HIGHER ORDER STATISTICS AND SPECTRA ANALYSIS OF SLEEP SPINDLES

In this paper we analyze sleep spindles, observed in EEG recorded from humans during sleep, using both time and frequency domain methods which depend on higher order statistics and spectra. The time domain method combines the use of second and third order correlations to reveal information on the stationarity of periodic spindle rhythms, detecting transitions between multiple activities. The frequency domain method, based on the normalized bispectrum, describes the frequency interactions associated with the second order nonlinearities occuring in the observed EEG. Results for real data are presented. 1