[The upper airway in obstructive sleep apnea patients is pathological even when awake]. / Der obere Atemweg bei OSA-Patienten ist auch im Wachzustand pathologisch.

Obstructive sleep apnea (OSA) is characterized by partial or complete obstruction of the pharyngeal airway. Anatomical factors can be distinguished from non-anatomical factors. Age and obesity are the main risk factors for OSA; however, approximately 50% of patients are not obese. In older patients (>60 years), the importance of obesity decreases. There is an increased prevalence of OSA among patients with normal weight. The effects of chronic intermittent hypoxemia, low-grade inflammation, increased sympathetic tone and mechanical stress contribute to a transformation of muscle fibers in the upper airway, resulting in reduced muscle mass and strength. Less frequently encountered non-anatomical factors include decreased muscle tone, increased arousal threshold, and altered sensitivity of CO2 chemoreceptors.

[Why you should know the "nose cycle" as a pneumologist and sleep medicine specialist]. / Warum man auch als Pneumologe und Schlafmediziner den "Nasenzyklus" kennen sollte.

The nasal cycle refers to the anticyclic swelling and decongestion of the two nasal cavities that occur during the day and during sleep, while the overall nasal flow remains constant. The nasal cycle was first described by R. Kayser in 1895. Each cycle consists of a working phase and a subsequent resting phase, the purpose of which is the rehydration and regeneration of the mucosa. A nasal cycle occurs in about 70-90% of people. The duration of the phase is affected by age, body position, physical activity, mucociliary clearance and time of day. Typically, the cycle lengthens during sleep. Long-term rhinoflowmetry enables assessment of the circadian course of the alternating cyclic changes of the nasal mucosa.

[Negative-pressure pulmonary edema and alveolar hemorrhage are potentially life-threatening complications of upper airway obstruction]. / "Negativdruck-Lungenödem" und "alveoläre Hämorrhagie" als Komplikationen einer oberen Atemwegsobstruktion.

Negative pressure pulmonary edema and alveolar hemorrhage are potentially life-threatening complications after relief of upper airway obstruction. The laryngeal-pharyngeal obstruction results in high negative intrapleural pressures. The increased intrapleural pressures affect the integrity of the alveolo-capillary membrane due to various factors. This review describes clinical symptoms, etiologic factors, pathophysiology and treatment strategies associated with each of these factors. The aim of this review is to equip clinicians with the knowledge base necessary to identify patients at increased risk for negative pressure pulmonary edema and alveolar hemorrhage.

Predisposing factors of daytime sleepiness in obese OSA patients.

Excessive daytime sleepiness is a common symptom in obese patients with obstructive sleep apnea. We investigated predisposing factors of excessive daytime sleepiness by comparing obese non-sleepy with sleepy patients with obstructive sleep apnea. Excessive daytime sleepiness was determined by the Epworth Sleepiness Scale in 43 patients (34 men and 9 women) with obstructive sleep apnea (apnea-hypopnea index ≥ 15 events per hr) and obesity (body mass index ≥ 30 kg m-2 ). Two subgroups were formed with (Epworth Sleepiness Scale ≥ 11) and without (Epworth Sleepiness Scale < 11) excessive daytime sleepiness. The concept of excessive daytime sleepiness was compared with other established daytime performance tests (Stanford Sleepiness Scale, Multiple Sleep Latency Test, Pupillographic Sleepiness Test, Marburger Vigilance test). Associations were calculated between excessive daytime sleepiness and demographic, metabolic and polysomnographic data. We included 19 sleepy patients (mean Epworth Sleepiness Scale score 15.2) and 24 non-sleepy patients (mean Epworth Sleepiness Scale score 5.8). Epworth Sleepiness Scale was negatively correlated with age and morning cortisol. Epworth Sleepiness Scale was positively correlated with body mass index, Stanford Sleepiness Scale, Beck's Depression Inventory and Marburger Vigilance test. Sleepy obese patients were significantly younger (mean 49.1 years), showed lower morning cortisol level (mean 9.41 µg L-1 ) and a trend to higher body mass index (mean 37.5 kg m- ²) compared with non-sleepy obese patients (mean: 59.3 years, 5.7 µg L-1 , 34.6 kg m- ², respectively). Many different excessive daytime sleepiness phenotypes are probably enclosed in obese patients with obstructive sleep apnea. Epworth Sleepiness Scale scores were best reflected by the objective Marburger Vigilance test results. The objective test can be particularly useful in cohorts where subjective reports are unreliable and operational readiness is paramount. Sleepy and non-sleepy obese patients with obstructive sleep apnea were similar in all polysomnographic parameters. Sleepy patients were younger, heavier and showed lower morning cortisol levels than non-sleepy patients.

Systematic quantitative assessment of motor function in clinically isolated REM sleep behaviour disorder: A diagnostic window into early alpha-synucleinopathies.

Mild motor abnormalities can herald the beginning of Parkinson´s disease but their diagnostic value is limited by multifactorial ageing-related influences on motor function. We characterized mild motor abnormalities in different motor domains by conducting a systematic motor assessment in 20 patients with clinically isolated REM sleep behaviour disorder (iRBD) without parkinsonian motor signs and 20 healthy controls. We addressed the influence of lifestyle factors and age on motor function, which needs to be distinguished from neurodegenerative motor features, and assessed the diagnostic value of innovative and established quantitative motor tests in iRBD. Patients with iRBD showed abnormalities in perceptual motor speed (falling stick test), trunk movement coordination (bend, twist and touch test) and dynamic balance (line walk test) without alterations in simple motor speed (alternate tap test), dexterity (grooved pegboard), static balance (force plate) and gait (timed up and go test). The falling stick test showed the highest diagnostic accuracy in identifying subjects with RBD (ROC-AUC 0.85, p ≤ 0.001). Multivariate analysis revealed physical activity and age as additional determinants of motor test performance. iRBD comprises a wide spectrum of mild motor abnormalities which cannot be verified by established tests for motor speed, gait and balance. The falling stick test, an innovative screening test for perceptual motor speed, provides high diagnostic potential in identifying subjects with subclinical neurodegenerative symptoms before parkinsonian motor signs become apparent. Normative data for physical activity and age need to be obtained to ensure correct interpretation of motor test results in prodromal Parkinson-related disease.

Selective suppression of rapid eye movement sleep increases next-day negative affect and amygdala responses to social exclusion.

Healthy sleep, positive general affect, and the ability to regulate emotional experiences are fundamental for well-being. In contrast, various mental disorders are associated with altered rapid eye movement (REM) sleep, negative affect, and diminished emotion regulation abilities. However, the neural processes mediating the relationship between these different phenomena are still not fully understood. In the present study of 42 healthy volunteers, we investigated the effects of selective REM sleep suppression (REMS) on general affect, as well as on feelings of social exclusion, cognitive reappraisal (CRA) of emotions, and their neural underpinnings. Using functional magnetic resonance imaging we show that, on the morning following sleep suppression, REMS increases general negative affect, enhances amygdala responses and alters its functional connectivity with anterior cingulate cortex during passively experienced experimental social exclusion. However, we did not find effects of REMS on subjective emotional ratings in response to social exclusion, their regulation using CRA, nor on functional amygdala connectivity while participants employed CRA. Our study supports the notion that REM sleep is important for affective processes, but emphasizes the need for future research to systematically investigate how REMS impacts different domains of affective experience and their neural correlates, in both healthy and (sub-)clinical populations.

Comparison of computerized methods for rapid eye movement sleep without atonia detection.

Rapid eye movement (REM) sleep without atonia detection is a prerequisite for diagnosis of REM sleep behavior disorder (RBD). As the visual gold standard method is time-consuming and subjective, several automated methods have been proposed. This study aims to compare their performances: The REM atonia index (RAI), the supra-threshold-REM-activity metric, the Frandsen index, the short/long muscle activity indices, and the Kempfner index algorithms were applied to 27 healthy control participants (C), 25 patients with Parkinson's disease (PD) without RBD (PD-RBD), 29 patients with PD and RBD (PD + RBD), 29 idiopathic patients with RBD, and 36 patients with periodic limb movement disorder (PLMD). The indices were calculated in various configurations: (1) considering all muscle activities; (2) excluding the ones related to arousals; (3) excluding the ones during apnea events; (4) excluding the ones before and after apnea events; (5) combining configurations 2 and 3; and (6) combining configurations 2 and 4. For each of these configurations, the discrimination capability of the indices was tested for the following comparisons: (1) (C, PD-RBD, PLMD) vs (PD + RBD, RBD); (2) C vs RBD; (3) PLMD vs RBD; (4) C vs PD-RBD; (5) C vs PLMD; (6) PD-RBD vs PD + RBD; and (7) C vs PLMD vs RBD. Results showed varying methods' performances across the different configurations and comparisons, making it impossible to identify the optimal method and suggesting the need of further improvements. Nevertheless, RAI seems the most sensible one for RBD detection. Moreover, apnea and arousal-related movements seem not to influence the algorithms' performances in patients' classification.

FDG PET, dopamine transporter SPECT, and olfaction: Combining biomarkers in REM sleep behavior disorder.

BACKGROUND: Idiopathic REM sleep behavior disorder is a prodromal stage of Parkinson's disease and dementia with Lewy bodies. Hyposmia, reduced dopamine transporter binding, and expression of the brain metabolic PD-related pattern were each associated with increased risk of conversion to PD. The objective of this study was to study the relationship between the PD-related pattern, dopamine transporter binding, and olfaction in idiopathic REM sleep behavior disorder. METHODS: In this cross-sectional study, 21 idiopathic REM sleep behavior disorder subjects underwent 18 F-fluorodeoxyglucose PET, dopamine transporter imaging, and olfactory testing. For reference, we included 18 F-fluorodeoxyglucose PET data of 19 controls, 20 PD patients, and 22 patients with dementia with Lewy bodies. PD-related pattern expression z-scores were computed from all PET scans. RESULTS: PD-related pattern expression was higher in idiopathic REM sleep behavior disorder subjects compared with controls (P = 0.048), but lower compared with PD (P = 0.001) and dementia with Lewy bodies (P < 0.0001). PD-related pattern expression was higher in idiopathic REM sleep behavior disorder subjects with hyposmia and in subjects with an abnormal dopamine transporter scan (P < 0.05, uncorrected). CONCLUSION: PD-related pattern expression, dopamine transporter binding, and olfaction may provide complementary information for predicting phenoconversion. © 2017 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Sodium oxybate treatment in narcolepsy and its effect on muscle tone.

AIMS: To estimate the effect of the compound sodium oxybate (SO) on chin muscle tone in sleep, a re-analysis of the results of the international multicenter study SXB-15 was performed, applying a validated semi-automatic analysis of muscle tone. This analysis distinguishes short (<0.5 s) and long (>0.5 s) muscle activity indices per hour (SMI, LMI) in 116 patients with narcolepsy-cataplexy. While stable stimulant medication was permitted, tricyclics and SSRIs were withdrawn. Polysomnographies were performed at baseline (V5), four weeks after titration of SO to 4.5 g, 6 g, or 9 g or placebo (V6) and after another four weeks on stable SO dose (V7). RESULTS: SMI and LMI decreased significantly during light sleep. LMI remained stable in all SO groups during slow wave sleep (SWS), but decreased significantly during REM sleep. SMI decreased non-significantly, but consistently during SWS and REM in the 9 g group only. A subgroup analysis of patients who stayed on stimulants showed that they had higher SMIs and LMIs in all groups. Patients who had been treated with anticataplectic medication prior to study inclusion had lower LMIs in the 9 g group during REM sleep in all visits. CONCLUSION: SO has a differential effect on muscle tone that is dose and sleep stage dependent. Low dosages increase short muscle activity, possibly enabling the occurrence of parasomnias. High doses are especially efficacious in REM sleep, suggesting that SO could be used to treat REM sleep behavior disorder. Comedication with stimulants and prior medication with anticataplectic medication exerts an influence on muscle tone.

Cheyne-stokes respiration during wakefulness in patients with chronic heart failure.

PURPOSE: Cheyne-Stokes respiration (CSR) during sleep has been studied extensively in patients with chronic heart failure (CHF). Prevalence and prognostic significance of CSR during wakefulness in CHF, however, are largely unknown. METHODS: CSR during wakefulness with an apnea-hypopnea cut-off ≥5/h and moderate to severe CSR with an apnea-hypopnea cutoff ≥15/h were analyzed using polysomnographic recordings in 267 patients with stable CHF with reduced left ventricular (LV) ejection fraction at our institution. Primary endpoint during follow-up was heart transplant-free survival. RESULTS: Fifty of 267 patients (19%) had CSR during wakefulness and 73 of 267 patients (27%) had CSR during sleep. CSR during wakefulness was associated with advanced age, atrial fibrillation, decreased LV ejection fraction, increased LV end-diastolic diameter, brain natriuretic peptide, New York Heart Failure class, and CSR during sleep. During 43 months mean follow-up, 67 patients (25%) died and 4 patients (1%) underwent heart transplantation. Multivariate Cox analysis identified age, male gender, chronic kidney disease, and LV ejection fraction as predictors of reduced transplant-free survival. CSR during wakefulness with an apnea-hypopnea cutoff ≥5/h as well as moderate to severe CSR while awake using an apnea-hypopnea cutoff ≥15/h did not predict reduced transplant-free survival independently from confounding factors. CONCLUSION: CSR during wakefulness appears to be a marker of heart failure severity.

Work of Breathing in Fixed and Pressure Relief Continuous Positive Airway Pressure (C-Flex™): A post hoc Analysis.

BACKGROUND: Expiratory pressure relief continuous positive airway pressure (pressure relief CPAP; C-Flex™) causes increases in inspiratory duty cycle and shortening of expiratory time. It has been suggested that these changes are caused by an increase in work of breathing. OBJECTIVES: We studied the effects of C-Flex on work of breathing and intrinsic positive end-expiratory pressure as compared to fixed CPAP. METHODS: Work of breathing was analyzed in 24 patients with obstructive sleep apnea during treatment with fixed CPAP and C-Flex with 3 different pressure relief settings in a randomized order during rapid-eye-movement (REM) and non-REM sleep. Work of breathing was assessed on a breath-by-breath basis using a piezoelectric esophageal pressure catheter and a pneumotachograph for measuring airflow. RESULTS: We found there was no increase in inspiratory work of breathing observed using C-Flex compared to fixed CPAP. Instead, we found a linear decrease in inspiratory work of breathing with increasing pressure relief, with a mean difference of 1.22 J/min between CPAP and maximum pressure release (C-Flex 3; 90% of the value with nasal CPAP); however, the decrease was not statistically significant. The decrease in inspiratory work of breathing associated with C-Flex has a significant inverse correlation with BMI. CONCLUSIONS: The C-Flex technology does not change work of breathing but shows a tendency towards a reduction of inspiratory work of breathing in patients with a lower BMI using higher C-Flex. The effect is probably caused by diminishing airway resistance generated by the positive end-expiratory pressure. Our findings may lead to additional fields of application of the C-Flex technology, such as chronic obstructive pulmonary disease or muscular dystrophy.

Rotigotine's effect on PLM-associated blood pressure elevations in restless legs syndrome: An RCT.

OBJECTIVE: This double-blind, placebo-controlled, interventional trial was conducted to investigate the effects of rotigotine patch on periodic limb movement (PLM)-associated nocturnal systolic blood pressure (SBP) elevations. METHODS: Patients with moderate to severe restless legs syndrome (RLS) were randomized to rotigotine (optimal dose [1-3 mg/24 h]) or placebo. Continuous beat-to-beat blood pressure (BP) assessments were performed during polysomnography at baseline and at the end of 4-week maintenance. Primary outcome was change in number of PLM-associated SBP elevations (defined as slope of linear regression ≥2.5 mm Hg/beat-to-beat interval over 5 consecutive heartbeats [≥10 mm Hg]). Additional outcomes were total SBP elevations, PLM-associated and total diastolic BP (DBP) elevations, periodic limb movements index (PLMI), and PLM in sleep arousal index (PLMSAI). RESULTS: Of 81 randomized patients, 66 (37 rotigotine, 29 placebo) were included in efficacy assessments. PLM-associated SBP elevations were significantly reduced with rotigotine vs placebo (least squares mean treatment difference [95% confidence interval (CI)] -160.34 [-213.23 to -107.45]; p < 0.0001). Rotigotine-treated patients also had greater reduction vs placebo in total SBP elevations (-161.13 [-264.47 to -57.79]; p = 0.0028), PLM-associated elevations (-88.45 [-126.12 to -50.78]; p < 0.0001), and total DBP elevations (-93.81 [-168.45 to -19.16]; p = 0.0146), PLMI (-32.77 [-44.73 to -20.80]; p < 0.0001), and PLMSAI (-7.10 [-11.93 to -2.26]; p = 0.0047). Adverse events included nausea (rotigotine 23%; placebo 8%), headache (18% each), nasopharyngitis (18%; 8%), and fatigue (13%; 15%). CONCLUSIONS: Further investigation is required to determine whether reductions in nocturnal BP elevations observed with rotigotine might modify cardiovascular risk. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that for patients with moderate to severe RLS, rotigotine at optimal dose (1-3 mg/24 h) reduced PLM-associated nocturnal SBP elevations.

Significant association between systolic and diastolic blood pressure elevations and periodic limb movements in patients with idiopathic restless legs syndrome.

OBJECTIVE: A new and unique methodology was developed to evaluate the association between periodic limb movements (PLMs) and nocturnal blood pressure (BP) excursions in patients with restless legs syndrome (RLS). METHODS: All data were collected at baseline of the ENCORE (Effects of Neupro on Cardiovascular Observations in Patients with Restless Legs Syndrome) study, a placebo-controlled polysomnographic study of rotigotine in patients with idiopathic RLS. Continuous beat-by-beat BP and heart rate assessments were performed during a full night of polysomnography. All BP elevations occurring with and without PLMs were systematically identified and analyzed. RESULTS: Patients (n = 89) had a mean total of 508.9 ± 405.7 PLMs, 788.4 ± 261.9 systolic BP elevations, and 349.7 ± 242.9 diastolic BP elevations during the night. Higher time-adjusted frequencies of systolic BP elevations [mean difference (95% confidence interval, CI): 543.0 (487.2, I); p <0.0001] and diastolic BP elevations (205.8 (169.3, I); p <0.0001) were observed with PLMs than without PLMs. A peak in the frequency of PLM onset coincided with BP elevation onset. CONCLUSION: Our methodology allowed the first evaluation of the total number of nocturnal PLM-associated BP elevations occurring in patients with RLS. Our data clearly indicate an interdependence between BP elevations and PLMs, and they have clinical relevance as BP variability is a potential cardiovascular risk factor.

[Diagnosis of sleep apnea]. / Diagnostik der Schlafapnoe.

Obstructive sleep apnea (OSA) is a clinically significant condition associated with an increase in cardiovascular risk, daytime sleepiness and in risk of accidents. Diagnosis usually relies on a detailed anamnesis and an ambulatory nocturnal polygraphy. Suspecting the presence of OSA or a persisting unclear daytime sleepiness in need of treatment further polysomnographic diagnosis should be performed in a specialized sleep center. Cardiorespiratory polysomnography is the diagnostic gold standard in differentiating sleep-related breathing and movement disorders.

Chest Compression Synchronized Ventilation versus Intermitted Positive Pressure Ventilation during Cardiopulmonary Resuscitation in a Pig Model.

BACKGROUND: Guidelines recommend mechanical ventilation with Intermitted Positive Pressure Ventilation (IPPV) during resuscitation. The influence of the novel ventilator mode Chest Compression Synchronized Ventilation (CCSV) on gas exchange and arterial blood pressure compared with IPPV was investigated in a pig model. METHODS: In 12 pigs (general anaesthesia/intubation) ventricular fibrillation was induced and continuous chest compressions were started after 3 min. Pigs were mechanically ventilated in a cross-over setting with 5 ventilation periods of 4 min each: Ventilation modes were during the first and last period IPPV (100% O2, tidal volumes = 7 ml/kgKG, respiratory rate = 10/min), during the 2nd, 3rd and 4th period CCSV (100% O2), a pressure-controlled and with each chest compression synchronized breathing pattern with three different presets in randomized order. Presets: CCSVA: P insp = 60 mbar, inspiratory time = 205 ms; CCSVB: P insp = 60 mbar, inspiratory time = 265 ms; CCSVC: P insp = 45 mbar, inspiratory time = 265 ms. Blood gas samples were drawn for each period, mean arterial (MAP) and central venous (CVP) blood pressures were continuously recorded. Results as median (25%/75%percentiles). RESULTS: Ventilation with each CCSV mode resulted in higher PaO2 than IPPV: PaO2: IPPV first: 19.6(13.9/36.2)kPa, IPPV last: 22.7(5.4/36.9)kPa (p = 0.77 vs IPPV first), CCSVA: 48.9(29.0/58.2)kPa (p = 0.028 vs IPPV first, p = 0.0001 vs IPPV last), CCSVB: 54.0 (43.8/64.1) (p = 0.001 vs IPPV first, p = 0.0001 vs IPPV last), CCSVC: 46.0 (20.2/58.4) (p = 0.006 vs IPPV first, p = 0.0001 vs IPPV last). Both the MAP and the difference MAP-CVP did not decrease during twelve minutes CPR with all three presets of CCSV and were higher than the pressures of the last IPPV period. CONCLUSIONS: All patterns of CCSV lead to a higher PaO2 and avoid an arterial blood pressure drop during resuscitation compared to IPPV in this pig model of cardiac arrest.

Application of Grid technology for automated detection of sleep disordered breathing.

Sleep related breathing disorders (SRBD) represent a major disease in sleep medicine. For diagnosis and therapy control, extensive overnight investigations are required, encompassing long-term measurement of multiple biosignals in specialized sleep disorders centers. To date, evaluation of the examination is realized by comprehensive visual inspection of the data by an expert. Therefore, many approaches have been made to facilitate diagnosis, among them automated analysis of the ECG signal. In this article, we present a grid based infrastructure for computer aided diagnosis of SRBD, accessible for distributed users. As the analysis algorithms itself are still in a validation phase, and the Grid infrastructure is not approved for clinical applications, the application is currently used for research purposes only. But as important aspects of data-security, accessibility from protected environments, usability and fault-tolerance are already covered, the implementation is a solid base for further enhancement of the platform and paves the way for a sustainable service grid for sleep medicine.

C-Flex technology: effects on breathing parameters and inspiratory flow limitation.

BACKGROUND: Expiratory pressure relief continuous positive airway pressure (pressure relief CPAP, C-Flex) is known to be as effective in the treatment of obstructive sleep apnea (OSA) as conventional CPAP while improving overall patients' adherence. However, the effects of C-Flex on ventilation during sleep have not been studied yet. OBJECTIVE: This study investigates the effects of pressure relief CPAP on respiratory parameters and possible inspiratory flow limitation with increased difference between inspiratory and expiratory pressure compared with conventional CPAP. METHODS: In total, 24 patients were investigated both during conventional CPAP and during three C-Flex pressure relief settings in randomized order during rapid-eye-movement (REM) and non-REM (NREM) sleep. Airflow was monitored with a pneumotachograph; inspiratory flow limitation was assessed by analyzing airflow and esophageal pressure swings. RESULTS: Using higher C-Flex gains, expiratory time decreased in favor of the inspiratory duty cycle while there was no significant change in tidal volume. Analysis of inspiratory flow limitation showed no significant difference between conventional CPAP and the C-Flex gains studied. CONCLUSIONS: The increase in the inspiratory duty cycle with C-Flex might either indicate an increase in the work of breathing or a decrease in the work of breathing due to a lower peak end-expiratory pressure and consecutive alleviation of passive expiration. Both treatments appeared equivalent regarding the occurrence of inspiratory flow limitation.

Quantification of tonic and phasic muscle activity in REM sleep behavior disorder.

REM sleep behavior disorder (RBD) is characterized by excessive tone of the chin muscle and limb movement during sleep. In the past, quantification of increased muscle tone in REM sleep has been performed visually, using no stringent criteria. The aim of this study was to develop an automatic analysis, allowing the quantification of muscle activity and its amplitude for all sleep stages, with a focus on REM sleep in patients with RBD. Forty-eight patients (27 male, 21 female) with RBD were included in the analysis. Twenty-one had idiopathic RBD; 28 had narcolepsy plus RBD. Twenty-five patients without confirmed sleep disorder served as control subjects. The amplitude of the EMG was generated from the difference of the upper and lower envelope of the mentalis muscle recordings. By smoothing the amplitude curve, a threshold curve was defined. Any muscle activity beyond the threshold curve was defined as motor activity. The means of the motor activity per second were summarized statistically and calculated for each sleep stage. Due to variable distribution of REM sleep, the latter was assigned to respective quartiles of the recorded night. Muscle activity was defined according to a histogram as short-lasting (<0.5 second) and long-lasting (>0.5 second) activity. No difference in the distribution of REM sleep/quartile and mean muscle tone throughout the sleep cycle could be found within the RBD groups and control subjects. Muscle activity was in the range of 200 ms. No clusters or regular distribution of muscle activity were found. Long muscle activity in the group with manifest clinical RBD was significantly higher than in control subjects, whereas it was nonsignificantly higher in subclinical RBD. The correlation between the frequency of long muscle activity in REM sleep and age was highly significant only for patients with idiopathic RBD. Automatic analysis of muscle activity in sleep is a reliable, easy method that may easily be used in the evaluation for REM sleep behavior disorder, creating indices of muscle activity similar to the indices for sleep apnea or PLMS. Together with the overt behavior, the analyses provides an important tool to get a deeper insight into the pathophysiology of RBD. Long movements appear to represent the motor disinhibition in REM sleep more distinct than short movements. The positive correlation of age and increased motor activity in REM sleep in idiopathic RBD highlights the idea of age dependant motor disinhibition as a continuum of a neurodegenerative disorder, which in narcolepsy patients with RBD only seems to happen as a single temporal event at onset of the disorder.