Investigação das funções cognitivas do sono e dos sonhos através de eletroencefalografia, relatos verbais e jogos eletrônicos

Abstract

Sleep is an important mental and bodily state for the consolidation of memories. It is very conserved across animal species, and likely had an early and sustained influence on the evolution of prey and predator behaviors. The Threat Simulation Theory states that dreaming was also important along evolution, due to the capacity of alerting about possible future threats. Methodological limitations complicate comparisons of sleep and dreams between preys and predators in non-human animals, but this can be addressed by inviting humans to play videogames. We set out to address the link between sleep, dreaming, and the prey vs. predator dichotomy in 13 pairs of adult volunteers that came to the laboratory and had their brain activity simultaneously recorded through electroencephalography (EEG), while they played a videogame against each other for 45 minutes, then slept for 2 hours, had their dream reports collected, and then played again for another 45 minutes. In the videogame, one participant was hunted by the other in a predator-versus-prey simulated confrontation. The results indicate that preys reported more dreams than predators, and that dreams related to the game contributed to prey score. Preys also benefited from having a deeper sleep than predators, which was also positively correlated with prey score. Furthermore, preys showed greater EEG power in the delta frequency band (slow wave oscillations between 1 and 3Hz), which also favored their score. No effect was found for sleep spindles. The prey's performance was impaired by the number of occurrences of microstate C, a task-negative pattern of electrical activity. These results suggest that slow waves during sleep and game-related dream contents improve the post-sleep performance of individuals in the role of prey, while no benefits were detected for those in the role of predator. Altogether, the results show that both sleep and dreams are important for adapting to the very difficult situation of being preyed upon, but not so relevant in the context of being a predator, which does not represent a very stressful challenge.