Sniffing out safety: canine detection and identification of SARS-CoV-2 infection from armpit sweat.

Detection dogs were trained to detect SARS-CoV-2 infection based on armpit sweat odor. Sweat samples were collected using cotton pads under the armpits of negative and positive human patients, confirmed by qPCR, for periods of 15-30 min. Multiple hospitals and organizations throughout Belgium participated in this study. The sweat samples were stored at -20°C prior to being used for training purposes. Six dogs were trained under controlled atmosphere conditions for 2-3 months. After training, a 7-day validation period was conducted to assess the dogs' performances. The detection dogs exhibited an overall sensitivity of 81%, specificity of 98%, and an accuracy of 95%. After validation, training continued for 3 months, during which the dogs' performances remained the same. Gas chromatography/mass spectrometry (GC/MS) analysis revealed a unique sweat scent associated with SARS-CoV-2 positive sweat samples. This scent consisted of a wide variety of volatiles, including breakdown compounds of antiviral fatty acids, skin proteins and neurotransmitters/hormones. An acceptability survey conducted in Belgium demonstrated an overall high acceptability and enthusiasm toward the use of detection dogs for SARS-CoV-2 detection. Compared to qPCR and previous canine studies, the detection dogs have good performances in detecting SARS-CoV-2 infection in humans, using frozen sweat samples from the armpits. As a result, they can be used as an accurate pre-screening tool in various field settings alongside the PCR test.

Efficacy and safety of camostat mesylate in early COVID-19 disease in an ambulatory setting: a randomized placebo-controlled phase II trial.

OBJECTIVES: This study aimed to assess the efficacy and safety of 300 mg camostat mesylate three times daily in a fasted state to treat early phase COVID-19 in an ambulatory setting. METHODS: We conducted a phase II randomized controlled trial in symptomatic (maximum 5 days) and asymptomatic patients with confirmed COVID-19 infection. Patients were randomly assigned in a 2:1 ratio to receive either camostat mesylate or a placebo. Outcomes included change in nasopharyngeal viral load, time to clinical improvement, the presence of neutralizing antibodies, and safety. RESULTS: Of 96 participants randomized between November 2020 and June 2021, analyses were performed on the data of 90 participants who completed treatment (N = 61 camostat mesylate, N = 29 placebo). The estimated mean change in cycle threshold between day 1 and day 5 between the camostat and placebo group was 1.183 (P = 0.511). The unadjusted hazard ratio for clinical improvement in the camostat group was 0.965 (95% confidence interval, 0.480-1.942, P = 0.921 by Cox regression). The percentage distribution of the 50% neutralizing antibody titer at day 28 visit and frequency of adverse events were similar between the two groups. CONCLUSION: Under this protocol, camostat mesylate was not found to be effective as an antiviral drug against SARS-CoV-2. TRIAL REGISTRATION: ClinicalTrials.gov NCT04625114; November 12, 2020.

Slow Wave Sleep of Elite and Nonelite Gymnasts Is Influenced by Weekly Training Hours, Not by Fitness Level.

PURPOSE: This study aimed to determine the influencing factors of potential differences in sleep architecture between elite (EG) and nonelite (NEG) female artistic gymnasts. METHODS: Twelve EG (15.1 [1.5] y old) and 10 NEG (15.3 [1.8] y old) underwent a nocturnal polysomnography after a regular training day (5.8 [0.8] h vs 2.6 [0.7] h), and, on a separate test day, they performed an incremental treadmill test after a rest day in order to determine physical fitness status. A multiple linear regression assessed the predictive value of training and fitness parameters toward the different sleep phases. Total sleep time and sleep efficiency (proportion of time effectively asleep to time in bed), as well as percentage of nonrapid eye movement sleep phase 1 (NREM1) and 2 (NREM2), slow wave sleep (SWS), and rapid eye movement sleep (REM), during a single night were compared between EG and NEG using an independent-samples t test. RESULTS: Peak oxygen uptake influenced NREM1 (ß = 1.035, P = .033), while amount of weekly training hours predicted SWS (ß = 1.897, P = .032). No differences were documented between EG and NEG in total sleep time and sleep efficiency. SWS was higher in EG (36.9% [11.4%]) compared with NEG (25.9% [8.3%], P = .020), compensated by a lower proportion of NREM2 (38.7% [10.2%] vs 48.4% [6.5%], P = .017), without differences in NREM1 and REM. CONCLUSIONS: The proportion of SWS was only predicted by weekly training hours and not by training hours the day of the polysomnography or physical fitness, while NREM1 was linked with fitness level. Sleep efficiency did not differ between EG and NEG, but in EG, more SWS and less NREM2 were identified.

Upper respiratory tract symptoms and salivary immunoglobulin A of elite female gymnasts: a full year longitudinal field study.

The aim of this study was to determine the frequency of upper respiratory tract symptoms (URS) in elite female gymnasts during a training season. In addition, we aimed to observe the extent to which salivary immunoglobulin A (sIgA) is associated with URS in these athletes, including potential effects of the season and timing of sample collection. Over one year, 18 elite female gymnasts completed URS and fatigue questionnaires weekly and provided 1 mL of saliva after a minimum 36 h of rest (morning or afternoon) to measure relative sIgA concentration (= mean absolute sIgA value of the week divided by the mean absolute sIgA value of the weeks without URS). Mean weekly URS and mean relative sIgA values per gymnast correlated negatively (r = -0.606, P = 0.022). Most URS were noted in the most fatigued gymnasts (7.4 ± 10.1 vs. 2.5 ± 5.6 (P < 0.001) for 'normal' and 2.1 ± 3.7 (P = 0.001) for 'better than normal' rested). In spring, relative sIgA was higher compared to autumn (112 ± 55 vs. 89 ± 41%, P < 0.001) and winter (92 ± 35%, P = 0.001), while during summer, relative sIgA appeared higher compared to autumn (110 ± 55 vs. 89 ± 41%, P = 0.016). The interaction effect with timing of sample collection showed higher relative sIgA values in morning samples in spring and summer compared to afternoon samples, with the inverse observed in autumn and winter (F = 3.565, P = 0.014). During a gymnastics season, lower relative sIgA values were linked to higher susceptibility to URS in elite gymnasts. However, relative sIgA values were influenced by season and timing of sample collection and thus should be considered when interpreting sIgA data.

Retrospective Analysis of Risk Factors for Periodic Limb Movements in a Large Cohort of Insomnia and Chronic Fatigue Patients.

INTRODUCTION: Although the pathophysiology of periodic limb movements in sleep (PLMS) is not well understood, there is increasing belief that management of PLMS can modulate humans' general health. The aim of this study is to investigate the associations between risk factors including the use of antidepressants, hypnotics, and antihistamines as well as of caffeine, alcohol, and nicotine and the occurrence of PLMS and periodic limb movement disorder (PLMD). METHODS: Patients with either chronic fatigue or insomnia who underwent polysomnography as standardized clinical assessment were included in a retrospective study. Associations were calculated between substance use and sleep variables. RESULTS: Tricyclic antidepressants and serotonin and norepinephrine reuptake inhibitor (SNRI) are significantly associated with higher rates of PLMS. Additionally, SNRI is significantly positive associated with PLMD, as also seen for selective serotonin reuptake inhibitors (SSRI). The most frequently used SSRI escitalopram was significantly positively associated with PLMS and PLMD. A significantly negative association was found between paroxetine and PLMS. Benzodiazepines are negatively associated with PLMS and PLMD. Sedative antidepressants, antihistamines, and substance use are not associated with PLMS nor PLMD in this study. DISCUSSION: This retrospective study adds supportive evidence to the association of drug classes with PLMS and PLMD. These findings may impact on clinical management of patients with a combined anxiety or mood disorder in need for these drug classes on the one hand and a significant sleep architecture disturbance through PLMS, potentially contributing to daytime symptoms, on the other hand.

The role of basic psychological need satisfaction, sleep, and mindfulness in the health-related quality of life of people living with HIV.

Research has not yet examined the relationship between psychological need satisfaction, sleep, mindfulness, and health-related quality of life in people living with HIV. This cross-sectional study ( N = 101; 84% male; mean age = 45.48, SD = 12.75) found need satisfaction to relate positively to physical and mental health. Sleep quality fully mediated the association with physical health and partially mediated the association with mental health. Furthermore, mindfulness related to higher sleep quality through higher need satisfaction. Findings underscore the role of need satisfaction in determining health-related quality of life and sleep quality in people living with HIV and suggest that mindfulness may facilitate need satisfaction.

Medically unexplained physical symptoms in patients visiting the emergency department: an international multicentre retrospective study.

OBJECTIVE: The objective of this study was to assess the incidence and characteristics of patients presenting with physical symptoms that remain medically unexplained at the emergency department (ED). PATIENTS AND METHODS: A retrospective chart study was carried out in three hospitals in The Netherlands and Belgium. All patients (age > 18 years) visiting the ED in 4 selected weeks in 2013 at the Erasmus University Medical Center (Erasmus MC) in Rotterdam, The Netherlands, and 1 selected week in 2013 at the Haaglanden Medical Center, Westeinde HMC in The Hague, The Netherlands, and the University Hospital Ghent (UZG), Belgium, were included. Descriptive statistics were used for data analysis. RESULTS: A total of 2869 patients (Erasmus MC 1674, HMC 691, UZG 504) were included. Medically unexplained physical symptoms in the emergency department (EDMUPS) were present in 13.4% of all ED visits (Erasmus MC 12.5%, HMC 18.7%, UZG 9.1%). No EDMUPS were identified in trauma patients. When excluding trauma patients, EDMUPS were present in 18.5% (Erasmus MC 16.8%, HMC 26.5%, UZG 13.3%) of the visits. The characteristics of patients with and without EDMUPS differed significantly; patients with EDMUPS were more often younger, female, self-referred, frequent visitors, were prescribed less medication and more often had a psychiatric disease. Dutch and Belgian Hospital differed in the distribution of patients in triage categories and in the incidence of psychiatric illnesses. CONCLUSION: Physical symptoms remain unexplained in a significant number of patients at the time of ED assessment.

Opinion paper: the role of work in the management of medically unexplained physical symptoms.

OBJECTIVES: Patients with medically unexplained physical symptoms suffer from chronic fatigue and/or pain in combination with a variety of other symptoms. A flexible, biopsychosocial approach is needed for diagnostic screening and global management. It is crucial to involve the direct patient environment, including family, friends, colleagues as well as health providers, evaluation, and reintegration sector. The aim of this paper is to review the importance of work in the management of medically unexplained physical symptoms. METHODS: In this paper, different actors involved explain their views and handling concerning work in the management of MUPS. RESULTS: Symptom severity and lack of understanding from the environment can negatively impact on earning an independent income from labor for years. Work, whether or not paid, is however, an important life domain with positive effects on physical, psychological, and social well-being. Therefore, health actors are pivotal in starting the professional reintegration process as soon as possible and should discuss this item from the early stage onward. Support services can be consulted in mutual interaction as required. A case manager, acting as a central intermediator within this multidisciplinary approach, may promote effective communication and coordination between the patients and their surrounding actors. CONCLUSION: The professional reintegration process should start as soon as possible within the management of medically unexplained physical symptoms. As such, the care sector, the evaluation sector, and the professional integration sector should collaborate and effectively communicate with each other.

Reciprocal associations between daily need-based experiences, energy, and sleep in chronic fatigue syndrome.

OBJECTIVE: Previous findings indicate that patients with chronic fatigue syndrome (CFS) report significant day-to-day fluctuations in subjective energy and sleep. Herein, we examined whether daily variation in the satisfaction and frustration of the basic psychological needs for autonomy, competence, and relatedness would contribute to daily variation in subjective energy and quality and quantity of sleep. In addition, we examined whether daily variation in sleep would contribute to daily need-based experiences through (i.e., mediated by) daily fluctuations in subjective energy. METHOD: CFS patients (N = 120; 92% female; Mage = 42.10 years, SD = 10.46) completed a diary for 14 days which assessed their need-based experiences and subjective energy every evening and sleep every morning. RESULTS: Results indicated that subjective energy, sleep, and need experiences fluctuated significantly from day to day. Daily need satisfaction related to less daily fatigue and more daily vitality, while the opposite pattern was observed for daily need frustration. Daily need frustration was also uniquely related to poorer daily sleep quality. Lastly, better daily sleep quality was also uniquely related to more daily need satisfaction and less daily need frustration via (i.e., mediated by) daily variation in subjective energy. These reciprocal within-day associations remained significant after controlling for the previous day's level of each outcome, with the exception of the relation between need frustration and sleep quality. CONCLUSION: The present findings underscore the reciprocal day-to-day association between need-based experiences and subjective energy in CFS. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Near-Infrared Spectroscopy Screening to Allow Detection of Pathogenic Mitochondrial DNA Variants in Individuals with Unexplained Abnormal Fatigue: A Preliminary Study.

Unexplained abnormal fatigue is characterized by chronic fatigue persisting for at least six months and not sufficiently explained by any recognized medical condition. In this pilot study, twelve individuals with abnormal fatigue remaining unexplained after thorough screening were investigated using a near-infrared (NIR) spectroscopy handgrip test. Four of them were found to have an abnormal oxygen extraction pattern similar to participants with documented mitochondrial myopathy. In three of the four individuals, diverse mitochondrial abnormalities were documented by spectrophotometric, immunocytological, fluorescent, and morphological analyses performed in skeletal muscle and in cultured skin fibroblasts. Three of the four participants with decreased muscular oxygen extraction were each shown to harbor a different homoplasmic pathogenic mitochondrial DNA point mutation (m.961T > C, m.1555A > G, m.14484T > C). In the fourth participant, the presence of multiple large mitochondrial DNA deletions was suspected in muscle tissue. In contrast, none of the eight abnormally fatigued participants with normal NIR spectroscopy results harbored either a pathogenic mitochondrial DNA point mutation or large deletions ( P < 0.001). This pilot study shows that NIR spectroscopy may serve as a noninvasive screening tool to delineate a subgroup (of participants) with mitochondrial dysfunction among the large group of individuals with unexplained abnormal fatigue.

Intraorganizational Communication and Job Satisfaction Among Flemish Hospital Nurses: An Exploratory Multicenter Study.

Intraorganizational communication affects job satisfaction and turnover. The goal of this study was to explore relationships between communication and job satisfaction, intention to leave, and burnout among Flemish hospital nurses. A multicenter questionnaire study was conducted in three hospitals using the Communication Satisfaction Questionnaire, the Turnover Intention subscale of the Questionnaire on the Experience and Evaluation of Work, and the Maslach Burnout Inventory. A visual analog scale measured job satisfaction. The mean job satisfaction score was 7.49/10 (±1.43). Almost 7% of nurse participants (93/1,355) reported a high intent to leave, and 2.9% of the respondents (41/1,454) had a score indicative of burnout. All dimensions of communication were associated with job satisfaction. A low score on any dimension of communication satisfaction, except "Relationship With Employees," was associated with higher intent to leave and burnout. Study findings support the need for management interventions to enhance efficient communication and ensure high-quality care and patient safety.

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.

Effects of continuous positive airway pressure on fatigue in two patients with obstructive sleep apnea presenting with chronic fatigue: case report and lessons learned from a failed trial.

INTRODUCTION: Patients referred to tertiary care for multidisciplinary investigation of unexplained chronic fatigue are not seldom diagnosed with obstructive sleep apnoea (OSA). As standard treatment for OSA, continuous positive airway pressure (CPAP) has been shown to decrease daytime sleepiness in OSA patients. However, the effect on fatigue as major complaint in chronic fatigue patients without excessive daytime sleepiness, is not fully understood nor explored. CASE REPORT: A prospective cross-over trial using effective and sham CPAP treatment periods in patients with unexplained chronic fatigue and OSA was interrupted because of poor recruitment and retainment due to complex design issues. We report the effect of CPAP after one month and one to two years follow-up on fatigue as primary outcome and on daytime sleepiness, global sleep quality and global mental and physical health as secondary outcomes in two patients completing the trial. In both patients, comparison of sequential effective and sham CPAP treatments failed to demonstrate consistent short-term effects in outcome measures, in spite of significant differences in apnoea-hypopnea index. However, substantial improvements of fatigue scores were observed at long-term follow-up in both individuals. CONCLUSION: This is the first report of both short- and long-term effects of CPAP treatment on fatigue in patients with OSA and disabling chronic fatigue as primary complaint. A feasible prospective trial remains warranted in order to answer the question of CPAP responsiveness of fatigue in this patient population.

Comparison of subjective sleep and fatigue in breast- and bottle-feeding mothers.

OBJECTIVES: Artificial milk supplementation remains a popular practice in spite of the well documented and indisputable advantages of breast feeding for both mother and child. However, the association between maternal sleep, fatigue and feeding method is understudied and remains unclear. The aim of this study is to investigate whether perceived sleep and fatigue differ between breast- and bottle feeding post partum women. In addition, the relationship between subjective sleep characteristics and fatigue is examined. METHODS: Post partum women (four to 16 weeks) filled out a socio-demographic questionnaire, the Pittsburgh Sleep Quality Index (PSQI) and the Checklist Individual Strength (CIS). FINDINGS: Sixty-one within the past week exclusively breast- and 44 exclusively bottle-feeding mothers were included. The first group showed better subjective sleep quality, but lower habitual sleep efficiency as measured by the PSQI. Global PSQI, as well as subjective fatigue and global CIS, did not differ between the two groups. Significant positive correlations were found between global CIS and the number of night feeds and global PSQI. However, only global PSQI significantly predicted global CIS in relation to the number of night feeds. CONCLUSIONS: Within a general pattern of deteriorated sleep quality, breast-feeding women showed better subjective sleep quality, but lower habitual sleep efficiency, between four and fourteen weeks after childbirth. However, the PSQI component scores compensated for each other, resulting in absence of any difference in global PSQI sleep quality between the two groups. Global PSQI significantly predicted global CIS, resulting in an absence of any difference in post partum fatigue according to feeding method. IMPLICATIONS FOR PRACTICE: Midwives and nurses should, together with the parents, continue to focus on exploring ways to improve maternal sleep quality and to reduce postnatal fatigue.

Exploring the potential role of the advanced nurse practitioner within a care path for patients with chronic fatigue syndrome.

AIMS: To explore the experiences and expectations of patients with chronic fatigue syndrome and general practitioners to develop the potential role of an advanced nurse practitioner at the diagnostic care path of abnormal fatigue developed for regional transmural implementation in the Belgian provinces of East and West Flanders. BACKGROUND: Patients with chronic fatigue syndrome experience an incapacitating chronic fatigue that is present for at least 6 months. Since many uncertainties exist about the causes and progression of the disease, patients have to cope with disbelief and scepticism. Access to health care may be hampered, which could lead to inappropriate treatments and guidance. DESIGN: Qualitative design. METHODS: Individual semi-structured interviews were conducted with patients with chronic fatigue syndrome and general practitioners in Belgium. Data were collected over 9 months in 2014-2015. All interviews were audio recorded and transcribed for qualitative analysis using open explorative thematic coding. RESULTS: Fifteen patients and 15 general practitioners were interviewed. Three themes were identified: mixed feelings with the diagnosis, lack of one central intermediator and insufficient coordination. Participants stressed the need for education, knowledge and an intermediator to provide relevant information at the right time and to build up a trust relationship. CONCLUSION: This qualitative exploration underscores some clear deficiencies in the guidance of patients suffering from chronic fatigue syndrome and abnormal fatigue. An advanced nurse practitioner as a central intermediator in the transmural care of these patients could promote interdisciplinary/multidisciplinary collaboration and effective communication, provide education and ensure a structured and coordinated approach.

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.

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.

Sleep in the chronic fatigue syndrome.

Chronic fatigue syndrome (CFS) is a disabling condition characterized by severe fatigue lasting for more than six months and the presence of at least four out of eight minor criteria. Sleep disturbance presenting as unrefreshing or nonrestorative sleep is one of these criteria and is very common in CFS patients. Biologically disturbed sleep is a known cause of fatigue and could play a role in the pathogenesis of CFS. However, the nature of presumed sleep impairment in CFS remains unclear. Whilst complaints of NRS persist over time, there is no demonstrable neurophysiological correlate to substantiate a basic deficit in sleep function in CFS. Polysomnographic findings have not shown to be significantly different between subjects with CFS and normal controls. Discrepancies between subjectively poor and objectively normal sleep suggest a role for psychosocial factors negatively affecting perception of sleep quality. Primary sleep disorders are often detected in patients who otherwise qualify for a CFS diagnosis. These disorders could contribute to the presence of daytime dysfunctioning. There is currently insufficient evidence to indicate that treatment of primary sleep disorders sufficiently improves the fatigue associated with CFS. Therefore, primary sleep disorders may be a comorbid rather than an exclusionary condition with respect to CFS.

Behavioural hyperventilation as a novel clinical condition associated with central sleep apnoea: a report of three cases.

Central sleep apnoea (CSA) is a disorder characterised by repetitive episodes of decreased ventilation due to complete or partial reduction in the central neural outflow to the respiratory muscles. Hyperventilation plays a prime role in the pathogenesis of CSA. Chronic heart failure and dwelling at high altitude are classical conditions in which CSA is induced by hyperventilation. Hyperventilation syndrome (HVS) is a prevalent behavioural condition in which minute ventilation exceeds metabolic demands, resulting in haemodynamic and chemical changes that produce characteristic dysphoric symptoms. HVS is frequently caused by anxiety disorders and panic attacks. Until now, medical literature has focussed primarily on daytime symptoms of behavioural hyperventilation. It is currently unknown how this condition may affect sleep. Three cases are reported in which behavioural hyperventilation was associated with occurrence of significant central sleep apnoea, which was not present during normal tidal breathing in steady sleep. Therefore, behavioural hyperventilation should be added to the list of known clinical conditions associated with CSA.