Time frequency analysis of biological signals during sleep

We have developed a relevance between sleep stage (Stage MT, W, 1, 2, 3, 4, REM) and rhythm of autonomic nerve activity computed by frequency analysis of heartbeat interval. Heartbeat during sleep was changed by sleep state. Extraction of relationships between sleep stage and heartbeat interval from signal of pressure sensor located in bed is goal. Then, we tried to apply continuous wavelet analysis to ECG in order to extract more precise information for the relationships. Moreover, we applied wavelet transform of impulse as mother wavelet that is impulse response of signal of pressure sensor on one heartbeat. In this paper we had six all-night sleep experiments, and compared result each subjects. As a result, we were able to estimate sleep state freely from sensor of pressure signal.