Sleep in the chronic fatigue syndrome

Gender medicine and sleep disorders: from basic science to clinical research

Several pivotal differences in sleep and sleep disorders are recognized between women and men. This is not only due to changes in hormonal balance during women's reproductive life, such as in pregnancy and menopause. Women are more likely to report insomnia and non-specific symptoms of apneas, such as fatigue or mood disturbance, compared to men. Thus, it is important for clinicians and researchers to take sex and gender differences into account when addressing sleep disorders in order to acknowledge the biology unique to women. We present a narrative review that delves into the primary sleep disorders, starting from basic science, to explore the impact of gender differences on sleep and the current status of research on women's sleep health.

Bioinformatics and systems biology approach to identify the pathogenetic link of Long COVID and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Background

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a global crisis. Although many people recover from COVID-19 infection, they are likely to develop persistent symptoms similar to those of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) after discharge. Those constellations of symptoms persist for months after infection, called Long COVID, which may lead to considerable financial burden and healthcare challenges. However, the mechanisms underlying Long COVID and ME/CFS remain unclear.

Methods

We collected the genes associated with Long COVID and ME/CFS in databases by restricted screening conditions and clinical sample datasets with limited filters. The common genes for Long COVID and ME/CFS were finally obtained by taking the intersection. We performed several advanced bioinformatics analyses based on common genes, including gene ontology and pathway enrichment analyses, protein–protein interaction (PPI) analysis, transcription factor (TF)–gene interaction network analysis, transcription factor–miRNA co-regulatory network analysis, and candidate drug analysis prediction.

Results

We found nine common genes between Long COVID and ME/CFS and gained a piece of detailed information on their biological functions and signaling pathways through enrichment analysis. Five hub proteins (IL-6, IL-1B, CD8A, TP53, and CXCL8) were collected by the PPI network. The TF–gene and TF–miRNA coregulatory networks were demonstrated by NetworkAnalyst. In the end, 10 potential chemical compounds were predicted.

Conclusion

This study revealed common gene interaction networks of Long COVID and ME/CFS and predicted potential therapeutic drugs for clinical practice. Our findings help to identify the potential biological mechanism between Long COVID and ME/CFS. However, more laboratory and multicenter evidence is required to explore greater mechanistic insight before clinical application in the future.

Assessing sleep and pain among adults with myalgic encephalomyelitis/chronic fatigue syndrome: psychometric evaluation of the PROMIS® sleep and pain short forms

PURPOSE

To evaluate the psychometric properties of the patient-reported outcome measurement information system® (PROMIS) short forms for assessing sleep disturbance, sleep-related impairment, pain interference, and pain behavior, among adults with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

METHODS

Data came from the Multi-Site ME/CFS study conducted between 2012 and 2020 at seven ME/CFS specialty clinics across the USA. Baseline and follow-up data from ME/CFS and healthy control (HC) groups were used to examine ceiling/floor effects, internal consistency reliability, differential item functioning (DIF), known-groups validity, and responsiveness.

RESULTS

A total of 945 participants completed the baseline assessment (602 ME/CFS and 338 HC) and 441 ME/CFS also completed the follow-up. The baseline mean T-scores of PROMIS sleep and pain measures ranged from 57.68 to 62.40, about one standard deviation above the national norm (T-score = 50). All four measures showed high internal consistency (ω = 0.92 to 0.97) and no substantial floor/ceiling effects. No DIF was detected by age or sex. Known-groups comparisons among ME/CFS groups with low, medium, and high functional impairment showed significant small-sized differences in scores (η² = 0.01 to 0.05) for the two sleep measures and small-to-medium-sized differences (η² = 0.01 to 0.15) for the two pain measures. ME/CFS participants had significantly worse scores than HC (η² = 0.35 to 0.45) for all four measures. Given the non-interventional nature of the study, responsiveness was evaluated as sensitivity to change over time and the pain interference measure showed an acceptable sensitivity.

CONCLUSION

The PROMIS sleep and pain measures demonstrated satisfactory psychometric properties supporting their use in ME/CFS research and clinical practice.

The Qigong of Prolong Life With Nine Turn Method Relieve Fatigue, Sleep, Anxiety and Depression in Patients With Chronic Fatigue Syndrome: A Randomized Controlled Clinical Study

Background

Chronic fatigue syndrome (CFS) is a complex disease of unknown etiology and mechanism. The purpose of this study was to investigate the effect of Prolong Life with Nine Turn Method (PLWNT) Qigong exercise on CFS focusing on fatigue, sleep quality, depression, and anxiety.

Methods

A total of 90 participants diagnosed with CFS were randomly assigned into two parallel groups: PLWNT and cognitive behavioral therapy (CBT). The participants in the PLWNT or CBT group participated in qigong exercise or cognitive behavior education program, respectively, once a week in-person and were supervised online during the remaining 6 days at home, over 12 consecutive weeks. The primary outcome was fatigue (Multi-dimensional Fatigue Inventory 20 [MFI-20]), and secondary outcomes were sleep quality (Pittsburgh Sleep Quality Index [PSQI]), anxiety, depression (Hospital Anxiety and Depression Scale [HADS]), and changes in the Neuropeptide Y (NPY) of peripheral blood.

Results

The within-group comparisons of the PLWNT and CBT groups revealed significant improvement in both groups in MFI-20, PSQI, and HADS scores (P < 0.05). No significant difference were found between the PLWNT and CBT groups, even though the effective rate of the PLWNT group was 62.22%, which is slightly than 50.00% of the CBT group. The fatigue scores in the PLWNT group were positively correlated with sleep degree (r = 0.315) and anxiety degree (r = 0.333), only anxiety degree (r = 0.332) was found to be positively correlated with fatigue in the CBT group. The analysis of peripheral blood showed that NPY decreased after PLWNT intervention but increased significantly in the CBT.

Conclusion

The PLWNT qigong exercise has potential to be an effective rehabilitation method for CFS symptoms including fatigue, sleep disturbance, anxiety, and depression. Future studies should expand study sample size for in-depth investigation to determine the optimal frequency and intensity of PLWNT qigong intervention in CFS patients. The study was registered in the ClinicalTrials.gov database on April 12, 2018, with registration number NCT03496961.

Treatments of chronic fatigue syndrome and its debilitating comorbidities: a 12-year population-based study

Background

This study aims to provide 12-year nationwide epidemiology data to investigate the epidemiology and comorbidities of and therapeutic options for chronic fatigue syndrome (CFS) by analyzing the National Health Insurance Research Database.

Methods

6306 patients identified as having CFS during the 2000–2012 period and 6306 controls (with similar distributions of age and sex) were analyzed.

Result

The patients with CFS were predominantly female and aged 35–64 years in Taiwan and presented a higher proportion of depression, anxiety disorder, insomnia, Crohn’s disease, ulcerative colitis, renal disease, type 2 diabetes, gout, dyslipidemia, rheumatoid arthritis, Sjogren syndrome, and herpes zoster. The use of selective serotonin receptor inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), Serotonin antagonist and reuptake inhibitors (SARIs), Tricyclic antidepressants (TCAs), benzodiazepine (BZD), Norepinephrine-dopamine reuptake inhibitors (NDRIs), muscle relaxants, analgesic drugs, psychotherapies, and exercise therapies was prescribed significantly more frequently in the CFS cohort than in the control group.

Conclusion

This large national study shared the mainstream therapies of CFS in Taiwan, we noticed these treatments reported effective to relieve symptoms in previous studies. Furthermore, our findings indicate that clinicians should have a heightened awareness of the comorbidities of CFS, especially in psychiatric problems.

Volumetric differences in hippocampal subfields and associations with clinical measures in myalgic encephalomyelitis/chronic fatigue syndrome

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) patients suffer from a cognitive and memory dysfunction. Because the hippocampus plays a key role in both cognition and memory, we tested for volumetric differences in the subfields of the hippocampus in ME/CFS. We estimated hippocampal subfield volumes for 25 ME/CFS patients who met Fukuda criteria only (ME/CFS_Fukuda), 18 ME/CFS patients who met the stricter ICC criteria (ME/CFS_ICC), and 25 healthy controls (HC). Group comparisons with HC detected extensive differences in subfield volumes in ME/CFS_ICC but not in ME/CFS_Fukuda. ME/CFS_ICC patients had significantly larger volume in the left subiculum head (p < 0.001), left presubiculum head (p = 0.0020), and left fimbria (p = 0.004). Correlations of hippocampus subfield volumes with clinical measures were stronger in ME/CFS_ICC than in ME/CFS_Fukuda patients. In ME/CFS_Fukuda patients, we detected positive correlations between fatigue and hippocampus subfield volumes and a negative correlation between sleep disturbance score and the right CA1 body volume. In ME/CFS_ICC patients, we detected a strong negative relationship between fatigue and left hippocampus tail volume. Strong negative relationships were also detected between pain and SF36 physical scores and two hippocampal subfield volumes (left: GC‐ML‐DG head and CA4 head). Our study demonstrated that volumetric differences in hippocampal subfields have strong statistical inference for patients meeting the ME/CFS_ICC case definition and confirms hippocampal involvement in the cognitive and memory problems of ME/CFS_ICC patients.

Association between Sleep Duration and Depression among the Elderly Population in China

OBJECTIVES

The objective of this study was to understand how sleep duration could affect depression among elderly in China.

METHOD

A total of 7103 individuals aged 60 and older were selected from China Health and Retirement Longitudinal Study. A generalized linear mixed-effects model was used to estimate the relationship between sleep duration and depression, and we performed stratified analyses by age: young-old elderly, old-old elderly and oldest-old elderly.

RESULTS

Short sleep duration significantly incresased CES-D10 depression scores. In addition, the participants with middle sleep duration had higher CES-D10 scores compared to the participants with long sleep duration among young-old elderly, and we found that middle sleep duration was not significantly different from CES-D10 scores after adjustment for demographics, frequencies of activities and Chronic diseases.

CONCLUSIONS

These findings suggested that there was a complex association between depression and sleep duration among elderly in China. Different from previous research results on the middle or normal sleep time of the elderly, the middle sleep duration maybe not optimal sleep duration in this study. Investigation of sleep extension to prevent depression may be warranted among the elderly.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Neurological Entity?

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a disorder of unknown physiopathology with multisystemic repercussions, framed in ICD-11 under the heading of neurology (8E49). There is no specific test to support its clinical diagnosis. Our objective is to review the evidence in neuroimaging and dysautonomia evaluation in order to support the neurological involvement and to find biomarkers serving to identify and/or monitor the pathology. The symptoms typically appear acutely, although they can develop progressively over years; an essential trait for diagnosis is "central" fatigue together with physical and/or mental exhaustion after a small effort. Neuroimaging reveals various morphological, connectivity, metabolic, and functional alterations of low specificity, which can serve to complement the neurological study of the patient. The COMPASS-31 questionnaire is a useful tool to triage patients under suspect of dysautonomia, at which point they may be redirected for deeper evaluation. Recently, alterations in heart rate variability, the Valsalva maneuver, and the tilt table test, together with the presence of serum autoantibodies against adrenergic, cholinergic, and serotonin receptors were shown in a subgroup of patients. This approach provides a way to identify patient phenotypes. Broader studies are needed to establish the level of sensitivity and specificity necessary for their validation. Neuroimaging contributes scarcely to the diagnosis, and this depends on the identification of specific changes. On the other hand, dysautonomia studies, carried out in specialized units, are highly promising in order to support the diagnosis and to identify potential biomarkers. ME/CFS orients towards a functional pathology that mainly involves the autonomic nervous system, although not exclusively.

Korean Red Ginseng Ameliorates Fatigue via Modulation of 5-HT and Corticosterone in a Sleep-Deprived Mouse Model

Central fatigue, which is neuromuscular dysfunction associated with neurochemical alterations, is an important clinical issue related to pathologic fatigue. This study aimed to investigate the anti-central fatigue effect of Korean red ginseng (KRG) and its underlying mechanism. Male BALB/c mice (8 weeks old) were subjected to periodic sleep deprivation (SD) for 6 cycles (forced wakefulness for 2 days + 1 normal day per cycle). Simultaneously, the mice were administered KRG (0, 100, 200, or 400 mg/kg) or ascorbic acid (100 mg/kg). After all cycles, the rotarod and grip strength tests were performed, and then the changes regarding stress- and neurotransmitter-related parameters in serum and brain tissue were evaluated. Six cycles of SD notably deteriorated exercise performance in both the rotarod and grip strength tests, while KRG administration significantly ameliorated these alterations. KRG also significantly attenuated the SD-induced depletion of serum corticosterone. The levels of main neurotransmitters related to the sleep/wake cycle were markedly altered (serotonin was overproduced while dopamine levels were decreased) by SD, and KRG significantly attenuated these alterations through relevant molecules including brain-derived neurotropic factor and serotonin transporter. This study demonstrated the anti-fatigue effects of KRG in an SD mouse model, indicating the clinical relevance of KRG.

The Epidemiology of Insomnia and Sleep Duration Across Mental and Physical Health: The SHoT Study

Objective

Numerous epidemiological studies have been conducted to examine the prevalence and comorbidities of insomnia and document sleep duration, but a common limitation in many studies is the lack of use of agreed-upon definitions of insomnia, as well as insufficient statistical power to examine comorbid mental and physical disorders/conditions.

Aim

To examine the prevalence of insomnia operationalized according to formal DSM-5 criteria and differences in mean sleep duration across a wide range of mental and physical disorders, examining men and women separately.

Materials and Methods

Data stem from the SHoT study (Students' Health and Wellbeing Study), a national survey of all college and university students in Norway. In all, 162,512 students aged 18-35 received an invitation to participate, of whom 50,054 students completed the internet-based survey (attendance rate: 30.8%). Insomnia was defined according to the Diagnostic and Statistical Manual of Mental Disorders (5th ed.) criteria and sleep duration was calculated separately for weekdays and weekends. Self-reported mental and physical disorders/conditions were assessed using a pre-defined list modified to fit this age group. Pearson chi-squared tests were used to examine the prevalence of insomnia across the various mental and physical disorders/conditions in men and women separately, and log-link binomial regression analysis were used to calculate effect-sizes, adjusting for age.

Results

The prevalence of insomnia in both sexes was significantly higher across all mental disorders compared with a healthy reference group. Among females, the prevalence of insomnia ranged from 61.3% for comorbid depression (adj. RR = 2.49, 95% CI: 2.40) to 83.3% for comorbid schizophrenia (adj. RR = 3.37, 95% CI: 2.61-4.35). For males, the insomnia prevalence ranged from 32.3% for comorbid autism/Asperger (adj. RR = 2.02, 95% CI: 1.39-2.92) to 74.2% for comorbid eating disorder (adj. RR = 4.51, 95% CI: 3.87-5.27). The overall prevalence of insomnia was also significantly higher across most physical conditions compared with the healthy reference group, although generally lower compared to the mental disorders. For females, the insomnia prevalence ranged from 25% for comorbid multiple sclerosis (not significant) to 65.4% for comorbid chronic fatigue syndrome/ME (adj. RR = 2.66, 95% CI: 2.44-2.89). For males, the insomnia prevalence ranged from 20% for both comorbid cancer and diabetes (not significant) to 74.2% for comorbid fibromyalgia (adj. RR = 4.35, 95% CI: 2.96-6.39). Similar patterns were observed for sleep duration, with a significantly shorter sleep duration for across many physical disorders, but especially mental disorders.

Conclusion

Insomnia and short sleep duration are strongly associated with a range of different disorders and conditions. Insomnia is most strongly associated with mental disorders, and physical conditions characterized by some level of psychological or psychosomatic properties.

Associations Between Psychological and Immunological Variables in Chronic Fatigue Syndrome/Myalgic Encephalomyelitis: A Systematic Review

Background: Little emphasis has been given to the fact that various psychological processes and behaviors in chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) have neural correlates that affect-and are affected by-the immune system. The aim of this paper is to provide a systematic review of the literature on cross-sectional and longitudinal associations between psychological and immunological variables/changes in CFS/ME. Methods: The systematic literature search was conducted on Dec 10, 2020 using PubMed. Original research studies investigating associations between a predefined set of psychological and immunological variables in CFS/ME were included. Specifically, the review was focused on studies examining the following psychological variables: executive function, emotion regulation, interpersonal function, sleep, mental health, anxiety, depression, and/or other psychiatric symptoms. In terms of immunological variables, studies investigating interleukin (IL)-1, IL-2, IL-4, IL-6, tumor necrosis factor (TNF), CD4⁺, and/or CD8⁺ were included. Besides original research papers, other potentially relevant papers (e.g., literature reviews) were carefully read and reference lists were checked in order to identify any additional relevant studies. Available data was summarized in text and tables. Results: The literature search identified 897 potentially relevant papers. Ultimately, 14 studies (807 participants in total) were included in the review of which only two were longitudinal in nature. The review indicated that executive function is associated with IL-1 and IL-6, and interpersonal function is associated with IL-6 and TNF-α. Further, the available data suggested that emotion regulation is associated with IL-2 and sleep is associated with IL-1, IL-6, TNF-α, and IL-2. Interestingly, poorer emotion regulation, interpersonal function, and sleep have all been found to be associated with higher cytokine levels. Executive function has shown both positive and negative relationships with cytokines and among these psychological constructs, it is also the only one that has been found to be associated with CD4⁺ and CD8⁺ counts/percentages. Conclusions: Correlations exist between psychological and immunological variables in CFS/ME. However, there are few consistent findings and there is almost a complete lack of longitudinal studies. This review points to a gap in existing CFS/ME research and hopefully, it will inspire to the generation of innovative, psychoneuroimmunological hypotheses within the CFS/ME research field.

Emotional Awareness Correlated With Number of Awakenings From Polysomnography in Patients With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome-A Pilot Study

INTRODUCTION

Unrefreshing sleep is one of the diagnostic criteria in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), which could be explained by sleep disorders, for example obstructive sleep apnea, reported in our previous study with polysomnography. Our previous findings also indicate difficulties in emotional regulation when measuring alexithymia by TAS-20 (Toronto Alexithymia Scale) and level of emotional awareness by LEAS (Level of Emotional Awareness Scale) in ME/CFS patients. However, the reasons for this are unknown. The purpose of this study was to investigate correlations between data from subjective emotional regulation and polysomnography.

METHODS

Twenty-three ME/CFS patients (5 men and 18 women) of mean age 43, and 30 matched healthy controls (9 males and 21 women) of mean age 45, filled in TAS-20, LEAS, and Hospital Depression and Anxiety Scale (HADS). A polysomnography was performed on patients but not on healthy controls. Thus, values of normal population were used for sleep evaluation in ME/CFS patients.

RESULT

There were significant differences between patients and controls in several aspects of emotional regulation, for example LEAS-self and LEAS-total. Seventy percent of the patients had increased numbers of awakenings (shifts from any sleep stage to awake), 22% had obstructive sleep apneas, and 27% had periodic limb movements. Correlation analysis showed that number of awakenings significantly correlated with LEAS-self and LEAS-total, p < 0.01, respectively. There were no other significant correlations.

CONCLUSION

This pilot study demonstrated significant correlations between reduced emotional awareness and number of awakenings in polysomnography. Future studies with larger cohorts need to be conducted.

Parasympathetic activity is reduced during slow-wave sleep, but not resting wakefulness, in patients with chronic fatigue syndrome

STUDY OBJECTIVES

Physiological dearousal characterized by an increase in parasympathetic nervous system activity is important for good-quality sleep. Previous research shows that nocturnal parasympathetic activity (reflected by heart rate variability [HRV]) is diminished in individuals with chronic fatigue syndrome (CFS), suggesting hypervigilant sleep. This study investigated differences in nocturnal autonomic activity across sleep stages and explored the association of parasympathetic activity with sleep quality and self-reported physical and psychological wellbeing in individuals with CFS.

METHODS

Twenty-four patients with medically diagnosed CFS, and 24 matched healthy control individuals participated. Electroencephalography and HRV were recorded during sleep in participants' homes using a minimally invasive ambulatory device. Questionnaires were used to measure self-reported wellbeing and sleep quality.

RESULTS

Sleep architecture in patients with CFS differed from that of control participants in slower sleep onset, more awakenings, and a larger proportion of time spent in slow-wave sleep (SWS). Linear mixed-model analyses controlling for age revealed that HRV reflecting parasympathetic activity (normalized high frequency power) was reduced in patients with CFS compared to control participants, particularly during deeper stages of sleep. Poorer self-reported wellbeing and sleep quality was associated with reduced parasympathetic signaling during deeper sleep, but not during wake before sleep, rapid eye movement sleep, or with the proportion of time spent in SWS.

CONCLUSIONS

Autonomic hypervigilance during the deeper, recuperative stages of sleep is associated with poor quality sleep and self-reported wellbeing. Causal links need to be confirmed but provide potential intervention opportunities for the core symptom of unrefreshing sleep in CFS.

[Modern concepts about insomnia in mental disorders: clinical aspects]

Insomnia is one of the most common symptoms of mental pathology (affective, anxious, hypochondriac, asthenic, psychotic) and reveals a number of characteristic features depending on the structure of the mental disorder. Psychopharmacotherapy for insomnia in mental disorders is an important aspect of patient supervision. Doxylamine (donormil) is one of the promising drugs for the correction of insomnia, both in combination with other psychotropic drugs and in monotherapy.

Nonrestorative sleep scale: reliable and valid for the Chinese population

PURPOSE

To conduct a linguistic and psychometric evaluation of a Chinese version of the Nonrestorative Sleep Scale (NRSS).

METHODS

The Chinese NRSS was created from a standard forward-backward translation and trialed on 10 Chinese adults. Telephone interviews were then conducted with 100 adults, who completed the Chinese NRSS, the Pittsburgh Sleep Quality Index (PSQI), the Athens Insomnia Scale (AIS), the Center for Epidemiological Studies Depression Scale (CES-D), and the Toronto Hospital Alertness Test (THAT). A household survey was conducted with 20 subjects, followed by a confirmatory factor analysis (CFA), and a bifactor model was developed to evaluate the reliability and validity of the NRSS.

RESULTS

The bifactor model had the root mean square error of approximation (RMSEA), standardized root mean square residual (SRMR), and comparative fit index (CFI) of 0.06, 0.06, and 0.97, respectively. Convergent validity was shown from the moderate associations with PSQI (r = - 0.66, P < 0.01), AIS (r = - 0.65, P < 0.01), CES-D (r = - 0.54, P < 0.01), and THAT (r = 0.68, P < 0.01). The coefficient omega (0.92), omega hierarchical (0.81), factor determinacy (0.93), H value (0.91), explained common variance (0.63), and percentage of uncontaminated correlations (0.80) derived from the bifactor CFA supported the essential unidimensionality of NRSS.

CONCLUSIONS

The Chinese NRSS is a valid and reliable essential unidimensional tool for the assessment of nonrestorative sleep in the Chinese population.

Sleep in Women with Chronic Pain and Autoimmune Conditions: A Narrative Review

Chronic pain and sleep disturbances are intricately intertwined. This narrative review provides comments on observations related to pain, stress-immunity, and sleep. Sleep evidence is reviewed from studies of select conditions involving pain (ie, functional somatic syndromes and autoimmune) that are predominant in women. Chronic pain and poor sleep encompass persistent stress-immune activation with systemic inflammation, cellular oxidative stress, and sick behavior indicators that increase morbidity and threaten quality of life. In painful conditions, sleep impairments are nearly ubiquitous, and exaggerated combined effects should not be underestimated or ignored, nor should crucial implications for clinical practice and research.

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.

The Effect of Insomnia on Neuropsychological Functioning in Patients with Comorbid Symptoms of Pain, Fatigue, and Mood Disorders

OBJECTIVES

To examine if elevated symptoms of insomnia affects neuropsychological functioning in patients with concurrent symptoms of pain, fatigue, and mood disorders.

METHODS AND RESULTS

A total of seventy-six subjects participated in this (cross-sectional) study. Based on the cut-off score guidelines from The Insomnia Severity Index subjects were assigned to either a clinical insomnia group (N = 35) or a comparison group (N = 41). Factors such as age, general cognitive functioning, and symptoms of pain, fatigue, depression, and anxiety did not differ between the groups. Both groups completed a questionnaire which assessed subjective memory functioning. In addition they completed a set of neuropsychological tests measuring general cognitive functioning, spatial and verbal working memory, and inhibitory control. Although the subjects with clinical insomnia did not report more memory problems than the comparison group, they presented significant deficiencies on the tests assessing spatial and verbal working memory. There was no difference between the groups in inhibitory control.

CONCLUSIONS

This study shows that as the symptom severity of insomnia increases and become clinically significant, it has substantial effect on both spatial and verbal-numeric working memory functioning. By differentiating and testing different domains of working memory, this study provides a more detailed and nuanced characterization of working memory deficiencies than the previous studies within this field. The results need to be transferred to clinical practice so that neuropsychologists include assessments of sleep as part of their routine screenings.

Basic psychological need experiences, fatigue, and sleep in individuals with unexplained chronic fatigue

Grounded in self-determination theory, this study tested the hypothesis that the satisfaction and frustration of the psychological needs for autonomy, competence, and relatedness would relate to fatigue and subjective and objective sleep parameters, with stress and negative sleep cognitions playing an explanatory role in these associations. During a stay at a sleep laboratory in Belgium, individuals with unexplained chronic fatigue (N = 160; 78% female) underwent polysomnography and completed a questionnaire at 3 different points in time (i.e., after arrival in the sleep lab, before bedtime, and the following morning) that assessed their need-based experiences and stress during the previous week, fatigue during the preceding day, and sleep-related cognitions and sleep during the previous night. Results indicated that need frustration related to higher stress, which in turn, related to higher evening fatigue. Need frustration also related to poorer subjective sleep quality and shorter sleep duration, as indicated by both subjective and objective shorter total sleep time and subjective (but not objective) longer sleep latency. These associations were accounted for by stress and negative sleep cognitions. These findings suggest that health care professionals working with individuals with unexplained chronic fatigue may consider focusing on basic psychological needs within their therapeutic approach.

Poor sleep quality is associated with greater circulating pro-inflammatory cytokines and severity and frequency of chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) symptoms in women

OBJECTIVE

Poor sleep quality has been linked to inflammatory processes and worse disease outcomes in the context of many chronic illnesses, but less is known in conditions such as chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME). This study examines the relationships between sleep quality, pro-inflammatory cytokines, and CFS/ME symptoms.

METHODS

Sixty women diagnosed with CFS/ME were assessed using the Pittsburgh Sleep Quality Index (PSQI), Fatigue Symptom Inventory (FSI) and Center for Disease Control and Prevention (CDC)-based CFS/ME symptom questionnaires. Circulating plasma pro-inflammatory cytokine levels were measured by ELISA. Multiple regression analyses examined associations between sleep, cytokines and symptoms, controlling for age, education, and body mass index.

RESULTS

Poor sleep quality (PSQI global score) was associated with greater pro-inflammatory cytokine levels: interleukin-1β (IL-1β) (β=0.258, p=0.043), IL-6 (β=0.281, p=0.033), and tumor necrosis factor-alpha (TNF-α) (β=0.263, p=0.044). Worse sleep quality related to greater fatigue severity (β=0.395, p=0.003) and fatigue-related interference with daily activities (β=0.464, p<0.001), and more severe and frequent CDC-defined core CFS/ME symptoms (β=0.499, p<0.001, and β=0.556, p<0.001, respectively).

CONCLUSIONS

Results underscore the importance of managing sleep-related difficulties in this patient population. Further research is needed to identify the etiology of sleep disruptions in CFS/ME and mechanistic factors linking sleep quality to symptom severity and inflammatory processes.

Measurement of fatigue: Comparison of the reliability and validity of single-item and short measures to a comprehensive measure

BACKGROUND

Evidence is needed on the clinicometric properties of single-item or short measures as alternatives to comprehensive measures.

OBJECTIVES

We examined whether two single-item fatigue measures (i.e., Likert scale, numeric rating scale) or a short fatigue measure were comparable to a comprehensive measure in reliability (i.e., internal consistency and test-retest reliability) and validity (i.e., convergent, concurrent, and predictive validity) in Korean young adults.

METHODS

For this quantitative study, we selected the Functional Assessment of Chronic Illness Therapy-Fatigue for the comprehensive measure and the Profile of Mood States-Brief, Fatigue subscale for the short measure; and constructed two single-item measures. A total of 368 students from four nursing colleges in South Korea participated. We used Cronbach's alpha and item-total correlation for internal consistency reliability and intraclass correlation coefficient for test-retest reliability. We assessed Pearson's correlation with a comprehensive measure for convergent validity, with perceived stress level and sleep quality for concurrent validity and the receiver operating characteristic curve for predictive validity.

RESULTS

The short measure was comparable to the comprehensive measure in internal consistency reliability (Cronbach's alpha=0.81 vs. 0.88); test-retest reliability (intraclass correlation coefficient=0.66 vs. 0.61); convergent validity (r with comprehensive measure=0.79); concurrent validity (r with perceived stress=0.55, r with sleep quality=0.39) and predictive validity (area under curve=0.88). Single-item measures were not comparable to the comprehensive measure.

CONCLUSIONS

A short fatigue measure exhibited similar levels of reliability and validity to the comprehensive measure in Korean young adults.

Factors determining fatigue in the chronic fatigue syndrome: a path analysis

OBJECTIVES

To explore the interrelationship of different dimensions (fatigue, neuroticism, sleep quality, global mental and physical health) in patients with chronic fatigue syndrome (CFS).

METHODS

Patients meeting the Fukuda criteria of CFS filled out two independent fatigue scales (Fatigue Questionnaire, FQ and Checklist Individual Strength, CIS), NEO-Five Factor Inventory (NEO-FFI), Pittsburgh Sleep Quality Index (PSQI) and Medical Outcomes Study 36-item Short Form Health Survey (SF36). Exploratory and confirmatory path analyses were performed.

RESULTS

Out of 226 eligible patients, 167 subjects were included (mean age 39.13 years, SD 10.14, 92% female). In a first exploratory path analysis, using FQ for assessment of fatigue, night-time PSQI sleep quality had a direct effect on SF36 physical quality of life (PQoL) and no effect on FQ fatigue. This was confirmed by a subsequent path analysis with CIS fatigue and by confirmatory path analyses in 81 patients. These unexpected results raised the question whether FQ or CIS fatigue sufficiently operationalizes fatigue in CFS patients.

CONCLUSIONS

Poor sleep quality seems to directly impact on mental quality of life (MQoL) and PQoL without mediation of fatigue assessed with FQ and CIS. A more cohesive framework needs to be developed with more comprehensive clinical tools for the different dimensions in the construct of CFS.

Chronic fatigue syndrome - an update

BACKGROUND

Chronic fatigue syndrome is a widespread condition with a huge impact not only on a patient's life, but also on society as evidenced by substantial losses of productivity, informal costs, and medical expenses. The high prevalence rates (0.2-6.4%) and the low employment rates (27-41%) are responsible for the enormous burden imposed on society, with loss of productivity representing the highest cost. The objective of this review is to systematically review the recent literature on chronic fatigue syndrome/myalgic encephalomyelitis.

METHODS

The published literature between 1 January 1990 and 1 April 2015 was searched using the MEDLINE, Cochrane Library, and Web of Sciences databases. The reference lists of the selected articles were screened for other relevant articles.

RESULTS AND CONCLUSIONS

Despite extensive research, none of the proposed etiological factors have shown strong, reproducible scientific evidence. Over the years, the biopsychosocial model integrating many of the proposed hypotheses has been gaining popularity over the biomedical model, where the focus is on one physical cause. Since the etiological mechanism underlying chronic fatigue syndrome is currently unknown, disease-specific treatments do not exist. Various treatments have been investigated but only cognitive behavior therapy (CBT) and graded exercise therapy (GET) have shown moderate effectiveness.

Sleep and sleepiness in environmental intolerances: a population-based study

BACKGROUND

About one fourth of the general population report environmental intolerance (EI) to odorous/pungent chemicals, certain buildings, electromagnetic fields (EMFs), and/or sounds. EI sufferers show various clinical features, of which sleep disturbance is one. Sleep disturbance is common also in the general population, but it is not known whether the disturbance is more prominent in EI sufferers than in individuals who do not experience EI. Therefore, EI was compared on various sleep aspects with referents without EI.

METHODS

A population-based sample of 3406 individuals, aged 18-79 years, was recruited from Northern Sweden. Sleep quality, non-restorative sleep, daytime sleepiness, obstructive breathing, and nocturnal insomnia were assessed with the Karolinska Sleep Questionnaire. Single questions assessed time slept, amount of hours of needed sleep, and extent of enough time slept.

RESULTS

All four EI groups, compared to the referents, reported significantly poorer sleep quality, more non-restorative sleep, more daytime sleepiness, more obstructive breathing and higher prevalence of nocturnal insomnia than the referents. Nocturnal insomnia was an important factor for EI groups attributing their most prevalent symptoms to chemicals and sounds, irrespective of distress and certain syndromes. None of the EI groups differed significantly from the referents on time slept, but reported needing more sleep time (the EMF-intolerance group showing only a tendency), and all four groups reported to perceive enough sleep to a significantly lesser extent.

CONCLUSION

Sleep disturbance and daytime sleepiness are more common in individuals reporting EI compared to normal referents. Moreover, nocturnal insomnia is an important symptom in its own right in various types of EI. This evokes the question of whether or not sleep therapy may attenuate the severity of the EI.

Do evidence based interventions for chronic fatigue syndrome improve sleep? A systematic review and narrative synthesis

Cognitive behavioural therapy (CBT) and graded exercise therapy (GET) are recommended evidence based treatments for chronic fatigue syndrome (CFS), with research supporting their effectiveness in reducing fatigue and functional impairment. However, little research has focussed on the effect of these treatments on sleep, despite high reported sleep disturbance in CFS. Using a narrative synthesis approach, we aimed to 1) systematically identify and summarise the current evidence for the effectiveness of CBT and GET in improving sleep; 2) consider factors influencing treatment effectiveness, including incorporation of sleep management techniques; and 3) consider the appropriateness of sleep outcome measures used within evaluations. Studies evaluating CBT and/or GET for CFS, and including a sleep outcome were eligible for inclusion. Eight studies were identified. We found that GET interventions can improve sleep but this effect is inconsistent across studies. For CBT the evidence is limited with only one of two evaluations demonstrating sleep-related improvements. We conclude from existing research that we know little about the effects of including sleep management components within CBT and GET interventions. We suggest that future research should explore the effectiveness of sleep components within interventions, and sleep specific interventions, using comprehensive outcome measures that fully capture the range of sleep difficulties experienced in CFS.

Subjective but Not Actigraphy-Defined Sleep Predicts Next-Day Fatigue in Chronic Fatigue Syndrome: A Prospective Daily Diary Study

STUDY OBJECTIVES

This study aimed to (1) examine the relationship between subjective and actigraphy-defined sleep, and next-day fatigue in chronic fatigue syndrome (CFS); and (2) investigate the potential mediating role of negative mood on this relationship. We also sought to examine the effect of presleep arousal on perceptions of sleep.

METHODS

Twenty-seven adults meeting the Oxford criteria for CFS and self-identifying as experiencing sleep difficulties were recruited to take part in a prospective daily diary study, enabling symptom capture in real time over a 6-day period. A paper diary was used to record nightly subjective sleep and presleep arousal. Mood and fatigue symptoms were rated four times each day. Actigraphy was employed to provide objective estimations of sleep duration and continuity.

RESULTS

Multilevel modelling revealed that subjective sleep variables, namely sleep quality, efficiency, and perceiving sleep to be unrefreshing, predicted following-day fatigue levels, with poorer subjective sleep related to increased fatigue. Lower subjective sleep efficiency and perceiving sleep as unrefreshing predicted reduced variance in fatigue across the following day. Negative mood on waking partially mediated these relationships. Increased presleep cognitive and somatic arousal predicted self-reported poor sleep. Actigraphy-defined sleep, however, was not found to predict following-day fatigue.

CONCLUSIONS

For the first time we show that nightly subjective sleep predicts next-day fatigue in CFS and identify important factors driving this relationship. Our data suggest that sleep specific interventions, targeting presleep arousal, perceptions of sleep and negative mood on waking, may improve fatigue in CFS.

The role of the hippocampus in the pathogenesis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a severe acquired illness characterized by a profound sensation of fatigue, not ameliorated by rest and resulting in a substantial decrease in the amount and quality of occupational, social and recreational activities. Despite intense research, the aetiology and pathogenesis of ME/CFS is still unknown and no conclusive biological markers have been found. As a consequence, an accepted curative treatment is still lacking and rehabilitation programmes are not very effective, as few patients recover. Increased knowledge of the mechanisms leading to the emergence and maintenance of the illness is called for. In this study, I will put forth an alternative hypothesis to explain some of the pathologies associated with ME/CFS, by concentrating on one of the major strategic organs of the brain, the hippocampus. I will show that the ME/CFS triggering factors also impact the hippocampus, leading to neurocognitive deficits and disturbances in the regulation of the stress system and pain perception. These deficits lead to a substantial decrease in activity and to sleep disorders, which, in turn, impact the hippocampus and initiate a vicious circle of increased disability.

Sleep Disturbances in Pediatric Chronic Fatigue Syndrome: A Review of Current Research

OBJECTIVE

Children and adolescents with chronic fatigue syndrome (CFS) frequently report sleep disturbances. However, little is known about the nature and severity of sleep disturbance and factors associated with sleep problems in pediatric CFS. The purpose of this review was to synthesize and critically appraise existing literature relating to sleep disturbances in pediatric CFS.

METHODS

Embase, CINAHL, PsychINFO, PubMed. and Medline databases were searched to retrieve all studies that included an assessment of sleep in pediatric CFS. Two reviewers independently assessed eligibility, extracted data, and systematically assessed reporting quality.

RESULTS

Six studies were included and these were mostly case-controlled designs. Findings varied across studies; however, most studies found that children and adolescents with CFS had significantly more sleep disturbances when compared to healthy controls. Significant methodological variations and limitations were apparent.

CONCLUSIONS

This review suggests that children and adolescents with CFS experience sleep disturbances. However, results need to be interpreted cautiously given the limited evidence available and its overall low quality. More research is required to elucidate the nature and extent of sleep disturbance in pediatric CFS and should focus on (1) identifying the specific types, causes, and severity of sleep disturbances; (2) the specific consequences of sleep disturbances; and (3) the most effective interventions for sleep problems in this population.

The role of insomnia in the treatment of chronic fatigue

BACKGROUND

The definition of Chronic Fatigue Syndrome (CFS) overlaps with definitions of insomnia, but there is limited knowledge about the role of insomnia in the treatment of chronic fatigue.

AIMS

To test if improvement of insomnia during treatment of chronic fatigue was associated with improved outcomes on 1) fatigue and 2) cortisol recovery span during a standardized stress exposure.

METHODS

Patients (n = 122) with chronic fatigue received a 3.5-week inpatient return-to-work rehabilitation program based on Acceptance and Commitment Therapy, and had been on paid sick leave>8 weeks due their condition. A physician and a psychologist examined the patients, assessed medication use, and SCID-I diagnoses. Patients completed self-report questionnaires measuring fatigue, pain, depression, anxiety, and insomnia before and after treatment. A subgroup (n = 25) also completed the Trier Social Stress Test for Groups (TSST-G) before and after treatment. Seven cortisol samples were collected during each test and cortisol spans for the TSST-G were calculated.

RESULTS

A hierarchical regression analysis in nine steps showed that insomnia improvement predicted improvement in fatigue, independently of age, gender, improvement in pain intensity, depression and anxiety. A second hierarchical regression analysis showed that improvement in insomnia significantly predicted the cortisol recovery span after the TSST-G independently of improvement in fatigue.

CONCLUSION

Improvement in insomnia severity had a significant impact on both improvement in fatigue and the ability to recover from a stressful situation. Insomnia severity may be a maintaining factor in chronic fatigue and specifically targeting this in treatment could increase treatment response.

Qigong exercise alleviates fatigue, anxiety, and depressive symptoms, improves sleep quality, and shortens sleep latency in persons with chronic fatigue syndrome-like illness

Objectives. To evaluate the effectiveness of Baduanjin Qigong exercise on sleep, fatigue, anxiety, and depressive symptoms in chronic fatigue syndrome- (CFS-) like illness and to determine the dose-response relationship. Methods. One hundred fifty participants with CFS-like illness (mean age = 39.0, SD = 7.9) were randomly assigned to Qigong and waitlist. Sixteen 1.5-hour Qigong lessons were arranged over 9 consecutive weeks. Pittsburgh Sleep Quality Index (PSQI), Chalder Fatigue Scale (ChFS), and Hospital Anxiety and Depression Scale (HADS) were assessed at baseline, immediate posttreatment, and 3-month posttreatment. The amount of Qigong self-practice was assessed by self-report. Results. Repeated measures analyses of covariance showed a marginally nonsignificant (P = 0.064) group by time interaction in the PSQI total score, but it was significant for the “subjective sleep quality” and “sleep latency” items, favoring Qigong exercise. Improvement in “subjective sleep quality” was maintained at 3-month posttreatment. Significant group by time interaction was also detected for the ChFS and HADS anxiety and depression scores. The number of Qigong lessons attended and the amount of Qigong self-practice were significantly associated with sleep, fatigue, anxiety, and depressive symptom improvement. Conclusion. Baduanjin Qigong was an efficacious and acceptable treatment for sleep disturbance in CFS-like illness. This trial is registered with Hong Kong Clinical Trial Register: HKCTR-1380.

Non-REM sleep EEG power distribution in fatigue and sleepiness

OBJECTIVES

The aim of this study is to contribute to the sleep-related differentiation between daytime fatigue and sleepiness.

METHODS

135 subjects presenting with sleep apnea-hypopnea syndrome (SAHS, n=58) or chronic fatigue syndrome (CFS, n=52) with respective sleepiness or fatigue complaints and a control group (n=25) underwent polysomnography and psychometric assessments for fatigue, sleepiness, affective symptoms and perceived sleep quality. Sleep EEG spectral analysis for ultra slow, delta, theta, alpha, sigma and beta power bands was performed on frontal, central and occipital derivations.

RESULTS

Patient groups presented with impaired subjective sleep quality and higher affective symptom intensity. CFS patients presented with highest fatigue and SAHS patients with highest sleepiness levels. All groups showed similar total sleep time. Subject groups mainly differed in sleep efficiency, wake after sleep onset, duration of light sleep (N1, N2) and slow wave sleep, as well as in sleep fragmentation and respiratory disturbance. Relative non-REM sleep power spectra distributions suggest a pattern of power exchange in higher frequency bands at the expense of central ultra slow power in CFS patients during all non-REM stages. In SAHS patients, however, we found an opposite pattern at occipital sites during N1 and N2.

CONCLUSIONS

Slow wave activity presents as a crossroad of fatigue and sleepiness with, however, different spectral power band distributions during non-REM sleep. The homeostatic function of sleep might be compromised in CFS patients and could explain why, in contrast to sleepiness, fatigue does not resolve with sleep in these patients. The present findings thus contribute to the differentiation of both phenomena.

Undiagnosed and comorbid disorders in patients with presumed chronic fatigue syndrome

OBJECTIVE

To assess undiagnosed and comorbid disorders in patients referred to a tertiary care center with a presumed diagnosis of chronic fatigue syndrome (CFS).

METHODS

Patients referred for chronic unexplained fatigue entered an integrated diagnostic pathway, including internal medicine assessment, psychodiagnostic screening, physiotherapeutic assessment and polysomnography+multiple sleep latency testing. Final diagnosis resulted from a multidisciplinary team discussion. Fukuda criteria were used for the diagnosis of CFS, DSM-IV-TR criteria for psychiatric disorders, ICSD-2 criteria for sleep disorders.

RESULTS

Out of 377 patients referred, 279 (74.0%) were included in the study [84.9% female; mean age 38.8years (SD 10.3)]. A diagnosis of unequivocal CFS was made in 23.3%. In 21.1%, CFS was associated with a sleep disorder and/or psychiatric disorder, not invalidating the diagnosis of CFS. A predominant sleep disorder was found in 9.7%, 19.0% had a psychiatric disorder and 20.8% a combination of both. Only 2.2% was diagnosed with a classical internal disease. In the total sample, a sleep disorder was found in 49.8%, especially obstructive sleep apnea syndrome, followed by psychophysiologic insomnia and periodic limb movement disorder. A psychiatric disorder was diagnosed in 45.2%; mostly mood and anxiety disorder.

CONCLUSIONS

A multidisciplinary approach to presumed CFS yields unequivocal CFS in only a minority of patients, and reveals a broad spectrum of exclusionary or comorbid conditions within the domains of sleep medicine and psychiatry. These findings favor a systematic diagnostic approach to CFS, suitable to identify a wide range of diagnostic categories that may be subject to dedicated care.