Abstract Mkid 119

Activity states based on static charge sensitive bed (SCSB) recording were assessed as indicators of sleep depth. Twelve subjects’ instructed responses to auditory stimuli were studied in relation to the sleep stages and to three categories of SCSB activity, quiet (QS), intermediate (IS), and active state (AS), which were automatically defined according to the variability of motor, respiratory, and cardiac parameters. The differences in responsiveness during sleep stages were consistent with earlier findings. The response rates (without polygraphic signs of awakening) were as follows: stage 1, 52.8%; stage 2, 11.0%; stage REM, 8.5%; slow wave sleep, 0.5%. The lacking of responses in wakefulness occurred mostly during trials after the initial sleep onset. In the SCSD data responsiveness was lowest in QS and highest in AS. After the first hour in bed the response rates were 3.9% in QS, 13.3% in IS, and 30.3 % during AS (for most subjects even lower in QS and IS). QS seems to reflect a behaviorally deep sleep and IS and AS appear as lighter states respectively. The results suggest that the SCSB activity states are useful measures of sleep quality, QS providing an approximate estimate of deep sleep.