We Lose One Crucial Feature of Consciousness While We Sleep, an 8-Year Study Reveals

When we dream, we experience something similar to being awake, but also very different to being awake, and scientists are still trying to figure out what is going on.

A new clue has been found. The ability to be aware of sounds or to identify them is one of the most important features of consciousness.

It's not easy to map the brains of living people while they're awake and asleep, but the team took advantage of medical research being carried out on patients with ecstasy

"We were able to utilize a special medical procedure in which electrodes were implanted in the brains of patients, monitoring activity in different parts of their brain for purposes of diagnosis and treatment."

Patients volunteered to help look at the brain's response to stimulation.

The researchers were able to see the differences in the cerebral cortex when patients were in different stages of sleep.

The researchers used speakers at the bedsides of the volunteers to play a variety of sounds. The data was collected over eight years.

While the brain's response to sound remained mostly switched on during sleep, there was a rise in the level of alpha-beta waves. Incoming sounds are being analyzed but not passed to the consciousness.

Previous thinking was that sound- related signals decay in the brain during sleep. It's just that there's one significant difference in the way they're processed while we're sleeping.

The strength of brain response during sleep was similar to the response seen during wakefulness, but the level of activity of alpha-beta waves was different.

The feedback from higher up in the brain helps us figure out which sounds are important and need to be heard.

It hasn't been seen in people sleeping, but it has been seen in patients under anesthesia. The researchers describe it as a way of understanding how the conscious and unconscious brains differ.

Scientists can use this method of measuring if someone is unconscious or not during hospital operations, comatose individuals, and so on.

"Our findings have far-reaching implications beyond this particular experiment," he said. We intend to look at the mechanisms responsible for the difference in the future.

The research has appeared in a journal.