Understanding Why We Remember (Or Don’t) Last Night's Dreams

Concluding that the “hardware” of brain activity when we sleep is basically the same as when we don’t, Italian researchers have been able to measure brain activity of people who have remembered their dreams after waking up.

A dream-catcher (Shandi-lee)

By Gianni Parrini
LA STAMPA/Worldcrunch

ROME - Have you ever asked yourself whether you were awake or asleep? As it turns out, in our brain, and especially in our memory, there is not much difference between being awake or being asleep. A new study by Italian researchers delves into this gray area, discovering clues about the brain process that allows us to remember our dreams the morning after.

The study, whose findings were just published in the Journal of Neuroscience, aims to answer two key questions: “Why do we sometimes forget and other times remember the dreams when we awake?” and “Do these two options involve different areas of our brain?” To the latter, the Italian team concluded that the brain areas and activities that are involved in dreams are basically the same as our cognitive process when we are awake.

The neurological findings help explain that simple morning question we’ve all asked ourselves, explains Professor Luigi De Gennaro, who worked with a group of researchers from the psychology department of Rome’s La Sapienza University, the Fatebenefratelli Research Association and L’Aquila and Bologna Universities. 

“We have monitored a high number of patients’ brain electric activities, comparing the data recorded when they remembered their dreams to data recorded when they forgot them,” says De Gennaro. “It clearly appeared that only when the electroencephalography (electrical measuring of brain activity) showed a slow oscillatory pattern during REM sleep, did people remember their dream when they awoke.”

The experiment has again confirmed that people dream during all the stages of sleep, and not only during the REM sleep. The team monitored 65 people who slept normally for around seven-and-a-half hours. When they awoke, the subjects filled an exhaustive form about their dreams. “Their sleep was interrupted in two different moments: during REM sleep and at stage 2 of non-REM sleep,” explains De Gennaro. “In the latter, the memory of the dreams is not linked to the presence, but to the absence of alpha waves.”

Comparing the brain to a pc
The researchers found that the brain areas that control the emotional intensity of dreams, also work during waking hours. “Basically, the same cerebral areas and similar neurophysiological automatisms allow the access to ‘episodic memory,’ which consists of images and scenes which remain in our long term memory,” says De Gennaro. “Comparing the brain to a pc, we can say that the hardware does not change from sleep to waking. Only the way it works changes.” In other words, night thoughts and day thoughts consist of the same electricity and matter.

Many researchers think that dreaming has an important role in strengthening memories, given that while asleep, the brain processes the information which have been acquired during waking hours. Sigmund Freud hypothesized that dreams came from “daily remnants” of psychic activity. But Professor De Gennaro explains that their studies have a different target. “Our studies of physiology or electro-physiology are about how we dream, not about why we dream. That question is for the psychoanalysts and psychologists.”

Zeroing in on the difference between people who tend to remember their dreams and people who tend to forget them will be the next step of the Italian research. “During our tests, we have observed that there are some people who tend to keep permanent memory of their dream, while others do not,” says De Gennaro. “Our goal is to understand if this difference is due to structural features of the brain or to its way of working.”

Even if the research is making progress, dreams are still a mystery. “Our knowledge covers about 20-30% of dreams. We cannot study the dream directly, but just its memories, and we can reach it only through the dreamer’s report. For this reason, we still cannot know if newborn babies and animals dream like we do.”

Read the original story in Italian