A sleep electroencephalogram was analyzed by non-linear analysis. The polys
omnography of a healthy male subject was analyzed and the correlation dimen
sions calculated. The correlation dimensions decreased from the 'awake' sta
ge to sleep stages 1-3 and increased during rapid eye movement (REM) sleep.
These results were seen during each sleep cycle. In each sleep cycle, the
correlation dimensions decrease for slow wave sleep, and increase for REM s
leep.