Sleep stage dynamics in fibromyalgia patients and controls

Non-inflammatory pain in inflammatory arthritis

'Non-inflammatory' pain, pain that is not associated with measures of inflammation, is common in patients with inflammatory arthritis including RA. One important cause of non-inflammatory pain is concomitant fibromyalgia. Systematic review has shown that fibromyalgia is common in inflammatory arthritis including RA affecting 1 in 5 patients and is associated with higher disease activity scores due to inflated tender joint count and patient global assessment. Consequently, many patients with RA and concomitant fibromyalgia may fail to reach treatment target and switch to alternate disease modifying drugs frequently. European Alliance of Association for Rheumatology has highlighted that concomitant fibromyalgia is an important consideration in assessing difficult-to-treat RA. The incidence and prevalence of fibromyalgia are higher in RA than the general population, raising the possibility that fibromyalgia may be 'secondary' to RA rather than a concomitant disease. The precise mechanisms whereby patients with RA develop fibromyalgia are unknown. In this review, we discussed fibromyalgia in RA, its clinical impact and epidemiology as well as data suggesting fibromyalgia might be 'secondary'. Lastly, we reviewed potential pathogenic mechanisms which included inflammatory cytokines sensitizing nociceptive neurones, temporal summation, also known as windup, from chronic pain and impaired coping from poor quality sleep and mental well-being. Deciphering the exact mechanisms may lead to treatment strategies that prevent development of secondary fibromyalgia and will address a common factor associated with difficult-to-treat RA.

Sleep as a random walk: a super-statistical analysis of EEG data across sleep stages

In clinical practice, human sleep is classified into stages, each associated with different levels of muscular activity and marked by characteristic patterns in the EEG signals. It is however unclear whether this subdivision into discrete stages with sharply defined boundaries is truly reflecting the dynamics of human sleep. To address this question, we consider one-channel EEG signals as heterogeneous random walks: stochastic processes controlled by hyper-parameters that are themselves time-dependent. We first demonstrate the heterogeneity of the random process by showing that each sleep stage has a characteristic distribution and temporal correlation function of the raw EEG signals. Next, we perform a super-statistical analysis by computing hyper-parameters, such as the standard deviation, kurtosis, and skewness of the raw signal distributions, within subsequent 30-second epochs. It turns out that also the hyper-parameters have characteristic, sleep-stage-dependent distributions, which can be exploited for a simple Bayesian sleep stage detection. Moreover, we find that the hyper-parameters are not piece-wise constant, as the traditional hypnograms would suggest, but show rising or falling trends within and across sleep stages, pointing to an underlying continuous rather than sub-divided process that controls human sleep. Based on the hyper-parameters, we finally perform a pairwise similarity analysis between the different sleep stages, using a quantitative measure for the separability of data clusters in multi-dimensional spaces.

To improve our understand of how EEG activity reflects the dynamics of human sleep, Metzner et al. use human EEG data and superstatistical analysis to demonstrate that each sleep stage has a characteristic distribution and temporal correlation function of raw EEG signals. They also show that the hyper-parameters controlling the EEG signals have characteristic, sleep-stage-dependent distributions, which can be exploited for a simple Bayesian sleep stage detection.

Analysis and visualization of sleep stages based on deep neural networks

Automatic sleep stage scoring based on deep neural networks has come into focus of sleep researchers and physicians, as a reliable method able to objectively classify sleep stages would save human resources and simplify clinical routines. Due to novel open-source software libraries for machine learning, in combination with enormous recent progress in hardware development, a paradigm shift in the field of sleep research towards automatic diagnostics might be imminent. We argue that modern machine learning techniques are not just a tool to perform automatic sleep stage classification, but are also a creative approach to find hidden properties of sleep physiology. We have already developed and established algorithms to visualize and cluster EEG data, facilitating first assessments on sleep health in terms of sleep-apnea and consequently reduced daytime vigilance. In the following study, we further analyze cortical activity during sleep by determining the probabilities of momentary sleep stages, represented as hypnodensity graphs and then computing vectorial cross-correlations of different EEG channels. We can show that this measure serves to estimate the period length of sleep cycles and thus can help to find disturbances due to pathological conditions.

Sleep-wake regulation in preterm and term infants

Study Objectives

In adults, wakefulness can be markedly prolonged at the expense of sleep, e.g. to stay vigilant in the presence of a stressor. These extra-long wake bouts result in a heavy-tailed distribution (highly right-skewed) of wake but not sleep durations. In infants, the relative importance of wakefulness and sleep are reversed, as sleep is necessary for brain maturation. Here, we tested whether these developmental pressures are associated with the unique regulation of sleep–wake states.

Methods

In 175 infants of 28–40 weeks postmenstrual age (PMA), we monitored sleep–wake states using electroencephalography and behavior. We constructed survival models of sleep–wake bout durations and the effect of PMA and other factors, including stress (salivary cortisol), and examined whether sleep is resilient to nociceptive perturbations (a clinically necessary heel lance).

Results

Wake durations followed a heavy-tailed distribution as in adults and lengthened with PMA and stress. However, differently from adults, active sleep durations also had a heavy-tailed distribution, and with PMA, these shortened and became vulnerable to nociception-associated awakenings.

Conclusions

Sleep bouts are differently regulated in infants, with especially long active sleep durations that could consolidate this state’s maturational functions. Curtailment of sleep by stress and nociception may be disadvantageous, especially for preterm infants given the limited value of wakefulness at this age. This could be addressed by environmental interventions in the future.

Comparison of sleep structure in patients with fibromyalgia and healthy controls

BACKGROUND

Sleep disturbances such as nonrestorative sleep and nighttime awakenings play a crucial role in fibromyalgia (FMS). Pain and sleep disturbances show a bidirectional relationship which affect outcomes in FMS. This study aims to compare sleep structures between patients with fibromyalgia and healthy controls.

METHODS

We evaluated subjective and objective sleep structures of 33 patients with fibromyalgia and 34 healthy controls using the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, and polysomnography. Student's T test, chi-square, discriminant analysis, the Kruskal-Wallis, and Mann-Whitney U test were used for statistical analysis.

RESULTS

Patients with FMS reported poorer sleep quality than controls (p = 0.003). Polysomnography data showed patients with FMS exhibited a greater number of awakenings (p = 0.01), more arousals (p = 0.00), higher arousal index (p = 0.00), greater apnea hypopnea index (p = 0.03), and less N1 sleep (p = 0.02) than healthy controls. The discriminant analysis revealed that number of arousals, arousal index, and N1 sleep were able to distinguish patients with FMS from healthy controls with 78.5% accuracy. Twelve of the 33 patients with FMS were diagnosed with obstructive sleep apnea syndrome (OSAS). When we excluded patients with OSAS, a statistically significant difference was maintained.

CONCLUSIONS

Our findings may explain the deterioration of subjective sleep, symptoms as unrefreshing sleep, fatigue, and pain in patients with FMS. Despite similar clinical manifestations, patients with FMS should be evaluated for OSAS due to treatment differences. The role of sleep alterations in the clinical manifestation and severity of FMS suggest that effective treatments to improve sleep quality may lead to more effective management of FMS.

Sleep stage dynamics in young patients with sleep bruxism

Study Objectives

We hypothesized that sleep stage dynamics are different in patients with sleep bruxism (SB) and that these changes are associated with the occurrence of rhythmic masticatory muscle activity (RMMA).

Methods

Fifteen healthy controls and 15 patients with SB underwent overnight polysomnography. Sleep variables and survival curves of continuous runs of each sleep stage were compared between the groups. Stage transition dynamics and the probability of stage fragmentation were analyzed for three epochs before and after the epoch with RMMA. Survival curves of continuous runs of each sleep stage, terminated with or without RMMA, were also compared.

Results

There were no significant differences in sleep variables between the groups, except for shorter sleep latency, shorter rapid eye movement (REM) latency, and longer total N1 duration in SB patients than in controls. REM sleep and N2 were significantly less continuous in SB patients than in controls. In the SB group, stage fragmentation probability was significantly increased for the epoch with RMMA compared with the baseline for all stages. Meanwhile, the occurrence of RMMA did not affect the continuity of N2 or REM; however, the occurrence of RMMA was preceded by more continuous N3 runs.

Conclusions

Sleep stage dynamics differed between SB patients and controls. RMMA does not result in sleep disruption but is likely associated with dissipation of sleep pressure. Less continuity of REM sleep in SB may provide insights into the underlying pathophysiological mechanisms of SB, which may be related to REM sleep processes such as cortical desynchronized states or brainstem activation.

Sleep disorder-related headaches

Migraine with and without aura, cluster headache, hypnic headache, and paroxysmal hemicranias are each reported as intrinsically related to sleep. Chronic migraine, chronic tension-type headache, and medication overuse headache may cause sleep disturbance. Otherwise, both headache and sleep disorder may be manifestations of a same systemic dysfunction. There is a vicious cycle linking sleep disorders and migraine. The poor quality or poor duration of sleep could be a trigger of migraine attack and migraineurs with poor sleep reported a higher headache frequency. Moreover, coping behaviors of migraineurs (e.g., going to sleep early to relieve migraine attacks) can be factors precipitating and perpetuating sleep disturbances themselves. During cluster headache, patients report a poor quality of sleep correlated with the amount of daylight. In particular, it was demonstrated that melatonin levels have influences on cluster headache attacks. Concerning the pathophysiology of hypnic headache, it has been hypothesized a possible role of obstructive sleep apnea in triggering nocturnal attacks: an increased number of apnea episodes has been reported in hypnic headache patients, but a lack of a temporal correlation of headache attacks with the drop of oxygen saturation has been observed. Tension-type headache is the most common headache with sleep dysregulation (lack of sleep or oversleeping) frequently reported as a triggering factor for acute attacks: management of sleep disturbances seems crucial in this form of headache.

Influence of craniocervical and craniomandibular dysfunction to nonrestorative sleep and sleep disorders

Objective: Nonrestorative sleep and sleep disorders are commonly reported in patients suffering from craniomandibular (CMD) and craniocervical dysfunctions (CCD). This study aimed to investigate polysomnographic characteristics and the reduction of pain before and after treatment in these patients.Methods: Seventy-four patients with sleep disorders and evident CMD and CCD were included. Manual therapy and an Aqualizer® were used in the therapeutic group. Polysomnographic measurements were conducted pre- and post-therapy.Results: The number of sleep stage alterations and the sleep stage index differed significantly between pre- and post-therapeutic measurements. Between both groups, these parameters were significantly different, as well (p = .001 and p = .012). The subjective perception of sleep quality improved in 81.6% post-therapy (p < .001).Discussion: Manual therapy and the application of an Aqualizer® may improve sleep quality in patients suffering from CMD and CCD. Pain may not be the main cause for the sleep disorders in CMD and CCD.

Accuracy of Fitbit Wristbands in Measuring Sleep Stage Transitions and the Effect of User-Specific Factors

BACKGROUND

It has become possible for the new generation of consumer wristbands to classify sleep stages based on multisensory data. Several studies have validated the accuracy of one of the latest models, that is, Fitbit Charge 2, in measuring polysomnographic parameters, including total sleep time, wake time, sleep efficiency (SE), and the ratio of each sleep stage. Nevertheless, its accuracy in measuring sleep stage transitions remains unknown.

OBJECTIVE

This study aimed to examine the accuracy of Fitbit Charge 2 in measuring transition probabilities among wake, light sleep, deep sleep, and rapid eye movement (REM) sleep under free-living conditions. The secondary goal was to investigate the effect of user-specific factors, including demographic information and sleep pattern on measurement accuracy.

METHODS

A Fitbit Charge 2 and a medical device were used concurrently to measure a whole night's sleep in participants' homes. Sleep stage transition probabilities were derived from sleep hypnograms. Measurement errors were obtained by comparing the data obtained by Fitbit with those obtained by the medical device. Paired 2-tailed t test and Bland-Altman plots were used to examine the agreement of Fitbit to the medical device. Wilcoxon signed-rank test was performed to investigate the effect of user-specific factors.

RESULTS

Sleep data were collected from 23 participants. Sleep stage transition probabilities measured by Fitbit Charge 2 significantly deviated from those measured by the medical device, except for the transition probability from deep sleep to wake, from light sleep to REM sleep, and the probability of staying in REM sleep. Bland-Altman plots demonstrated that systematic bias ranged from 0% to 60%. Fitbit had the tendency of overestimating the probability of staying in a sleep stage while underestimating the probability of transiting to another stage. SE>90% (P=.047) was associated with significant increase in measurement error. Pittsburgh sleep quality index (PSQI)<5 and wake after sleep onset (WASO)<30 min could be associated to significantly decreased or increased errors, depending on the outcome sleep metrics.

CONCLUSIONS

Our analysis shows that Fitbit Charge 2 underestimated sleep stage transition dynamics compared with the medical device. Device accuracy may be significantly affected by perceived sleep quality (PSQI), WASO, and SE.

Comparison of support vector machines based on particle swarm optimization and genetic algorithm in sleep staging

BACKGROUND:

Heart rate variability (HRV) can reflect the relationship between heart rhythm and sleep structure.

OBJECTIVE:

In order to study the effect of support vector machine (SVM) on the results of automatic sleep staging and improve the effectiveness of heart rate variability (HRV) as a sleep structure biomarker, thereby realize long term and non-contact monitoring of sleep quality.

METHODS:

Two kinds of parameter optimization methods are applied to stage sleep experiments when the known SVM can be used for automatic sleep staging. By factor analysis of the time domain, frequency domain, and nonlinear dynamic characteristics of subjects’ HRV signals, the accuracy of the cross-validation method (K-CV) is used as the fitness function value in genetic algorithm (GA) and particle swarm optimization (PSO). Furthermore, GA and PSO are used to optimize the SVM parameters.

RESULTS:

The results show that the accuracy rate of sleep stage is 64.44% when parameters are not optimized, the accuracy rate based on PSO is improved to 78.89% and the accuracy rate based on GA is improved to 84.44%.

CONCLUSION:

Both optimization algorithms can improve the accuracy of SVM for sleep staging and better results based on GA in the experiment.

Learning Using Concave and Convex Kernels: Applications in Predicting Quality of Sleep and Level of Fatigue in Fibromyalgia

Fibromyalgia is a medical condition characterized by widespread muscle pain and tenderness and is often accompanied by fatigue and alteration in sleep, mood, and memory. Poor sleep quality and fatigue, as prominent characteristics of fibromyalgia, have a direct impact on patient behavior and quality of life. As such, the detection of extreme cases of sleep quality and fatigue level is a prerequisite for any intervention that can improve sleep quality and reduce fatigue level for people with fibromyalgia and enhance their daytime functionality. In this study, we propose a new supervised machine learning method called Learning Using Concave and Convex Kernels (LUCCK). This method employs similarity functions whose convexity or concavity can be configured so as to determine a model for each feature separately, and then uses this information to reweight the importance of each feature proportionally during classification. The data used for this study was collected from patients with fibromyalgia and consisted of blood volume pulse (BVP), 3-axis accelerometer, temperature, and electrodermal activity (EDA), recorded by an Empatica E4 wristband over the courses of several days, as well as a self-reported survey. Experiments on this dataset demonstrate that the proposed machine learning method outperforms conventional machine learning approaches in detecting extreme cases of poor sleep and fatigue in people with fibromyalgia.

Increased Risk of Myofascial Pain Syndrome Among Patients with Insomnia

Objective

The aim of this study is to evaluate the risk of developing myofascial pain syndrome among patients diagnosed with insomnia.

Methods

We conducted a population-based longitudinal study of a matched cohort with 7,895 participants (1,579 patients with insomnia and 6,316 controls) who were selected from the Taiwan National Health Insurance Research Database. The patients were observed for a maximum of 10 years to determine the incidence of newly diagnosed myofascial pain syndrome. A Cox regression analysis was performed to identify the risk factors associated with myofascial pain syndrome in patients with insomnia.

Results

During the 10-year follow-up period, 182 insomnia patients (14.9 per 1,000 person-years) and 379 controls (7.5 per 1,000 person-years) were diagnosed with myofascial pain syndrome. The incidence risk ratio of myofascial pain syndrome between the insomnia and control patients was 2.00 (95% confidence interval [CI] = 1.67-2.38, P  < 0.001). After adjusting for age, sex, monthly income, urbanization, and comorbidities, the insomnia patients were 1.93 times more likely to develop myofascial pain syndrome (95% CI = 1.62-2.31, P  < .001) than the control patients. Malignant neoplasm (hazard ratio = 3.08) and living in urban areas (hazard ratio = 3.05) were identified as independent risk factors for myofascial pain syndrome in patients with insomnia.

Conclusions

Patients with insomnia had a higher risk of developing myofascial pain syndrome than controls. This study adds to the understanding of the complex relationship between sleep disturbance and pain.

Objective measures of sleep in fibromyalgia syndrome: Relationship to clinical, psychiatric, and immunological variables

We aimed to investigate the changes in the objective and subjective sleep variables during painful episodes of fibromyalgia and post-episode period, and to evaluate the impact of the sleep variables on the current clinical, psychological, and immunologic parameters. Thirty-one consecutive patients who were referred to the Erenköy Physical Therapy and Rehabilitation Polyclinic with a diagnosis of fibromyalgia were evaluated before and in the sixth week of the acute pain treatment. The sleep variables were measured by polysomnography, Pittsburgh Sleep Quality Index, and Epworth Sleepiness Scale. The clinical and psychiatric assessment of patients was performed by using Fibromyalgia Impact Questionnaire; Patient Health Questionnaire-Somatic, Anxiety, and Depressive Symptoms; and Visual Analog Scale. Serum pro-inflammatory molecules were measured to evaluate the immunological status. The pain treatment significantly affected subjective sleep variables, psychiatric variables, clinical variables, and IL-6 levels. The subjective sleep parameters, clinical and psychiatric variables, and IL-6 levels were improved with pain treatment in fibromyalgia. The objective sleep variables, IL-1 and TNF-alpha levels were not significantly improved with the pain treatment, and they were not related to clinical presentation of patients with fibromyalgia. Subjective variability of sleep contributes to the clinical presentation, suggesting that the objective structure is trait-specific with IL-1 and TNF-alpha.

Sleep disturbances in fibromyalgia: A meta-analysis of case-control studies

OBJECTIVE

Sleep disturbances are common in fibromyalgia, but the features of sleep disturbances are not well understood. We performed a systematic review and meta-analysis of case-control studies to compare the sleep outcomes of individuals with fibromyalgia and healthy controls.

METHODS

We systematically searched eight databases (PubMed, Ovid MEDLINE, Embase, CINAHL, PsycINFO, Web of Science, Airiti Library and Wanfang Data) for articles published before April 2016.

RESULTS

Twenty-five case-controlled studies and a total of 2086 participants were included in the meta-analysis. Sleep was assessed using polysomnography and the Pittsburgh Sleep Quality Index. When sleep was assessed using polysomnography (19 studies), significant differences were observed in wake time after sleep onset (g=0.81, 95% confidence interval [CI] 0.21-1.41), total sleep time (g=-0.78, 95% CI=-1.34 to -0.15), sleep efficiency (g=-0.78, 95% CI=-1.23 to -0.32), percentage of stage 1 sleep (g=0.55, 95% CI=0.15-0.95), and percentage of slow-wave sleep (g=-0.66, 95% CI=-1.21 to -0.12) between participants with fibromyalgia and healthy controls. When sleep was assessed using the Pittsburgh Sleep Quality Index (7 studies), significant differences were observed in global scores (g=2.19, 95% CI 1.58-2.79), sleep onset latency (g=1.75, 95% CI 0.80-2.70), and sleep efficiency (g=-1.08, 95% CI -1.65 to -0.51) between participants with fibromyalgia and healthy controls.

CONCLUSION

Individuals with fibromyalgia experience lower sleep quality and sleep efficiency; longer wake time after sleep onset, short sleep duration, and light sleep when objectively assessed and more difficulty in initiating sleep when subjectively assessed. Sleep difficulties in fibromyalgia appear to be more when reported subjectively than when assessed objectively.

COMPLIANCE WITH ETHICAL STANDARDS

This study received no funding from any source. All authors declare that they have no conflict of interest. This article does not contain any studies with human participants performed by any of the authors.

[Treatment of fibromyalgia syndrome with gamma-hydroxybutyrate : A randomized controlled study]

BACKGROUND

The etiology of fibromyalgia syndrome is not yet fully understood. Current hypotheses suggest a potential role of gamma-hydroxybutyrate (GHB) in influencing endocrinological abnormalities in patients with fibromyalgia.

OBJECTIVE

The aim of the study was to investigate whether low dose GHB as a growth-hormone releasing substance reduces pain intensity and improves depressive mood, physical impairment and sleep quality in outpatients with fibromyalgia. Additionally, adverse events were recorded.

MATERIAL AND METHODS

The pilot study was conducted in the outpatient clinic for pain at the clinic for anesthesiology and surgical intensive care of the Charité Universitätsmedizin Berlin. In the study 25 female patients with fibromyalgia according to the criteria of the American College of Rheumatology were randomized into 2 groups. Over 15 weeks patients of the intervention group received 25 mg/kg body weight oral GHB before going to bed and were compared with a placebo control group. In addition, all patients participated in operant behavioral pain treatment in a group setting. Dependent variables were pain intensity, depressive mood, physical impairment and quality of sleep.

RESULTS

There were no group differences in the course of pain intensity (p = 0.61), depressive mood (p = 0.16), physical impairment (p = 0.25) and quality of sleep (p = 0.44); however, all symptoms improved across the groups from pretherapy to posttherapy. Low dose GHB did not increase growth hormone blood concentrations. The number of adverse events that were reported more than two times was similar in both groups.

DISCUSSION

Administration of low dose GHB did not yield clinical improvements in female outpatients with fibromyalgia. General improvement in the course of treatment may have resulted from operant behavioral pain therapy. Future studies on GHB should control hypothetical risk factors for identification of non-responders.

Decrease of Serum IGF-1 Level is Not Associated With Obstructive Sleep Apnea in Fibromyalgia Patients

Objectives

This study aims to investigate the relationship of serum insulin-like growth factor 1 (IGF-1) level with obstructive sleep apnea, the Pittsburgh sleep quality index (PSQI), age, body mass index, and fibromyalgia impact questionnaire (FIQ) in fibromyalgia syndrome (FMS) patients.

Patients and methods

A total of 105 female patients (mean age 41.8±9.0 years; range 26 to 55 years) with fibromyalgia (FMS group) who were diagnosed according to 2010 American College of Rheumatology criteria, and 51 female patients (mean age 39.9±10.8 years; range 24 to 54 years) with mechanical low back pain (MLBP) (control group) were included in the study. Age, smoking, educational status, tender point number, body mass index, duration of disease, FIQ, PSQI, and polysomnographic assessment of both FMS and control groups were recorded.

Results

Sleep disorder was detected in 88 patients in FMS group and 15 patients in control group (p<0.05). The PSQI score was higher in the FMS group compared to the control group (9.9±4.6 vs. 5.7±3.5). The FIQ score was higher in the FMS group compared to the control group (53.4±17.4 vs. 26.4±13.9; p<0.05). The serum IGF-1 level of FMS group was significantly lower than that of the control group (140.6±49.5 ng/mL vs. 177.2±58.5 ng/mL; p<0.05). In the FMS group, an examination of the correlation between serum IGF-1 level with the age, body mass index, obstructive sleep apnea syndrome, FIQ, and PSQI revealed a negative correlation between serum IGF-1 with the age and PSQI. The obstructive sleep apnea syndrome ratios of study groups were comparable with regard to the frequencies of mild, moderate, and severe obstructive sleep apnea syndrome.

Conclusion

In FMS patients, serum IGF-1 levels may decrease due to age and PSQI; however, this may not be related to the severity of obstructive sleep apnea.

The Effects of Milnacipran on Sleep Disturbance in Fibromyalgia: A Randomized, Double-Blind, Placebo-Controlled, Two-Way Crossover Study

OBJECTIVE

This study examined the effects of milnacipran on polysomnographic (PSG) measures of sleep and subjective complaints in patients with fibromyalgia and disturbed sleep.

METHODS

This was a single-site, double-blind, placebo-controlled, two-period crossover PSG study. Eligible subjects (aged 28-72 y) were randomized (1:1) to milnacipran (100 mg/d) or placebo for crossover period 1, and vice versa for period 2. Each crossover period comprised a dose-escalation and dose-maintenance phase, with a 2-w taper/washout between periods. In-laboratory PSGs were collected at baseline, and at the end of each treatment period. The primary endpoints were the difference in PSG-recorded wake after sleep onset (WASO), number of awakenings after sleep onset (NAASO), and sleep efficiency (SE) between 4 w of maintenance treatment with milnacipran and placebo. Other PSG measures, subject-rated sleep, fatigue, physical functioning, and pain were assessed. Post hoc analysis was performed in subjects showing at least 25% reduction in pain from baseline in the Brief Pain Inventory Score (responders).

RESULTS

Of 19 subjects randomized, 15 completed both periods. Subjects treated with milnacipran showed no significant improvements in WASO and NAASO, but showed reduced SE (p = 0.049). Milnacipran did not show significant improvement in other PSG parameters or subjective endpoints. Two thirds of completers met responder criteria and additionally showed a significant improvement in daily effect of pain (p = 0.043) and subjective sleep quality (p = 0.040).

CONCLUSION

The data suggest that milnacipran is not sedating in most patients with fibromyalgia and improvements in sleep are likely a result of pain improvement.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, identifier: NCT01234675.

Polysomnographic characteristics in nonmalignant chronic pain populations: A review of controlled studies

Sleep and pain are critical homeostatic systems that interact in a bidirectional manner. Complaints of sleep disturbance are ubiquitous among patients with chronic pain disorders, and conversely, patients with persistent insomnia symptoms commonly report suffering from chronic pain. Sleep deprivation paradigms demonstrate that partial or complete sleep loss induce hyperalgesia, possibly due to shared mechanistic pathways including neuroanatomic and molecular substrates. Further, chronic pain conditions and sleep disturbances are intertwined through comorbidities, which together cause detrimental psychological and physical consequences. This critical review examines 29 polysomnography studies to evaluate whether nonmalignant chronic pain patients, as compared to controls, show differences in objective measures of sleep continuity and sleep architecture. Whereas these controlled studies did not reveal a consistent pattern of objective sleep disturbances, alterations of sleep continuity were commonly reported. Alterations of sleep architecture such as increases in light sleep or decreases in slow-wave sleep were less commonly reported and findings were mixed and also inconsistent. Methodological flaws were identified, which complicated interpretation and limited conclusions; hence, recommendations for future research are suggested. Knowledge of abnormalities in the sleep process has implications for understanding the pathophysiology of chronic pain conditions, which might also direct the development of novel intervention strategies.

Nonrestorative Sleep, Musculoskeletal Pain, Fatigue in Rheumatic Disorders, and Allied Syndromes: A Historical Perspective

This chapter provides a historical perspective of the notion that the sleeping–waking brain is intimately related to complaints of unrefreshing sleep, widespread musculoskeletal pain, fatigue, and suffering. Such a constellation of symptoms extend from the remote biblical past, and involve various religious and cultural belief systems up to the recent evolution in Western medicine application of scientific methods for classification of illness. The contemporary application of scientific principles is directed to the etiology of diseases and to derive procedures for the management of such ill-understood illnesses. Historically, this constellation of rheumatic pain and fatigue symptoms have been given ever-changing medical and psychiatric labels that have been devoid of satisfactory medical understanding. In this chapter, the hypothesis that the sleeping/waking brain is integral to the somatic and behavioral symptoms of these disabling rheumatic chronic illness, termed fibromyalgia and various allied disorders, that are being examined and treated by a variety of health care professionals. Contemporary advances in mechanisms of how the sleeping–waking brain connects to these somatic and behavioral symptoms are reviewed. Potential avenues for further scientific understanding are described. Advances in such understanding are influencing current pharmacological and behavioral management of these suffering patients.

Sleep disturbances of adult women suffering from fibromyalgia: a systematic review of observational studies

Although sleep complaints are often reported in patients with fibromyalgia syndrome (FMS), there is no conclusive evidence that these complaints represent symptomatic disorders of sleep physiology. Thus, the question of the role of sleep disturbances as an etiological or maintenance factor in FMS remains open. This study identifies the subjective and objective characteristics of sleep disturbances in adult women diagnosed with FMS. We carried out a systematic review of publications since 1990, the publication year of the American College of Rheumatology criteria of FMS. We selected empirical studies comparing sleep characteristics of adult women with FMS and healthy women or women with rheumatic diseases. We identified 42 articles. Patients with FMS were more likely to exhibit sleep complaints and also a less efficient, lighter and fragmented sleep. The evidence of a FMS signature on objective measures of sleep is inconsistent, however, as the majority of studies lacks statistical power. Current evidence cannot confirm the role played by sleep physiology in the pathogenesis or maintenance of FMS symptoms; nonetheless, it is clear that sleep disturbances are present in this syndrome.

Obesity and sleepiness in women with fibromyalgia

Fibromyalgia (FM) is associated with a number of comorbidities, including chronic widespread pain, fatigue and non-restorative sleep. Evidence has shown that FM is closely associated with overweight and obesity. The objective of the present study was to investigate the relationship between obesity and sleepiness in women with FM. A total of 100 adult female patients with a prior medical diagnosis of FM participated in the study. Body mass, height and waist circumference were measured, and body mass index (BMI) was calculated. The diet quality was evaluated by the Healthy Eating Index. Subjective analyses of daytime sleepiness [Epworth Sleepiness Scale (ESS)] and sleep quality (Pittsburgh Sleep Quality) were performed. An obesity rate of 41 % was found in all women (56.1 % were sleepy and 43.9 % were not, p = 0.04). Obese women showed a greater level of sleepiness when compared with non-obese (10.2 and 7.0, respectively, p = 0.004). Sleepy women showed a greater weight gain after the diagnosis of FM when compared with non-sleepy women (11.7 and 6.4 kg, respectively, p = 0.04). A positive and significant correlation between BMI and sleepiness (r = 0.35, p = 0.02) was also found. In multivariate logistic regression, moderate or severe sleepiness (ESS >12) was associated with obesity (odds ratio 3.44, 95 % CI 1.31-9.01, p = 0.04). These results demonstrate an important association between sleepiness and FM, suggesting that the occurrence of obesity may be involved with sleepiness in these patients.

Sleep measures expressing 'functional uncertainty' in elderlies' sleep

BACKGROUND

The notion of 'functional uncertainty' during sleep was first proposed to indicate an inability of the central nervous system to maintain stable states by coordinating physiological processes. While the presence of functional uncertainty phenomena has been shown in infants and hypothesized in the elderly, its actual occurrence in the aged population has never been systematically investigated.

OBJECTIVE

The aim of the study is to identify, in the sleep of aged individuals, indexes of sleep instability and fragmentation as markers of functional uncertainty, by comparing a sample of healthy elderly subjects to one of young adults.

METHODS

We compared polysomnograhic recordings of 20 healthy elderly subjects (age range 65-85 years) with those of 20 young individuals (age range 22-32 years), with special regard to the variables expressing functional uncertainty in sleep, such as continuity (e.g. arousals, awakenings), stability (e.g. state transitions, periods of marked 'functional uncertainty') and cyclic organization parameters.

RESULTS

Significant differences emerged for all variables of interest: the elderly group showed higher indexes of fragmentation and instability than the young, as well as less and shorter cycles, and a lower percentage of time spent in cycles.

CONCLUSION

Our results support the hypothesis of a progressive sleep quality disruption with aging, expressed by pronounced sleep instability, fragmentation and disorganization. We propose that functional uncertainty measures could usefully be included in standard sleep assessments on both aged and sleep-disordered populations as accurate sleep quality indexes.

Effect of pregabalin on sleep in patients with fibromyalgia and sleep maintenance disturbance: a randomized, placebo-controlled, 2-way crossover polysomnography study

OBJECTIVE

To assess the effect of pregabalin on polysomnographic (PSG) measures of sleep and patient-rated sleep, tiredness, and pain in fibromyalgia patients.

METHODS

We performed a randomized, double-blind, placebo-controlled, 2-period crossover PSG study. Patients ages ≥18 years with fibromyalgia satisfied subjective and objective sleep disturbance criteria prior to randomization. Eligible patients were randomized (1:1) to pregabalin (300-450 mg/day) or placebo for crossover period 1, and vice versa for period 2. Each crossover period comprised a dose-adjustment and dose-maintenance phase, with a 2-week taper/washout between periods. In-laboratory PSGs were recorded during 2 consecutive nights at screening and at the end of each crossover period. The primary end point was the difference in sleep maintenance defined by PSG-recorded wake after sleep onset (WASO; minutes) between 4 weeks of treatment with pregabalin and with placebo. Other PSG measures; patient-rated sleep, tiredness, and pain; and tolerability were assessed.

RESULTS

Of 119 patients randomized (103 women [86.6%], mean age 48.4 years), 102 (85.7%) completed both periods. Patients treated with pregabalin showed a reduction in PSG-determined WASO versus treatment with placebo (week 4 difference: -19.2 minutes [95% confidence interval (95% CI) -26.7, -11.6]; P < 0.0001). Pain score improved (decreased) with pregabalin versus placebo treatment at all 4 weeks (week 4 difference: -0.52 [95% CI -0.90, -0.14]; P = 0.0084). Modest (ρ = <0.3) but significant correlations were found between PSG sleep assessments and ratings of pain and sleep quality. Frequently reported all-causality adverse events (pregabalin versus placebo) were: dizziness (30.4% versus 9.9%), somnolence (20.5% versus 4.5%), and headache (8.9% versus 8.1%).

CONCLUSION

Patients with fibromyalgia treated with pregabalin had statistically significant and meaningful improvements in sleep, as assessed by PSG. Patients with fibromyalgia also reported decreased daily pain. Pregabalin was well tolerated.

Sleep-stage dynamics in patients with chronic fatigue syndrome with or without fibromyalgia

STUDY OBJECTIVES

Chronic fatigue syndrome (CFS) and fibromyalgia (FM) are medically unexplained conditions that often have overlapping symptoms, including sleep-related complaints. However, differences between the 2 conditions have been reported, and we hypothesized that dynamic aspects of sleep would be different in the 2 groups of patients.

PARTICIPANTS

Subjects were 26 healthy control subjects, 14 patients with CFS but without FM (CFS alone), and 12 patients with CFS and FM (CFS+FM)-all women.

MEASUREMENTS AND RESULTS

We studied transition probabilities and rates between sleep stages (waking, rapid eye movement [REM] sleep, stage 1 [S1], stage 2 [S2], and slow-wave sleep [SWS]) and duration distributions of each sleep stage. We found that the probability of transition from REM sleep to waking was significantly greater in subjects with CFS alone than in control subjects, which may be the specific sleep problem for people with CFS alone. Probabilities of (a) transitions from waking, REM sleep, and S1 to S2 and (b) those from SWS to waking and S1 were significantly greater in subjects with CFS+FM than in control subjects; in addition, rates of these transitions were also significantly increased in subjects with CFS+FM. Result (a) might indicate increased sleep pressure in subjects with CFS+FM whereas result (b) may be the specific sleep problem of subjects with CFS+FM. We also found that shorter durations of S2 sleep are specific to patients with CFS+FM, not to CFS alone.

CONCLUSIONS

These results suggest that CFS and FM may be different illnesses associated with different problems of sleep regulation.

Neurobiology underlying fibromyalgia symptoms

Fibromyalgia is characterized by chronic widespread pain, clinical symptoms that include cognitive and sleep disturbances, and other abnormalities such as increased sensitivity to painful stimuli, increased sensitivity to multiple sensory modalities, and altered pain modulatory mechanisms. Here we relate experimental findings of fibromyalgia symptoms to anatomical and functional brain changes. Neuroimaging studies show augmented sensory processing in pain-related areas, which, together with gray matter decreases and neurochemical abnormalities in areas related to pain modulation, supports the psychophysical evidence of altered pain perception and inhibition. Gray matter decreases in areas related to emotional decision making and working memory suggest that cognitive disturbances could be related to brain alterations. Altered levels of neurotransmitters involved in sleep regulation link disordered sleep to neurochemical abnormalities. Thus, current evidence supports the view that at least some fibromyalgia symptoms are associated with brain dysfunctions or alterations, giving the long-held “it is all in your head” view of the disorder a new meaning.

Nightly analyses of subjective and objective (actigraphy) measures of sleep in fibromyalgia syndrome: what accounts for the discrepancy?

OBJECTIVES

To evaluate the concordance between the subjective and objective methods of sleep assessment in patients with fibromyalgia syndrome (FMS) and to delineate factors associated with discrepancy between the 2 sleep assessment methods.

METHODS

Seventy-five patients with FMS completed a 7-day home assessment protocol. They wore an actigraphic device at all times. In the morning, they used the electronic diary to record the subjective report of sleep from the previous night and current severity of the FMS-related symptoms.

RESULTS

On average, the 2 assessment methods yielded a 73 absolute minute difference per night per patient. About half of the nights, sleep duration was underestimated. Approximately 20% of the nights had greater than 2-hour difference between the 2 methods. Factors related to this large discrepancy were (1) objective indicator of restless sleep, (2) subjective report of difficulty falling asleep, and (3) report of fatigue at the time of reporting. FMS-related symptoms were related to subjective report of poor sleep but not to objective sleep data.

DISCUSSION

Misestimation of sleep seems common in FMS patients, particularly when their sleep quality is poor. Careful considerations for evaluating the severity of patients' sleep complaints are critical in adequate management of sleep disturbance that is commonly reported by FMS patients.

Sodium oxybate for the treatment of fibromyalgia

INTRODUCTION

Gamma-hydroxybutyrate (GHB) is a short-chain fatty acid that is synthesized within the CNS, mostly from its parent compound gamma amino butyric acid (GABA). GHB acts as a neuromodulator/neurotransmitter to affect neuronal activity of other neurotransmitters and so, stimulate the release of growth hormone. Its sodium salt (sodium oxybate: SXB) was approved by the Food and Drug Administration (FDA) for the treatment of narcolepsy. SXB has shown to improve disrupted sleep and increase NR3 (slow-wave restorative) sleep in patients with narcolepsy. It is rapidly absorbed and has a plasma half-life of 30 - 60 min, necessitating twice-nightly dosing. Most of the observed effects of SXB result from binding to GABA-B receptors.

AREAS COVERED

Several randomized, controlled trials demonstrated significantly improved fibromyalgia (FM) symptoms with SXB. As seen in narcolepsy trials, SXB improved sleep of FM patients, increased slow-wave sleep duration as well as delta power, and reduced frequent night-time awakenings. Furthermore, FM pain and fatigue was consistently reduced with nightly SXB over time. Commonly reported adverse events included headache, nausea, dizziness and somnolence. Despite its proven efficacy, SXB did not receive FDA approval for the management of FM in 2010, mostly because of concerns about abuse.

EXPERT OPINION

Insomnia, fatigue and pain are important clinical FM symptoms that showed moderate improvements with SXB in several large, well-designed clinical trials. Because of the limited efficacy of currently available FM drugs additional treatment options are needed. In particular, drugs like SXB - which belong to a different drug class than other Food and Drug Administration (FDA)-approved FM medications such as pregabalin, duloxetine and milnacipran - would provide a much-needed addition to presently available treatment options. However, the FDA has set the bar high for future SXB re-submissions, with requirements of superior efficacy and improved risk mitigation strategies. At this time, no future FDA submission of SXB for the fibromyalgia indication is planned.

Functional somatic syndromes, anxiety disorders and the upper airway: a matter of paradigms

The relationship between the functional somatic syndromes, anxiety disorders and the upper airway (particularly, sleep disordered breathing) remains ambiguous. This ambiguity, despite a growing body of research supporting a relationship, may result from the absence of a paradigm to explain how upper airway dysfunction can promote disorders commonly associated with one's mental health. This review models the functional somatic syndromes and anxiety disorders as consequences of chronically increased hypothalamic-pituitary-adrenal axis activity. It then examines the literature supporting a relationship between these disorders and upper airway dysfunction during wakefulness and sleep. Finally, building upon an existing paradigm of neural sensitization, sleep disordered breathing is linked to functional somatic syndromes and anxiety disorders through chronic activation of the hypothalamic-pituitary-adrenal axis.

Chronic interferon-alpha administration disrupts sleep continuity and depth in patients with hepatitis C: association with fatigue, motor slowing, and increased evening cortisol

BACKGROUND

Consequences of chronic exposure to cytokines of the innate immune system on sleep in humans and the association of cytokine-induced sleep alterations with behavior, motor performance, and cortisol secretion are unknown.

METHODS

Thirty-one patients with hepatitis C without pre-existing sleep disorders underwent nighttime polysomnography, daytime multiple sleep latency testing, behavioral assessments, neuropsychological testing, and serial blood sampling at baseline and after ∼12 weeks of either treatment with the innate immune cytokine interferon (IFN)-alpha (n = 19) or no treatment (n = 12). Fatigue and sleepiness were assessed using the Multidimensional Fatigue Inventory and Epworth Sleepiness Scale.

RESULTS

Interferon-alpha administration led to significant increases in wake after sleep onset and significant decreases in stage 3/4 sleep and sleep efficiency. Rapid eye movement latency and stage 2 sleep were significantly increased during IFN-alpha treatment. Decreases in stage 3/4 sleep and increases in rapid eye movement latency were associated with increases in fatigue, whereas decreases in sleep efficiency were associated with reduced motor speed. Increased wake after sleep onset was associated with increased evening plasma cortisol. Despite IFN-alpha-induced increases in fatigue, daytime sleepiness did not increase. In fact, IFN-alpha-treated patients exhibited decreased propensity to fall asleep during daytime nap opportunities.

CONCLUSIONS

Chronic exposure to an innate immune cytokine reduced sleep continuity and depth and induced a sleep pattern consistent with insomnia and hyperarousal. These data suggest that innate immune cytokines may provide a mechanistic link between disorders associated with chronic inflammation, including medical and/or psychiatric illnesses and insomnia, which, in turn, is associated with fatigue, motor slowing, and altered cortisol.

The effect of nasal continuous positive airway pressure on the symptoms of Gulf War illness

PURPOSE

We performed a pilot study to determine whether nasal continuous positive airway pressure (CPAP) alleviates the symptoms of veterans with Gulf War illness (GWI) and sleep disordered breathing (SDB).

METHODS

Eighteen male veterans with GWI and SDB recruited by advertisement, participated in a randomized, single-masked, sham-controlled treatment trial. Participants received 3 weeks of treatment during sleep with either therapeutic nasal CPAP or sham nasal CPAP. Using validated questionnaires, pain, fatigue, cognitive function, sleep disturbance, and general health were assessed by self-report before and after treatment. One of the participants assigned to therapeutic CPAP was excluded from the trial before starting treatment, leaving 17 participants.

RESULTS

Compared to the nine sham nasal CPAP recipients, the eight participants receiving therapeutic nasal CPAP experienced improvements in pain (34%; p = 0.0008), fatigue (38%; p = 0.0002), cognitive function (33%; p = 0.004), sleep quality (41%; p = 0.0003), physical health (34%; p = 0.0003), and mental health (16%; p = 0.03).

CONCLUSIONS

Our findings in this pilot study suggest that nasal CPAP may greatly improve symptoms in veterans with GWI and SDB.

Effects of sodium oxybate on sleep physiology and sleep/wake-related symptoms in patients with fibromyalgia syndrome: a double-blind, randomized, placebo-controlled study

OBJECTIVE

To determine the effects of sodium oxybate (SXB) on sleep physiology and sleep/wake-related symptoms in patients with fibromyalgia syndrome (FM).

METHODS

Of 304 patients with FM (American College of Rheumatology tender point criteria) in the screened study population, 209 underwent polysomnography, 195 were randomized, and 151 completed this 8-week, double-blind, placebo-controlled study of SXB 4.5 g and 6 g/night. We evaluated changes in objective sleep measures and subjective symptoms, including daytime sleepiness [Epworth Sleepiness Scale (ESS)], fatigue visual analog scale (FVAS), sleep [Jenkins Scale for Sleep (JSS)], and daytime functioning [Functional Outcome of Sleep Questionnaire (FOSQ), SF-36 Vitality domain, and Fibromyalgia Impact Questionnaire (FIQ) general and morning tiredness].

RESULTS

Pretreatment screening revealed an elevated incidence of maximum alpha EEG-intrusion > 24 min/hour of sleep (66%), periodic limb movements of sleep (20.1% ≥ 5/hour), and moderate to severe obstructive sleep apnea disorder (15.3% apnea-hypopnea index ≥ 15/hour). Compared with placebo, both doses of SXB achieved statistically significant improvements in ESS, morning FVAS, JSS, FOSQ, SF-36 Vitality, and FIQ general and morning tiredness; both doses also demonstrated decreased rapid eye movement (REM) sleep (all p ≤ 0.040). SXB 6 g/night improved afternoon, evening and overall FVAS, reduced wakefulness after sleep onset, and increased Stage 2, slow-wave, and total non-REM sleep (all p ≤ 0.032) versus placebo. Moderate correlations (≥ 0.40) were noted between changes in subjective sleep and pain measures. Adverse events occurring significantly more frequently with SXB than placebo were nausea, pain in extremity, nervous system disorders, dizziness, restlessness, and renal/urinary disorders (including urinary incontinence).

CONCLUSION

This large cohort of patients with FM demonstrated that SXB treatment improved EEG sleep physiology and sleep-related FM symptoms.