Brain waves control the impact of noise on sleep
During sleep, our perception of the environment decreases. However the extent to which the human brain responds to surrounding noises during sleep remains unclear. In a study published this week in Proceedings of the National Academy of Sciences (PNAS), researchers from University of Liege (Belgium) used brain imaging to study responses to sounds during sleep. They show that brain activity in the face of noise is controlled by specific brain waves during sleep. In particular, waves called sleep spindles prevent the transmission of sounds to auditory brain regions. Conversely, when sounds are associated with brain waves called K-complexes, activation of auditory areas is larger. Our perception of the environment is therefore not continuously reduced during sleep, but rather varies throughout sleep under the influence of particular brain waves.