CHAOTIC BEHAVIOR OF EEG SLOW-WAVE ACTIVITY DURING SLEEP

The study of the dynamics of non-linear systems allows the evaluation of the correlation dimension which, in turn, provides an estimate of t he number of variables needed to model the process. In such a view, th e correlation dimension was calculated for the profiles of the EEG slo w-wave activity during sleep obtained from 7 young normal controls and in their corresponding artificial stochastic signals. It was possible to evaluate the complexity of all the real profiles which exhibited a n average dimension of 3.76 (SD 0.331), but not that of the artificial control ones. This allows us to conclude that sleep relation might be considered as a deterministic non-linear process and that the already proposed two-process model of sleep regulation needs to include addit ional variables with non-linear interactions. Copyright (C) 1996 Elsev ier Science Ireland Ltd.