Quran memorisation and heart rate variability:How do they correlate?

BACKGROUND Heart rate variability(HRV)was shown to be affected by performing religious activities.AIM To examine the relationship between the level of Quran(the holy book of Muslims)memorisation and HRV among teenagers.METHODS This experimental study included 16 Tahfiz students and 16 non-Tahfiz students(n=32).The HRV was measured in three tasks:Recalling familiar verses,memorising new verses,and recalling the newly memorised verses of the Quran.HRV analysis was done using these parameters:Standard deviation of N-N(heartbeat peak)interval;low frequency(LF);high frequency(HF)and LF/HF ratio.RESULTS There were significant differences between tasks for all parameters(P<0.05).However,between the groups,only the LF/HF ratio had significant differences,with F=5.04,P<0.05.Pearson correlation showed a moderate positive correlation between the number of pages memorised and the LF/HF ratio(r=0.61,P<0.05).CONCLUSION Quran memorisation increased the HRV and our results suggested that this activity could be developed as an effective sympathovagal modulation training activity.

A comprehensive review of heart rate variability as an indicator in the regulation of the autonomic nervous system by acupuncture:a bibliometric analysis

This study sought to conduct a bibliometric analysis of acupuncture studies focusing on heart rate variability(HRV)and to investigate the correlation between various acupoints and their effects on HRV by utilizing association rule mining and network analysis.A total of 536 publications on the topic of acupuncture studies based on HRV.The disease keyword analysis revealed that HRV-related acupuncture studies were mainly related to pain,inflammation,emotional disorders,gastrointestinal function,and hypertension.A separate analysis was conducted on acupuncture prescriptions,and Neiguan(PC6)and Zusanli(ST36)were the most frequently used acupoints.The core acupoints for HRV regulation were identified as PC6,ST36,Shenmen(HT7),Hegu(LI4),Sanyinjiao(SP6),Jianshi(PC5),Taichong(LR3),Quchi(LI11),Guanyuan(CV4),Baihui(GV20),and Taixi(KI3).Additionally,the research encompassed 46 reports on acupuncture animal experiments conducted on HRV,with ST36 being the most frequently utilized acupoint.The research presented in this study offers valuable insights into the global research trend and hotspots in acupuncture-based HRV studies,as well as identifying frequently used combinations of acupoints.The findings may be helpful for further research in this field and provide valuable information about the potential use of acupuncture for improving HRV in both humans and animals.

Heart Rate Variability as an Indicator of Stress in Students’ Athletes

Introduction: The wellbeing of student’s athletes has a paramount importance, a prolonged period of cognitive and physical performance that characterizes the life of student’s athletes often leads to fatigue, and a psychobiological state that increases the risk of injury and accidents. The use of Heart rate variability (HRV) has become increasingly popular as a non-invasive methodology that provides an indirect insight into the autonomic nervous system. HRV can be utilized as a diagnostic tool in detection of autonomic nervous system impairment and sympatho-vagal imbalance. HRV technology is employed to monitor the internal response of athletes to workload and identify athletes’s psychophysical stress to predict and therefore prevent injuries. Objective: The objective of the investigation is to establish whether the use of Polar H10 sensor heart rate monitors worn by athletes in a sitting position (inclination 60 degrees) during periods characterized by stress can provide a valid and non-invasive method to assess the psychophysiological state during sports competition and school exams. Method and Statistics: In the study, the HRV of 12 basketball students athletes and 4 students non-athletes was analyzed as a control group. The autonomic nervous system activity was assessed based on heart variability parameters (HRV): SDNN, rMSSD, LF, HF, and LF/HF. The measurements were made after establishing the baseline at rest, during the training phase (CT), competition phase (CC) and during the acute phase of stressors due to school exams coinciding with the competitive season (CC + E). Results: Compared to the respective values prior to the stress of the competitions and exams, a significant decrease in HRV indices was found: SDNN (P Conclusions: The analysis and examination of the data on the sample of the student population also showed a statistically significant correlation between decreased cardiac variability and injuries or indisposition to physical exertion.

Modeling Dynamical Noises Corrupted Chaotic System for Heart Rate Variability Analysis

It is difficult to establish the process of chaos in time series from cardiac dynamics. The output from such a system is probably the result of both its internal dynamics, and the input to the system from its surroundings. We present an optimization algorithm to find a time series that is as close as possible to the heart rate series subject to the constraint that it is deterministic with respect to some dynamics. The algorithm is tested by some famous forced dynamical systems, and applied to heart rate data. We find that the deterministic components of heart rate variability are chaotic.

Does heart rate variability correlate with long-term prognosis in myocardial infarction patients treated by early revascularization?

AIMTo assess the prevalence of depressed heart rate variability (HRV) after an acute myocardial infarction (MI), and to evaluate its prognostic significance in the present era of immediate reperfusion.METHODSTime-domain HRV (obtained from 24-h Holter recordings) was assessed in 326 patients (63.5 ± 12.1 years old; 80% males), two weeks after a complicated MI treated by early reperfusion: 208 ST-elevation myocardial infarction (STEMI) patients (in which reperfusion was successfully obtained within 6 h of symptoms in 94% of cases) and 118 non-ST-elevation myocardial infarction (NSTEMI) patients (percutaneous coronary intervention was performed within 24 h and successful in 73% of cases). Follow-up of the patients was performed via telephone interviews a median of 25 mo after the index event (95%CI of the mean 23.3-28.0). Primary end-point was occurrence of all-cause or cardiac death; secondary end-point was occurrence of major clinical events (MCE, defined as mortality or readmission for new MI, new revascularization, episodes of heart failure or stroke). Possible correlations between HRV parameters (mainly the standard deviation of all normal RR intervals, SDNN), clinical features (age, sex, type of MI, history of diabetes, left ventricle ejection fraction), angiographic characteristics (number of coronary arteries with critical stenoses, success and completeness of revascularization) and long-term outcomes were analysed.RESULTSMarkedly depressed HRV parameters were present in a relatively small percentage of patients: SDNN < 70 ms was found in 16% and SDNN < 50 ms in 4% of cases. No significant differences were present between STEMI and NSTEMI cases as regards to their distribution among quartiles of SDNN (χ2 =1.536, P = 0.674). Female sex and history of diabetes maintained a significant correlation with lower values of SDNN at multivariate Cox regression analysis (respectively: P = 0.008 and P = 0.008), while no correlation was found between depressed SDNN and history of previous MI (P = 0.999) or number of diseased coronary arteries (P = 0.428) or unsuccessful percutaneous coronary intervention (PCI) (P = 0.691). Patients with left ventricle ejection fraction (LVEF) < 40% presented more often SDNN values in the lowest quartile (P < 0.001). After > 2 years from infarction, a total of 10 patients (3.1%) were lost to follow-up. Overall incidence of MCE at follow-up was similar between STEMI and NSTEMI (P = 0.141), although all-cause and cardiac mortality were higher among NSTEMI cases (respectively: 14% vs 2%, P = 0.001; and 10% vs 1.5%, P = 0.001). The Kaplan-Meier survival curves for all-cause mortality and for cardiac deaths did not reveal significant differences between patients with SDNN in the lowest quartile and other quartiles of SDNN (respectively: P = 0.137 and P = 0.527). Also the MCE-free survival curves were similar between the group of patients with SDNN in the lowest quartile vs the patients of the other SDNN quartiles (P = 0.540), with no difference for STEMI (P = 0.180) or NSTEMI patients (P = 0.541). By the contrary, events-free survival was worse if patients presented with LVEF < 40% (P = 0.001).CONCLUSIONIn our group of patients with a recent complicated MI, abnormal autonomic parameters have been found with a prevalence that was similar for STEMI and NSTEMI cases, and substantially unchanged in comparison to what reported in the pre-primary-PCI era. Long-term outcomes did not correlate with level of depression of HRV parameters recorded in the subacute phase of the disease, both in STEMI and in NSTEMI patients. These results support lack of prognostic significance of traditional HRV parameters when immediate coronary reperfusion is utilised.

Relationship between Ambient Fine Particles and Ventricular Repolarization Changes and Heart Rate Variability of Elderly People with Heart Disease in Beijing, China

Objective To explore the effects of particulate matters less than 2.5 μm in aerodynamic diameter （PM2.5） on heart repolarization/depolarization and heart rate variability （HRV）. Methods We conducted a panel study for elderly subjects with heart disease in Beijing from 2007 to 2008. PM2.5 was measured at a fixed station for 20 h continuously each day while electrocardiogram （ECG） indexes of 42 subjects were also recorded repeatedly. Meteorological data was obtained from the China Meteorological Data Sharing Service System. A mixed linear regression model was used to estimate the associations between PMz.s and the ECG indexes. The model was adjusted for age, body mass index, sex, day of the week and meteorology. Results Significant adverse effects of PM2.5 on ECG indexes reflecting HRV were observed statistically and the strongest effect of PM2.s on HRV was on lag i day in our study. However, there were no associations between PM2.5 and ECG indexes reflecting heart repolarization/depolarization. Additionally, the effects of PM2.5 on subjects with hypertension were larger than on the subjects without hypertension. Conclusion This study showed ambient PM2.5could affect cardiac autonomic function of the elderly people with heart disease, and subjects with hypertension appeared to be more susceptive to the autonomic dysfunction induced by PM2.5.

Heart rate variability： a new tool to predict complications in adult cardiac surgery

Heart rate variability （HRV） refers to the variations between consecutive heartbeats, which depend on the continuous modulation of the sympathetic and parasympathetic branches of the autonomic nervous system. HRV has been shown to be effective as a predictor of risk after myocardial infarction and an early warning sign of diabetic neuropathy, and in the cardiology setting is now recognized to be a useful tool for risk-stratification after hospital admission and after discharge. Recent evidences suggest that HRV analysis might predict complications even in patients undergoing cardiac surgery, and the present review summarizes the importance of HRV analysis in adult cardiac surgery and the perspectives for HRV use in current clinical practice. Although future larger studies are warranted before HRV can be included into daily clinical practice in adult cardiac surgery, HRV is a novel tool which might detect autonomic instability in the early postoperative phase and during hospital stay, thus predicting or prompt-diagnosing many of the post-operative complications.

Effects of Impaired Glucose Metabolism on Heart Rate Variability and Blood Pessure Variability in Essential Hpertensive Patients

To investigate the effects of impaired glucose metabolism （IGM） on cardiovascular autonomic nervous systems in essential hypertensive （EH） patients by comparing heart rate variability （HRV） and blood pressure variability （BPV） in EH patients with or without type 2 diabetes mellitus （T2DM）. Simultaneous 24-h recordings of ambulatory ECG and blood pressure monitoring were performed in 36 male old patients with simple EH and 33 male old patients with EH combined with T2DM. HRV analysis included time domain parameters such as SDNN, SDANN, SDNNi, rMSSD and pNN50, and total spectral power （TP） of HRV, which mainly consists of VLF, LF and HF component along with LF/HF ratio, was also obtained. The value of ambulatory blood pressure was represented as the mean blood pressure （mean systolic/mSBP, diastolic/mDBP and pulse pressure/mPP） during different periods （24 h/24 h, day time/d and night time/n）. Standard deviation （SD） as well as coefficient of variance （CV） of blood pressure during each above-mentioned period were obtained to reflect the long-term BPV. Our result showed that SDNN, SDNNi, SDANN, rMSSD, PNN50, TP and HF of HRV in cases of EH with T2DM were all significantly lower than those in simple EH subjects （P〈0.05）. No significant differences in VLF or LF was found between the two groups （P〉0.05）, while LF/HF ratio was significantly higher in EH with T2DM patients than in simple EH subjects （P〈0.01）. Moreover, dmSBP, 24 h-mPP and dmPP were all significantly higher in EH with T2DM patients than in simple EH subjects （P〈0.05）, while nmSBP, 24 h-mSBP, 24 h-mDBP, dmDBP, nmDBP or nmPP showed no significant difference between this two groups of patients （P〉0.05）. And dSBPSD, dSBPCV and 24 h-SBPSD were all significantly higher in EH with T2DM patients than in simple EH subjects （P〈0.05）, while the other BPV indexes showed no significant difference between this two groups （P〉0.05）. It is concluded that the cardiovascular autonomic nervous systems in EH patients was further impaired by T2DM, displaying lowering of HRV and enlargement of BPV, which in turn induced abnormal structural and functional changes of cardiovascular systems. Therefore, improving cardiovascular autonomic nervous systems might reduce the occurrence of cardiovascular complications in the EH patients with IGM.

Analysis of heart rate variability based on singular value decomposition entropy

Assessing the dynamics of heart rate fluctuations can provide valuable information about heart status. In this study, regularity of heart rate variability （HRV） of heart failure patients and healthy persons using the concept of singular value decomposition entropy （SvdEn） is analyzed. SvdEn is calculated from the time series using normalized singular values. The advantage of this method is its simplicity and fast computation. It enables analysis of very short and non-stationary data sets. The results show that SvdEn of patients with congestive heart failure （CHF） shows a low value （SvdEn： 0.056±0.006, p 〈 0.01） which can be completely separated from healthy subjects. In addition, differences of SvdEn values between day and night are found for the healthy groups. SvdEn decreases with age. The lower the SvdEn values, the higher the risk of heart disease. Moreover, SvdEn is associated with the energy of heart rhythm. The results show that using SvdEn for discriminating HRV in different physiological states for clinical applications is feasible and simple.

Power Spectral Analysis of Heart Rate Variability of Driver Fatigue

This investigation was to evaluate the driving fatigue based on power spectral analysis of heart rate variability (HRV) under vertical vibration. Forty healthy male subjects (29.7±3.5 years) were randomly divided into two groups, Group A (28.8±4.3 years) and Group B (30.6±2.7 years). Group A (experiment group) was required to perform the simulated driving and Group B (control group) kept calm for 90 min. The frequency domain indices of HRV such as low frequency (0.04 0.15 Hz, LF), high frequency (0.150.4 Hz, HF), LF/HF together with the indices of hemodynamics such as blood pressure (BP) and heart rate (HR) of the subjects between both groups were calculated and analyzed after the simulated driving. There were significances of the former indices between both groups (P<0.05). All the data collected after experiment of Group A was observed the remarkable linear correlation (P<0.05) and parameters and errors of their linear regression equation were stated (α=0.05, P<0.001) in this paper, respectively. The present study investigated that sympathetic activity of the subjects enhanced after the simulated driving while parasympathetic activities decreased. The sympathovagal balance was also improved. As autonomic function indictors of HRV reflected fatigue level, quantitative evaluation of driving mental fatigue from physiological reaction could be possible.

Altered heart rate variability and pulse-wave velocity after spinal cord injury

BACKGROUND Heart rate variability(HRV) and pulse-wave velocity(PWV),indicators of cardiac function,are altered in patients with spinal cord injury(SCI),suggesting that autonomic cardiac function and arterial stiffness may underlie the high risk of cardiovascular complications in these patients.No study has simultaneously investigated HRV and PWV in the same patients.AIM To evaluate cardiovascular complications in SCI patients by comparing HRV and PWV between patients with and without SCI.METHODS In this cross-sectional pilot study,patients with(n = 60) and without SCI(n = 60) were recruited from December 7,2019 to January 21,2020.Each participant received a five-minute assessment of HRV and the cardiovascular system using the Medicore HRV Analyzer SA-3000 P.Differences in HRV and PWV parameters between participants with and without SCI were statistically examined.RESULTS We observed a significant difference between participants with and without SCI with respect to the standard deviation of all normal-to-normal intervals,square root of the mean sum of squared successive risk ratio interval differences,physical stress index,total power,very-low frequency,low frequency,high frequency,and arterial elasticity.CONCLUSION Patients with SCI have weaker sympathetic and parasympathetic activity as well as lower arterial elasticity compared to those without,suggesting that SCI may increase cardiac function loading.

Qi Gong and Heart Rate Variability: A Systematic Review

Qì Gōng is a type of exercise that involves meditation and is used for health. With a background from the martial arts, it is known also as an auto healing exercise with three main elements according to Traditional Chinese Medicine (TCM): body focus (posture and movement), breathing and mind focus (meditative elements). Heart rate variability is a tool that allows us to measure the autonomic system velocity to detect and respond to unexpected stimuli. So our goal was to build a systematic review of Qi Gong and Heart rate variability. PUBMED, EBSCO and Science Direct data bases were searched. Key terms (MeSH) were Heart Rate Variability and Ch’i Kung OR Qi Gong with a 10-year filter. Four independent reviewers analyzed all articles and excluded duplicated articles, articles in Chinese and articles with no adherence to the subject. The end result was 5 studies selected. Our results showed no significant improvements in HRV with the practice of Qì Gōng, probably because of data heterogeneity. We found 5 types of Qì Gōng, 3 different instruments and different time intervals to measure HRV and 2 different age groups in the studies. We can conclude that there is evidence that Qì Gōng can improve HRV but studies that would use the same parameters are needed to further confirm that.

Correlation between heart rate variability and pupillary reflex in healthy adult subjects under the influence of alcohol

This study explored the association between pupil area variation, heart rate variability, and fatigue, caused by alcohol consumption. Sixteen healthy young male volunteers were enrolled in this study for a series of structured physical examinations. Individual drinking volume was strictly assessed in accordance with the normalized experimental design. The motions of the subjects＇ pupils, as well as electrocardiograms were recorded by a computerized recording system, both before and after drinking alcohol. After alcohol intake, the pupil diameter, and both low frequency and standard deviation of all heartbeat interval indices of heart rate variability showed significant variations compared with the baseline. In addition, time- and frequency-domain indices of heart rate variability were negatively associated with pupil area. Thus the current study suggests that fatigue status may be determined by significant changes in pupil area and heart rate variability.

Protective effects of rice bran hydrolysates on heart rate variability,cardiac oxidative stress,and cardiac remodeling in high fat and high fructose diet-fed rats

Objective:To examine the ameliorative effect of rice bran hydrolysates(RBH)on metabolic disorders,cardiac oxidative stress,heart rate variability(HRV),and cardiac structural changes in high fat and high fructose(HFHF)-fed rats.Methods:Male Sprague-Dawley rats were daily fed either standard chow diet with tap water or an HFHF diet with 10%fructose in drinking water over 16 weeks.RBH(500 and 1000 mg/kg/day)was orally administered to the HFHF-diet-fed rats during the last 6 weeks of the study period.At the end of the treatment,metabolic parameters,oxidative stress,HRV,and cardiac structural changes were examined.Results:RBH administration significantly ameliorated metabolic disorders by improving lipid profiles,insulin sensitivity,and hemodynamic parameters.Moreover,RBH restored HRV,as evidenced by decreasing the ratio of low-frequency to highfrequency power of HRV,a marker of autonomic imbalance.Cardiac oxidative stress was also mitigated after RBH supplementation by decreasing cardiac malondialdehyde and protein carbonyl,upregulating eNOS expression,and increasing catalase activity in the heart.Furthermore,RBH mitigated cardiac structural changes by reducing cardiac hypertrophy and myocardial fibrosis in HFHFdiet-fed rats.Conclusions:The present findings suggest that consumption of RBH may exert cardioprotective effects against autonomic imbalances,cardiac oxidative stress,and structural changes in metabolic syndrome.

Modeling of Heart Rate Variability Using Time-Frequency Representations

The heart rate variability signal is highly correlated with the respiration even at high workload exercise.It is also known that this phenomenon still exists during increasing exercise.In the current study,we managed to model this correlation during increasing exercise using the time varying integral pulse frequency modulation(TVIPFM)model that relates the mechanical modulation(MM)to the respiration and the cardiac rhythm.This modulation of the autonomic nervous system(ANS)is able to simultaneously decrease sympathetic and increase parasympathetic activity.The TVIPFM model takes into consideration the effect of the increasing exercise test,where the effect of a time-varying threshold on the heart period is studied.Our motivation is to analyze the heart rate variability(HRV)acquired by time varying integral pulse frequency modulation using time frequency representations.The estimated autonomic nervous system(ANS)modulating signal is filtered throughout the respiration using a time varying filtering,during exercise stress testing.And after summing power of the filtered signal,we compare the power of the filtered modulation of the ANS obtained with different time frequency representations:smoothed pseudo Wigner–Ville representation,spectrogram and their reassignments.After that,we used a student t-test p<0.01 to compare the power of heart rate variability in the frequency band of respiration and elsewhere.

A very high frequency index of heart rate variability for evaluation of left ventricular systolic function and prognosis in chronic heart failure patients using five-minute electrocardiogram

Objective A novel index based on fi-equency-domain analysis of heart rate variability （HRV） was tested on patients with reduced left ventricular systolic function. This index, namely VHFI, was defined as the very high frequency （VHF） component of the power spectrum normalized to represent its relative value in proportion to the total power minus the very low frequency component. Methods Patients （n = 130） were divided into a study group, consisting 66 patients with decreased left ventricular systolic function, and a control group, consisting 64 patients with normal heart structure and function and without severe coronary artery stenosis （〈 50%）. Results VHFI in the study group was significantly higher than that in the control group （19.17 ± 13.35 vs 11.37 ± 10.77, P 〈 0.001）. Cardiac events occurred in 18 patients during follow-up （33.34 i 3.26 months）. Defining the positive test as VHFI =15 and negative test as VHFI 〈15, achieved a sensitivity of 57.58% and a specificity of78.13% for predicting decreased left ventricular systolic function, and achieved a sensitivity of 66.67% and a specificity of 64.29% for predicting cardiac events. Univariate Cox regression analysis showed that positive VHFI test was an independent variable in predictive cardiac events. Conclusions The results suggest that VHFI is a useful tool for quick evaluation of left ventricular systolic function and prediction of prognosis

Change of Nonlinear Heart Rate Variability Indices in Different Seasons

The study investigates the nonlinear heart rate variability indices in different seasons and their dependence on current meteorological factors. The study included 61 relatively healthy student volunteers, their age were 19-23 and they were examined repeatedly in different seasons. The HRV （heart rate variability） recording was performed with the use of the hardware-software complex ＂Varikard 2.51＂ Nonlinear HRV indices were calculated by means of the Kubios HRV 2.1. The following indicators： SD1, SD2, SD1/SD2, D2, DFA, SampEn and quantitative indicators of recurrence analysis （RQA ）---Lmean, Lmax, REC, DET, ShanEn had been analyzed. Statistical analysis was performed using the Statistica 6.0. For the detection of between-group differences were used Repeated Measures ANOVA, and the dependence of nonlinear HRV indices on meteorological was analyzed with the use of multiple non-linear regression. The investigation showed a relative increase in SampEn and the reduction of al in winter and spring seasons, strengthening relationships SampEn correlation with other indicators in the winter season as well as the dependence SampEn on meteorological factors in summer. The detected changes can be considered as the realization of adaptive response of a healthy body.

The Effect of Circuit Training on Resting Heart Rate Variability, Cardiovascular Disease Risk Factors and Physical Fitness in Healthy Untrained Adults

The purpose of the present study was to examine the effect of circuit training (CT) on resting heart rate variability (HRV) and other cardiovascular disease (CVD) risk factors such as blood lipids and blood glucose and on fitness components. Twenty-four healthy untrained adults (age 26.5 ± 5.1 years;height 1.67 ± 8.4 m;weight 66.8 ± 15.1 kg;26.3% ± 5.2%;maximum oxygen uptake (VO2max) 48.5 ± 10.0 ml.kg-1.min-1) were assigned to either CT (n = 12) involving bodyweight exercises, or control (CON, n = 12) groups. Prior to the start and following the end of the six-week training period, time-, frequency-domain and nonlinear measures of resting HRV, arterial blood pressure, body composition, fasting blood lipids, lipoproteins and glucose, VO2max, upper body muscular endurance (UBME) and abdominal and hip flexor (AHFME), back strength (BS) and handgrip were assessed. None of the resting HRV measures (P > 0.05) were affected by the CT intervention. However, diastolic blood pressure decreased (P = 0.03), lean body weight (P = 0.03) increased, VO2max (P = 0.03), UBME (P = 0.001), AHFME (P = 0.04), and BS (P = 0.03) were significantly higher following CT, whereas the other variables were not influenced by the CT. Six-week of CT involving bodyweight exercises has no significant impact on resting HRV. However, this type of training might decrease the risk for development of CVD by reducing arterial blood pressure and by improving body composition, aerobic capacity, muscular endurance and strength.

The association of salivary alpha-amylase, heart rate variability, and psychological stress on objectively measured sleep behaviors among college students

Objective:This study aimed to evaluate sleep behaviors among college students,to assess salivary alpha-amylase(sAA)and heart rate variability(HRV)in association with stress,and to investigate sleep-related factors including sAA,HRV,and stress among them.Methods:Saliva samples for sAA assessment and HRV measurements in the supine position were taken between 3 PM and 6 PM.The level of prolonged psychological stress for the previous week was evaluated using the Korean version of the Global Assessment of Recent Stress(GARS-K),and sleep behaviors were assessed using an actigraphy device.Results:A total of 86 healthy college students participated in this study.Sleep behaviors of the college students were not good,with 84%sleep efficiency(SE)and 62.7 min wake after sleep onset(WASO).The average sAA level was 65.8 U/mL in the participants.Although neither the sAA level nor HRV indices were significantly correlated with prolonged psychological stress,decreased normalized high frequency(nHF)on HRV was independently associated with a higher level of stress when adjusted for age and sex.Higher stress(r=-0.276,P=0.011)and lower sAA(r=0.266,P=0.030)had significant correlations with shorter time in bed;however,it was sAA that was independently associated with time in bed(β=0.244,p=0.044).Decreased nHF(β=0.245,P=0.027)and higher body mass index(BMI)(β=-0.224,P=0.043)were independently related to and poorer SE.Conclusions:Poor sleep behaviors were associated with decreased parasympathetic activity,a physiological change to psychological stress,rather than with psychological stress itself among college students.Thus,sAA and HRV should be considered as significant factors for impaired sleep behaviors in relation to psychological stress.

Modified Multiple Scale/Segment Entropy （MMPE） Analysis of Heart Rate Variability of NHH, CHF ＆ AF Subjects

Nonlinear analysis of heart rate variability （HRV） has become important as heart behaves as a complex system. In this work, the approximate entropy （ApEn） has been used as a nonlinear measure. A new concept of estimating the ApEn in different segments of long length of the recorded data called modified multiple scale （segment） entropy （MMPE） is introduced. The idea of estimating the approximate entropy in different segments is useful to detect the nonlinear dynamics of the heart present in the entire length of data. The present work has been carried out for three cases namely the normal healthy heart （NHH） data, congestive heart failure （CHF） data and Atrial fibrillation （AF） data and the data are analyzed using MMPE techniques. It is observed that the mean value of ApEn for NHH data is much higher than the mean values for CHF data and AF data. The ApEn profiles of CHF, AF and NHH data for different segments obtained using MPE profiles measures the heart dynamism for the three different cases. Also the power spectral density is obtained using fast fourier transform （FFT） analysis and the ratio of LF/HF （low frequency/high frequency） power are computed on multiple scales/segments namely MPLH （multiple scale low frequency to high frequency） for the NHH data, CHF data and AF data and analyzed using MPLH techniques. The results are presented and discussed in the paper.