Study On Modes Of Heart Rate Variability In Sleep State Modulation

The cardiovascular system is an important physiological system of the body, it has complex structure and physiological function.Due to its phase are controlled by many of factors,such as autonomic nerve,blood pressure,body fluid,emotion and so on,so it presents a complex variability,we call it the heart rate variability(HRV).Analysis and treatment of HRV signals was widely used to evaluation of cardiac health and autonomic nerve activity.Sleep deals with regulation of the autonomic nerve,the activity of autonomic nervous system is not the same during day and night,and because the HRV signals is mainly affected by the cardiac sympathetic and vagal modulation,it must be contain information relate to sleep.Study of the HRV signals to reveal the circadian rhythm and the interaction of autonomic nerve has important significance.Meanwhile,in today’s society,many people are often in the state of abnormal rest time(awake at night,sleep at daytime),such as nurse,night shift taxi drivers,security and so on,with the development of society,the number of people who under inverted sleep is growing,inverted sleep become an increasingly serious problem,study on reversal of sleep behavior how to influence the autonomic nerve of cardiac is also concerned.In this paper,we discuss the HRV signals of sleep and inverted sleep. The main conclusion as following:(1) We used nonlinear methods to study the HRV signals in wake and sleep state, first we adopted theory period signal and two different kinds of noise to study the the physical significance of m-words forms and forbidden words, and then we combined with the power spectrum analysis to study the physiological significance. The results show that:the probability of (1200) and (3312) represents the sympathetic nerve activity level, and the probability of (1332) and (3120) represents the parasympathetic nerve activity level; changes of forbidden words number reflect corresponding changes in autonomic outflow, with the dominance of parasympathetic nerve and suppression of sympathetic nerve at night, the variety of m-words forms reduce and the number of forbidden words increase lead to HRV signal has more rules fluctuations; with the sympathetic nerve activity enhance and parasympathetic nerve activity wakened in daytime, the variety of m-words forms increase and the number of forbidden words reduce bring about HRV signal has the disorder fluctuations, the number of forbidden words can effectively distinguish HRV signal between daytime and night,though t test, p<0.05.Meanwhile, the number of forbidden words of healthy people and heart disease patients also have significant differences, the number of forbidden words can be used as quantitative index to assessment heart health state.(2) To set up inverted sleep model,and then we combined power spectrum analysis and base-scale entropy to study the inverted sleep behavior how to influence autonomic nerve and the chaotic intensity of HRV signals.The results show that:Because the sleep upside down, lead activities of autonomic nerve changes in inverted sleep state,which is contrary to the normal state,changes of the autonomic nervous regulation mechanism to change the chaotic characteristic of HRV signals,the base-scale entropy under inverted sleep showed a reverse trend compared with normal state.This means that the chaotic strength of HRV signals is closely related with autonomic nerve,further analysis of the relationship between the base-scale entropy and high frequency power is found that:The variation trend of high frequency and base-scale entropy is opposite,changes of high frequency reflect corresponding changes of the chaotic strength of HRV signals, combined with the physiological significance of high frequency power can be launched that:chaotic intensity of HRV signals is positive correlation with the modulation intensity of sympathetic,and negative correlation with the modulation intensity of vagus.Meanwhile,the base-scale entropy of inverted sleep state is less than normal state in24hours,this means inverted sleep behavior was damage to the heart health.