dreams following somatosensory stimulation of leg muscles during REM sleep. Dreaming; 3(2) 99-113. 10.1037/h0094374
  6. Nir Y., Tononi G. (2010). Dreaming and the brain: from phenomenology to neurophysiology. Trends Cogn. Sci. 14 88–100. 10.1016/j.tics.2009.12.001
  7. Ruby, P. M. (2011). Experimental research on dreaming: State of the art and neuropsychoanalytic perspectives. Front Psychol. 2011; 2:286. 10.3389/fpsyg.2011.00286
  8. Schredl, M., Noveski, A. (2017). Lucid Dreaming: A Diary Study. Imagination, Cognition and Personality. 38(1). 10.1177/0276236617742622
  9. van Eeden, F. (1913). A Study of Dreams. Proceedings of the Society for Psychical Research. 1913; 26.
  10. Velluti, R. (1997). Interactions between sleep and sensory physiology. European Sleep Research Society: 61-77  10.1046/j.1365-2869.1997.00031.x
  11. Voss, U., Hobson, A. (2015). What is the State-of-the-Art on Lucid Dreaming? – Recent Advances and Questions for Future Research. Open MIND: 38(T). 10.15502/9783958570306
  12. Voss, U. Holzmann, R. Tuin, I. Hobson, A. (2009). Lucid dreaming: a state of consciousness with features of both waking and non-lucid dreaming. SLEEP: 32(9) 1191-1200.
  13. Voss U., Holzmann R., Hobson A., Paulus W., Koppehele-Gossel J., Klimke A., et al. (2014). Induction of self awareness in dreams through frontal low current stimulation of gamma activity. Nat. Neurosci. 17 810–812. 10.1038/nn.3719
  14. Zadra, A. L., Nielsen, T. A., Donderi, D. C. (1998). Prevalence of auditory, olfactory, and gustatory experiences in home dreams. Percept Mot Skills 87(3 Pt 1):819-26. 10.2466/pms.1998.87.3.819 

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