Chaos Methods In The Study Of Sleep EEG

A person spends about one third time on sleeping in the whole life. Many physiological processes happened and evoluted in those. It is very impotant for us to study the sleeping process and it is also a signify task to observe and ward the sleeping process and study the life mechanism.People can eliminate fatigue and be energic thorough sleeping. The determinant about sleeping and relax not only lie on the length of seeping, but also the understandability of the sleeping content. People have observed that the sleeping process has its complex structure and many kinds of physiological change. Different sleeping stage has different sleeping effect and physiological process. So we can research the sleeping characteristic and structure to post the sleeping mechanism and improve the sleeping quality.The EEG(electroencephalograph) is a kind of fathomable electricity physiological reaction that gernerated in nerve system, it can be measured no hurt. It is a long time using EEG to study the sleeping while dispute still exit about if the EEG a chaos system. If we ensure that the EEG signal is chaos signal, we can use nolinear methods to analysis the EEG. The EEG is more regular in sleeping, The research result about chaos of the EEG is not the same. This paper studies the different stage sleeping EEG of chaos. First, we ensure the embedding dimmesion m and delay time t with the space theory for the different sleeping stage and reconstruct the phase space. Second, we estimate the EEG is chaos signal with the methods of The Largest LyapunovLyapnov Exponent, Cao and surrogate data. We compute the fractial dimension of the different sleep stage. At last, we draw the attactor's picture in the phase space and draw the Poincare section, it is better explaination that the sleep EEG signal is chaos signal.