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The Neuroscience of Lucid Dreams

Lucid dreams are perhaps the most bizarre perceptual experience one can have. You are asleep and dreaming, but suddenly you realize that it's all just a dream.

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American


 

Dreaming of Snow White and the Seven Dwarves. (Wikimedia Commons)

 


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Lucid dreams are perhaps the most bizarre perceptual experience one can have. You are asleep and dreaming, but suddenly you realize that it’s all just a dream. At that point, you can choose to wake up (I usually do… I don’t think I’ve ever had a lucid dream that wasn’t a nightmare) or you can continue to dream on, with one important advantage. You’re now aware that the world around you is completely made up by your brain. As with the post-awakening of Neo in the movie “The Matrix”, you can bend the physical laws to your liking. You can fly, stop bullets with your bare hands, or even deliver magical punches to the bad guys to make them shrink in size (yeah, I have weird dreams). There is no spoon.

The very first dream that I remember having, at the age of 4 or 5, was a lucid dream. I was waiting for my mother to finish her purchases at the neighborhood newsstand, when the boogeyman showed up. He must have been a philosophical boogeyman interested in moral dilemmas, because he asked me to decide the menu for his next meal: me or my mother. If I didn’t decide, he would eat us both. My mother, just a couple of meters away, was blissfully unaware of this exchange. I felt paralyzed. I didn’t want to be eaten, but feeding my mamá to the monster for dinner was unthinkable. I’d never been in such a horrible situation in my short life. Then it occurred to me: this is just too awful to be real, so it follows that I must be dreaming. I woke up with a start.

There have been other lucid dreams since. Sometimes I have two in a month, other times I go for the better part of a year without them. It turns out, the ability to experience lucid dreams differs wildly from one person to another.

A recent study, published earlier this month in the Journal of Neuroscience, set out to determine if people with high and low dream lucidity were also dissimilar in their metacognitive ability, that is, the ability to reflect on, and report, one’s mental states.

The study participants completed questionnaires that assessed their lucid dreaming frequency, intensity, and degree of control, and also their metacognitive skills, including their self-reflection and self-consciousness. The experimental subjects moreover underwent brain imaging while conducting a thought monitoring task. This consisted of two 11-minute runs during which the subjects had to evaluate the each and every thought that entered their heads on an externally-internally oriented scale. Externally oriented thoughts meant thoughts related to the external environment, such as the visual surroundings, or the noise from the scanner. Internally oriented thoughts were not related to the immediate environment, such as remembering past events or planning for the day ahead.

The research showed that the brains of people with high and low dream lucidity were different. Subjects with high lucidity had greater gray matter volume in the frontopolar cortex, compared to those with low lucidity. This brain region also showed higher activity during thought monitoring in both high- and low-lucidity subjects, with stronger increases in the high-lucidity group. The scientists concluded that lucid dreaming and metacognition share some underlying mechanisms, particularly with regards to thought monitoring. This relationship had been previously suspected, but never before explored at the neural level.

Future research may tell us if it’s possible to control the frequency and contents of our lucid dreaming by training ourselves to monitor our thoughts while we’re awake. I, for one, would love some lucid dreams that don’t involve Freddy Krueger every now and then.

Susana Martinez-Conde is a professor of ophthalmology, neurology, and physiology and pharmacology at SUNY Downstate Health Sciences University in Brooklyn, N.Y. She is author of the Prisma Prize–winning Sleights of Mind, along with Stephen Macknik and Sandra Blakeslee, and of Champions of Illusion, along with Stephen Macknik.

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