The association between the subjective quality of sleep and the phase of a 90-minute periodic signal for the wake-up support system

Abstract

In this paper, we discuss the association between the phase of a 90-minute periodic signal (90-MPS) and the subjective quality of sleep in sleep experiments of multi-subjects using sensors for the wake-up support system. When 90-MPS is extracted from the sensor data using Fast Fourier Transform (FFT) and filtering, the change in period appears as a phase shift of 90-MPS. Therefore, it is necessary to focus on the phase of extracted 90-MPS and analyze the association between that and subjective quality. The sympathetic nervous system index that has data with a clear 90-minute period from the sensor data during sleep was selected using FFT. Furthermore, a 90-MPS is extracted by using the filter, and the association between the phase of 90-MPS at the wake-up time and quality of sleep using the Oguri-Shirakawa-Azumi sleep inventory, middle-aged and aged version (OSA-MA) was analyzed. When quality of sleep was the highest, the distribution was centered on phase III of 90-MPS at four categories excluding refreshing (OSA-MA 4) among the five categories of OSA-MA. It has been confirmed that the highest quality of sleep can be obtained when the waking up phase is III.