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Substantial evidence suggests that the circadian decline of core body temperature (CBT) triggers the initiation of human sleep, with CBT continuing to decrease during sleep. Although the connection between habitual sleep and CBT patterns is established, the impact of external body cooling on sleep remains poorly understood. The main aim of the present study is to show whether a decline in body temperatures during sleep can be related to an increase in slow wave sleep (N3). This three-center study on 72 individuals of varying age, sex, and BMI used an identical type of a high-heat capacity mattress as a reproducible, non-disturbing way of body cooling, accompanied by measurements of CBT and proximal back skin temperatures, heart rate and sleep (polysomnography). The main findings were an increase in nocturnal sleep stage N3 (7.5 ± 21.6 min/7.5 h, mean ± SD; p = 0.0038) and a decrease in heart rate (− 2.36 ± 1.08 bpm, mean ± SD; p < 0.0001); sleep stage REM did not change (p = 0.3564). Subjects with a greater degree of body cooling exhibited a significant increase in nocturnal N3 and a decrease in REM sleep, mainly in the second part of the night. In addition, these subjects showed a phase advance in the NREM-REM sleep cycle distribution of N3 and REM. Both effects were significantly associated with increased conductive inner heat transfer, indicated by an increased CBT- proximal back skin temperature -gradient, rather than with changes in CBT itself. Our findings reveal a previously far disregarded mechanism in sleep research that has potential therapeutic implications: Conductive body cooling during sleep is a reliable method for promoting N3 and reducing heart rate. [ABSTRACT FROM AUTHOR]

Substantial evidence suggests that the circadian decline of core body temperature (CBT) triggers the initiation of human sleep, with CBT continuing to decrease during sleep. Although the connection between habitual sleep and CBT patterns is established, the impact of external body cooling on sleep remains poorly understood. The main aim of the present study is to show whether a decline in body temperatures during sleep can be related to an increase in slow wave sleep (N3). This three-center study on 72 individuals of varying age, sex, and BMI used an identical type of a high-heat capacity mattress as a reproducible, non-disturbing way of body cooling, accompanied by measurements of CBT and proximal back skin temperatures, heart rate and sleep (polysomnography). The main findings were an increase in nocturnal sleep stage N3 (7.5 ± 21.6 min/7.5 h, mean ± SD; p = 0.0038) and a decrease in heart rate (− 2.36 ± 1.08 bpm, mean ± SD; p < 0.0001); sleep stage REM did not change (p = 0.3564). Subjects with a greater degree of body cooling exhibited a significant increase in nocturnal N3 and a decrease in REM sleep, mainly in the second part of the night. In addition, these subjects showed a phase advance in the NREM-REM sleep cycle distribution of N3 and REM. Both effects were significantly associated with increased conductive inner heat transfer, indicated by an increased CBT- proximal back skin temperature -gradient, rather than with changes in CBT itself. Our findings reveal a previously far disregarded mechanism in sleep research that has potential therapeutic implications: Conductive body cooling during sleep is a reliable method for promoting N3 and reducing heart rate. [ABSTRACT FROM AUTHOR]

The global number of people with Alzheimer's disease (AD) doubles every 5 years. It has been established that unless an effective treatment for AD is found, the incidence of AD will triple by 2060. However, pharmacological therapies for AD have failed to show effectiveness and safety. Therefore, the search for alternative methods for treating AD is an urgent problem in medicine. The lymphatic drainage and removal system of the brain (LDRSB) plays an important role in resistance to the progression of AD. The development of methods for augmentation of the LDRSB functions may contribute to progress in AD therapy. Photobiomodulation (PBM) is considered to be a non-pharmacological and safe approach for AD therapy. Here, we highlight the most recent and relevant studies of PBM for AD. We focus on emerging evidence that indicates the potential benefits of PBM during sleep for modulation of natural activation of the LDRSB at nighttime, providing effective removal of metabolites, including amyloid-β, from the brain, leading to reduced progression of AD. Our review creates a new niche in the therapy of brain diseases during sleep and sheds light on the development of smart sleep technologies for neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

The 'catalogue of knowledge and skills' for sleep medicine presents the blueprint for a curriculum, a textbook, and an examination on sleep medicine. The first catalogue of knowledge and skills was presented by the European Sleep Research Society in 2014. It was developed following a formal Delphi procedure. A revised version was needed in order to incorporate changes that have occurred in the meantime in the International Classification of Sleep Disorders, updates in the manual for scoring sleep and associated events, and, most important, new knowledge in sleep physiology and pathophysiology. In addition, another major change can be observed in sleep medicine: a paradigm shift in sleep medicine has taken place. Sleep medicine is no longer a small interdisciplinary field in medicine. Sleep medicine has increased in terms of recognition and importance in medical care. Consequently, major medical fields (e.g. pneumology, cardiology, neurology, psychiatry, otorhinolaryngology, paediatrics) recognise that sleep disorders become a necessity for education and for diagnostic assessment in their discipline. This paradigm change is considered in the catalogue of knowledge and skills revision by the addition of new chapters. [ABSTRACT FROM AUTHOR]

Purpose: Since 2001, hypoglossal nerve stimulators have been implanted in patients with obstructive sleep apnea around the world, initially in trial situations but more recently also in regular care settings. Medium term data indicate effectiveness and tolerability of treatment. However, when assessing the safety of the procedure, the safe feasibility of explantation or reimplantation must also be considered. Patients and methods: Nine patients with an implanted respiratory-driven hypoglossal nerve stimulator. We have evaluated the feasibility and safety of explantation or re-implantation with another stimulation system. Results: In 2012, nine patients were implanted with a respiratory-driven hypoglossal nerve stimulator as part of the Apnex Medical Pivotal Study. The study was ended in 2013. For a variety of reasons, the system was explanted from all nine patients by the year 2019. Three of these patients were re-implanted with a different system with respiratory sensing during the same session (mean incision to closure time for explantation 88.2 ± 35.01 min., mean incision to closure time for re-implantation 221.75 ± 52.73 min.). Due to extensive scar tissue formation, all procedures were technically challenging. Complication rate was significantly higher when re-implantation was performed or attempted in the same surgical session (0 of 5 patients with explantation versus 3 of 4 patients with attempted re-implantation; p = 0.018). There was no significant difference between the AHI values before and after implantation in patients with re-implantation. Conclusion: Explantation and re-implantation are technically challenging though possible procedures. The single-staged equilateral reimplantation of another hypoglossal nerve stimulation system can, but need not, be successful. [ABSTRACT FROM AUTHOR]

Network physiology describes the human body as a complex network of interacting organ systems. It has been applied successfully to determine topological changes in different sleep stages. However, the number of network links can quickly grow above the number of parameters that are typically analyzed with standard statistical methods. Artificial Neural Networks (ANNs) are a promising approach as they are successful in large parameter spaces, such as in digital imaging. On the other hand, ANN models do not provide an intrinsic approach to interpret their predictions, and they typically require large training data sets. Both aspects are critical in biomedical research. Medical decisions need to be explainable, and large data sets of quality assured patient and control data are rare. In this paper, different models for the classification of insomnia—a common sleep disorder—have been trained with 59 patients and age and gender matched controls, based on their physiological networks. Feature relevance evaluation is employed for all methods. For ANNs, the extrinsic interpretation method DeepLift is applied. The results are not identical across methods, but certain network links have been rated as relevant by all or most of the models. While ANNs show less classification accuracy (0.89) than advanced tree-based models (0.92 and 0.93), DeepLift provides an in-depth ANN interpretation with feature relevance scores for individual data samples. The analysis revealed modifications in the pulmonar, ocular, and cerebral subnetworks that have not been described before but are consistent with known findings on the physiological impact of insomnia. [ABSTRACT FROM AUTHOR]

Summary The accreditation of sleep centres aims to ensure high‐quality diagnosis and management of sleep centres. European accreditation standards were introduced in 2006, and were aimed at centres offering inpatient polysomnography and vigilance tests (Mean Sleep Latency Test and Maintenance of Wakefulness Test). Since then, the practice of sleep medicine has evolved, with greater use of ambulatory polysomnography and polygraphy. As a result, in many sleep centres, actual clinical practice, although of a high standard, is no longer in accordance with the published guidelines. The current criteria have been revised with the introduction of level‐based criteria. Level 1 and 2 centres offer full diagnostic testing in a laboratory‐based setting. Level 1 practices will usually be university affiliated, and have a full teaching and active research role. Level 3 and 4 practices may offer both inpatient and ambulatory testing. Level 3 practices perform polysomnography, while level 4 practices (usually monodisciplinary and focussed on sleep apnea) perform polygraphy only. The role of the medical and paramedical team, training, appropriate equipment, patient care pathways and patient management according to national/European recommendations is underlined for accreditation at each level. It is anticipated that the guidelines will be reviewed and if necessary revised after 4 years. [ABSTRACT FROM AUTHOR]

Die Schlafmedizin hat sich in den letzten Jahrzehnten weiterentwickelt. Die Prävalenz von Schlafstörungen hat zugenommen, und die Schlaflabore in Kliniken und privaten Einrichtungen sind ebenfalls größer geworden, um dem Andrang gerecht zu werden. Die Schlafmedizin verfügt über evidenzbasierte Leitlinien für die Diagnose und Therapie von Schlafstörungen. Jedoch sind Schlaflabore und schlafmedizinisch geschultes Personal nicht ausreichend verfügbar. Es wurden viele neue Methoden zur Aufzeichnung des Schlafs und zur Diagnose von Schlafstörungen entwickelt, deren Sensitivität und Spezifität hier aufgeführt werden. Viele Schlafstörungen sind chronisch und erfordern eine kontinuierliche Behandlung und Überwachung des Therapieerfolgs. Kosteneffiziente Techniken für die Erstdiagnose und für die Therapieüberwachung sind wichtig. Die Technologien der Telemedizin können helfen, die Anforderungen an Diagnose und Therapieüberwachung zu erfüllen. Die drahtlose Aufzeichnung des Schlafs und der Biosignale im Schlaf ermöglicht es, diagnostische Geräte mit teils guter Validität breiter zur Verfügung zu stellen.Darüber hinaus erfordert die Schlafforschung moderne Techniken, um zugrunde liegende Regulationsmechanismen des Schlafs zu erforschen und ein besseres Verständnis für die Physiologie und die Pathophysiologie der Schlafstörungen zu erreichen. Die Aufzeichnung des Schlafs zuhause und die nicht beeinträchtigende Aufzeichnung mit telemedizinischen Methoden unterstützen die Schlafforschung und erlauben es, Interferenzen zu reduzieren und längere Zeiträume zu erfassen. [ABSTRACT FROM AUTHOR]

Summary: In this research study we have developed a clustering‐based automatic sleep spindle detection method that was evaluated on two different databases. The databases consisted of 20 all‐night polysomnograph recordings. Past detection methods have been based on subject‐independent and some subject‐dependent parameters, such as fixed or variable thresholds to identify spindles. Using a multivariate Gaussian mixture model clustering technique, our algorithm was developed to use only subject‐specific parameters to detect spindles. We have obtained an overall sensitivity range (65.1–74.1%) at a (59.55–119.7%) false positive proportion. [ABSTRACT FROM AUTHOR]

Extrinsic effects on health and sleep are getting more and more attention. Studies have been conducted that aim to quantify annoyance due to increases in external noise increases and its physiological effects. Recent research on noise effects was performed in order to identify the causes and effects of these extrinsic influences. Research on aircraft and airfield noise near airports is of special interest because air traffic increases and airports expand. This noise has special characteristics compared to other forms of traffic noise. A large study near the Frankfurt airport with sub-studies near the Stuttgart and Cologne airports (NORAH study) could confirmed results from previous studies and even presented more precise results on some aspects. This study had a special focus on an excellent quantitative assessment of blood pressure and sleep by unattended home polysomnography according to AASM recommendations. Effects on blood pressure were not significant. Only trends were shown which were within the confidence intervals of previous studies. Related to the effects on sleep, a sound pressure exposure-response relationship could be shown for the objective wake-up probability. After the opening of a new landing runway and the introduction of night landing restrictions, wake-up probability decreased. Remarkably the study demonstrated that personal opinion on aircraft noise is a strong modifier for objective sleep quality. In our paper we compare the results of the NORAH study with results from previous studies with a focus on annoyance, blood pressure and sleep. [ABSTRACT FROM AUTHOR]

The first German Charité Jet Lag Scale (CJS), based on the only validated English questionnaire, was introduced in a former study. In addition to providing further jet lag investigations, this second method-comparison study aims to evaluate the CJS. Consistent interviewing methods are essential for future research in identifying possible cross-cultural tendencies, advancing jet lag definition, and establishing potential alleviation methods. Jet lag in 17 German chorus members (5 male, 12 female, mean age 42.35 ± 13.06 years) was monitored on their 2½-week trip from Germany to Argentina and back by use of actigraphy, sleep diaries, and the CJS. Cronbach’s alpha, Pearson and Lin correlations, and Bland-Altman diagrams were applied to assess CJS reliability and validity between all measurement methods. CJS study analysis results reconfirmed the prevalence of jet lag at approximately 60%. Moreover, the study assessed high Cronbach’s alpha values and significant positive correlations for several corresponding and related sleep parameters and CJS items such as total sleep time (TST) and sleep onset latency (SOL). The confidence limits in the Bland-Altman diagrams remained within the limits of earlier studies (TST ± 1 h, SOL ± 30 min). Overall, jet lag measures in this study confirmed previous jet lag studies. Evidence indicates positive reliability and validity of the CJS, with lower specificity in some parameters. We conclude that the CJS is applicable for complex jet lag studies. The findings provide support for further development of the scale and its capability as a consistent jet lag interviewing method. [ABSTRACT FROM AUTHOR]

The recording of ECG and heart rate are indispensable parameters of cardiorespiratory polysomnography. Complementing neurophysiological signals this allows an assessment of the autonomous nervous regulation during sleep. An evaluation of the nocturnal ECG is possible in terms of cyclical variations of heart rate and in terms of respiration modulated changes of ECG morphology (amplitude of R wave and T wave). This provides a reliable estimation of sleep disordered breathing. The autonomous nervous system is regulated in a totally different way during slow wave sleep and during REM sleep. An assessment of beat-to-beat variability of heart rate allows deriving sleep stages based on the difference in autonomous nervous system regulation. In addition the transitions from wakefulness to sleep can be tracked to some degree by an analysis of heart rate variability. This paper presents the technical development of the analysis in a historical sequence from 1980 to 2015. Linked to this the increase in physiological and pathophysiological knowledge derived from the technical developments is presented. [ABSTRACT FROM AUTHOR]

Jet lag is a consequence of desynchronisation of human endogenous circadian rhythm with respect to the immediate environment. The slower adaptation rate of the internal rhythm in contrast to rapid travel in commercial aircraft results in symptoms such as insomnia or daytime fatigue. A group of 53 travelling subjects answered the Charité Jet Lag Scale (CJLS) questionnaire, the first of its kind in German. The CJLS represents a holistic approach to the individual symptoms of jet lag. Study results indicate a possible enhancement by shortening the CJLS to a morning and evening report. Moreover, our study determined a decreasing exponential gradient for jet lag during the first days after travel. Physical and mental symptoms are identified as the primary predictors of jet lag. The CJLS and its future translations could lead to a consistent interviewing method – one key factor for development of future intervention methods to manage jet lag. [ABSTRACT FROM AUTHOR]

Emerging evidence suggests that an important function of the sleeping brain is the removal of wastes and toxins from the central nervous system (CNS) due to the activation of the brain waste removal system (BWRS). The meningeal lymphatic vessels (MLVs) are an important part of the BWRS. A decrease in MLV function is associated with Alzheimer's and Parkinson's diseases, intracranial hemorrhages, brain tumors and trauma. Since the BWRS is activated during sleep, a new idea is now being actively discussed in the scientific community: night stimulation of the BWRS might be an innovative and promising strategy for neurorehabilitation medicine. This review highlights new trends in photobiomodulation of the BWRS/MLVs during deep sleep as a breakthrough technology for the effective removal of wastes and unnecessary compounds from the brain in order to increase the neuroprotection of the CNS as well as to prevent or delay various brain diseases. [ABSTRACT FROM AUTHOR]

Summmary Sleep medicine is evolving globally into a medical subspeciality in its own right, and in parallel, behavioural sleep medicine and sleep technology are expanding rapidly. Educational programmes are being implemented at different levels in many European countries. However, these programmes would benefit from a common, interdisciplinary curriculum. This 'catalogue of knowledge and skills' for sleep medicine is proposed, therefore, as a template for developing more standardized curricula across Europe. The Board and The Sleep Medicine Committee of the European Sleep Research Society ( ESRS) have compiled the catalogue based on textbooks, standard of practice publications, systematic reviews and professional experience, validated subsequently by an online survey completed by 110 delegates specialized in sleep medicine from different European countries. The catalogue comprises 10 chapters covering physiology, pathology, diagnostic and treatment procedures to societal and organizational aspects of sleep medicine. Required levels of knowledge and skills are defined, as is a proposed workload of 60 points according to the European Credit Transfer System ( ECTS). The catalogue is intended to be a basis for sleep medicine education, for sleep medicine courses and for sleep medicine examinations, serving not only physicians with a medical speciality degree, but also PhD and MSc health professionals such as clinical psychologists and scientists, technologists and nurses, all of whom may be involved professionally in sleep medicine. In the future, the catalogue will be revised in accordance with advances in the field of sleep medicine. [ABSTRACT FROM AUTHOR]

The deposition of amyloid-β (Aβ) in the brain is a risk factor for Alzheimer's disease (AD). Therefore, new strategies for the stimulation of Aβ clearance from the brain can be useful in preventing AD. Transcranial photostimulation (PS) is considered a promising method for AD therapy. In our previous studies, we clearly demonstrated the PS-mediated stimulation of lymphatic clearing functions, including Aβ removal from the brain. There is increasing evidence that sleep plays an important role in Aβ clearance. Here, we tested our hypothesis that PS at night can stimulate Aβ clearance from the brain more effectively than PS during the day. Our results on healthy mice show that Aβ clearance from the brain occurs faster at night than during wakefulness. The PS course at night improves memory and reduces Aβ accumulation in the brain of AD mice more effectively than the PS course during the day. Our results suggest that night PS is a more promising candidate as an effective method in preventing AD than daytime PS. These data are an important informative platform for the development of new noninvasive and nonpharmacological technologies for AD therapy as well as for preventing Aβ accumulation in the brain of people with disorder of Aβ metabolism, sleep deficit, elderly age, and jet lag. [ABSTRACT FROM AUTHOR]

Sleep is an active and regulated process with restorative functions for physical and mental conditions. Based on recordings of brain waves and the analysis of characteristic patterns and waveforms it is possible to distinguish wakefulness and five sleep stages. Sleep and the sleep stages modulate autonomous nervous system functions such as body temperature, respiration, blood pressure, and heart rate. These functions consist of a sympathetic tone usually related to activation and to parasympathetic (or vagal) tone usually related to inhibition. Methods of statistical physics are used to analyze heart rate and respiration to detect changes of the autonomous nervous system during sleep. Detrended fluctuation analysis and synchronization analysis and their applications to heart rate and respiration during sleep in healthy subjects and patients with sleep disorders are presented. The observed changes can be used to distinguish sleep stages in healthy subjects as well as to differentiate normal and disturbed sleep on the basis of heart rate and respiration recordings without direct recording of brain waves. Of special interest are the cardiovascular consequences of disturbed sleep because they present a risk factor for cardiovascular disorders such as arterial hypertension, cardiac ischemia, sudden cardiac death, and stroke. New derived variables can help to find indicators for these health risks. [ABSTRACT FROM AUTHOR]

The ENN project was developed by a multidisciplinary European consortium including 39 partners. The main objective was the creation of a multimedia telematics network to give support to GPs in the fields of sleep, headache and epilepsy, which are considered high global-burden diseases. A multi-step strategy was used to evaluate user needs: evaluation of GPs' knowledge and needs; prediction of GPs' attitudes concerning the use of telematics tools; evaluation of sleep recording costs. These evaluations led to the development of a set of prototypes: three tutorials for the education of users; a sleep atlas establishing examples of case studies; expert systems on sleep and headaches; signal processing and remote monitoring systems. These were supported by communication network facilities. Dissemination of activities and adequate management of the consortiurn assured teamwork efficiency. [ABSTRACT FROM AUTHOR]

Compares the detrended fluctuation analysis (DFA) and the spectral analysis for heart rate variability in sleep and sleep apnea. Significance for the effects of sleep stages, the effects of apnea severity for both sets of parameters stemming from spectral analysis and from DFA; Situation wherein the separation of sleep stages was performed best.

Sleep is not just the absence of wakefulness but a regulated process with an important restorative function. Based on electroencephalographic recordings and characteristic patterns and waveforms we can distinguish wakefulness and five sleep stages grouped into light sleep, deep sleep, and rapid-eye-movement (REM) sleep. In order to explore the functions of sleep and sleep stages, we investigated the dynamics of sleep stages over the night and of heart-rate variability during the different sleep stages. Sleep stages and intermediate wake states have different distributions of their duration and this allows us to create a model for the temporal sequence of sleep stages and wake states. Heart rate is easily accessed with a high precision by the recording and analysis of the electrocardiogram (ECG). Heart-rate regulation is part of the autonomous nervous system and sympathetic tone is strongly influenced by the sleep stages. [ABSTRACT FROM AUTHOR]

Presents a study which examined the inter-rater reliability of a computer-based visual sleep scoring system in a number of accredited sleep centers in Germany. Overview of the study population; Methodology; Results and discussion.

Introduces two non-invasive methods for assessing autonomous nervous function during sleep. Components of the pulse transit time (PTT) method; Correlation of PTT with the rigidity of arterial vessels; Factors influencing the vascular tone reflected by the signal of the peripheral arterial tonometry method; Results of a study using peripheral arterial tonometry in sleep apnea.

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Restless legs syndrome (RLS) has been associated with anxiety, depression, insomnia, lifestyle factors and infections. We aimed to study the prevalence of symptoms of RLS during the COVID-19 pandemic versus pre-pandemic. We hypothesized that pre-existing RLS symptoms worsened and pandemic-related factors may have triggered new symptoms of RLS. Adults (≥18 years) from fifteen countries across four continents participated in an online survey between May and August 2020. The harmonized questionnaire included a validated single question on RLS with response alternatives from 1 to 5 on a scale from never to every/almost every evening or night. Other measures were the Insomnia Severity Index (ISI), measures of symptoms of anxiety (GAD-2) and depression (PHQ-2), and questions on different pandemic-related factors. Altogether, 17 846 subjects (63.8 % women) were included in the final analyses. The mean age was 41.4 years (SD 16.1). During the pandemic, symptoms of RLS (≥3 evenings/nights per week) were more common 9.1 % (95 % CI 8.7–10.1) compared to 5.4 % (95 % CI 4.9–6.0) before the pandemic (P < 0.0001). Alltogether 1.3 % (95 % CI 1.1–1.6) respondents had new-onset symptoms (≥3 evenings/nights per week). Moderate-severe insomnia was strongly associated with RLS symptoms. The occurrences of new-onset RLS symptoms were 5.6 % (95 % CI 0.9–13.0) for participants reporting COVID-19 and 1.1 % (95 % CI 0.7–1.5) for non-COVID-19 participants. In the fully adjusted logistic regression model, the occurrence of new-onset RLS symptoms was associated with younger age, social restrictions and insomnia severity. In a similar analysis, RLS symptoms (≥3 evenings/nights per week) were associated with lower education, financial hardship, sleep apnea symptoms, use of hypnotics, insomnia severity, symptoms of depression and possible post-traumatic stress disorder. Our findings indicate that RLS symptoms were more common during the pandemic than before. Usually, the prevalence of RLS increases with age. However, during the pandemic, new-onset symptoms of RLS were more common in younger age groups. This may be due to the pandemic-related factors being more pronounced in the younger compared to the older. The association between insomnia, psychiatric symptoms and RLS warrants clinical attention. • Restless legs symptoms were more prevalent during the COVID-19 pandemic than before. • Insomnia and psychiatric symptoms were associated with RLS symptoms. • New-onset RLS symptoms were more common among younger subjects. [ABSTRACT FROM AUTHOR]

Summary Sleep trackers are used widely by patients with sleep complaints, however their metrological validation is often poor and relies on healthy subjects. We assessed the metrological validity of two commercially available sleep trackers (Withings Activité/Fitbit Alta HR) through a prospective observational monocentric study, in adult patients referred for polysomnography (PSG). We compared the total sleep time (TST), REM time, REM latency, nonREM1 + 2 time, nonREM3 time, and wake after sleep onset (WASO). We report absolute and relative errors, Bland–Altman representations, and a contingency table of times spent in sleep stages with respect to PSG. Sixty‐five patients were included (final sample size 58 for Withings and 52 for Fitbit). Both devices gave a relatively accurate sleep start time with a median absolute error of 5 (IQR −43; 27) min for Withings and −2.0 (−12.5; 4.2) min for Fitbit but both overestimated TST. Withings tended to underestimate WASO with a median absolute error of −25.0 (−61.5; −8.5) min, while Fitbit tended to overestimate it (median absolute error 10 (−18; 43) min. Withings underestimated light sleep and overestimated deep sleep, while Fitbit overestimated light and REM sleep and underestimated deep sleep. The overall kappas for concordance of each epoch between PSG and devices were low: 0.12 (95%CI 0.117–0.121) for Withings and VPSG indications 0.07 (95%CI 0.067–0.071) for Fitbit, as well as kappas for each VPSG indication 0.07 (95%CI 0.067–0.071). Thus, commercially available sleep trackers are not reliable for sleep architecture in patients with sleep complaints/pathologies and should not replace actigraphy and/or PSG. [ABSTRACT FROM AUTHOR]

This document is an editorial discussing a special issue of the European Physical Journal: Special Topics focused on the study of the sleeping brain and brain pathology. The editorial emphasizes the importance of sleep for restoring energy and brain health, and highlights the potential for developing new technologies and therapies for brain diseases through the study of sleep patterns. The special issue includes research papers on various topics such as hemispheric asymmetry during sleep, mechanisms controlling sleep-wake stages, and innovative methods for analyzing the sleeping brain. The authors express gratitude to the contributors and reviewers of the studies, and provide information on data availability. [Extracted from the article]

Guidelines for the evaluation and management of sleep disorders from national societies provide recommendations that may be regionally appropriate but may not always be practical or relevant in other parts of the world. A task force of experts from the World Sleep Society's (WSS) International Sleep Medicine Guidelines Committee and Sleep and Breathing Disorders Taskforce reviewed the American Academy of Sleep Medicine's Clinical Practice Guideline on the Treatment of Adult Obstructive Sleep Apnea (OSA) with Positive Airway Pressure with respect to its relevance and applicability to the practice of sleep medicine by sleep specialists in various regions of the world. To improve the evaluation of the guideline, surveys were sent by the senior author and the WSS to approximately 800 sleep doctors around the world to query the availability of OSA treatments in their respective region. The task force and the WSS guidelines committee endorsed the AASM's CPAP guidelines with respect to the indications for PAP therapy, utilization of different PAP modalities, and concurrent strategies to improve outcomes, noting appropriate caveats for universal applicability. [ABSTRACT FROM AUTHOR]

Summary: Recent evidence supports the use of pulse wave analysis during sleep for assessing functional aspects of the cardiovascular system. The current study compared the influence of pulse wave and sleep study‐derived parameters on cardiovascular risk assessment. In a multi‐centric study design, 358 sleep apnea patients (age 55 ± 13 years, 64% male, body mass index 30 ± 6 kg m−2, apnea–hypopnea index 13 [5–26] events per hr) underwent a standard overnight sleep recording. A novel cardiac risk index was computed based on pulse wave signals derived from pulse oximetry, reflecting vascular stiffness, cardiac variability, vascular autonomic tone and nocturnal hypoxia. Cardiovascular risk was determined using the ESC/ESH cardiovascular risk matrix, and categorized to high/low added cardiovascular risk. Comparisons between cardiac risk index and sleep parameters were performed for cardiovascular risk prediction. Apnea–hypopnea index, oxygen desaturation index and cardiac risk index were associated with high cardiovascular risk after adjustment for confounders (p =.002,.001, <.001, respectively). In a nested reference model consisting of age, gender and body mass index, adding cardiac risk index but not apnea–hypopnea index or oxygen desaturation index significantly increased the area under the receiver operating characteristic curve (p =.012,.22 and.16, respectively). In a direct comparison of oxygen desaturation index and cardiac risk index, only the novel risk index had an independent effect on cardiovascular risk prediction (pCRI <.001, pODI =.71). These results emphasize the association between nocturnal pulse wave and overall cardiovascular risk determined by an established risk matrix. Thus, pulse wave analysis during sleep provides a powerful approach for cardiovascular risk assessment in addition to conventional sleep study parameters. [ABSTRACT FROM AUTHOR]

Interactions between the cardiac and respiratory systems play a pivotal role in physiological functioning. Nonetheless, the intricacies of cardio-respiratory couplings, such as cardio-respiratory phase synchronization (CRPS) and cardio-respiratory coordination (CRC), remain elusive, and an automated algorithm for CRC detection is lacking. This paper introduces an automated CRC detection algorithm, which allowed us to conduct a comprehensive comparison of CRPS and CRC during sleep for the first time using an extensive database. We found that CRPS is more sensitive to sleep-stage transitions, and intriguingly, there is a negative correlation between the degree of CRPS and CRC when fluctuations in breathing frequency are high. This comparative analysis holds promise in assisting researchers in gaining deeper insights into the mechanics of and distinctions between these two physiological phenomena. Additionally, the automated algorithms we devised have the potential to offer valuable insights into the clinical applications of CRC and CRPS. [ABSTRACT FROM AUTHOR]

SUMMARY: Obstructive sleep apnea is a highly prevalent sleep‐related breathing disorder, resulting in a disturbed breathing pattern, changes in blood gases, abnormal autonomic regulation, metabolic fluctuation, poor neurocognitive performance, and increased cardiovascular risk. With broad inter‐individual differences recognised in risk factors, clinical symptoms, gene expression, physiological characteristics, and health outcomes, various obstructive sleep apnea subtypes have been identified. Therapeutic efficacy and its impact on outcomes, particularly for cardiovascular consequences, may also vary depending on these features in obstructive sleep apnea. A number of interventions such as positive airway pressure therapies, oral appliance, surgical treatment, and pharmaceutical options are available in clinical practice. Selecting an effective obstructive sleep apnea treatment and therapy is a challenging medical decision due to obstructive sleep apnea heterogeneity and numerous treatment modalities. Thus, an objective marker for clinical evaluation is warranted to estimate the treatment response in patients with obstructive sleep apnea. Currently, while the Apnea–Hypopnea Index is used for severity assessment of obstructive sleep apnea and still considered a major guide to diagnosis and managements of obstructive sleep apnea, the Apnea–Hypopnea Index is not a robust marker of symptoms, function, or outcome improvement. Abnormal cardiac autonomic modulation can provide additional insight to better understand obstructive sleep apnea phenotyping. Heart rate variability is a reliable neurocardiac tool to assess altered autonomic function and can also provide cardiovascular information in obstructive sleep apnea. Beyond the Apnea–Hypopnea Index, this review aims to discuss the role of heart rate variability as an indicator and predictor of therapeutic efficacy to different modalities in order to optimise tailored treatment for obstructive sleep apnea. [ABSTRACT FROM AUTHOR]

Summary: Poor sleep quality or sleep deprivation may be related to decreased bone mineral density. We aimed to assess whether associations of sleep characteristics and bone turnover or strength are present in adults from the general population and whether these are independent of common risk factors such as sex, age, and obesity. A total of 1037 participants from the Study of Health in Pomerania‐TREND underwent laboratory‐based polysomnography and quantitative ultrasound measurements at the heel. Of these participants, 804 completed standardised questionnaires to assess daytime sleepiness, insomnia, and sleep quality. Serum concentrations of two bone turnover markers, intact amino‐terminal propeptide of type 1 procollagen (P1NP) and carboxy‐terminal telopeptide of type 1 collagen (CTX) were measured. Cross‐sectional associations of polysomnography variables (total sleep time, sleep efficiency, time spent wake after sleep onset, oxygen desaturation index, apnea–hypopnea index, and obstructive sleep apnea [OSA]), as well as sleep questionnaire scores with the bone turnover markers and the ultrasound‐based stiffness index were assessed in linear regression models. In adjusted models, higher insomnia scores and lower sleep quality scores were related to a higher bone turnover in women but not in men. However, associations between polysomnography variables or questionnaire scores and the stiffness index were absent. Our study provides limited evidence for relationships between sleep characteristics and bone turnover and strength independent of common risk factors for OSA and osteoporosis. Nevertheless, women reporting poor sleep or insomnia in combination with risk factors for osteoporosis might benefit from an evaluation of bone health. [ABSTRACT FROM AUTHOR]

Objective. In this perspective paper, we aim to highlight the potential of sleep as an auspicious time for diagnosis, management and therapy of non-sleep-specific pathologies. Approach. Sleep has a profound influence on the physiology of body systems and biological processes. Molecular studies have shown circadian-regulated shifts in protein expression patterns across human tissues, further emphasizing the unique functional, behavioral and pharmacokinetic landscape of sleep. Thus, many pathological processes are also expected to exhibit sleep-specific manifestations. Modern advances in biosensor technologies have enabled remote, non-invasive recording of a growing number of physiologic parameters and biomarkers promoting the detection and study of such processes. Main results. Here, we introduce key clinical studies in selected medical fields, which leveraged novel technologies and the advantageous period of sleep to diagnose, monitor and treat pathologies. Studies demonstrate that sleep is an ideal time frame for the collection of long and clean physiological time series data which can then be analyzed using data-driven algorithms such as deep learning. Significance.This new paradigm proposes opportunities to further harness modern technologies to explore human health and disease during sleep and to advance the development of novel clinical applications – from sleep medicine to medicine during sleep. [ABSTRACT FROM AUTHOR]

Background: Playing computer games before bedtime is a common behavior, especially among adolescents. Excessive computer game use can be associated with somatic complaints, attention deficits, and family interaction problems. However, there is little knowledge about the effects of computer games on subsequent sleep. Objectives: The aim of this pilot study was to investigate the effects of playing a computer game in the evening on the alertness and sleep of adolescents. Materials and methods: Twenty-five healthy adolescents (mean age 15 years, f = 20, m = 5) from one school class were included in this pilot study. In a randomized crossover design on two consecutive days, either a jump-and-run computer game or reading a youth magazine was performed for 2 h in the evening. Before and after each intervention, mood (ASTS) and drowsiness (KSS) were assessed by questionnaires and parameters of tonic alertness were measured by the psychomotor vigilance task (PVT). Subsequently, sleep was measured by polysomnography (PSG). Results: Two hours of computer gaming in the evening resulted in reduced alertness levels immediately thereafter: the PVT parameter response time (RT) increased from 272.0 ± 30.5 ms to 305.2 ± 41.3 ms (p < 0.01) while it remained unchanged under the reading condition the other evening. In comparison to reading, using computer games in the evening led to an increased amount of light sleep (N1 + N2: 48.9 ± 9.1%-TST vs. 44.6 ± 9.8%-TST, p < 0.05) and a reduced amount of deep sleep (N3: 36.0 ± 10.0%-TST vs. 39.5 ± 9.0%-TST, p < 0.05) the following night. Sleep latency and sleep efficiency did not differ between the two conditions. Conclusions: In the group of healthy adolescents examined in this pilot study, using computer games in the evening had immediate negative consequences on alertness and on sleep architecture the subsequent night. Together with frequently insufficient sleeping time on school days in adolescents, these findings cumulatively could have relevance for physiological development. Subsequent trials in different groups of adolescents with a sufficient number of subjects are needed in order to further verify these findings and possibly, to adapt sleep-hygiene behavioral recommendations for these age groups. [ABSTRACT FROM AUTHOR]

Guidelines for management of sleep disorders from national or regional societies provide recommendations that may be regionally appropriate but may not always be practical or relevant in other parts of the world. A task force of experts from the World Sleep Society's (WSS) International Sleep Medicine Guidelines Committee and Sleep and Breathing Disorders Task Force reviewed the European Respiratory Society's guideline on non-CPAP therapies for obstructive sleep apnea (OSA) with respect to its relevance and applicability to the practice of sleep medicine by sleep specialists in various regions of the world. The task force and the WSS guidelines committee endorsed the European Respiratory Society's guideline with respect to the utilization of bariatric surgery, mandibular advancement devices, positioning devices, myofunctional therapy, hypoglossal neurostimulation, maxilo-mandibular surgery, and carbonic anhydrase inhibitors for the treatment of OSA. The task force and the WSS guidelines committee noted that there is substantial new evidence for the role of soft tissue, upper airway surgery, not included in the guidelines paper. [ABSTRACT FROM AUTHOR]

Introduction: There are studies about polysomnographic (PSG) characteristics of patients with either obesity hypoventilation syndrome (OHS) or addiction. We aimed to investigate the PSG characteristics of obstructive sleep apnea (OSA) patients with opium addiction, those on methadone maintenance treatment (MMT), and non-addicts for the treatment of addiction. Methods: In this cross-sectional study, we enrolled 75 patients with OHS in the Bamdad Respiratory and Sleep Research Center affiliated with the Isfahan University of Medical Sciences between January 2020 and February 2021. The patients were categorized into three groups: Opium addicts (OA), MMT, and non-addicts (NA). All patients completed screening questionnaires for OSA. This included the Epworth sleepiness scale (ESS), stop-bang questionnaire, and Berlin questionnaire and the data analyzed by SPSS software, version 24. Results: A total of 75 OHS patients (54 men [72%] and 21 women [28%]) were studied in three groups, including OA (n=30), MMT (n=15), and NA (n=30). The apnea hypopnea index was not significantly different between the three groups. The longest apnea duration was higher in the OA than in other groups (P=0.001). Central apnea index (P=0.01), longest hypopnea duration (P=0.04), PaCO2 (P=0.04), and time with SpO2?90% (T90) (P=0.009) were higher in the MMT than in other groups. Furthermore, the minimum SpO2 was lower in the MMT than in other groups (P=0.03). Conclusion: Some of the sleep disturbances were worse in the MMT than in the OA group. This suggests the need for further studies to compare the effects of opium and methadone on sleep in OHS patients. [ABSTRACT FROM AUTHOR]

There is evidence of a strong association between insomnia and COVID-19, yet few studies have examined the relationship between insomnia and long COVID. This study aimed to investigate whether COVID-19 patients with pre-pandemic insomnia have a greater risk of developing long COVID and whether long COVID is in turn associated with higher incident rates of insomnia symptoms after infection. Data were collected cross-sectionally (May–Dec 2021) as part of an international collaborative study involving participants from 16 countries. A total of 2311 participants (18–99 years old) with COVID-19 provided valid responses to a web-based survey about sleep, insomnia, and health-related variables. Log-binomial regression was used to assess bidirectional associations between insomnia and long COVID. Analyses were adjusted for age, sex, and health conditions, including sleep apnea, attention and memory problems, chronic fatigue, depression, and anxiety. COVID-19 patients with pre-pandemic insomnia showed a higher risk of developing long COVID than those without pre-pandemic insomnia (70.8% vs 51.4%; adjusted relative risk [RR]: 1.33, 95% confidence interval [CI]: 1.07–1.65). Among COVID-19 cases without pre-pandemic insomnia, the rates of incident insomnia symptoms after infection were 24.1% for short COVID cases and 60.6% for long COVID cases (p <.001). Compared with short COVID cases, long COVID cases were associated with an increased risk of developing insomnia symptoms (adjusted RR: 2.00; 95% CI: 1.50–2.66). The findings support a bidirectional relationship between insomnia and long COVID. These findings highlight the importance of addressing sleep and insomnia in the prevention and management of long COVID. • COVID-19 patients with pre-pandemic insomnia showed a higher risk of developing long COVID than those without pre-pandemic insomnia. • Among COVID-19 cases without pre-pandemic insomnia, the rates of incident insomnia symptoms after infection were 24.1% for short COVID cases and 60.6% for long COVID cases. • The findings support a bidirectional relationship between insomnia and long COVID, which highlights the importance of addressing sleep and insomnia in the prevention and management of long COVID. [ABSTRACT FROM AUTHOR]

Relationship between stiffness of genioglossi (GG) and geniohyoidei (GH) muscles under electric hypoglossal nerve stimulation therapy (HNS) in relation to success of therapy was investigated with additional special focus on tongue movement. Patients and Methods: Clinical and sleep laboratory parameters of a cohort of 18 patients with known shear wave velocity (SWV) data of the ipsilateral and contralateral musculi GG and GH (sGG, sGH and nGG, nGH) before and under HNS therapy were analyzed. The SWV was already determined using the ultrasonic shear wave elastography (US-SWE) technique. Results: Median Epworth Sleepiness Scale (ESS) was 8 (IQR 12), median baseline Apnoe–Hypopnoe Index (AHI) 31.65 (IQR 25.1), median AHI under HNS therapy 16.3 (IQR 20.03). Therapy success: 9/18 patients (AHI during therapy < 15/h). There was no significant difference in SWV (sGG, sGH, nGG and nGH) between therapy responders and non-responders during therapy. Also, no difference could be seen with respect to the difference and increase in SWV values without and with stimulation. Examination of SWV values (sGG, sGH, nGG, nGH during stimulation, difference of SWV values stimulation − no stimulation, increase factor of SWV) revealed a significant negative correlation between the AHI under therapy and the measured SWV of the musculus GH of the contralateral side during stimulation (−0.622, p = 0.006). Patients with bilateral protrusion of the tongue differed regarding to therapy success in increase in SWV in sGG (p = 0.032). Tongue protrusion to contralateral: A significant difference between patients with AHI during therapy < 15/h in SWV values at sGG without stimulation (p = 0.021) was seen, with also a correlation to the current AHI under therapy (p = 0.047) and the change factor of the AHI (p = 0.015). Conclusion: Stiffness of the target muscle does not appear to be an isolated measure of the success of HNS therapy. This observation may have implications for future decision-making processes in the process of titrating electrical therapy parameters. But the technique of US-SWE may be useful for future research of the neurophysiology of the tongue and OSA phenotyping. [ABSTRACT FROM AUTHOR]

Background: Self-rated health (SRH) is widely recognized as a clinically significant predictor of subsequent mortality risk. Although COVID-19 may impair SRH, this relationship has not been extensively examined. The present study aimed to examine the correlation between habitual sleep duration, changes in sleep duration after infection, and SRH in subjects who have experienced SARS-CoV-2 infection. Methods: Participants from 16 countries participated in the International COVID Sleep Study-II (ICOSS-II) online survey in 2021. A total of 10,794 of these participants were included in the analysis, including 1,509 COVID-19 individuals (who reported that they had tested positive for COVID-19). SRH was evaluated using a 0-100 linear visual analog scale. Habitual sleep durations of < 6 h and > 9 h were defined as short and long habitual sleep duration, respectively. Changes in habitual sleep duration after infection of ≤ -2 h and ≥ 1 h were defined as decreased or increased, respectively. Results: Participants with COVID-19 had lower SRH scores than non-infected participants, and those with more severe COVID-19 had a tendency towards even lower SRH scores. In a multivariate regression analysis of participants who had experienced COVID-19, both decreased and increased habitual sleep duration after infection were significantly associated with lower SRH after controlling for sleep quality (β = −0.056 and −0.058, respectively, both p < 0.05); however, associations between current short or long habitual sleep duration and SRH were negligible. Multinomial logistic regression analysis showed that decreased habitual sleep duration was significantly related to increased fatigue (odds ratio [OR] = 1.824, p < 0.01), shortness of breath (OR = 1.725, p < 0.05), diarrhea/nausea/vomiting (OR = 2.636, p < 0.01), and hallucinations (OR = 5.091, p < 0.05), while increased habitual sleep duration was significantly related to increased fatigue (OR = 1.900, p < 0.01). Conclusions: Changes in habitual sleep duration following SARS-CoV-2 infection were associated with lower SRH. Decreased or increased habitual sleep duration might have a bidirectional relation with post-COVID-19 symptoms. Further research is needed to better understand the mechanisms underlying these relationships for in order to improve SRH in individuals with COVID-19. [ABSTRACT FROM AUTHOR]

The study of functions, mechanisms of generation, and pathways of movement of cerebral fluids has a long history, but the last decade has been especially productive. The proposed glymphatic hypothesis, which suggests a mechanism of the brain waste removal system (BWRS), caused an active discussion on both the criticism of some of the perspectives and our intensive study of new experimental facts. It was especially found that the intensity of the metabolite clearance changes significantly during the transition between sleep and wakefulness. Interestingly, at the cellular level, a number of aspects of this problem have been focused on, such as astrocytes–glial cells, which, over the past two decades, have been recognized as equal partners of neurons and perform many important functions. In particular, an important role was assigned to astrocytes within the framework of the glymphatic hypothesis. In this review, we return to the "astrocytocentric" view of the BWRS function and the explanation of its activation during sleep from the viewpoint of new findings over the last decade. Our main conclusion is that the BWRS's action may be analyzed both at the systemic (whole-brain) and at the local (cellular) level. The local level means here that the neuro-glial-vascular unit can also be regarded as the smallest functional unit of sleep, and therefore, the smallest functional unit of the BWRS. [ABSTRACT FROM AUTHOR]

Continuous positive airway pressure (CPAP) ventilation is considered the therapeutic standard for obstructed sleep apnea (OSA). Therapy success may also be affected by the patient's bed partner. A questionnaire was developed and tested that measures the attitude of the bed partner towards CPAP therapy and relationship effects. A new questionnaire to capture bed partners' attitude towards CPAP mask therapy was used with an anonymous sample of 508 bed partners. Possible constructs underlying the attitude of the bed partner towards mask appearance have been investigated by means of a Principal Components Analysis. Results: The survey revealed bed partners' positive attitude towards their partner's CPAP therapy (over 90% of bed partners were happy with the therapy, over 75% would recommend the therapy). Importantly, the bed partners' satisfaction with the relationship increased significantly during CPAP therapy (before therapy: 49% were satisfied, after therapy initiation: 70%; p<.001). There was a strong correlation between support for CPAP therapy and improved sleep quality of bed partners (r = 0.352, p>.001). Furthermore, the validation of the questionnaire through principal components analysis revealed three major factors: Attitude (of the bed partner towards CPAP therapy), Looks (of the mask perceived by the bed partner), Intimacy (effect of CPAP therapy on relationship and intimacy). Both, the OSA patient and the bed partner benefit from CPAP therapy. This is the first bed partner questionnaire – interviewing the bed partner alone and anonymously – that showed that CPAP therapy also positively influences the relationship. We recommend that the bed partner be involved in the CPAP treatment from the start of therapy. • Validation of a questionnaire to capture bed partners opinion towards CPAP therapy. • Bed partners support CPAP therapy. • Bed partners reveal that CPAP therapy improves relationship satisfaction. • Bed partner involvement in CPAP therapy may be beneficial. [ABSTRACT FROM AUTHOR]

Fatigue and sleepiness are complex bodily states associated with monotony as well as physical and cognitive impairment, accidents, injury, and illness. Moreover, these states are often characteristic of professional driving. However, most existing work has focused on motor vehicle drivers, and research examining train drivers remains limited. As such, the present study psychophysiologically examined monotonous driving, fatigue, and sleepiness in a group of passenger train drivers and a group of non-professional drivers. Sixty-three train drivers and thirty non-professional drivers participated in the present study, which captured 32-lead electroencephalogram (EEG) data during a monotonous driving task. Fatigue and sleepiness were self-evaluated using the Pittsburgh Sleep Quality Index, the Epworth Sleepiness Scale, the Karolinksa Sleepiness Scale, and the Checklist of Individual Strength. Unexpectedly, fatigue and sleepiness scores did not significantly differ between the groups; however, train drivers generally scored lower than non-professional drivers, which may be indicative of individual and/or industry attempts to reduce fatigue. Across both groups, fatigue and sleepiness scores were negatively correlated with theta, alpha, and beta EEG variables clustered towards the fronto-central and temporal regions. Broadly, these associations may reflect a monotony-associated blunting of neural activity that is associated with a self-reported fatigue state. [ABSTRACT FROM AUTHOR]