Measurement of an Arousal Level during Daytime Activities under Resting Conditions using Eye Image Analysis

Abstract

The utility of eye-movements and the eye aperture value as arousal measures was examined to apply for monitoring of bed confined patients. The horizontal and vertical eye-movements and the eye aperture value were obtained in time series by analysis of eye-images during reading. Simultaneously, standard arousal measures including electro-oculogram, electroencephalogram and level of sleepiness as judged by facial-expression, were measured. The reading speed obtained from eye-movements was determined over a range of arousal states. Although, the reading speed had large variations dependent on the content of the reading material, the eye aperture value showed a high correlation with level of sleepiness in all twelve subjects independent of the content. The eye aperture value also showed a correlation with electroencephalogram power in nine subjects. These results indicate that the eye aperture value can be used as a quantitative measure of arousal during a relaxed state, and be a useful addition to the monitoring of arousal and care of bed-confined patients.