Transition Of Sleep-stage And Influence Of Sleep Apnea

In this letter, we propose the first empirical analysis to study the duration fluctuation of individual sleep-stage and the transition across different sleep-stages. We find that with sleep apnea, the total time, average duration, root mean square standard deviation of light sleep increase significantly, those of deep sleep decrease significantly, and there are no significant changes in wake and REM sleep. We support that sleep apnea could be connected with sleep depth change, but not increase of wakefulness. Furthermore, we demonstrate that sleep dynamics are characterized by an endogenous pattern of sleep-stage transition that is universal for all subjects. Our findings raise the hypothesis that frequent sleep-stage transition between light sleep and deep sleep is an integral part of healthy sleep regulation, and it will break down with sleep disorders. We study the dynamical aspects of sleep-stage transitions.Then, we find that the sleep regulation neuro-system can undergo nonequilibrium reorganization to produce stage transitions over a broad range of time scales from minutes to hours. The entire class of sleep-stage transition throughout a whole night can be characterized by several independent transition modes, and these basic transition modes are preserved even under sleep disorders, such as sleep apnea. However, the complexity of sleep-stage transition modes are significantly reduced in sleep apnea subjects, indicating a dynamical alteration of sleep regulation under pathologic disturbance. Finally, the simple measures we used in this paper are effective markers to characterize the micro-structure of sleep, and would be useful in the clinical evaluation of sleep disorders.