Brain waves control the impact of noise on sleep

September 6, 2011
Left: Auditory brain regions remain active in response to sounds during human non-rapid eye movement sleep. Right: When sounds occur during brain waves called sleep ‘spindles’, their transmission to the auditory cortex is distorted. Only a small region in the brainstem (arrow) remains activated in response to sounds. (c) ULg CRC

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.

In this study, the research team led by Dr Thanh Dang-Vu and Prof. Pierre Maquet (Cyclotron Research Center, University of Liège) shows that induced by sounds during sleep closely depends on brain waves that constitute our sleep.

By using functional magnetic resonance imaging (fMRI) combined with electroencephalography (EEG), researchers have evidenced that auditory brain regions remain active in response to sounds during sleep [see image, left panels], except when sounds occur during brain waves called sleep ‘spindles’. The study indeed shows that spindles prevent the transmission of sounds to the auditory cortex [see image, right panels].

Conversely, sounds can induce the production during sleep of brain waves called ‘K-complexes’. The results brought by this new study demonstrate that production of K-complexes by sounds is associated with a larger activation of auditory brain areas. While spindles prevent the transmission of sounds, K-complexes reflect a more important transmission of sounds to the sleeping brain.

The effects of noise on sleep are therefore controlled by specific brain waves. In particular, the human brain is isolated from the environment during sleep spindles, which might allow essential sleep functions to operate such as the consolidation of memory for previously acquired information. These thus play a crucial role in sleep quality and stability in the face of noise.

Explore further: Need a nap? Find yourself a hammock

More information: “Interplay between spontaneous and induced brain activity during human non-rapid eye movement sleep”, PNAS, 2011, doi 10.1073, by T.T. Dang-Vu, M. Bonjean, M. Schabus, M. Boly, A. Darsaud, M. Desseilles, C. Degueldre, E. Balteau, C. Phillips, A. Luxen, T. Sejnowski et P. Maquet.

Related Stories

Need a nap? Find yourself a hammock

June 20, 2011

For grownups, drifting off for an afternoon snooze is often easier said than done. But many of us have probably experienced just how simple it can be to catch those zzz's in a gently rocking hammock. By examining brain waves ...

Study finds brain regions go offline at different intervals

April 14, 2011

(PhysOrg.com) -- A new study shows that, rather than being an "all or nothing" phenomenon, regions of the human brain go silent at different times through the night, losing their ability to communicate during certain phases ...

Recommended for you

Scientists develop new drug screening tool for dystonia

December 8, 2016

Duke University researchers have identified a common mechanism underlying separate forms of dystonia, a family of brain disorders that cause involuntary, debilitating and often painful movements, including twists and turns ...

Honeybee memories: Another piece of the Alzheimer's puzzle?

December 8, 2016

A breakdown of memory processes in humans can lead to conditions such as Alzheimer's and dementia. By looking at the simpler brain of a honeybee, new research published in Frontiers in Molecular Neuroscience, moves us a step ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.