AUTOMATIC-ANALYSIS OF SLEEP USING 2 PARAMETERS BASED ON PRINCIPAL COMPONENT ANALYSIS OF ELECTROENCEPHALOGRAPHY SPECTRAL DATA

A computer program for the analysis of a sleep electroencephalogram (E EG) is presented. The method relies on two steps. First, a spectral an alysis is performed for signals recorded from one or more electrode lo cations. Then, two EEG parameters are obtained by storing the spectral activity in a multidimensional space, whose dimension is reduced usin g principal component analysis (PCA) techniques. The main advantage of these parameters is in describing the process of sleep on a continuou s scale as a function of time. Validation of the method was performed with the data collected from 16 subjects (8 young volunteers and 8 eld erly insomniacs). Results showed that the parameters correlate highly with the hypnograms established by conventional visual scoring. This s ignal parametrisation, however, offers more information regarding the time course of sleep, since small variations within individual sleep s tages as well as smooth transitions between stages are assessed. Final ly, the concurrent use of both parameters provides an original way of considering sleep as a dynamic process evolving cyclically in a single plane.