Journal of sleep research
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Journal of sleep research · Jun 2007
Trait interindividual differences in the sleep physiology of healthy young adults.
Despite decades of sleep research by means of polysomnography (PSG), systematic interindividual differences in PSG-assessed sleep parameters have been scarcely investigated. The present study is the first to quantify interindividual variability in standard PSG-assessed variables of sleep structure in terms of stability and robustness as well as magnitude. Twenty-one carefully screened healthy young adults were studied continuously in a strictly controlled laboratory environment, where their PSGs were recorded for eight nights interspersed with three separate 36 h sleep deprivation periods. ⋯ Notably, for non-REM delta power--a putative marker of sleep homeostasis--the interindividual differences were from 9.9 to 12.8 times greater than the group-average increase following sleep deprivation relative to baseline. Physiologic sleep variables did not vary among subjects in a completely independent manner--61.1% of their combined variance clustered in three trait dimensions, which appeared to represent sleep duration, sleep intensity, and sleep discontinuity. Any independent functional significance of these sleep physiologic phenotypes remains to be determined.
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Journal of sleep research · Mar 2007
Multicenter StudyMeasurement properties and hierarchical item structure of the Epworth Sleepiness Scale in Parkinson's disease.
The aim of this work was to evaluate the measurement properties and hierarchical item structure of the Epworth Sleepiness Scale (ESS) in patients with Parkinson's disease (PD). Data were taken from a cross-sectional study regarding fatigue and sleep-related aspects of PD. One hundred and eighteen consecutive patients with neurologist-diagnosed PD without significant co-morbidities (54% men; mean age, 64 years; mean PD duration, 8.4 years) from four Swedish neurological outpatient clinics participated. ⋯ Gaps in the levels of sleep propensity covered by ESS items and their response options were identified at the higher and lower ends of the underlying sleepiness continuum. This study provides an evidence base for using the ESS in PD by demonstrating good psychometric properties and a stable hierarchical item structure. However, addition of new items and use of Rasch scoring has potential to further enhance the clinical usefulness of the ESS.
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Journal of sleep research · Mar 2007
Sleep problems and daytime somnolence in a German population-based sample of snoring school-aged children.
Habitual snoring is associated with daytime symptoms like tiredness and behavioral problems. Its association with sleep problems is unclear. We aimed to assess associations between habitual snoring and sleep problems in primary school children. ⋯ Ex-habitual snorers were at increased risk for sleep-wake transition disorders (4.4, 1.4-14.2). Habitual snoring was associated with several sleep problems in our study. Long-term habitual snorers were more likely to have sleep problems than children who had stopped snoring spontaneously.
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Journal of sleep research · Mar 2007
Prevalence and correlates of clinical insomnia co-occurring with chronic back pain.
Given the suggestion of a reciprocal relationship between sleep and pain and the recognition of sleep as an important parameter in determining quality of life, there is increasing research interest in sleep disturbance linked to chronic pain. The present study aimed to provide an estimate of the prevalence of 'clinical insomnia' in patients attending a specialist pain clinic and identify factors associated with it. Seventy chronic back pain patients and 70 gender- and age-matched pain-free controls completed a set of questionnaires measuring sleep (Insomnia Severity Index; ISI), pain (Short-Form McGill Pain Questionnaire) and a selection of general and specific psychological variables (Hospital Anxiety and Depression Scale, Short Health Anxiety Inventory). ⋯ Affective pain ratings and health anxiety were the best predictors of insomnia severity in this sample, accounting for 30% of the total variance, even when present pain intensity was controlled for. Affective pain remained as a significant predictor of insomnia severity when both the effect of pain intensity and the effects of anxiety and depression were controlled for. Future research should consider investigating the role of pain appraisal and health anxiety in the development and manifestation of insomnia concomitant to chronic pain.
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Journal of sleep research · Dec 2006
N-terminal pro-brain natriuretic peptide for detection of cardiovascular stress in patients with obstructive sleep apnea syndrome.
Patients with obstructive sleep apnea syndrome (OSAS) have an elevated incidence of cardiovascular events that may be related to an increased ventricular load and hypoxemia caused by apneas and hypopneas. N-terminal pro-brain natriuretic peptide (NTproBNP) appears to be an excellent marker of myocardial stretch and could serve as an indicator of subclinical cardiac stress, thereby identifying a patient population at risk for cardiac effects from OSAS. Adult patients presenting with suspected OSAS and scheduled for nocturnal polysomnography were recruited. ⋯ Three patients had an abnormal NTproBNP value prior to sleep, but their levels decreased with sleep. No correlations were detected between the evening baseline or postsleep NTproBNP levels and OSAS. Monitoring pre- and postsleep NTproBNP levels revealed no association with the occurrence or degree of OSAS, making it unlikely that NTproBNP could serve as a marker of cardiac stress in OSAS patients with stable BP and without overt heart failure.