Development of technology to determine consciousness in sleep 

that can predict sleep disorders such as sleep paralysis.

The work of Professor Seong Whan Lee’s research team has been published in Scientific Reports.

A research team (first author, Dr. Lee Min-ji, Ph.D.) from the Department of Brain and Cognitive Engineering, Graduate School of Korea University, led by Professor Seong Whan Lee, has developed a consciousness determinative technique in sleep that can predict sleep disturbance intervals such as sleep paralysis.

The research was supported by the Ministry of Science and ICT and the Institute of Information & Communications Technology Planning & Evaluation Information’s 'SW Computing Industry Source Technology Development Project' and was published in the journal, Scientific Reports on March 26, 2019.

The paper, which was titled, ‘Connectivity differences between consciousness and unconsciousness in non-rapid eye movement sleep: a TMS-EEG study’, measures the connectivity between brain regions during sleep based on graph theory. As a result, the team could detect the consciousness section in dreams during NREM sleep, which has remained undetected by previous studies. They also developed a core source technology that enables real-time monitoring of one’s conscious state during sleep.

Sleep is generally divided into REM (Rapid Eye Movement) sleep and NREM (non-REM) sleep. Although it is commonly understood that dreaming occurs during REM sleep, this study is significant in that it detects the state of consciousness when dreaming in NREM sleep.

According to Professor Lee, who is a co-author on the paper, "Existing polysomnography technology only distinguished between REM sleep and NREM sleep based on the frequency characteristics of brainwaves. However, this study distinguished the dreaming consciousness state in NREM sleep dreaming which had been indistinguishable by previous studies.” Commenting on the significance of the study, Professor Lee went on to say, “The sleep paralysis phenomenon that many people experience mostly occurs from body discomfort in connection with dreaming during NREM sleep and as such, this study represents a remarkable accomplishment in that by determining the dreaming section during NREM sleep, a new sleeping phase was identified.”

[Introduction]

Title: Connectivity Differences between Consciousness and Unconsciousness in Non-rapid Eye Movement Sleep: a TMS–EEG Study

In general, sleep is divided into a REM sleep dreaming phase and an NREM non-dreaming deep sleep phase. However, it has recently been revealed that a conscious dreaming phase during NREM sleep exists. Considering that the sleep paralysis phenomenon experienced by many results from body discomfort in connection with dreaming during NREM sleep, it is important to measure dreaming during NREM sleep. However, it is impossible to measure dreams in NREM sleep with conventional sleep phase monitoring methods.

In this study, the research team measured the connectivity between brain regions by measuring brain waves during sleep. As a result, the team developed a core source technology that can distinguish dreaming consciousness intervals in NREM sleep and unconsciousness intervals of deep rest that previous studies could not. This study is significant because it presents a new sleep phase based on conscious experience. In addition to the measurement of sleep quality such as sleep monitoring and sleeping disorder diagnosis, expectations are that in the future it will also help in generating biomarkers for measuring the depth of consciousness required for anesthesia and surgery.

“Difference of brain connectivity according to NREM sleep level” Conscious Experience (CE, red) shows a strong connection of the brain to alpha and beta waves, and a deep sleeping phase (No Conscious Experience, NCE, blue) shows a strong brain connectivity in the low frequency delta wave.