The Brugmann Fatigue Scale: An Analogue to the Epworth Sleepiness Scale to Measure Behavioral Rest Propensity

Identifying comorbid obstructive sleep apnea in chronic musculoskeletal pain: a systematic review

Obstructive sleep apnea (OSA) is common in patients with chronic musculoskeletal pain (CMP). Understanding the characteristics of the CMP population with comorbid OSA is important for proper screening and management. This systematic review compiles evidence on methods used to identify OSA in patients with CMP and identifies the characteristic features of patients with CMP and comorbid OSA. A systematic search was conducted in Medline (PubMed), Embase and Web of Science. Broad search terms related to sleep apnea and CMP were used. Studies had to include individuals with CMP diagnosed with OSA or individuals with CMP in whom OSA symptoms were assessed as outcomes. The protocol was pre-registered on PROSPERO (CRD42024516140). The initial search identified 3,832 records, and 30 studies (total n=7,085 participants) were included. Laboratory sleep polysomnography was the most used objective assessment method, while the Berlin and STOP-BANG questionnaires were the most used self-report instruments. However, these questionnaires showed poor agreement with polysomnography. The results consistently showed that fatigue and pain distribution did not differ between CMP patients with and without OSA. Inconsistent results were found regarding higher age, higher body mass index, psychological factors, decreased sleep quality, increased sleepiness, and pain intensity as characteristic features of the CMP with OSA population compared to the CMP without OSA. No factors consistently characterized the CMP with OSA population. Further research is required to explore the factors that consistently characterize patients with CMP with comorbid OSA to improve the effectiveness of screening for OSA in daily practice. PERSPECTIVE: This work summarizes the tools used to assess obstructive sleep apnea in populations with chronic musculoskeletal pain and highlights the features of individuals with both conditions compared to those with only chronic musculoskeletal pain.

Sleep Fragmentation Modulates the Neurophysiological Correlates of Cognitive Fatigue

Cognitive fatigue (CF) is a critical factor affecting performance and well-being. It can be altered in suboptimal sleep quality conditions, e.g., in patients suffering from obstructive sleep apnea who experience both intermittent hypoxia and sleep fragmentation (SF). Understanding the neurophysiological basis of SF in healthy individuals can provide insights to improve cognitive functioning in disrupted sleep conditions. In this electroencephalographical (EEG) study, we investigated in 16 healthy young participants the impact of experimentally induced SF on the neurophysiological correlates of CF measured before, during, and after practice on the TloadDback, a working memory task tailored to each individual's maximal cognitive resources. The participants spent three consecutive nights in the laboratory two times, once in an undisrupted sleep (UdS) condition and once in an SF condition induced by non-awakening auditory stimulations, counterbalanced and performed the TloadDback task both in a high (HCL) and a low (LCL) cognitive load condition. EEG activity was recorded during wakefulness in the 5 min resting state immediately before and after, as well as during the 16 min of the TloadDback task practice. In the high cognitive load under a sleep-fragmentation (HCL/SF) condition, high beta power increased during the TloadDback, indicating heightened cognitive effort, and the beta and alpha power increased in the post- vs. pre-task resting state, suggesting a relaxation rebound. In the low cognitive load/undisturbed sleep (LCL/UdS) condition, low beta activity increased, suggesting a relaxed focus, as well as mid beta activity associated with active thinking. These findings highlight the dynamic impact of SF on the neurophysiological correlates of CF and underscore the importance of sleep quality and continuity to maintain optimal cognitive functioning.

Cognitive Behavioral Therapy for Insomnia in Pain Management for Nonspecific Chronic Spinal Pain: A Randomized Clinical Trial

Importance

Insomnia is highly prevalent in patients with nonspecific chronic spinal pain (nCSP). Given the close interaction between insomnia and pain, targeting sleep problems during therapy could improve treatment outcomes.

Objective

To evaluate the effectiveness of cognitive behavioral therapy for insomnia (CBTi) integrated in best-evidence pain management (BEPM) vs BEPM only in patients with nCSP and insomnia.

Design, Setting, and Participants

A multicenter randomized clinical trial with 1-year follow-up was conducted between April 10, 2018, and April 30, 2022. Data and statistical analysis were performed between May 1, 2022, and April 24, 2023. Patients with nCSP and insomnia were evaluated using self-report and at-home polysomnography, to exclude underlying sleep pathologic factors. Participants were treated at the University Hospital Brussels or University Hospital Ghent, Belgium. Intention-to-treat analysis was performed.

Interventions

Participants were randomized to either CBTi-BEPM or BEPM only. Both groups received 18 treatment sessions over 14 weeks. The CBTi-BEPM treatment included 6 CBTi sessions and 12 BEPM sessions. The BEPM treatment included pain neuroscience education (3 sessions) and exercise therapy (9 sessions in the CBTi-BEPM group, 15 sessions in the BEPM-only group).

Main Outcomes and Measures

The primary outcome was change in mean pain intensity (assessed with Brief Pain Inventory [BPI]) at 12 months after the intervention. Exploratory secondary outcomes included several pain- and sleep-related outcomes. Blinded outcome assessment took place at baseline, posttreatment, and at 3-, 6-, and 12-month follow-up.

Results

A total of 123 patients (mean [SD] age, 40.2 [11.18] years; 84 women [68.3%]) were included in the trial. In 99 participants (80.5%) with 12-month BPI data, the mean pain intensity at 12 months decreased by 1.976 points (reduction of 40%) in the CBTi-BEPM group and 1.006 points (reduction of 24%) points in the BEPM-only group. At 12 months, there was no significant difference in pain intensity change between groups (mean group difference, 0.970 points; 95% CI, -0.051 to 1.992; Cohen d, 2.665). Treatment with CBTi-BEPM resulted in a response for BPI average pain with a number needed to treat (NNT) of 4 observed during 12 months. On a preliminary basis, CBTi-BEPM was, consistently over time and analyses, more effective than BEPM only for improving insomnia severity (Cohen d, 4.319-8.961; NNT for response ranging from 2 to 4, and NNT for remission ranging from 5 to 12), sleep quality (Cohen d, 3.654-6.066), beliefs about sleep (Cohen d, 5.324-6.657), depressive symptoms (Cohen d, 2.935-3.361), and physical fatigue (Cohen d, 2.818-3.770). No serious adverse effects were reported.

Conclusions and Relevance

In this randomized clinical trial, adding CBTi to BEPM did not further improve pain intensity reduction for patients with nCSP and comorbid insomnia more than BEPM alone. Yet, as CBTi-BEPM led to significant and clinically important changes in insomnia severity and sleep quality, CBTi integrated in BEPM should be considered in the treatment of patients with nCSP and comorbid insomnia. Further research can investigate the patient characteristics that moderate the response to CBTi-BEPM in terms of pain-related outcomes, as understanding of these moderators may be of utmost clinical importance.

Trial Registration

Clinical Trials.gov Identifier: NCT03482856.

Sleep deprivation increases the generalization of perceptual and concept-based fear: An fNIRS study

Insufficient sleep can initiate or exacerbate anxiety by triggering excessive fear generalization. In this study, a de novo paradigm was developed and used to examine the neural mechanisms governing the effects of sleep deprivation on processing perceptual and concept-based fear generalizations. A between-subject design was adopted, wherein a control group (who had a typical night's sleep) and a one-night sleep deprivation group completed a fear acquisition task at 9:00 PM on the first day and underwent a generalization test the following morning at 7:00 AM. In the fear acquisition task, navy blue and olive green were used as perceptual cues (P+ and P-, respectively), while animals and furniture items were used as conceptual cues (C+ and C-, respectively). Generalization was tested for four novel generalized categories (C+P+, C+P-, C-P+, and C-P-). Shock expectancy ratings, skin conductance responses, and functional near-infrared spectroscopy were recorded during the fear acquisition and generalization processes. Compared with the group who had a typical night's sleep, the sleep deprived group showed higher shock expectancy ratings (especially for P+ and C-), increased oxygenated hemoglobin in the dorsolateral prefrontal cortex, and increased activation in the triangular inferior frontal gyrus during the generalization test. These findings suggest that sleep deprivation increases the generalization of threat memories, thus providing insights into the overgeneralization characteristics of anxiety and fear-related disorders.

Integration of Cognitive Behavioral Therapy for Insomnia in Best-Practice Care for Patients With Knee Osteoarthritis and Insomnia: A Randomized Controlled Trial Protocol

OBJECTIVE

Knee osteoarthritis (KOA) is a common musculoskeletal problem worldwide and its key symptom is pain. Guidelines recommend incorporating comorbidity-specific therapies into patient-centered care. Patients diagnosed with KOA frequently have insomnia, which is associated with higher-pain severity. For this reason, this study protocol outlines the methodology of a randomized controlled trial (RCT) investigating the effectiveness of cognitive behavioral therapy for insomnia (CBTi) combined with best-practice KOA care (BPC) compared to best-practice KOA care and lifestyle education.

METHODS

A 2-arm RCT in patients with KOA and insomnia is conducted, in which a total of 128 patients are randomly allocated to an intervention or control group. The experimental intervention consists of 12 sessions of physical therapist-led BPC with an additional 6 sessions of CBTi. The control intervention also receives BPC, which is supplemented with 6 general lifestyle information sessions. The primary outcome is the between-group difference in change in pain severity at 6 months after intervention. Secondary outcomes are pain-related outcomes, sleep-related outcomes, symptoms of anxiety and depression, level of physical activity and function, perceived global improvement, biomarkers of inflammation, and health-related quality of life. Assessments are conducted at baseline, immediately after intervention, and 3, 6, and 12 months after intervention. Furthermore, a cost-utility analysis for the proposed intervention will be performed alongside the RCT.

IMPACT

This is the first RCT investigating the clinical and cost-effectiveness of a physical therapist-led intervention integrating CBTi into BPC in patients with KOA and insomnia. The results of this trial will add to the growing body of evidence on the effectiveness of individualized and comorbidity-specific KOA care, which can inform clinical decision-making and assist policymakers and other relevant stakeholders in optimizing the care pathway for patients with KOA.

The Role of Anxiety and Depression in Shaping the Sleep-Pain Connection in Patients with Nonspecific Chronic Spinal Pain and Comorbid Insomnia: A Cross-Sectional Analysis

(1) Background: This exploratory study aims to explore the relationship between nonspecific chronic spinal pain (nCSP) and insomnia symptoms, by examining the interconnections, strengths, and directional dependence of the symptoms. In addition, we aim to identify the key symptoms of the nCSP-insomnia relationship and shed light on the bidirectional nature of this relationship. (2) Methods: This study is a secondary analysis of the baseline data (cross-sectional) from a randomized controlled trial, which examined the added value of Cognitive Behavioral Therapy for Insomnia (CBT-I) combined with cognition-targeted exercise therapy, conducted in collaboration with the Universiteit Gent and Vrije Universiteit Brussel (Belgium). One hundred and twenty-three nCSP patients with comorbid insomnia were recruited through the participating hospitals, advertisements, announcements in local newspapers, pharmacies, publications from support groups, and primary care. To explore the interconnections and directionality between symptoms and the strengths of the relationships, we estimated a regularized Gaussian graphical model and a directed acyclic graph. (3) Results: We found only one direct, but weak, link between sleep and pain, namely, between average pain and difficulties maintaining sleep. (4) Conclusions: Despite the lack of strong direct links between sleep and pain, pain and sleep seem to be indirectly linked via anxiety and depression symptoms, acting as presumable mediators in the network of nCSP and comorbid insomnia. Furthermore, feeling slowed down and fatigue emerged as terminal nodes, implying their role as consequences of the network.

Outcome of severe COVID-19: spotlight on fatigue, fatigability, multidomain complaints and pattern of cognitive deficits in a case series without prior brain dysfunction and without COVID-19-related stroke and/or cardiac arrest

BACKGROUND

Population-wide surveys and large-scale investigations highlighted the presence of cognitive deficits in the acute and postacute stages of severe COVID-19; a few studies documented their occurrence in cases without prior or COVID-19-related brain damage. The evolution of cognitive deficits in the latter population and their relationship to the post-COVID-19 fatigue syndrome are poorly understood.

CASE PRESENTATION

We report the outcome at 12 months after severe COVID-19 involving an intensive care unit stay and mechanical ventilation in six (five Caucasian and one Asian) patients (age range: 53-71 years, mean age 61.7 ± 6.5 years) without history of prior brain dysfunction and without stroke and/or cardiac arrest during or after COVID-19. All patients reported pervading mental and physical fatigue as well as numerous multidomain complaints, which impacted everyday life. Individual patients described mental fatigability, apathy, and/or anxiety. Standardized neuropsychological tests revealed isolated symptoms of cognitive dysfunction or performance at the lower limit of the norm in the attentional, executive, and/or working memory domains in four of the six patients. Somatic scales documented dyspnoea, muscle weakness, olfactory disorder, and/or minor sleep problems in some, but not all, patients.

CONCLUSION

Fatigue, fatigability, multidomain complaints, cognitive difficulties, or dysfunction, as well as isolated neurobehavioral and/or psychiatric and/or somatic symptoms, tend to occur in the aftermath of severe COVID-19 and persist at 12 months, even in the absence of prior and/or COVID-19-related brain damage. This clinical situation, which impacts everyday life, calls for a detailed investigation of patients' complaints, its neural underpinning, and an elaboration of specific rehabilitation programs.

Do Patients with Chronic Spinal Pain and Comorbid Insomnia Have More Features of Central Sensitization? A Case-Control Study

BACKGROUND

Chronic spinal pain (CSP) is a major public health problem worldwide, frequently related to sleep problems. Central sensitization (CS) may worsen the clinical picture of CSP patients with insomnia. The aim of this study was to compare self-reported and objectively measured clinical outcomes between insomniac CSP patients with comorbid insomnia with and without symptoms of CS.

METHODS

A case-control study on baseline self-reported sleep, functioning, and psychological distress through online questionnaires. Objective sleep and physical activity parameters and pressure pain thresholds (PPTs) were assessed through polysomnography, actigraphy, and digital algometry, respectively. Independent sample t-test and Mann-Whitney U tests were used to examine possible differences in the outcome measures between the groups.

RESULTS

Data from 123 participants were included and revealed no statistically significant group for objective sleep and physical activity parameters. The CS group, however, presented with worse self-reported sleep (quality sleep, insomnia severity, and dysfunctional beliefs about sleep), increased mental and physical fatigue, and higher psychological distress (anxiety and depressive symptoms), and reported lower PPTs.

CONCLUSIONS

symptoms of CS may influence perceived sleep and affect functional health and well-being perception but do not seem to affect objective sleep and physical activity.

Psychological changes in athletes infected with Omicron after return to training: fatigue, sleep, and mood

Background

This study aims to analyze the changes of approximately 1 month in fatigue, sleep, and mood in athletes after returning to training following infection with the COVID-19 Omicron strain and provide recommendations for returning to training after infection.

Methods

Two hundred and thirty professional athletes who had returned to training after being infected with COVID-19 in December 2022 were recruited to participate in three tests conducted from early January 2023. The second test was completed approximately 1 week after the first, and the third was completed about 2 weeks after the second. Each test consisted of completing scales and the exercise-induced fatigue measure. The scales included a visual analog scale, the Athens Insomnia Scale for non-clinical application, and the Depression-Anxiety-Stress scale. The exercise task was a six-minute stair climb test, and athletes evaluated subjective fatigue levels before and after exercise using another Visual Analog Scale and the Karolinska Sleepiness Scale.

Results

After returning to training, athletes' physical fatigue decreased initially but increased as training progressed. Cognitive fatigue did not change significantly. The exercise task led to elevated levels of physical fatigue after a longer duration of training. Sleep quality problems decreased rapidly after the start of training but remained stable with prolonged training. Depression levels continued to decline, while anxiety levels only reduced after a longer duration of training. Stress levels decreased rapidly after the start of training but did not change with prolonged training.

Conclusion

Athletes who return to training after recovering from COVID-19 experience positive effects on their fatigue, sleep, and mood. It is important to prioritize anxiety assessment and interventions during the short period after returning and to continue monitoring fatigue levels and implementing recovery interventions over a longer period of time.

Impact of Sleep Fragmentation on Cognition and Fatigue

Sleep continuity and efficacy are essential for optimal cognitive functions. How sleep fragmentation (SF) impairs cognitive functioning, and especially cognitive fatigue (CF), remains elusive. We investigated the impact of induced SF on CF through the TloadDback task, measuring interindividual variability in working memory capacity. Sixteen participants underwent an adaptation polysomnography night and three consecutive nights, once in a SF condition induced by non-awakening auditory stimulations, once under restorative sleep (RS) condition, counterbalanced within-subject. In both conditions, participants were administered memory, vigilance, inhibition and verbal fluency testing, and for CF the TloadDback, as well as sleep questionnaires and fatigue and sleepiness visual analog scales were administered. Subjective fatigue increased and sleep architecture was altered after SF (reduced sleep efficiency, percentage of N3 and REM, number of NREM and REM phases) despite similar total sleep time. At the behavioral level, only inhibition deteriorated after SF, and CF similarly evolved in RS and SF conditions. In line with prior research, we show that SF disrupts sleep architecture and exerts a deleterious impact on subjective fatigue and inhibition. However, young healthy participants appear able to compensate for CF induced by three consecutive SF nights. Further studies should investigate SF effects in extended and/or pathological disruption settings.

Responsiveness of the Italian version of the Pediatric Quality of Life Multidimensional Fatigue Scale in adult inpatients with obesity

This study aimed to evaluate the responsiveness of the Italian version of the Paediatric Quality of Life Inventory Multidimensional Fatigue Scale (PedsQL-MFS) to changes in BMI, fatigue and depressive symptoms in adult inpatients with obesity. 198 adults (81% female, mean age = 44.7 years) with obesity completed the PedsQL-MFS, the Fatigue Severity Scale (FFS) and the Centre for Epidemiologic Studies Depression Scale (CESD) before and after completing a 3-week body weight reduction program. Internal responsiveness was measured via paired t-tests, standardized mean response (SMR) and Glass’s delta (d). Changes in FFS, CESD and BMI were used as anchors to categorize participants as “improved”, “unchanged” or “deteriorated”. External Responsiveness was assessed by comparing mean post-intervention PedsQL-MFS scores across change groups, adjusting for pre-intervention PedsQL-MFS scores and in area-under-curve (AUC) analysis. PedsQL-MFS Total, Sleep/Rest Fatigue and Cognitive Fatigue scores demonstrated significant reductions in response to an established body weight reduction program. Post-intervention PedsQL-MFS scale scores were lower among those who had improved on the CESD and FSS than among those whose CESD and FSS scores had not significantly changed. There was no difference in PedsQL-MFS scale scores according to whether participants had reduced their BMI by at least 5%. AUC analyses indicated that change in PedsQL-MFS scores was somewhat more predictive of improvement in CESD than FSS scores. The Italian version of the PedsQL-MFS demonstrated both internal and external responsiveness. It appeared more sensitive to improvement than deterioration in fatigue symptoms and its sensitivity to deterioration in depressive symptoms and weight loss could not be evaluated in the present study as there was no reliable deterioration in CESD scores and weight loss was modest. Future studies should include a control group to assess the sensitivity of the PedsQL-MFS more thoroughly.

Predictors for physical activity and its change after active physical therapy in people with spinal pain and insomnia: Secondary analysis of a randomized controlled trial

BACKGROUND

In healthy people and people with nonspecific chronic spinal pain (nCSP) and/or insomnia, participation in physical activity on a regular basis has several physical and psychological health benefits. However, people with chronic conditions often tend to reduce physical activity participation which can lead to deconditioning over time. Currently, there are no known predictors for an (in)active lifestyle (before and after physical therapy treatment) in people with chronic spinal pain and comorbid insomnia.

OBJECTIVE

To examine predictors of pre-treatment moderate-to-vigorous physical activity (MVPA) and to examine determinants for a change in MVPA in response to 14-weeks of active physical therapy treatment in people with nonspecific chronic spinal pain (nCSP) and comorbid insomnia.

METHODS

Baseline data and post-treatment data were analyzed for 66 participants. A linear multiple regression analysis was conducted to examine which factors predict MVPA at baseline. Linear mixed-effects modeling was used to identify determinants for change in MVPA in response to an active physical therapy treatment.

RESULTS

Physical fatigue (b = -0.9; 95%CI: -1.59, -0.15), less limitations in functioning as a result of emotional problems (b = 0.1; 95%CI: 0.03, 0.10), mental fatigue (b = -1.0; 95%CI: -1.67, -0.43), lower general sleep quality (b= 0.7; 95%CI: 0.22, 1.17), and body mass index (b = -0.5; 95%CI: -0.93, -0.16) were significant predictors of baseline MVPA. The regression model explained 33.3% of the total variance in baseline MVPA. The change of MVPA in response to the treatment ranged from a decrease of 17.5 to an increase of 16.6 hours per week. No determinants for change in MVPA after treatment could be identified.

CONCLUSION

People with nCSP and comorbid insomnia are more likely to engage in MVPA if they report, at baseline, lower sleep quality, fewer limitations in functioning resulting from emotional problems, lower body mass index, as well as less physical and mental fatigue.

Dissecting the fatigue experience: A scoping review of fatigue definitions, dimensions, and measures in non-oncologic medical conditions

INTRODUCTION

Fatigue is a prevalent and potentially debilitating symptom that impacts the health-related quality-of-life of individuals diagnosed with acute and chronic medical conditions. Yet, its etiologic mechanism is not fully understood. Additionally, the assessment and determination of the clinical meaning of fatigue and its multidimensionality may vary by medical condition.

METHODS

A scoping literature review was conducted to investigate how fatigue is defined and measured, including its dimensions, in non-oncologic medical conditions. The PubMed database was searched using keywords.

RESULTS

Overall, 8376 articles were screened at the title/abstract levels, where 293 articles were chosen for full-text review that mentioned fatigue or included fatigue measures. The review of the full text excluded 246 articles that did not assess at least one fatigue dimension using validated questionnaires and clinical tests. The final set included 47 articles. Physical fatigue was the most assessed fatigue dimension and the Multidimensional Fatigue Inventory was the most widely used questionnaire to assess fatigue in this review.

LIMITATIONS

This review was limited by including only English-language publications and using PubMed as the sole database for the search.

CONCLUSIONS

This review affirms that fatigue is a multidimensional construct, agnostic of medical condition, and that individual fatigue dimensions can be measured by validated clinical measures. Future research should focus on expanding the repertoire of clinical measures to assess specific fatigue dimensions.

Mental fatigue measurement using eye metrics: A systematic literature review

Mental fatigue measurement techniques utilize one or a combination of the cognitive, affective, and behavioral responses of the body. Eye-tracking and electrooculography, which are used to compute eye-based features, have gained momentum with increases in accuracy and robustness of the lightweight equipment emerging in the markets and can be used for objective and continuous assessment of mental fatigue. The main goal of this systematic review was to summarize the various eye-based features that have been used to measure mental fatigue and explore the relation of eye-based features to mental fatigue. The review process, following the preferred reporting items for systematic reviews and meta-analyses, used the electronic databases Web of Science, Scopus, ACM digital library, IEEE Xplore, and PubMed. Of the 1,385 retrieved documents, 34 studies met the inclusion criteria, resulting in 21 useful eye-based features. Categorizing these into eight groups revealed saccades as the most promising category, with saccade mean and peak velocity providing quick access to the cognitive states within 30 min of fatiguing activity. Complex brain networks involving sympathetic and parasympathetic nervous systems control the relation of mental fatigue to tonic pupil size and have the potential to indicate mental fatigue in controlled experimental conditions. Other categories, like blinks, are derived from the field of sleep research and should be used with caution. Several limitations emerged in the analysis, including varied experimental methods, use of dim lighting during the experiment (that could possibly also induce sleepiness), and use of unclear data analysis techniques, thereby complicating comparisons between studies.

Reversible Verbal Memory Integration Deficits in Obstructive Sleep Apnoea

When presented with novel but semantically related elements after learning verbal material, healthy participants tend to endorse these items as previously learned. This reflects the normal integration and association of novel verbal information into long-term memory. How obstructive sleep apnoea (OSA) negatively impacts verbal memory performance, and whether deficits are reversible following positive airway pressure (PAP) treatment, remain elusive. We investigated immediate and delayed OSA- and PAP treatment-related effects on verbal memory integration, using a false memory paradigm. Twenty-three patients with OSA learned lists of words semantically related to target non-presented words (1) at baseline after a polysomnography diagnosis night, (2) after a consecutive polysomnography night under PAP titration, and (3) after three months of compliant PAP treatment. At each session, participants learned 10 different lists of words, each list comprising 15 semantically related items. They had then to recognize 15 minutes later (after an intermediate vigilance task) previously learned words within a list including studied words (learned), unstudied but semantically related items (lures), and non-related unstudied items (controls). Sleep quality and fatigue questionnaires, and psychomotor vigilance tests (PVT) were administered at each session. PAP treatment led to OSA remission and improvement in objective and subjective sleep quality. Crucially, recognition of learned and lure words increased after the first night under treatment and remained stable three months later, suggesting successful memory integration and restoration of semantic processes. No treatment-related outcome was found on PVT performance. OSA exerts a detrimental but PAP-reversible effect on verbal learning and semantic memory integration mechanisms underlying the acquisition of novel memory representations.

Interpersonal brain synchronization with instructor compensates for learner's sleep deprivation in interactive learning

Recent advances shifted the focus on single-brain functioning toward two-brain communication during learning interactions, following the demonstration that interpersonal brain synchronization (IBS) can track instructor-learner information exchange. Here, we investigated (i) whether sleep deprivation (SD) that potentially impacts both social interactions and learning abilities modulates IBS, and (ii) conversely whether and to what extent IBS might compensate for SD-related learning deficits. Instructors (always with regular sleep, RS) were asked to teach numerical reasoning strategies to learners (either SD or RS), during which the activity of both brains was simultaneously recorded using functional near-infrared spectroscopy (fNIRS). SD learners initially performed below their baseline level, worse than RS learners, but learning improvement was comparable between RS and SD conditions after learning with the instructor. IBS within the instructor-learner dyads was higher in the SD (vs. RS) condition in the left inferior frontal cortex. In addition, clustered IBS (estimated by nonnegative matrix factorization) was correlated with performance improvement. Finally, Granger Causality analyses revealed biased causality with higher instructor-to-learner than learner-to-instructor directionality in brain signal processing. Together, these results indicate that SD-related learning deficits can to some extent be compensated via interactions with an instructor, as reflected by increased IBS and preserved learning ability. It suggests an essential role of the instructor in driving synchrony between teaching and SD learning brains during interactions.

Consequences of ignoring the response-shift and measure non-invariant items in sleep studies: an empirical data based simulation of the treatment effect of CBT-I on dysfunctional sleep beliefs

INTRODUCTION

Previous studies have shown that psychological interventions do not only improve patients' mental symptoms (i.e., true change) but may also change the internal standards patients use to evaluate their symptoms (i.e., response shifts). Although the response shifts could reflect patients' cognitive changes toward their disorders as the interventions aim to achieve, failing to differentiate them from the true change during data analyses could bias the research conclusions. Considering this issue is seldom discussed in sleep studies, this study thus examined the impacts of response-shift items in an intervention study of cognitive behavioral therapy for insomnia (CBT-I) via empirical-data based simulations.

METHOD

We used longitudinal measurement invariance tests to identify the items in an abbreviated version of the Dysfunctional Beliefs and Attitudes about Sleep Scale that are non-invariant (response shifted) against CBT-I based on data from 114 insomnia patients. The partial invariance model built accordingly was then used as a population model for simulations to examine the impacts of the response-shift items on follow-up paired t-tests.

RESULTS

Invariance tests indicate CBT-I would lift the intercept of one item in DBAS-10 and cause non-uniform calibrations in three items. The following up simulations showed that failing to exclude the intercept-lifted item from the calculations of the subscale scores would lower the probability of using paired t-test to correctly detect the treatment effect by up to 53%.

CONCLUSIONS

We recommend sleep researchers to consider the issues of response-shift when assessing sleep-related constructs in interventional studies for insomnia.

Sex-Related Differences in Sleep-Related PSG Parameters and Daytime Complaints in a Clinical Population

BACKGROUND

Recent research suggested that perception of sleep impairments might present sex-related effects (ie, women appear to be more prone to report fatigue rather than sleepiness). The latter has been evidenced in sleep-related breathing disorders (SRBD). Differently, it has been suggested that sleep-related movement disorders may also be associated to fatigue rather than to sleepiness. Whether sex-related differences would be similar irrespective of diagnosis remains unclear.

METHODS

During a one-year period, systematic clinical evaluation, by means of structured symptom scales, was performed for a cohort of 921 consecutive patients attending an academic sleep center for polysomnography. The Brugmann Fatigue Scale (BFS), an instrument designed for the assessment of rest propensity was used among other scales (ie, Epworth Sleepiness Scale, ESS). According to inclusion and exclusion criteria, 420 men and 376 women were finally included in the study and retained for data analysis.

RESULTS

While men and women presented with similar age, BMI, total sleep time and sleep efficiency, men presented with higher levels of respiratory events and more periodic limb movements. Irrespective of diagnosis, women presented with significantly higher levels of sleep-associated complaints on all scales. Comparative stratifications of daytime symptoms, per diagnostic groups (SRBD, Movement Disorders (SRMD) and Insomnia), revealed significant main effects for diagnosis alongside with main effects of biological sex. Associations between common markers of disease severity for SRBD or SRMD and sleep or rest propensity, respectively, only showed significant correlation between periodic limb movements and rest propensity. The strength of association was similarly significant for both sexes.

CONCLUSION

While men displayed more objective impairment on polysomnography (PSG) and lower symptom levels, the opposite was true in women. However, both men and women present with statistically significant associations between SRMD severity (PLMS index) and physical fatigue.

A Scientometric Review of Rasch Measurement: The Rise and Progress of a Specialty

A recent review of the literature concluded that Rasch measurement is an influential approach in psychometric modeling. Despite the major contributions of Rasch measurement to the growth of scientific research across various fields, there is currently no research on the trends and evolution of Rasch measurement research. The present study used co-citation techniques and a multiple perspectives approach to investigate 5,365 publications on Rasch measurement between 01 January 1972 and 03 May 2019 and their 108,339 unique references downloaded from the Web of Science (WoS). Several methods of network development involving visualization and text-mining were used to analyze these data: author co-citation analysis (ACA), document co-citation analysis (DCA), journal author co-citation analysis (JCA), and keyword analysis. In addition, to investigate the inter-domain trends that link the Rasch measurement specialty to other specialties, we used a dual-map overlay to investigate specialty-to-specialty connections. Influential authors, publications, journals, and keywords were identified. Multiple research frontiers or sub-specialties were detected and the major ones were reviewed, including “visual function questionnaires”, “non-parametric item response theory”, “valid measures (validity)”, “latent class models”, and “many-facet Rasch model”. One of the outstanding patterns identified was the dominance and impact of publications written for general groups of practitioners and researchers. In personal communications, the authors of these publications stressed their mission as being “teachers” who aim to promote Rasch measurement as a conceptual model with real-world applications. Based on these findings, we propose that sociocultural and ethnographic factors have a huge capacity to influence fields of science and should be considered in future investigations of psychometrics and measurement. As the first scientometric review of the Rasch measurement specialty, this study will be of interest to researchers, graduate students, and professors seeking to identify research trends, topics, major publications, and influential scholars.

The added value of cognitive behavioral therapy for insomnia to current best evidence physical therapy for chronic spinal pain: protocol of a randomized controlled clinical trial

BACKGROUND

Insomnia is a highly prevalent and debilitating comorbidity that is often not addressed in therapy for chronic spinal pain (CSP). Given the close interaction between insomnia and CSP severity and related disability, targeting sleep problems during therapy could improve treatment outcomes in these patients.

OBJECTIVE

Can cognitive behavioral therapy for insomnia (CBT-I) combined with the modern neuroscience approach (i.e. pain neuroscience education and cognition-targeted exercise therapy) reduce pain and improve sleep, physical activity and function in people with CSP and comorbid insomnia?

METHODS

Participants: One-hundred-twenty participants with chronic spinal pain and comorbid insomnia Intervention: CBT-I combined with the modern neuroscience approach (experimental) compared to the modern neuroscience approach alone (control). Both interventions start with three sessions of pain neuroscience education, followed by six sessions of CBT-I and nine sessions of cognition-targeted exercise therapy in the experimental group, or 15 sessions of cognition-targeted exercise therapy in the control group.

MEASUREMENTS

Primary outcome measure: self-reported pain severity (Brief Pain Inventory).

SECONDARY OUTCOME MEASURES

pain sensitivity (pressure pain thresholds, and online questionnaires), sleep-related outcomes (home-based polysomnography and online questionnaires), physical activity (actigraphy), and function (online questionnaires). Online questionnaires will be completed at baseline, directly post-treatment, and at 3, 6 and 12 months post-treatment. Polysomnography, pressure pain thresholds and actigraphy will be carried out at baseline, post-treatment and at 12 months follow-up.

DISCUSSION

Findings may provide (1) a novel therapeutic approach for people with CSP and comorbid insomnia to improve pain, sleep, physical activity and function, and (2) new treatment guidelines for professionals.

TRIAL REGISTRATION

Clinicaltrials.gov NCT03482856 (https://clinicaltrials.gov/ct2/show/NCT03482856).

Bridging Exercise Science, Cognitive Psychology, and Medical Practice: Is "Cognitive Fatigue" a Remake of "The Emperor's New Clothes"?

Fatigue is such a multifaceted construct it has sprouted specific research fields and experts in domains as different as exercise physiology, cognitive psychology, human factors and engineering, and medical practice. It lacks a consensus definition: it is an experimental concept, a symptom, a risk, a cause (e.g., of performance decrement) and a consequence (e.g., of sleep deprivation). This fragmentation of knowledge leads to slower dissemination of novel insights, and thus to a poorer research. Indeed, what may seem as a novel result in one field, may very well be old news in another, hence leading to this "innovation" being a scientific equivalent to the emperor's new clothes. The current paper aims to describe the common denominator in the different areas of expertise where fatigue is investigated. Indeed, rather than focusing on the differences in semantics and conceptualization, we hope that identifying common concepts may be inductive of easier multidisciplinary research. Considering the vastness of fatigue research in all areas identified as relevant-cognitive science, exercise physiology, and medical practice, this analysis has not the ambition to be an exhaustive review in all domains. We have reviewed the fatigue concepts and research in these areas and report the ones that are used to describe the proposed common model to be further investigated. The most promising common feature to cognitive science, exercise physiology and clinical practice is the notion of "perceived effort." This allows to account for interindividual differences, as well as for the situational variations in fatigue. It is applicable to both mental and physical constructs. It integrates motivational and emotional dimensions. It overcomes current polemics in various research fields, and it does not draw on any semantic ambiguity. We thus suggest a new model of fatigue and performance, whether this performance is mental or physical; and whether it is in a clinical range or relates to optimal functioning.