2009 年 47 巻 1 号 p. 7-14
The present study was conducted in order to clarify the features of the occurrences of body movement during nighttime sleep and estimate the depth of sleep. Sleep experiments were conducted on seven healthy, non-medicated subjects, aged20-23years (5 males and 2 females) for 7 hours. During sleep, body movement was measured by electroencephalography (electroencephalography body movement: EEGBM) and by a passive infrared type motion sensor (NapVIEW body movement: NapVIEWBM) . Among all subjects, the mean concordance rate between EEGBM and NapVIEWBM was 0.95 ± 0.03. This finding suggests that it is possible to measure body movement with a 90% or greater concordance with EEGBM using a non-contact method, such as NapVIEW. Analysis of the relationship between body movement intervals and depth of sleep showed that the interval between body movements was longer during deep sleep and shorter during light sleep. Sleep state was evaluated based on data obtained by detailed analysis of the interval between body movements. Linear discriminant analysis was conducted on the interval data obtained by NapVIEWBM to divide into a group of light sleep stages and a group of deep sleep stages. A concordance rate of 90.5% between estimated depth of sleep and actual sleep stage was obtained during light sleep, while a concordance rate of 70.8% was obtained during deep sleep. These findings indicate that sleep state can be adequately evaluated based on depth of sleep as indicated by body movement.