Published : 2018-12-23 11:13:30
Categories : Councils to sleep well
How does the brain do to remember certain dreams ?
Some people remember their dream experiences more often than others. They would have more nocturnal awakenings.
David is a dream hunter able to get into people's sleep to bring back objects. Perrine wants to discover the neurophysiological signature of dreams. David is the hero of a novel by the prolific Serge Brussolo, published fifteen years ago, The scuba diver's syndrome. Dr. Perrine Ruby is a real scientist working in the Dycog laboratory (Brain Dynamics and Cognition) of the Lyon Neuroscience Research Center. She is also a professor at the University of Swansea (Wales). Last year she published the results of her work on dreams in the international journals Cerebral Cortex and Neuropharmacology. "Everybody wants to know the dream better," notes Perrine Ruby, "but it's a research object that is not easy to catch." First obstacle, impossible to know for sure when a sleeper is dreaming ! Of course, the theory commonly accepted since the 1950s is that the dream periods coincide with a particular activity of the brain that can be identified through the electroencephalogram, paradoxical sleep.
Paradoxical, because the sleeper presents a "cortical activation that simulates a real active awakening", explained one of the pioneers of research on sleep and dream, Professor Michel Jouvet, in De la science et des dreams, Mémoires d an onirologist (Odile Jacob, 2013).
Logical interpretation because, at the time, studies had shown that if we awoke sleepers during a paradoxical sleep phase, 80% of them were followed by a report of dreams, whereas if we woke them in another phase of sleep (slow sleep), only 6% of awakenings were followed by dream memories. Whence the theory, almost a dogma, assimilating dreams to periods of paradoxical sleep. A true paradigm for researchers for nearly half a century.
However, the dogma cracked in the 2000s. "By synthesizing all the studies carried out, one realizes that in fact 50% of awakenings in slow sleep are also followed by a report of dreams," says the author. Dr. Ruby. It's not as good as 80%, but it's significantly better than 6%! In any case, we can no longer say that there is only paradoxical sleep that makes dreams. "Without being able to record brain activity during the dream (since we do not know when it occurs), focused on the remembrance frequency of the dream to try to better understand what made it vary.
Her research on young, healthy, sleep-free people shows that "big dreamers, in other words frequently able to remember, are also the ones with the greatest amount of awakenings (which does not mean that they have a bad sleep) during their sleep, "she explains. "We were able to show that they are also more responsive to environmental stimuli since they have a greater brain response to unexpected sounds than small dreamers." A more responsive brain, so sleepers more easily awake? That would explain everything. This idea is supported by a second study which shows that at rest, with closed eyes, the cerebral activity of a region involved in the orientation of attention to sounds is greater in the great dream rapporteurs than in others. The veil opens up a little more about the mysteries of the dream but there is still much to discover. Why, for example, is the most reliable setting for remembering one's dreams? For example by filling each morning a notebook of dreams with what we remember when we wake up. "We know that it increases the frequency of memories of dreams, even if we do not know why," notes the scientist.
Another mystery: How does the Imagery Rehearsal Therapy (Repetition of Visual Mental Imagery) therapy consist of repeating, after having modified, the scenario of an annoying nightmare? On the research website www.imaginerever.org, psychologist Benjamin Putois and his colleagues invite all concerned to participate in a study based on this technique. "It's extremely effective," says Dr. Ruby. There are 70% good answering machines.
Moreover, perhaps it is because the dream is an elusive object of study for the researchers that Perrine Ruby has teamed up with the artist Manuel Salvat, author of the "Dream Club", to present in June- next July poetry and the mechanics of dreams through an exhibition ("Dream, between science and art") at the Municipal Archives of Lyon.
Author: Damien Macret