Automatic sleep analysis

Abstract

Automatic systems to analyse sleep have been in existence for over twenty years [17, 34]. They were rarely commercialised in the past, being restricted to a limited number of laboratories. There have been such rapid development recently that virtually all the sleep polygraphs designed in the last five years are equipped with automatic sleep stagers, with varying levels of performance. The recent trend in automatic sleep analysis largely stems from the combination of marked technological advances in the field of micro-processing (resulting in the expansion of digital polygraphs) and the demands created by developments in the understanding of sleep medicine (sleep apnoea syndrome, exploration of sleep microstructure etc.). A large number of systems of analysis are available whether automatic, ambulant or stationary. These systems cannot all be described here as this would go beyond the limits of the present article, whose intention is to provide an introduction to the automatic analysis of sleep. Thus we will restrict ourselves to a brief presentation of the most widely used methods of signal analysis employed in the principle systems, and offer some advice on using them, based on our own experience.