Identification of sleeping quality by EEGs in humans

The relationship between “quality of sleep” (especially comfortableness) and electroencephalography (EEG) was investigated. Fourteen healthy males slept three nights with three types of pillows. After waking in the morning, the comfortableness of sleep was evaluated. For generating hypnograms, simultaneous electromyography (EMG), electrooculography (EOG) and EEG recordings were made during sleep. A significant correlation was found between the comfortableness of sleep and the first appearance of REM sleep from the hypnograms with a correlation coefficient r = -0.62 (p <; 0.001). The predicted occurrence of first REM sleep was then examined using single channel EEG. It was found that the combination of delta and beta power ratios was able to predict the occurrence of first REM sleep with 12.5±13.1 min accuracy. A significant correlation was also found between the comfortableness of sleep and the predicted latency to first REM sleep with a correlation coefficient r = -0.62 (p <; 0.001). Single-channel EEG therefore shows potential as a tool for the objective evaluation of “quality of sleep.”