Objective assessment of sleep and sleep problems in older adults with intellectual disabilities

Little is known about sleep in older adults with intellectual disability (ID). Aim of this study was to investigate sleep and its associated factors, and to estimate the prevalence of sleep problems in this population. This study was part of the healthy aging and intellectual disabilities study. Sleep was assessed using the Actiwatch, a watch-like device that measures sleep and wakefulness based on movement activity. Participants (n = 551) wore the Actiwatch at least seven days and nights continuously. Variables of interest were time in bed (TIB), sleep onset latency, total sleep time, wake after sleep onset, sleep efficiency and get-up time latency. Multivariate analyses were used to investigate factors associated with these sleep parameters. Provisional definitions were drafted to estimate the prevalence of sleep problems. Mean TIB was 630 min. Longer TIB was independently associated with higher age, more severe level of ID, living at a central facility, wheelchair dependence, female gender and depressive symptoms (adjusted R² = .358, F-change = 8.302, p < .001). The prevalence of sleep problems was 23.9% settling problem, 63.1% night waking problem, 20.9% short sleep time, 9.3% early waking problem. 72% of the participants had at least one problem, 12.3% had three or more sleep problems. Older adults with ID lie in bed very long, and the prevalence of sleep problems is high. Further research should focus on causality of the relationships found in this study, and effects of sleep problems on health and well-being in this population.     

Nocturnal heart rate variation in diabetic and non-diabetic patients with sleep apnea syndrome

ObjectivesHeart rate variability (HRV) analysis is used for the evaluation of autonomic function in the cardiovascular system. Decreased HRV is associated with disorders affecting the autonomous system such as diabetes mellitus (DM) and obstructive sleep apnea (OSA). Previous studies have shown an association between OSA and DM. However, the interrelationships of HRV with OSA and DM are not well known. The aim of this study was to assess nocturnal HRV in patients who suffered from OSA with and without DM.MethodsSixty patients with OSA (27 with DM and 33 non-DM) underwent polysomnography for eight hours starting at midnight. From electrocardiogram (ECG) recordings taken as a part of polysomnography, time-domain and frequency-domain HRV parameters were evaluated to compare patients with regard to nocturnal HRV components such as low frequency (LF) and high frequency (HF), apnea–hypopnea index (AHI) and sleep parameters.ResultsIn the non-DM group, a direct relationship was observed between AHI and HRV rather than very low frequency (VLF) and LF/HF variables. This relationship was just significant between AHI and standard deviation of five-min average of normal R–R intervals and adjacent R–R intervals differing by 0.50 ms over 24 h (p < 0.05). In the DM group, the correlation between AHI and HRV parameters except HF and waking frequency was direct and non-significant. Intergroup comparison showed a significant difference between groups regarding AHI and HRV-index, LF and VLF (p < 0.05).ConclusionsDM can affect HRV; however, this is not the case in OSA patients. This means that in the presence of OSA, the DM effect on HRV disappears.     

快眼动睡眠行为障碍与心率变异性的关系研究

目的 探讨快眼动睡眠行为障碍(REM sleep behavior disorder,RBD)患者的心率变异指标,评估心脏自主神经功能的情况。方法 本研究选取2016年1月-2017年12月就诊于新疆医科大学第五附属医院神经内科门诊及住院的患者,并经视频多导睡眠监测(vPSG)且符合RBD诊断标准的患者30例作为病例组,其中特发性RBD 5例,帕金森病(PD)伴RBD 12例,多系统萎缩(MSA)伴RBD 8例,进行性核上性麻痹(PSP)伴RBD 5例。另选健康对照者25例。使用动态心电图的心率变异(HRV)分析来定量测定30例RBD患者和25例健康对照者的时域及频域分析指标,比较2组的HRV情况。结果 病例组患者的时域分析指标如NN间期标准差(SDNN)、每5 min NN间期标准差(SDANN)、每5 min NN间期标准差的均值(ASDNN)及相邻NN间期差值的均方根(rMSSD)均较健康对照组低(P均<0.05)。病例组频域分析指标低频功率(LF)、高频功率(HF)、LF/HF均较健康对照组低(P均<0.05)。结论 RBD患者存在不同程度的HRV下降情况,提示心脏自主神经功能损害。     

心率变异指标在焦虑症评估中的应用

目的 探讨心率变异指标在焦虑症评估中的作用.方法 对33例焦虑症患者及28例正常对照者进行心率变异检测,结束后进行焦虑自评量表及匹兹堡睡眠质量指数评定.结果 焦虑症患者的窦性RR间期的标准差、极低频带低于正常对照者,差异非常显著,总频谱、高频带低于正常组,差异显著,睡眠质量指数得分明显低于对照组;时域指标窦性RR间期的标准差与频域各指标存在明显相关.结论 焦虑症患者心率变异性降低.     

Relationship between frequency spectrum of heart rate variability and autonomic nervous activities during sleep in newborns

Introduction

We analyzed the frequency spectrum of two neonatal sleep stages, namely active sleep and quiet sleep, and the relationship between these sleep stages and autonomic nervous activity in 74 newborns and 16 adults as a comparison.

The effect of aging and severity of sleep apnea on heart rate variability indices in obstructive sleep apnea syndrome

Objective

This study aims to analyze how much heart rate variability (HRV) indices discriminatively respond to age and severity of sleep apnea in the obstructive sleep apnea syndrome (OSAS).

Methods

176 male OSAS patients were classified into four groups according to their age and apnea-hypopnea index (AHI). The HRV indices were compared via analysis of covariance (ANCOVA). In particular, the partial correlation method was performed to identify the most statistically significant HRV indices in the time and frequency domains. Stepwise multiple linear regressions were further executed to examine the effects of age, AHI, body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), and sleep parameters on the significant HRV indices.

Results

The partial correlation analysis yielded the NN50 count (defined as the number of adjacent R-wave to R-wave intervals differing by more than 50 ms) and low frequency/high frequency (LF/HF) ratio to be two most statistically significant HRV indices in both time and frequency domains. The two indices showed significant differences between the groups. The NN50 count was affected by age (p<0.001) and DBP (p=0.039), while the LF/HF ratio was affected by AHI (p<0.001), the amount of Stage 2 sleep (p=0.005), and age (p=0.021) in the order named in the regression analysis.

Conclusion

The NN50 count more sensitively responded to age than to AHI, suggesting that the index is mainly associated with an age-related parasympathetic system. On the contrary, the LF/HF ratio responded to AHI more sensitively than to age, suggesting that it is mainly associated with a sympathetic tone likely reflecting the severity of sleep apnea.     

周期性肢动症相关心率变化特点的研究进展

周期性肢动症(Periodic Limb Movement Dur-ing Sleep ,PLMS)是一种睡眠相关的运动障碍 ,以睡眠期出现反复发作的刻板性肢体运动为特征[1] .国外研究证实,伴随 PLMS 的发生 ,心率出现典型的"心动过速-过缓"变化,并提示 PL MS 与交感系统活性存在一定关系 ,从而对心脑血管系统产生一定的影响.相关研究还提示 ,PL M S 相关的心率变化受多种客观因素影响 ,并且涉及多种疾病.现就不同客观因素及疾病状态时PLMS相关心率变化的特点作一综述.     

Multimodal brain imaging investigation of self-reported sleep quality and daytime sleepiness in older adults with heart failure

ABSTRACT

Purpose of the study: Individuals with heart failure (HF) have a high frequency of sleep problems. Patients with HF present with structural brain changes different from normal aging including reductions in brain volume, increases in white matter hyperintensity (WMH) and reduced cerebral blood flow. These structural changes in the brain may explain the pathophysiology of sleep and daytime problems. The objective of this study was to determine whether multimodal imaging data are related to self-reported sleep problems and daytime sleepiness in older adults with HF.

Methods: Participants in this study underwent magnetic resonance imaging scans on the General Electric 3.0 T Discovery MR750 to acquire WMH, cerebral blood flow and brain volume. Data on 37 stable HF patients (mean age = 68; SD = 5.75) were included.

Results: In this sample, WMH was associated with daytime sleepiness (p = 0.025). However, gray and white matter volume and cerebral blood flow were not associated with daytime sleepiness, sleep quality or insomnia.

Conclusion: Although further studies are needed to determine the relationship between WMH and sleep and daytime problems, the findings preliminarily support that increases in WMH from ischemic changes could explain increases in daytime sleepiness among people with HF.     

Objective sleep measures between patients with Parkinson's disease and community-based older adults

ObjectivesPrevious studies comparing objective sleep measures between patients with Parkinson's disease (PD) and control participants were limited by their small sample size. The purpose of this study was to compare objective sleep measures between large-scale cohorts of PD outpatients and community-based older adults.MethodsIn this cross-sectional study, we measured sleep parameters for 157 PD patients using an actigraph on the non-dominant wrist for six consecutive nights (95 Hoehn–Yahr stage I/II; 62 Hoehn–Yahr stage III–V). Moreover, two consecutive nights of actigraphy were performed on 1101 community-based control participants aged ≥60 years.ResultsIn multivariable analysis, sleep efficiency (SE) was significantly lower in patients with late-stage PD by 17.5% [95% confidence interval: 15.3%–19.7%] and early-stage PD by 9.4% [7.6%–11.1%] compared to the controls (67.1% and 75.3% vs. 84.6%, respectively). Similar results were observed for wake after sleep onset (WASO) and fragmentation index (FI). Total sleep time and sleep onset latency (SOL) were significantly shorter in patients with late- and early-stage PD stage compared to the controls. Among PD patients, significant association trends between advancement of individual Hoehn–Yahr stages and worsened sleep measures of SE, WASO, and FI were observed independently of age, gender, levodopa equivalent dose, and motor function parameter.ConclusionThis study demonstrated significant and quantitative differences in objective sleep quality and quantity between PD patients and control participants. Furthermore, with advancement of disease stages, objectively measured sleep quality worsened in PD patients.     

Genetic factors contribute to the variance in frequency domain measures of heart rate variability

Power spectral analysis of heart rate variability (HRV) provides quantitative phenotypic markers of autonomic nervous system activity. Reported determinants of HRV only partially explain its variability in the population. The purpose of this study was to estimate the contribution of genetic factors to the variance in HRV measures and assess the heritability of HRV. Subjects who underwent Holter recordings at a routine examination were eligible, excluding subjects with congestive heart failure, coronary artery disease, diabetes mellitus and those taking cardioactive medications. We analyzed the low-frequency power (LF), high-frequency power (HF), LF/HF ratio, very low-frequency power (VLF) and total power (TP). Heritability analysis was done by studying correlations between siblings (n = 682, in 291 sibships, 517 pairs) and between spouse pairs (n = 206 pairs). Adjustments were made for sex, age, systolic and diastolic blood pressure, heart rate, coffee and alcohol intake. SAS procedure MIXED was used to estimate and test significance of correlation within sibling pairs and within spouse pairs. Results from separate models were combined to estimate the components of variance of each phenotype, i.e. variance attributable to measured covariates, additive genetic effects (heritability) and household effects. After adjusting for covariates, the correlations were consistently higher among siblings (0.21-0.26) compared to spouses (0.01-0.19). The measured covariates in general accounted for 13-40% of the total phenotypic variance, whereas genes accounted for 13-23% of the variation among HRV measures. Genetic factors contribute towards a substantial proportion of the variance in heart rate and HRV. Recognition of the genetic determinants of HRV may provide additional insight into the pathophysiology of the autonomic nervous system and offer clues toward its modulation.     

Subjective sleep quality in stable neuromuscular patients under non-invasive ventilation

Objectives

Patients with neuromuscular diseases improve their sleep when treated with noninvasive ventilation (NIV), but their sleep architecture during NIV may still be disturbed by side effects of NIV or inadequacy of the ventilator setting. Little is known about subjective sleep quality during NIV. The aims of this study were to evaluate subjective sleep quality of stable neuromuscular patients under long-term NIV by using Pittsburgh questionnaire (PSQI), and to assess its possible determinants.

Methods

Fifty stable neuromuscular patients under long-term NIV were administered PSQI and underwent polysomnography. Arterial blood gases, forced vital capacity, and respiratory muscular strength were measured.

Results

Thirty-three patients had global PSQI ≥ 5 and were classified as bad sleepers. Good and poor sleepers differed in age (P = 0.005), base excess (BE) (P = 0.02), NIV inspiratory pressure (P = 0.04), %N1 (P = 0.0006), and %N3 sleep stage (P = 0.02). Percent N3 duration and Arousal/Awakening Index were correlated with rate of patient–ventilator asynchronies (r = −0.41 and 0.37, respectively, P < 0.05) and with NIV inspiratory pressure (r = −0.44 and 0.36, P < 0.01 and <0.05, respectively). At the final multivariate regression model, only BE and %N3 independently predicted global PSQI (r² = 0.326, P < 0.001).

Conclusions

Subjective sleep quality is often poor in neuromuscular patients under long-term NIV. Amount of slow wave sleep and chronic hypoventilation resulting in increased BE are independent predictors of subjective sleep quality. Since inadequate NIV setting or application can influence sleep structure and alveolar ventilation, great care should be paid to the setting and the correct application of NIV to ensure a better subjective sleep quality.     

Heart rate recovery after the 10-m incremental shuttle walking test in older adults with intellectual disabilities

Heart rate recovery (HRR) after exercise is an independent predictor for cardiovascular and all-cause mortality. To investigate the usefulness of HRR in cardiorespiratory exercise testing in older adults with intellectual disabilities (ID), the aims of this study were (a) to assess HRR in older adults with ID after the 10-m incremental shuttle walking test (ISWT) and (b) its association with personal characteristics (gender, age, distance walked on the ISWT, level of ID, genetic syndrome causing ID, autism, behavioral problems, and peak heart rate (HRpeak)). HRR was assessed after the 10-m incremental shuttle walking test in 300 older adults (>50 years) with borderline to profound ID. HRR was defined as the change from HRpeak during the ISWT to heart rate measured after 1, 2, 3, 4, and 5 min of passive recovery. The largest decrease in heart rate was in the first minute of recovery leveling off toward the fifth minute of recovery. An abnormal HHR (≤12 bpm) was seen in 36.1% of the participants with Down syndrome (DS) and in 30.7% of the participants with ID by other causes. After the fifth minute the heart rates of 69.4% of the participants with DS and of 61.4% of the participants with ID by other causes returned to resting levels. HRpeak and distance walked on the ISWT were positively related to all HRR measures. More severe ID was negatively related and having DS positively related to HRR after 3–5 min of recovery. The other characteristics were not significantly associated to HRR. HRR is a potentially useful outcome measure in cardiorespiratory fitness testing of older adults with ID with a direct, objective, and non-invasive measurement. Further research is needed to identify the relation between HRR and adverse health outcomes in this population.     

Correlation between electroencephalography and heart rate variability during sleep

It is known that autonomic nervous activities change in correspondence with sleep stages. However, the characteristics of continuous fluctuations in nocturnal autonomic nerve tone have not been clarified in detail. The study aimed to determine the possible correlation between the electroencephalogram (EEG) and autonomic nervous activities, and to clarify in detail the nocturnal fluctuations in autonomic nerve activities. Overnight EEGs and electrocardiograms of seven healthy males were obtained. These EEGs were analyzed by fast Fourier transformation algorithm to extract delta, sigma and beta power. Heart rate and heart rate variability (HRV) were calculated in consecutive 5-min epochs. The HRV indices of low frequency (LF), high frequency (HF) and LF/HF ratio were calculated from the spectral analysis of R-R intervals. The sleep stages were manually scored according to Rechtschaffen and Kales' criteria. Low frequency and LF/HF were significantly lower during non-rapid eye movement (NREM) than REM, and were lower in stages 3 and 4 than in stages 1 and 2. Furthermore, delta EEG showed inverse correlations with LF (r = - 0.44, P < 0.001) and LF/HF (r = - 0.41, P < 0.001). In contrast, HF differed neither between REM and NREM nor among NREM sleep stages. Detailed analysis revealed that correlation was evident from the first to third NREM, but not in the fourth and fifth NREM. Delta EEG power showed negative correlations with LF and LF/HF, suggesting that sympathetic nervous activities continuously fluctuate in accordance with sleep deepening and lightening.     

Lacunar stroke and heart rate variability during sleep

ObjectiveAutonomic instability during sleep can influence the risk of cerebrovascular diseases. In this study, we performed a polygraphy to evaluate, heart rate variability (HRV) in a group of patients with lacunar stroke that is a condition at high risk of recurrence.MethodsTwenty-one lacunar stroke patients were enrolled one month after stroke occurrence. Sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI). The presence of common sleep disorders and autonomic changes during the night was investigated by a polygraphy monitoring. Results were compared with those obtained in a group of 21 healthy subjects.ResultsPatients and controls were similar for age, sex distribution and main cardiovascular risk factors with the exception of the body mass index. Significant differences were detected for all polysomnographic (PSG) parameters and for the PSQI score. By considering HRV values, patients with pathologic values (12 patients, HRV>2) showed significantly higher values in BMI (31 ± 2.9 vs. 26.6 ± 3.6, p = 0.006) and PSQI scores (7.9 ± 2.6 vs. 4.2 ± 1.9) with respect to patients with normal HRV values (nine patients, HRV≤2).ConclusionsThe results of this study suggest that the prevalence of nocturnal autonomic dysfunction is high in lacunar stroke patients even in the absence of the commonest sleep-related disorders. An abnormal HRV may contribute to increase the risk of stroke recurrence. Based on our results, the indication to polygraphy in patients with lacunar stroke should be carefully considered.     

Agreement between sleep diary and actigraphy in a highly educated Brazilian population

ObjectiveThis study evaluated the agreement between a sleep diary and actigraphy on the assessment of sleep parameters among school teachers from Brazil.MethodsA total of 163 teachers (66.3% women; aged 45 ± 9 years) filled out a sleep diary and wore a wrist actigraph device for seven consecutive days. Data were collected from August 2014 to March 2015 in Londrina, a large city in southern Brazil. Intraclass correlation coefficients (ICC) and Pearson correlation coefficients (r) were used to compare self-reported and actigraphic data.ResultsSelf-reported total sleep time (TST), sleep onset latency (SOL), and sleep efficiency were higher than measured by actigraphy (mean difference: 22.6 ± 46.9 min, 2.6 ± 13.3 min, and 7.3± 5.7%, respectively). Subjective total time in bed (TIB) and wake-up time were lower than measured by actigraphy (mean difference: −10.7 ± 37.6 and −19.7 ± 29.6, respectively). Moderate or good agreement and correlation were found between the sleep diary and the actigraphic data for TST (ICC = 0.70; r = 0.60), TIB (ICC = 0.83; r = 0.73), bedtime (ICC = 0.95; r = 0.91), sleep start time (ICC = 0.94; r = 0.88), and wake-up time (ICC = 0.87; r = 0.78). However, SOL (ICC = 0.49; r = 0.38) and sleep efficiency (ICC = 0.16; r = 0.22) showed only fair or poor agreement and correlation.ConclusionIn this highly educated population, the sleep diary and the actigraphy showed moderate or good agreement to assess several sleep parameters. However, these methods seemed to measure different dimensions of sleep regarding sleep onset latency and efficiency. These findings moderately varied according to the individual's subjective sleep quality.     

Effects of caffeine on heart rate and QT variability during sleep

Administration of caffeine in the evening produces poor sleep. Patients with insomnia have characteristic electrocardiogram (ECG) changes, including increased heart rate (HR), increased sympathetic activity, and decreased parasympathetic activity. Fifteen young adult normal subjects slept in the laboratory for several nights prior to randomization into a caffeine protocol where subjects received caffeine 400 mg 30 min prior to one night of sleep and placebo randomly prior to another night. ECG was sampled at a rate of 500 Hz and recorded onto a PC. Data samples of 256-s periods of the ECG trace were taken from wake (before sleep), stage II, and REM for placebo and caffeine conditions. A peak detection algorithm was used to identify the R-R intervals (in milliseconds) from the ECG. A common QT variability algorithm was used to find the QT interval for each beat using the time-stretch model. The powers for HR and QT series were integrated in the bands of LF (low frequency: 0.04-0.15 Hz) and HF (high frequency: 0.15-0.5 Hz) bands. There was a significant caffeine by sleep stage interaction for LF/HF ratios (F = 4.0; df = 2, 18; P = .04). LF/HF ratios were significantly higher during REM following caffeine administration. There was also a significant caffeine by sleep stage interaction for QTvi (QT variability normalized for mean QT interval divided by HR variability normalized for mean HR; F = 5.6; df = 2, 12; P = .02). QTvi was also significantly higher during REM following caffeine administration. The higher LF/HF ratios and QTvi during REM are most likely due to the sympathetic effects of caffeine. These findings suggest that excessive caffeine intake may result in adverse cardiovascular events in vulnerable subjects.     

Subjective sleep quality in adult patients affected by Duchenne muscular dystrophy. Beyond nocturnal hypoventilation

ObjectiveIn stable neuromuscular patients under long-term non-invasive ventilation (NIV), subjective sleep quality may be predicted by chronic hypoventilation, as assessed by base excess (BE), and %N3 sleep stage duration. In this study, we explored how other variables, closely associated with self-reported health complaints, contributed to subjective sleep quality in adult patients with Duchenne muscular dystrophy (DMD).MethodsThis is a secondary analysis of a quality of life study in 48 adult DMD patients under NIV therapy, with little evidence of residual hypoventilation. Subjective sleep quality was evaluated by the Pittsburgh Sleep Quality Index (PSQI). A PSQI score >5 was considered indicative of poor sleep quality. Several other symptoms were evaluated: sleepiness, by the Epworth Sleepiness Scale (ESS); depression and anxiety, by the anxiety and depression subscales of the Hospital Anxiety and Depression Scale (HADS-A and HADS-D); autonomic symptoms, by the Composite Autonomic Symptom Score 31; pain, by the Numeric Pain Rating Scale (NPRS); and fatigue, by the Fatigue Severity Scale (FSS).ResultsMean PSQI was 6.1 ± 2.9. Abnormal scores were found for NPRS in 40, for HADS-A in 10 and for FSS in 24 subjects. The NPRS, HADS-A and FSS scores and the N3 sleep stage, independently predicted PSQI (R² = 0.47, p < 0.0001).ConclusionsIn adult DMD patients, pain, fatigue and anxiety may have a prominent influence on subjective sleep quality. Improvement of sleep quality may be of utmost importance in DMD, as it may ameliorate quality of life and extend its benefits to cardiovascular morbidity and life expectancy.     

Benzodiazepine use and quality of sleep in the community-dwelling elderly population

Background: About 50% of the elderly population report being dissatisfied with their sleep. Although benzodiazepines are the most prescribed drugs to treat sleep complaints, the effectiveness of their use on the quality of sleep is not well documented.

Objectives: This study aimed to assess the association between benzodiazepine use and global sleep quality, as well as six components of sleep quality.

Methods: Data from the cross-sectional Quebec Survey on Seniors’ Health (n = 2798) conducted in 2005–2006 were used. Quality of sleep was self-reported and use of benzodiazepines was assessed during the previous year.

Results: Benzodiazepine users reported poorer quality of sleep than non-users. The association between benzodiazepine use and each of the six quality of sleep components studied were similar except for the daytime dysfunction component.

Conclusion: The results suggest that there is no evidence that using benzodiazepines is associated with better quality of sleep than non-users in the elderly population. Future longitudinal population-based studies are needed to assess improvements in quality of sleep in the elderly associated with the use of benzodiazepines.     

Role of depressive symptoms and comorbid chronic disease on health-related quality of life among community-dwelling older adults

Objective

This study examined the influence of depressive symptoms on health-related quality of life (HRQOL) among community-dwelling older adults suffering from various categories of chronic comorbidity.

Methods

A population-based survey in adults aged 60 years or more was conducted within a random sample of 1085 beneficiaries of the Mexican Institute of Social Security in Mexico City. Depressive symptoms were evaluated with the 15-item Geriatric Depression Scale, and chronic comorbidity was determined with self-reports concerning prior medical diagnoses and the HRQOL Short Form-36 health survey. We carried out a stratified analysis by comorbidity category, evaluating the impact of depressive symptoms on HRQOL through an analysis of variance and modeling the independent association of depression symptoms with HRQOL using multiple linear regression analyses adjusted for comorbidity and other covariables.

Results

HRQOL scores were low in the presence of depressive symptoms, while their impact increased when chronic diseases were also present. The group with the poorest HRQOL was older adults suffering from both depressive symptoms and two or more chronic diseases (P<.05). The stratified analysis by comorbidity and multivariate analysis, adjusted for covariables, indicated that depressive symptoms and comorbidity had cumulative negative effects on HRQOL.

Conclusion

The HRQOL of older adults deteriorated when depressive symptoms were present and decreased even further with the simultaneous occurrence of chronic illnesses. Identifying depression symptoms—either alone or along with chronic conditions—is crucial for implementation of measures aimed at improving elderly people's HRQOL.     

Human heart rate variability and sleep stages

With the aim of better understanding the dynamic changes in sympatho-vagal tone occurring during the night, human heart rate variability (HRV) during the various sleep stages was evaluated by means of autoregressive spectral analysis.Each recording consisted of an electroencephalogram, an electrooculogram, and electromyogram, an electrocardiogram, and a spirometry trace. All of the data were sampled and stored in digital form.Sleep was analysed visually, but HRV was analysed off-line by means of original software using Burg's algorithm to calculate the LF/HF ratio (LF: 0.04–0.12 Hz; HF: 0.15–0.35 Hz) for each sleep stage.Seven healthy subjects (four males; mean age 35 years) were enrolled in the study.Our findings show a progressive and significant reduction in the LF/HF ratio through sleep stages S1–S4, as a result of an increase in the HF component; this indicates the prevalence of parasympathetic activity during slow-wave sleep. During wakefulness, S1 and REM, the LF/HF values were similar and close to 1.

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Sommario Allo scopo di comprendere meglio le modificazioni del tono del sistema nervoso autonomo durante la notte, è stata valutata la variabilità del ritmo cardiaco (HRV) negli stadi del sonno, impiegando una metodica autoregressiva di analisi spettrale.Ciascuna registrazione consisteva di elettroencefalogramma, elettro-oculogramma, elettromiografia, spirometria ed elettrocardiogramma, campionati e registrati in forma digitale.L'ipnogramma è stato ottenuto ispettivamente, mentre l'analisi dell'HRV è stata eseguita con un software dedicato, utilizzando l'algoritmo di Burg e calcolando il rapporto LF/HF (LF: 0.04–0.12 Hz; HF: 0.15–0.35 Hz) per ciascuno stadio del sonno.Sono stati arruolati nello studio 7 soggetti sani (4 maschi, età media 35 anni). I nostri risultati mostrano una progressiva e significativa diminuzione di LF/HF dallo stadio 1 al 4, imputabile ad un aumento del tono del parasimpatico (aumento della componente HF), mentre il valore del rapporto durante veglia, REM e fase 1 è risultato simile (circa 1).