Tag: sleep

Electroencephalographic correlates of Chronic Fatigue Syndrome

Abstract:

BACKGROUND: Unremitting fatigue and unrefreshing sleep, hallmark traits of Chronic Fatigue Syndrome (CFS), are also pathognomonic of sleep disorders. Yet, no reproducible perturbations of sleep architecture, multiple sleep latency times or Epworth Sleepiness Scores are found to be associated consistently with CFS. This led us to hypothesize that sleep homeostasis, rather than sleep architecture, may be perturbed in CFS. To probe this hypothesis, we measured and compared EEG frequencies associated with restorative sleep between persons with CFS and matched controls, both derived from a population-based sample.

METHODS: We evaluated overnight polysomnography (PSG) in 35 CFS and 40 control subjects. PSG records were manually scored and epochs containing artifact removed. Fast Fourier Transformation was utilized to deconstruct individual EEG signals into primary frequency bands of alpha, delta, theta, sigma, and beta frequency domains. The spectral power of each frequency domain for each sleep state was compared between persons with CFS and matched controls.

RESULTS: In persons with CFS, delta power was diminished during slow wave sleep, but elevated during both stage 1 and REM. Alpha power was reduced during stage 2, slow wave, and REM sleep. Those with CFS also had significantly lower theta, sigma, and beta spectral power during stage 2, Slow Wave Sleep, and REM.

DISCUSSION: Employing quantitative EEG analysis we demonstrate reduced spectral power of cortical delta activity during SWS. We also establish reduced spectral power of cortical alpha activity, with the greatest reduction occurring during REM sleep. Reductions in theta, beta, and sigma spectral power were also apparent.

CONCLUSION: Unremitting fatigue and unrefreshing sleep, the waking manifestations of CFS, may be the consequence of impaired sleep homeostasis rather than a primary sleep disorder.

 

Source: Decker MJ, Tabassum H, Lin JM, Reeves WC. Electroencephalographic correlates of Chronic Fatigue Syndrome. Behav Brain Funct. 2009 Oct 6;5:43. doi: 10.1186/1744-9081-5-43. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2765956/ (Full article)

 

High slow-wave sleep and low-light sleep: chronic fatigue syndrome is not likely to be a primary sleep disorder

Abstract:

The status of chronic fatigue syndrome (CFS) is still under debate. Mainstream views still often consider it as an undetected primary sleep disorder or as the psychosomatic expression of a related anxiety or depression syndrome. Both primary sleep disorder and CFS are often related to unrefreshing sleep and affective daytime symptoms.

The present study compares nonrapid eye movement sleep distribution between patients with a primary sleep disorder and “pure” CFS patients without sleep or mood disorders. Intensity measures of affective symptoms are also analyzed. Sleep variables of 32 pure CFS (mean age, 41.9 +/- 8.7 years; 25 women), 30 Sleep Apnea Hypopnea Syndrome patients (mean age, 43.7 +/- 6.7 years; 13 women), and 14 healthy controls (mean age, 40.2 +/- 7.6 years; 9 women) were compared. Related affective symptoms were assessed using the self-reported Zung anxiety and depression scales.

The study confirms previous reports on increased slow-wave sleep in CFS patients. Both patient groups showed similar sleep duration and efficiency. Sleep efficiency was lower in both patient groups compared with controls. CFS patients showed a higher microarousal index than controls. Anxiety, but not depression symptoms were more intense in the CFS group. The distribution of nonrapid eye movement sleep in CFS differs sizeably from what can be observed in a primary sleep disorder.

 

Source: Neu D, Cappeliez B, Hoffmann G, Verbanck P, Linkowski P, Le Bon O. High slow-wave sleep and low-light sleep: chronic fatigue syndrome is not likely to be a primary sleep disorder. J Clin Neurophysiol. 2009 Jun;26(3):207-12. doi: 10.1097/WNP.0b013e3181a1841b. https://www.ncbi.nlm.nih.gov/pubmed/19424087

 

Power spectral analysis of sleep EEG in twins discordant for chronic fatigue syndrome

Abstract:

OBJECTIVE: The purpose of the study was to evaluate quantitative sleep electroencephalogram (EEG) frequencies in monozygotic twins discordant for chronic fatigue syndrome.

METHODS: Thirteen pairs of female twins underwent polysomnography. During the first night, they adapted to the sleep laboratory, and during the second night, their baseline sleep was assessed. Visual stage scoring was conducted on sleep electroencephalographic records according to standard criteria, and power spectral analysis was used to quantify delta through beta frequency bands, processed in 6-s blocks. Data were averaged across sleep stage within each twin and coded for sleep stage and the presence or absence of chronic fatigue syndrome (CFS). A completely within-subjects repeated measure multivariate analysis of variance evaluated twin pairs by frequency band by sleep stage interactions and simple effects. The relationship between alpha and delta EEG was also assessed across twin pairs.

RESULTS: No significant differences in spectral power in any frequency band were found between those with CFS and their nonfatigued cotwins. Phasic alpha activity, coupled with delta was noted in five subjects with CFS but was also present in 4/5 healthy twins, indicating this finding likely reflects genetic influences on the sleep electroencephalogram rather than disease-specific sleep pathology.

CONCLUSIONS: The genetic influences on sleep polysomnography and microarchitecture appear to be stronger than the disease influence of chronic fatigue syndrome, despite greater subjective sleep complaint among the CFS twins. EEG techniques that focus on short duration events or paradigms that probe sleep regulation may provide a better description of sleep abnormalities in CFS.

 

Source: Armitage R, Landis C, Hoffmann R, Lentz M, Watson N, Goldberg J, Buchwald D. Power spectral analysis of sleep EEG in twins discordant for chronic fatigue syndrome. J Psychosom Res. 2009 Jan;66(1):51-7. doi: 10.1016/j.jpsychores.2008.08.004. Epub 2008 Nov 25. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2634600/ (Full article)

 

Evidence for T-helper 2 shift and association with illness parameters in chronic fatigue syndrome (CFS)

Abstract:

Few immunological markers have been consistently reported in CFS. However, a shift to a T-helper 2 (Th2) type immune response has been hypothesized for individuals with CFS. The current study investigated whether individuals with CFS who exhibited a stronger shift towards a Th2 type of immune response would also exhibit more severe symptoms, poorer neurocognitive functioning, and poorer physical and psychosocial functioning.

The current investigation measured the percentage of Th1-like and Th2-like memory cells using cell surface flow cytometry in 114 individuals with CFS. The associations between the ratio of Th1 and Th2 memory cells and various illness parameters measures were then examined, including symptom severity, psychiatric functioning, neurocognitive functioning, salivary cortisol levels, and chronic pain status.

Results indicated that individuals who exhibited a more extreme shift towards a Th2 immune response also exhibited poorer sleep and high levels of basal salivary cortisol. The implications of these findings are discussed.

 

Source: Torres-Harding S, Sorenson M, Jason LA, Maher K, Fletcher MA. Evidence for T-helper 2 shift and association with illness parameters in chronic fatigue syndrome (CFS). Bull IACFS ME. 2008 Fall;16(3):19-33. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3018761/ (Full article)

 

Dynamics of sleep stage transitions in healthy humans and patients with chronic fatigue syndrome

Abstract:

Physiological and/or pathological implications of the dynamics of sleep stage transitions have not, to date, been investigated. We report detailed duration and transition statistics between sleep stages in healthy subjects and in others with chronic fatigue syndrome (CFS); in addition, we also compare our data with previously published results for rats.

Twenty-two healthy females and 22 female patients with CFS, characterized by complaints of unrefreshing sleep, underwent one night of polysomnographic recording. We find that duration of deep sleep (stages III and IV) follows a power-law probability distribution function; in contrast, stage II sleep durations follow a stretched exponential and stage I, and REM sleep durations follow an exponential function. These stage duration distributions show a gradually increasing departure from the exponential form with increasing depth of sleep toward a power-law type distribution for deep sleep, suggesting increasing complexity of regulation of deeper sleep stages. We also find a substantial number of REM to non-REM sleep transitions in humans, while this transition is reported to be virtually nonexistent in rats.

The relative frequency of this REM to non-REM sleep transition is significantly lower in CFS patients than in controls, resulting in a significantly greater relative transition frequency of moving from both REM and stage I sleep to awake. Such an alteration in the transition pattern suggests that the normal continuation of sleep in light or REM sleep is disrupted in CFS. We conclude that dynamic transition analysis of sleep stages is useful for elucidating yet-to-be-determined human sleep regulation mechanisms with pathophysiological implications.

 

Source: Kishi A, Struzik ZR, Natelson BH, Togo F, Yamamoto Y. Dynamics of sleep stage transitions in healthy humans and patients with chronic fatigue syndrome. Am J Physiol Regul Integr Comp Physiol. 2008 Jun;294(6):R1980-7. doi: 10.1152/ajpregu.00925.2007. Epub 2008 Apr 16. http://ajpregu.physiology.org/content/294/6/R1980.long

 

Perception versus polysomnographic assessment of sleep in CFS and non-fatigued control subjects: results from a population-based study

Abstract:

BACKGROUND: Complaints of unrefreshing sleep are a prominent component of chronic fatigue syndrome (CFS); yet, polysomnographic studies have not consistently documented sleep abnormalities in CFS patients. We conducted this study to determine whether alterations in objective sleep characteristics are associated with subjective measures of poor sleep quality in persons with CFS.

METHODS: We examined the relationship between perceived sleep quality and polysomnographic measures of nighttime and daytime sleep in 35 people with CFS and 40 non-fatigued control subjects, identified from the general population of Wichita, Kansas and defined by empiric criteria. Perceived sleep quality and daytime sleepiness were assessed using clinical sleep questionnaires. Objective sleep characteristics were assessed by nocturnal polysomnography and daytime multiple sleep latency testing.

RESULTS: Participants with CFS reported unrefreshing sleep and problems sleeping during the preceding month significantly more often than did non-fatigued controls. Participants with CFS also rated their quality of sleep during the overnight sleep study as significantly worse than did control subjects. Control subjects reported significantly longer sleep onset latency than latency to fall asleep as measured by PSG and MSLT. There were no significant differences in sleep pathology or architecture between subjects with CFS and control subjects.

CONCLUSION: People with CFS reported sleep problems significantly more often than control subjects. Yet, when measured these parameters and sleep architecture did not differ between the two subject groups. A unique finding requiring further study is that control, but not CFS subjects, significantly over reported sleep latency suggesting CFS subjects may have an increased appreciation of sleep behaviour that may contribute to their perception of sleep problems.

 

Source: Majer M, Jones JF, Unger ER, Youngblood LS, Decker MJ, Gurbaxani B, Heim C, Reeves WC. Perception versus polysomnographic assessment of sleep in CFS and non-fatigued control subjects: results from a population-based study. BMC Neurol. 2007 Dec 5;7:40. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2231384/ (Full article)

 

Higher heart rate and reduced heart rate variability persist during sleep in chronic fatigue syndrome: a population-based study

Abstract:

Autonomic nervous system (ANS) dysfunction has been suggested in patients with chronic fatigue syndrome (CFS). In this study, we sought to determine whether increased heart rate (HR) and reduced heart rate variability (HRV) parameters observed in CFS patients during wakefulness persist during sleep. To this end, we compared heart rate (HR) and HRV as indicators of ANS function in CFS subjects and non-fatigued (NF) controls in a population-based, case-control study.

Thirty subjects with CFS and 38 NF controls, matched for age-, sex- and body mass index, were eligible for analysis. Main outcome measures included mean RR interval (RRI), HR, and HRV parameters derived from overnight ECG. Plasma aldosterone and norepinephrine levels, medicines with cardiovascular effect, and reported physical activity were examined as covariates. General Linear Models were used to assess significance of associations and adjust for potential confounders.

Compared to controls, CFS cases had significantly higher mean HR (71.4 vs 64.8 bpm), with a shorter mean RRI [840.4 (85.3) vs 925.4(97.8) ms] (p<0.0004, each), and reduced low frequency (LF), very low frequency (VLF), and total power (TP) of HRV (p<0.02, all). CFS cases had significantly lower plasma aldosterone (p<0.05), and tended to have higher plasma norepinephrine levels. HR correlated weakly with plasma norepinephrine (r=0.23, p=0.05) and moderately with vitality and fatigue scores (r=-0.49 and 0.46, respectively, p<0.0001). Limitation in moderate physical activity was strongly associated with increased HR and decreased HRV. Nevertheless, among 42 subjects with similar physical activity limitations, CFS cases still had higher HR (71.8 bpm) than respective controls (64.9 bpm), p=0.023, suggesting that reduced physical activity could not fully explain CFS-associated differences in HR and HRV. After adjusting for potential confounders case-control differences in HR and TP remained significant (p<0.05).

CONCLUSION: The presence of increased HR and reduced HRV in CFS during sleep coupled with higher norepinephrine levels and lower plasma aldosterone suggest a state of sympathetic ANS predominance and neuroendocrine alterations. Future research on the underlying pathophysiologic mechanisms of the association is needed.

 

Source: Boneva RS, Decker MJ, Maloney EM, Lin JM, Jones JF, Helgason HG, Heim CM, Rye DB, Reeves WC. Higher heart rate and reduced heart rate variability persist during sleep in chronic fatigue syndrome: a population-based study. Auton Neurosci. 2007 Dec 30;137(1-2):94-101. Epub 2007 Sep 12. https://www.ncbi.nlm.nih.gov/pubmed/17851136

 

Sleep disturbance in chronic fatigue syndrome

Abstract:

Attempts to elucidate the complex pathophysiology of chronic fatigue syndrome (CFS) must consider subjective and objective sleep. Several reports of CFS showed the high rate of sleep disturbance such as insomnia, hypersomnia, circadian rhythm sleep disorder, sleep apnea/hypopnea syndrome and so on. To analyze pulse wave continuously in sleep of CFS patients by laser blood flowmeter, we set base line component (0.01-0.08 Hz) and pulse wave component(0.70-1.50 Hz). Results of FFT analysis indicate that the CFS can have at least three subtypes of pulse dynamics in sleep. There probably are different types of illnesses now contained within the CFS construct, in which identifying subtypes of sleep disturbance can be one important key.

 

Source: Kumano-go T, Adachi H, Sugita Y. Sleep disturbance in chronic fatigue syndrome. Nihon Rinsho. 2007 Jun;65(6):1017-22. [Article in Japanese] https://www.ncbi.nlm.nih.gov/pubmed/17561691

 

The impact of a 4-hour sleep delay on slow wave activity in twins discordant for chronic fatigue syndrome

Abstract:

OBJECTIVES: Chronic fatigue syndrome (CFS) has been associated with altered amounts of slow wave sleep, which could reflect reduced delta electroencephalograph (EEG) activity and impaired sleep regulation. To evaluate this hypothesis, we examined the response to a sleep regulatory challenge in CFS.

DESIGN: The first of 3 consecutive nights of study served as laboratory adaptation. Baseline sleep was assessed on the second night. On the third night, bedtime was delayed by 4 hours, followed by recovery sleep. Total available sleep time was held constant on all nights.

SETTING: A research sleep laboratory.

PARTICIPANTS: 13 pairs of monozygotic twins discordant for CFS.

INTERVENTIONS: N/A.

MEASUREMENTS AND RESULTS: Power spectral analysis quantified slow wave activity (SWA) in the 0.5-3.9 Hz band in successive NREM periods (stage 2, 3, or 4) on each night. To ensure comparability, analyses were restricted to the first 4 NREM periods on each night. Data were coded for NREM period and twin pair. Repeated-measures analysis of variance (ANOVA) contrasted sleep delay effects across NREM periods between twin pairs. A second ANOVA calculated the SWA in each NREM period in recovery sleep relative to baseline SWA. The 2 groups of twins were similar on baseline SWA power. After sleep delay, CFS twins exhibited significantly less SWA power in the first NREM period of recovery sleep and accumulated a smaller percentage of SWA in the first NREM period than their co-twins.

CONCLUSIONS: CFS is associated with a blunted SWA response to sleep challenge, suggesting that the basic sleep drive and homeostatic response are impaired.

 

Source: Armitage R, Landis C, Hoffmann R, Lentz M, Watson NF, Goldberg J, Buchwald D. The impact of a 4-hour sleep delay on slow wave activity in twins discordant for chronic fatigue syndrome, Sleep. 2007 May;30(5):657-62. https://www.ncbi.nlm.nih.gov/pubmed/17552382

 

Defining the occurrence and influence of alpha-delta sleep in chronic fatigue syndrome

Abstract:

BACKGROUND: Patients with chronic fatigue syndrome (CFS) present a disordered sleep pattern and frequently undergo polysomnography to exclude a primary sleep disorder. Such studies have shown reduced sleep efficiency, a reduction of deep sleep, prolonged sleep initiation, and alpha-wave intrusion during deep sleep. Deregulation of the 2-5A synthetase/RNase L antiviral pathway and a potential acquired channelopathy are also found in a subset of CFS patients and could lead to sleep disturbances. This article compiles a large sleep study database on CFS patients and correlates these data with a limited number of immune parameters as it has been thought that RNase L could be associated with these sleep disturbances.

METHODS: Forty-eight patients who fulfilled 1994 Centers for Disease Control and Prevention criteria for CFS underwent extensive medical evaluation, routine laboratory testing, and a structured psychiatric interview. Subjects then completed a complaint checklist and a two-night polysomnographic investigation. RNase L analysis was performed by gel electrophoresis using a radiolabeled 2′,5′-oligoadenylate trimer. Basic descriptive statistical parameters were calculated.

RESULTS: Patients experienced a prolonged sleep latency, showed a low sleep efficiency index, and had a low percentage of slow wave sleep. The present alpha-delta intrusion correlated with anxiety; no correlations appeared, however, between alpha-delta sleep and immunologic parameters, including RNase L.

CONCLUSIONS: The main findings are 1) validation of sleep latency problems and other sleep disturbances as already suggested by several authors; 2) alpha-delta intrusion seems associated with anxiety; and 3) elevated RNase L did not correlate with alpha-delta sleep.

 

Source: Van Hoof E, De Becker P, Lapp C, Cluydts R, De Meirleir K. Defining the occurrence and influence of alpha-delta sleep in chronic fatigue syndrome. Am J Med Sci. 2007 Feb;333(2):78-84. https://www.ncbi.nlm.nih.gov/pubmed/17301585