Opinion – Reinaldo José Lopes: What’s left in dreams

Dreaming is a weird experience by definition, even if we go through it every single night. Among the many oddities of the kingdom of Morpheus, there is one that never ceases to annoy me. It’s about the fact that the dreamer’s “I” often faces terrifying or surreal situations with the greatest calm in the world, as if it wasn’t even happening to him.

It so happens that researchers from all over the world, including Brazil, have used extremely creative approaches to understand what happens in the brain of those who sleep and dream. In a recently published study, they obtained clues that help to understand how the experiences we have when awake become raw material for dream images, and how emotions associated with these experiences can weaken as sleep progresses.

Work investigating some of these issues is available in the specialist journal NeuroImage. In partnership with specialists from Argentine institutions, Natália Bezerra Mota, from UFRJ (Federal University of Rio de Janeiro), Sidarta Ribeiro, from UFRN (Federal University of Rio Grande do Norte), and other collaborators monitored the brain activity and memory of 28 volunteers during different stages of sleep.

Participants, men and women aged between 20 and 43, had been instructed to arrive at the lab early, having slept about half the time they normally would. (Unpleasant, of course, but the idea was to increase the chances that they would be able to fall asleep in the strange surroundings of the university.)

The team’s proposal was to test how sleep and dreams transform waking memories. To assess this, the first step was to show the volunteers an image, which could be emotionally positive (children smiling, for example), neutral (a truck, an umbrella) or negative (a bared-toothed shark, a decapitated person). ). While still awake, the person had to record an audio describing what they had seen and also say how the image affected them emotionally.

Next step: sleep — while each participant’s brain activity was monitored via EEG (electroencephalogram). Unfortunately, the group didn’t get much of a chance to rest, because the EEG told the researchers when a transition to different stages of sleep occurred. At moments of phase change, a beep would wake the poor volunteers, and they had to report what they were seeing and feeling in their dreams, which was compared, of course, with waking reports, with the help of linguistic analysis techniques. automated.

Well, the work showed, first of all, that the images seen before going to sleep actually become part of the plot of dreams — and, as sleep progresses, they appear even more frequently in people’s reports.

However, the emotional impact decays over the course of sleep, rather than increasing — and this starts to happen as soon as a person falls asleep.

“One of the functions of dreams would be to process emotions”, explains Natália Mota. “It would be analogous to a digestion process: to process food, we dissociate nutrients from toxins, retaining the former and eliminating the rest. In the case of dreams, what we retain is the memory of events, dissociating from it the excess emotional content, which would be toxic to learning.”

According to Sidarta Ribeiro, recurrent nightmares could be the result of traumas that overload this system. It’s something researchers want to investigate by looking at specific structures in dreamers’ brains.