A study published in Nature Neuroscience highlights brain activity that happens when a sleeping person hears music. A team of UCLA researchers examined brain activity in the cerebral cortex of epilepsy patients. They discovered a significant response to sound during sleep that resembles the brain’s response during wakefulness.

The researchers observed a key difference in the level of alpha-beta waves between a sleeping state and one of wakefulness. Neural feedback from higher brain centers provides insight into understanding the impact of sound and anticipating what may come next.

Study co-author and director of UCLA’s Epilepsy Surgery Program Dr. Itzhak Fried explained the sleeping brain’s neural activity. He stated that, “the neuronal orchestra is never shut from the environment when the person is deep asleep. The neurons are like musicians playing Mozart together. Only the conductor, the one who directs the performance, is missing.”

The study noted significant activity in the primary auditory cortex during sleep, but there was less neural feedback from higher brain regions responsible for regulating attention and expectation.