Microarousals during sleep are associated with increased levels of lipids, cortisol, and blood pressure

Bi-directional associations between psychological arousal, cortisol, and sleep

The aim was to elucidate the possible bi-directional relation between daytime psychological arousal, cortisol, and self-reported sleep in a group of healthy employees in active employment. Logbook ratings of sleep (Karolinska Sleep Questionnaire), stress, and energy, as well as positive and negative experiences in work and private life, were collected together with salivary cortisol over 3 days (n = 265). Higher bedtime ratings of stress and problems during the day were associated with morning ratings of poor sleep. Poorer morning ratings of sleep were associated with higher ratings of stress and problems during the day. The results underpin the possibility that arousal and poor sleep might create a self-reinforcing vicious circle that negatively affects a person's well-being.

Sleep duration and hypercholesterolaemia: Results from the National Health Interview Survey 2008

BACKGROUND

Previous studies have shown an inconsistent association between sleep duration and hypercholesterolaemia. This study examined the association between sleep duration and hypercholesterolaemia in a nationally representative sample of US adults.

METHODS

A cross-sectional study of 16,652 participants in the 2008 National Health Interview Survey (aged ⩾18years, 52.5% women) was conducted. Sleep duration was categorized as ⩽5, 6, 7, 8, or ⩾9h. Hypercholesterolaemia (n=5578) was assessed by questionnaire.

RESULTS

A significant gender difference was found in the association between sleep duration and hypercholesterolaemia (P interaction=0.003). Among women, sleep duration ⩽5h was positively associated with hypercholesterolaemia after adjusting for potential confounders and mediators including physical activity, psychological distress, body mass index, diabetes mellitus, and hypertension. Compared with a sleep duration of 7h (referent), the multivariate odds ratio (OR) of hypercholesterolaemia was 1.27 (95% confidence interval [CI] 1.04-1.54) for sleep duration ⩽5h. In contrast, among men, sleep duration ⩾8h was inversely associated with hypercholesterolaemia. Compared with a sleep duration of 7h (referent), the multivariate OR of hypercholesterolaemia was 0.80 (95% CI 0.69-0.94) and 0.78 (95% CI 0.60-1.00) for sleep durations of 8 and ⩾9h, respectively. In subgroup analyses, the positive association between sleep duration ⩽5h and hypercholesterolaemia in women, and the inverse association between sleep duration ⩾8h and hypercholesterolaemia in men, were more pronounced among those aged <60 years and race/ethnic groups other than non-Hispanic Whites.

CONCLUSION

Sleep duration ⩽5h was positively associated with hypercholesterolaemia in women, whereas sleep duration ⩾8h was inversely associated with hypercholesterolaemia in men.

Exposure to road traffic and railway noise and associations with blood pressure and self-reported hypertension: a cohort study

BACKGROUND

Epidemiological studies suggest that long-term exposure to transport noise increases the risk for cardiovascular disorders. The effect of transport noise on blood pressure and hypertension is uncertain.

METHODS

In 1993-1997, 57,053 participants aged 50-64 year were enrolled in a population-based cohort study. At enrollment, systolic and diastolic blood pressure was measured. Incident hypertension during a mean follow-up of 5.3 years was assessed by questionnaire. Residential long-term road traffic noise (Lden) was estimated for 1- and 5-year periods preceding enrollment and preceding diagnosis of hypertension. Residential exposure to railway noise was estimated at enrollment. We conducted a cross-sectional analysis of associations between road traffic and railway noise and blood pressure at enrollment with linear regression, adjusting for long-term air pollution, meteorology and potential lifestyle confounders (N = 44,083). Incident self-reported hypertension was analyzed with Cox regression, adjusting for long-term air pollution and potential lifestyle confounders.

RESULTS

We found a 0.26 mm Hg higher systolic blood pressure (95% confidence intervals (CI): -0.11; 0.63) per 10 dB(A) increase in 1-year mean road traffic noise levels, with stronger associations in men (0.59 mm Hg (CI: 0.13; 1.05) per 10 dB(A)) and older participants (0.65 mm Hg (0.08; 1.22) per 10 dB(A)). Road traffic noise was not associated with diastolic blood pressure or hypertension. Exposure to railway noise above 60 dB was associated with 8% higher risk for hypertension (95% CI: -2%; 19%, P = 0.11).

CONCLUSIONS

While exposure to road traffic noise was associated with systolic blood pressure in subgroups, we were not able to identify associations with hypertension.

Restless legs syndrome and hypertension in middle-aged women

Limited research suggests a relationship between restless legs syndrome and hypertension. We, therefore, assessed the relationship between restless legs syndrome and hypertension among middle-aged women. This is a cross-sectional study including 65 544 women (aged 41-58 years) participating in Nurses' Health Study II. The participants with diabetes mellitus and arthritis were excluded, because these conditions can mimic restless legs syndrome. Restless legs syndrome was assessed by a self-administered questionnaire based on the International Restless Legs Study Group criteria. Information on diagnosis of hypertension and blood pressure values were collected via questionnaires. Multivariable logistic regression models were used to analyze the relation between restless legs syndrome and hypertension, with adjustment for age, race, body mass index, physical activity, menopausal status, smoking, use of analgesics, and intake of alcohol, caffeine, folate, and iron. Compared with women with no restless legs symptoms, the multiple adjusted odds of having hypertension were 1.20 times (95% CI: 1.10-1.30; P<0.0001) higher among women with restless legs symptoms. The adjusted odds ratios for women who reported restless legs symptoms 5 to 14 times per month and ≥15 times per month were 1.06 (95% CI: 0.94-1.18) and 1.41 (95% CI: 1.24-1.61) respectively, compared with those without the symptoms (P trend: <0.0001). Greater frequency of restless legs symptoms was associated with higher concurrent systolic and diastolic blood pressures (P trend: <0.0001 for both). Women with restless legs syndrome have a higher prevalence of hypertension, and this prevalence increases with more frequent restless legs symptoms.

Sleep loss due to worry and future risk of cardiovascular disease and all-cause mortality: the Scottish Health Survey

BACKGROUND

The association between specific sleeping disorders and risk of cardiovascular disease (CVD) is unclear. We assessed the association between sleep loss due to worry and future risk of CVD and death in a representative sample of community dwelling adults.

METHODS

A cohort of 11,905 adults (aged 53.4 ± 12.2 years, 42.2% male) without known history of CVD were drawn from the Scottish Health Surveys. Self-reported sleep disturbance was measured using a single item from the General Health Questionnaire. Incident CVD events (comprising CVD death, nonfatal myocardial infarction, coronary surgical procedures, stroke, and heart failure) over 8-year follow up were ascertained by a linkage to national registers; a total of 1448 CVD events and 1249 all-cause deaths were recorded.

RESULTS

15.6% of the sample reported 'rather more' or 'much more than usual' sleep loss due to worry over the prior 4 weeks. Sleep loss due to worry (much more than usual) was associated with elevated risk of CVD [age- and sex-adjusted hazard ratio (HR) 1.74, 95% confidence interval (CI) 1.35-2.25] and all-cause mortality (age- and sex-adjusted HR 2.02, 95% CI 1.57-2.61). Adjustment for a range of psychosocial, behavioural, and clinical risk factors partly attenuated the association, and in particular health behaviours (smoking, alcohol, physical inactivity) accounted for approximately 40% of the sleep-CVD relation.

CONCLUSION

Sleep loss due to worry was associated with a greater risk of CVD and all-cause mortality, but the association can be largely explained by intermediate risk factors such as health behaviours.

Repeated exposure to severely limited sleep results in distinctive and persistent physiological imbalances in rats

Chronic sleep disruption in laboratory rats leads to increased energy expenditure, connective tissue abnormalities, and increased weights of major organs relative to body weight. Here we report on expanded findings and the extent to which abnormalities become long-lasting, potentially permanent changes to health status after apparent recuperation from chronic sleep disruption. Rats were exposed 6 times to long periods of disrupted sleep or control conditions during 10 weeks to produce adaptations and then were permitted nearly 4 months of undisturbed sleep. Measurements were made in tissues from these groups and in preserved tissue from the experimental and control groups of an antecedent study that lacked a lengthy recuperation period. Cycles of sleep restriction resulted in energy deficiency marked by a progressive course of hyperphagia and major (15%) weight loss. Analyses of tissue composition in chronically sleep-restricted rats indicated that protein and lipid amounts in internal organs were largely spared, while adipose tissue depots appeared depleted. This suggests high metabolic demands may have preserved the size of the vital organs relative to expectations of severe energy deficiency alone. Low plasma corticosterone and leptin concentrations appear to reflect low substrate availability and diminished adiposity. After nearly 4 months of recuperation, sleep-restricted rats were consuming 20% more food and 35% more water than did comparison control rats, despite normalized weight, normalized adipocytes, and elevated plasma leptin concentrations. Plasma cholesterol levels in recuperated sleep-restricted rats were diminished relative to those of controls. The chronically increased intake of nutriments and water, along with altered negative feedback regulation and substrate use, indicate that internal processes are modified long after a severe period of prolonged and insufficient sleep has ended.

Nutritional effects on sleep

The purpose of this study was to examine the nutritional effects on sleep using actigraphy measures. A repeated-measures, counterbalanced, crossover study design was used to administer treatment diets to 44 adult participants. Participants served as their own control and consumed high-protein, high-fat, high-carbohydrate, and control diets. The study participants wore Motionlogger Actigraph sleep watches while consuming weighed food intakes for 4 days over four different treatment periods. Demographic and laboratory data were also analyzed. Actigraph results showed that the wake episodes and sleep latencies were significantly different when comparing the macronutrient intakes of the participants. Post hoc test results showed that high-protein diets were associated with significantly fewer (p = .03) wake episodes and high-carbohydrate diets were associated with significantly shorter (p < .01) sleep latencies than control diets. Thus, consumption of specific macronutrient intakes may have a significant influence on sleep.

Biomarkers in burnout: a systematic review

BACKGROUND

Burnout is a stress state characterized by symptoms of mental exhaustion and physical fatigue, detachment from work, and feelings of diminished competence. Several biomarkers have been tested for association with burnout, but the results are conflicting.

AIM

The objective of this review was to identify potential biomarkers for burnout.

METHODS

We carried out a systematic review of studies comparing biomarkers in individuals with burnout and healthy controls, or individuals with low scores and those with high scores on burnout questionnaires. Literature searches in MEDLINE and EMBASE were performed. We describe biomarkers on which at least three studies were available. Where appropriate, a meta-analysis was carried out.

RESULTS

We identified 31 studies on 38 biomarkers involved in the hypothalamus-pituitary-adrenal axis, autonomic nervous system, immune system, metabolic processes, antioxidant defense, hormones, and sleep. At least 3 studies were available for cortisol in saliva and blood, blood pressure, heart rate, cholesterol, dehydroepiandrosterone sulfate, (numbers or activity of) natural killer cells, C-reactive protein, and prolactin. The comparability of studies was limited, due to differences in the methods used to characterize patients and controls, to assess biomarkers, and to control for confounders. Furthermore, burnout was operationalized in different ways. Meta-analyses showed no differences for cortisol awakening response and cortisol awakening response after administration of dexamethasone, cortisol in blood, and blood pressure.

CONCLUSIONS

No potential biomarkers for burnout were found, largely due to the incomparability of studies. We emphasize the need for a dimensional and longitudinal approach in future research to account for the heterogeneity of burnout.

The relation between Lp-PLA2 levels with periodic limb movements

OBJECTIVE

Lipoprotein-associated phospholipase A2 (Lp-PLA2), a novel marker of vulnerable plaque to prone rupture, is a predictor of both cardiovascular event and cerebrovascular event, and highly sensitive-C-reactive protein (hs-CRP) is an acute-phase response protein implicated in a broad range of cardiovascular diseases. We aimed to examine the association between periodic limb movements in sleep (PLMs) with circulating Lp-PLA2 and hs-CRP levels in patients with PLMs.

METHODS

Seventy patients with newly diagnosed PLM with polysomnography were enrolled this study. Patients were divided into two groups according to PLM index (normal PLM index, <15; elevated PLM index, ≥15). Lp-PLA2 and hs-CRP concentrations were measured in serum samples by turbidimetric and nephelometric methods, respectively. The concentrations of these parameters were compared between two groups and correlation analysis was performed between PLMs and Lp-PLA2 and hs-CRP levels.

RESULTS

Lp-PLA2 levels and hs-CRP were significantly increased in elevated PLM index group compared with the control group (206.8 ± 78.1 vs 157.8 ± 56.7, p = 0.003, and 4.2 ± 3.5 vs 2.4 ± 2.1, p = 0.02, respectively). PLM index was positively correlated with Lp-PLA2 levels (r = 0.40, p = 0.001) and hs-CRP (r = 0.24, p = 0.05). In the linear regression model, Lp-PLA2 was an independent predictor of PLM index (R(2) = 0.36, p = 0.005).

CONCLUSION

This study demonstrated an independent linear relation between PLM index and Lp-PLA2. In addition, it was seen increased Lp-PLA2 and hs-CRP levels in patients with elevated PLM index. Based on these results, we can suggest that risk of vascular events may be increased in patients with PLMs and with increased PLM index.

Energy expenditure is affected by rate of accumulation of sleep deficit in rats

STUDY OBJECTIVES

Short sleep is a putative risk factor for obesity. However, prolonged total sleep deprivation (TSD) leads to negative energy balance and weight loss in rodents, whereas sleep-restricted humans tend to gain weight. We hypothesized that energy expenditure (VO2) is influenced by the rate of accumulation of sleep deficit in rats.

DESIGN AND INTERVENTION

Six Sprague-Dawley rats underwent chronic sleep-restriction (CSR, 6-h sleep opportunity at ZT0-6 for 10 days) and stimulus-control protocols (CON, 12-h sleep opportunity for 10 days, matched number of stimuli) in a balanced cross-over design. Four additional rats underwent TSD (4 days). Sleep was manipulated using a motor-driven walking wheel.

MEASUREMENTS AND RESULTS

Electroencephalography, electromyography, and body temperature were measured by telemetry, and VO2, by respirometry. Total sleep deficits of 55.1 +/- 6.4 hours, 31.8 +/- 6.8 hours, and 38.2 +/- 2.3 hours accumulated over the CSR, CON, and TSD protocols, respectively. Responses to TSD confirmed previous reports of elevated VO2 and body temperature. These responses were attenuated in CSR, despite a greater cumulative sleep deficit. Rate of rise of VO2 was strongly correlated with rate of accumulation of sleep deficit, above a threshold deficit of 3.6 h x day(-1).

CONCLUSION

The change in VO2 is affected by rate of accumulation of sleep deficit and not the total sleep loss accrued. Negative energy balance, observed during TSD, is strongly attenuated when brief daily sleep opportunities are available to rats (CSR), despite greater accumulated sleep deficit.

Fibromyalgia syndrome is associated with hypocortisolism

BACKGROUND

Fibromyalgia syndrome (FMS) is a disease of unknown pathogenesis characterized by chronic musculoskeletal pain. FMS has been also associated with altered endocrinological responses, but findings are inconsistent.

PURPOSE

The aim of the present study was to investigate free salivary cortisol levels in FMS patients compared with healthy controls with a particular focus on the cortisol awakening response (CAR). The saliva samples were collected in a controlled hospital-hotel setting, in which the participants' compliance was high and a number of potential confounders were analyzed.

METHOD

Twenty-nine chronic female FMS patients and 29 age-matched healthy female controls were recruited. Salivary cortisol samples were investigated eight times: in the afternoon when participants arrived at the hospital, after stress provocation (to be reported separately), in the evening, before they went to sleep, upon awakening, 30 and 60 min later, and during the afternoon of the second day. Questionnaires measuring pain levels, sleeping problems, perceived stress, and personality were administered to the participants. Other psychophysiological measurements were used to assess sleep quality and heart rate.

RESULTS

Patients with FMS had significantly lower cortisol levels during the day, most pronounced in the morning (CAR). The potential confounders analyzed did not influence the results. As expected, FMS patients reported more pain, stress, sleeping problems, anxiety, and depression.

CONCLUSION

The results lend support to the hypothesis of a dysfunction in the hypothalamus-pituitary-adrenal axis in FMS patients, with generally lower cortisol values, most pronounced upon awakening (CAR).

Effects of obstructive sleep apnea on serum brain-derived neurotrophic factor protein, cortisol, and lipid levels

OBJECTIVES

Obstructive sleep apnea (OSA) is a sleep-disordered breathing leading to vascular endothelial cells dysfunction, cognitive impairment, and abnormal lipid metabolism. serum brain-derived neurotrophic factor (BDNF) protein, cortisol, and lipid levels in OSA were investigated.

MATERIALS AND METHODS

All middle-aged subjects including healthy individuals without signs and symptoms of apnea-hypopnea and ear nose throat (ENT) outpatients were randomly recruited and screened by overnight polysomnogram (PSG). Apnea-hypopnea index (AHI) was used as a criteria to determine subjects to enroll in this program. According to AHI, they were separated into control and OSA groups. A group of 39 OSA patients (AHI ≥ 10 events/h) and 24 control subjects (AHI < 5 events/h) were selected. Serum BDNF protein was analyzed by enzyme-linked immunosorbent assay (ELISA) from venous blood collection at 8:00 a.m. following PSG. Serum cortisol was assayed by enzyme-chemiluminescense immuno assay (ECLIA). Serum lipid profile levels were determined by enzymatic colorimetric and homogeneous method.

RESULTS

Characteristics of OSA patients and control groups including gender, age, AHI, body weight, height, and BMI showed significant differences. Serum BDNF protein, cortisol, triglyceride, and total cholesterol levels in OSA and control groups were not significantly different. High density lipoprotein-cholesterol (HDL-c) in OSA was significantly lower than that of control (p = 0.008) while low density lipoprotein-cholesterol (LDL-c) was significantly higher than that of control (p = 0.04).

CONCLUSIONS

OSA had no significant effect on serum BDNF, cortisol, triglyceride, or total cholesterol levels while LDL-c and HDL-c levels in OSA patients compared to control were significantly different at p = 0.04, and p = 0.008, respectively.

The modulatory effects of rostral ventromedial medulla on air-puff evoked microarousals in rats

This study tested whether the duration of microarousals from sleep evoked by innocuous air-puff is affected by intra-RVM administration of neurotensin and bicuculline, pharmacological manipulations that affect on and off cell activity. Air-puff evoked microarousal duration was unaffected by 0.05ng neurotensin, but decreased by 502ng neurotensin, and 5 and 50ng bicuculline. These results suggest a putative role for off cells in protecting sleep from interruption by non-noxious stimuli.

The effect of short sleep duration on coronary heart disease risk is greatest among those with sleep disturbance: a prospective study from the Whitehall II cohort

STUDY OBJECTIVES

Short sleep duration is associated with increased CHD (coronary heart disease) mortality and morbidity, although some evidence suggests that sleep disturbance is just as important. We investigated whether a combination of short sleep duration and sleep disturbance is associated with a higher risk of CHD than their additive effects.

SETTING

The Whitehall II study.

PATIENTS OR PARTICIPANTS

The Whitehall II study recruited 10,308 participants from 20 civil service departments in London, England. Participants were between the ages of 35 and 55 years at baseline (1985-1988) and were followed up for an average of 15 years.

INTERVENTIONS

N/A.

MEASUREMENTS

Sleep hours and sleep disturbance (from the General Heath Questionnaire-30) were obtained from the baseline survey. CHD events included fatal CHD deaths or incident nonfatal myocardial infarction or angina (ICD-9 codes 410-414 or ICD-10 120-25).

RESULTS

Short sleep duration and sleep disturbance were both associated with increased hazards for CHD in women as well as in men, although, after we adjusted for confounders, only those reporting sleep disturbance had a raised risk. There was some evidence for an interaction between sleep duration and sleep disturbance. Participants with short sleep duration and restless disturbed nights had the highest hazard ratios (HR) of CHD (relative risk:1.55, 95% confidence interval:1.33-1.81). Among participants who did not report any sleep disturbance, there was little evidence that short sleep hours increased CHD risk.

CONCLUSION

The effect of short sleep (< or = 6 hours) on increasing CHD risk is greatest among those who reported some sleep disturbance. However, among participants who did not report any sleep disturbance, there was little evidence that short sleep hours increased CHD risk.

Sleep, aging, and lifespan in Drosophila

Background

Epidemiological studies in humans suggest that a decrease in daily sleep duration is associated with reduced lifespan, but this issue remains controversial. Other studies in humans also show that both sleep quantity and sleep quality decrease with age. Drosophila melanogaster is a useful model to study aging and sleep, and inheriting mutations affecting the potassium current Shaker results in flies that sleep less and have a shorter lifespan. However, whether the link between short sleep and reduced longevity exists also in wild-type flies is unknown. Similarly, it is unknown whether such a link depends on sleep amount per se, rather than on other factors such as waking activity. Also, sleep quality has been shown to decrease in old flies, but it remains unclear whether aging-related sleep fragmentation is a generalized phenomenon.

Results

We compared 3 short sleeping mutant lines (Hk¹, Hk^Y and Hk²) carrying a mutation in Hyperkinetic, which codes for the beta subunit of the Shaker channel, to wild-type siblings throughout their entire lifespan (all flies kept at 20°C). Hk¹ and Hk^Y mutants were short sleeping relative to wild-type controls from day 3 after eclosure, and Hk² flies became short sleepers about two weeks later. All 3 Hk mutant lines had reduced lifespan relative to wild-type flies. Total sleep time showed a trend to increase in all lines with age, but the effect was most pronounced in Hk¹ and Hk^Y flies. In both mutant and wild-type lines sleep quality did not decay with age, but the strong preference for sleep at night declined starting in "middle age". Using Cox regression analysis we found that in Hk¹ and Hk^Y mutants and their control lines there was a negative relationship between total sleep amount during the first 2 and 4 weeks of age and hazard (individual risk of death), while no association was found in Hk² flies and their wild-type controls. Hk¹ and Hk^Y mutants and their control lines also showed an association between total daily wake activity over the first 2 and 4 weeks of age and hazard. However, when both sleep duration and wake activity were used in the same regression, the effects of activity were much reduced, while most of the sleep effects remained significant. Finally, Hk¹ flies and wild-type siblings were also tested at 25°C, and results were similar to those at 20°C. Namely, Hk¹ mutants were short sleeping, hyperactive, and short lived relative to controls, and sleep quality in both groups did not decrease with age.

Conclusions

Different Hk mutations affect the sleep phenotype, and do so in an age-dependent manner. In 4 of the 6 lines tested sleep associates significantly with lifespan variation even after any effect of activity is removed, but activity does not associate significantly with lifespan after the effects of sleep are removed. Thus, in addition to environmental factors and genetic background, sleep may also affect longevity. Sleep quality does not necessarily decay as flies age, suggesting that aging-related sleep fragmentation may also depend on many factors, including genetic background and rearing conditions.

Growth hormone/insulin-like growth factor-I axis in obstructive sleep apnea syndrome: an update

Obstructive sleep apnea syndrome (OSAS) is a serious, prevalent condition that has significant mortality and morbidity when untreated. It is strongly associated with obesity and is characterized by changes in the serum levels or secretory patterns of several hormones. In particular, obese patients with OSAS show a peculiar reduction of both spontaneous and stimulated GH secretion coupled with reduced IGF-I concentrations and impaired peripheral sensitivity to GH. These endocrine abnormalities are more marked than those observed in non-apneic obese subjects, and are likely to be due to the effects of hypoxia and sleep fragmentation on hormone secretory pattern. The GH/IGF-I axis activity disruption can be responsible, at least in part, for metabolic alterations, which are common in OSAS and increase the risk of cardiovascular events as well as mortality. Effective assessment and management of OSAS may correct endocrine changes, improve quality of life, and prevent associated morbidity or death.

Neuroendocrine alterations in obese patients with sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a serious, prevalent condition that has significant morbidity and mortality when untreated. It is strongly associated with obesity and is characterized by changes in the serum levels or secretory patterns of several hormones. Obese patients with OSAS show a reduction of both spontaneous and stimulated growth hormone (GH) secretion coupled to reduced insulin-like growth factor-I (IGF-I) concentrations and impaired peripheral sensitivity to GH. Hypoxemia and chronic sleep fragmentation could affect the sleep-entrained prolactin (PRL) rhythm. A disrupted Hypothalamus-Pituitary-Adrenal (HPA) axis activity has been described in OSAS. Some derangement in Thyroid-Stimulating Hormone (TSH) secretion has been demonstrated by some authors, whereas a normal thyroid activity has been described by others. Changes of gonadal axis are common in patients with OSAS, who frequently show a hypogonadotropic hypogonadism. Altogether, hormonal abnormalities may be considered as adaptive changes which indicate how a local upper airway dysfunction induces systemic consequences. The understanding of the complex interactions between hormones and OSAS may allow a multi-disciplinary approach to obese patients with this disturbance and lead to an effective management that improves quality of life and prevents associated morbidity or death.

Elevated diurnal salivary cortisol in nurses is associated with burnout but not with vital exhaustion

Studies on HPA axis regulation in burnout revealed heterogeneous results, possibly due to different psychometric and endocrine measurements, heterogeneous samples or small sample sizes. In the present study, the relationship between salivary cortisol during the day (four time points: 0700 h, 1130 h, 1730 h, and 2000 h) and burnout as well as vital exhaustion was investigated in a large sample of 279 nurses. Burnout was measured using the Maslach Burnout Inventory (MBI), which includes scales for emotional exhaustion, depersonalization, and personal accomplishment. A burnout criterion was assumed to be fulfilled, when any of the MBI scales was above the norm. Subjects with two burnout criterions fulfilled (N=18) were characterized by a higher cortisol release over the day compared to those reporting only one criterion (N=77) or no burnout (N=181) (ANOVA, p=.015). On the other hand, subjects who reported high levels of vital exhaustion did not differ from those who did not report signs of vital exhaustion. These findings provide further evidence for HPA axis dysregulation in burnout.

Review of the relationship of restless legs syndrome and periodic limb movements in sleep to hypertension, heart disease, and stroke

Evidence is reviewed documenting an intimate relationship among restless legs syndrome (RLS) / periodic limb movements in sleep (PLMS) and hypertension and cardiovascular and cerebrovascular disease. Sympathetic overactivity is associated with RLS/PLMS, as manifested by increased pulse rate and blood pressure coincident with PLMS. Causality is far from definitive. Mechanisms are explored as to how RLS/PLMS may lead to high blood pressure, heart disease, and stroke: (a) the sympathetic hyperactivity associated with RLS/PLMS may lead to daytime hypertension that in turn leads to heart disease and stroke; (b) in the absence of daytime hypertension, this sympathetic hyperactivity may predispose to heart disease and stroke either directly or indirectly via atherosclerotic plaque formation and rupture; and (c) comorbidities associated with RLS/PLMS, such as renal failure, diabetes, iron deficiency, and insomnia, may predispose to heart disease and stroke. One theoretical cause for sympathetic hyperactivity is insufficient All diencephalospinal dopaminergic neuron inhibition of sympathetic preganglionic neurons residing in the intermediolateral cell columns of the spinal cord. We cannot exclude the possibility that peripheral vascular, cardiovascular, and cerebrovascular disease may also contribute to RLS/PLMS, and mechanisms for these possibilities are also discussed.

Nonparametric Signal Extraction and Measurement Error in the Analysis of Electroencephalographic Activity During Sleep

We introduce methods for signal and associated variability estimation based on hierarchical nonparametric smoothing with application to the Sleep Heart Health Study (SHHS). SHHS is the largest electroencephalographic (EEG) collection of sleep-related data, which contains, at each visit, two quasi-continuous EEG signals for each subject. The signal features extracted from EEG data are then used in second level analyses to investigate the relation between health, behavioral, or biometric outcomes and sleep. Using subject specific signals estimated with known variability in a second level regression becomes a nonstandard measurement error problem. We propose and implement methods that take into account cross-sectional and longitudinal measurement error. The research presented here forms the basis for EEG signal processing for the SHHS.

Continuous positive airway pressure therapy decreases evening cortisol concentrations in patients with severe obstructive sleep apnea

Patients with obstructive sleep apnea syndrome (OSAS) show recurrent episodes of nightly hypoxic stress. The purpose of this study is the detection of alterations of the hypothalamic-pituitary-adrenal stress axis in OSAS patients before and after continuous positive airway pressure (CPAP) therapy. An activation of the hypothalamic-pituitary-adrenal axis was proposed because of the nightly hypoxic stress in these patients, but previous studies were not conclusive. Here we hypothesize that CPAP therapy decreases salivary cortisol concentrations in patients with severe OSAS. We performed a clinical within-subject study including 50 patients with newly diagnosed OSAS and an apnea-hypopnea index greater than or equal to 40 h(-1). Diurnal profiles of salivary cortisol concentrations were compiled before and after 3 months of treatment with CPAP. Therefore, 6 cortisol samples were collected: before and after lunch, in the evening, the next morning after awakening, and before and after breakfast. Thirty-eight patients returned after 3 months of CPAP therapy for follow-up. According to the reference range for healthy subjects, cortisol values were not pathologically increased. Analysis of variance revealed a significant effect of CPAP therapy on diurnal cortisol profiles (P = .048). Subjects with severe OSAS showed a decrease (3.04 +/- 0.55 nmol L(-1) pre-CPAP vs 2.48 +/- 0.78 nmol L(-1) post-CPAP, P = .038) of evening cortisol levels after CPAP treatment, whereas prelunch levels were increased after CPAP therapy (7.18 +/- 0.83 nmol L(-1) pre-CPAP vs 10.22 +/- 1.10 nmol L(-1) post-CPAP, P = .044). Our results show that CPAP therapy decreases evening cortisol concentrations in patients with severe OSAS. These data suggest that OSAS may increase the cortisol nadir that is reversed after CPAP therapy.

Hypoadiponectinemia is related to sympathetic activation and severity of obstructive sleep apnea

STUDY OBJECTIVES

Hypoadiponectinemia is associated with cardiovascular morbidity and diabetes mellitus. We hypothesize that adiponectin may be downregulated in sleep apnea through various mechanisms, contributing to cardiometabolic risks. This study investigated the relationship between serum adiponectin and sleep disordered breathing and its potential determinants.

DESIGN

Cross-sectional study.

SUBJECTS AND SETTING

Adult men without prevailing medical comorbidity from the sleep clinic in a teaching hospital.

MEASUREMENTS & RESULTS

One hundred thirty-four men underwent polysomnography, with mean age of 43.9 (9.8) years, and median apnea-hypopnea index (AHI) of 17.1 (5.7, 46.6). Overnight urine samples for catecholamines and blood samples for analyses of insulin, glucose and adiponectin levels from fasting subjects were taken. Insulin resistance was estimated by homeostasis model assessment (HOMA-IR). Magnetic resonance imaging was performed to quantify the amount of abdominal visceral fat. Serum adiponectin level, adjusted for age, body mass index, and visceral fat volume, was significantly lower in subjects with severe obstructive sleep apnea (AHI > or =30) compared with those with an AHI of less than 30: 4.0 (3.1, 5.4) versus 5.4 (3.6, 7.9) microg/mL, P = 0.039. After we adjusted for adiposity, adiponectin levels remained negatively correlated with AHI (P = 0.037), arousal index (P = 0.022), HOMA-IR/fasting insulin (P < 0.001), and urinary norepinephrine and normetanephrine (P < 0.008). In a multiple stepwise regression model, the independent determinants of adiponectin after adjustment for adiposity were HOMA-IR (P < 0.001) and urinary norepinephrine and normetanephrine (P = 0.037).

CONCLUSIONS

Adiponectin was suppressed in subjects with severe obstructive sleep apnea, independent of obesity. Adiponectin levels were determined by insulin resistance and sympathetic activation, factors that may be totally or partially attributed to sleep disordered breathing.

Novel biochemical markers of psychosocial stress in women

Background

Prolonged psychosocial stress is a condition assessed through self-reports. Here we aimed to identify biochemical markers for screening and early intervention in women.

Methods

Plasma concentrations of interleukin (IL) 1-α, IL1-β, IL-2, IL-4, IL-6, IL-8, IL-10, interferon-γ (INF-γ), tumor necrosis factor-α (TNF-α), monocyte chemotactic protein-1 (MCP-1), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), thyroid stimulating hormone (TSH), total tri-iodothyronine (TT3), total thyroxine (TT4), prolactin, and testosterone were measured in: 195 women on long-term sick-leave for a stress-related affective disorder, 45 women at risk for professional burnout, and 84 healthy women.

Results

We found significantly increased levels of MCP-1, VEGF and EGF in women exposed to prolonged psychosocial stress. Statistical analysis indicates that they independently associate with a significant risk for being classified as ill.

Conclusions

MCP-1, EGF, and VEGF are potential markers for screening and early intervention in women under prolonged psychosocial stress.

Long sleep duration is associated with serum cholesterol in the elderly: the Rotterdam Study

OBJECTIVE

Epidemiological studies have repeatedly found increased mortality associated with both habitual short and long sleep duration. The mechanisms behind these associations are unclear. We investigated whether objectively measured sleep duration, time in bed, and sleep fragmentation were associated with total cholesterol and high density lipoprotein (HDL) cholesterol in community-dwelling elderly.

METHODS

This cross-sectional study was conducted among 768 participants of the Rotterdam Study, aged 57 to 97 years. Sleep parameters were assessed with actigraphy, a validated method that infers wakefulness and sleep from arm movement. Cholesterol levels in serum were determined in fasting blood samples. All regression analyses were adjusted for age, gender, body mass index, smoking, depressive symptoms, and heart failure.

RESULTS

Sleep duration was positively associated with total cholesterol level: beta = 0.11 (95% confidence interval = 0.03-0.18) mmol/l per hour of sleep. Persons who slept longer, and spent more time in bed, also had a higher total/HDL cholesterol ratio. A less fragmented sleep was also associated with higher total cholesterol. Some of these associations showed significant interactions with age. The association between time in bed and total/HDL ratio was mainly driven by persons aged <65, whereas the relationship between sleep fragmentation and total cholesterol level was most prominent in persons aged >or=70.

CONCLUSIONS

A longer sleep duration was related to higher total cholesterol level and a higher total/HDL cholesterol ratio. Two separate mechanisms, a longer time in bed and sleep fragmentation, seem to explain these associations in different age categories.

Hall M, Strollo PJ, Owens JF, Buysse DJ, Lee L, Reis SE. Blood pressure dipping and sleep disturbance in African-American and Caucasian men and women

BACKGROUND

Elevated night time/daytime blood pressure (BP) ratios are associated with cardiovascular morbidity and mortality. We evaluated the associations between sleep/awake BP ratios and sleep disturbances.

METHODS

Sleep disturbances were assessed by in-home actigraphy and diary measures for nine nights, and polysomnography (PSG) for two nights; ambulatory BP was measured for at least 48 h. Participants were 186 middle-aged African-American and Caucasian men and women who were free from prevalent myocardial infarction, stroke, history of interventional cardiology procedures, diabetes, and diagnosed apnea or other sleep disorders.

RESULTS

Results showed that the greater the sleep/wake ratios of BP, the more fragmented the sleep, the greater the proportion in stage 1 (light) sleep and the smaller the proportion in rapid eye movement (REM) sleep, and the greater the number of arousals from sleep. These results were independent of age, race, gender, Framingham Risk status, cardiovascular medications, body mass index, and apnea/hypopnea index. Indicators of psychosocial stress were not greater among those with higher sleep/wake BP ratios.

CONCLUSIONS

Findings are consistent with the hypothesis that elevated night time/daytime pressure may be a consequence of poor sleep.

Autonomic arousals related to traffic noise during sleep

AIM

To analyze the heart rate (HR) response to traffic noise during sleep and the influence of acoustic parameters, time of night, and momentary sleep stage on these responses.

PARTICIPANTS

Twelve women and 12 men (19-28 years).

MEASUREMENTS AND RESULTS

The participants slept in the laboratory for 4 consecutive nights in each of 3 consecutive weeks and were exposed to aircraft, road, or rail traffic noise with weekly permutations. The 4 nights of each week consisted of a random sequence of a quiet night (32 dBA) and 3 nights during which aircraft, rail traffic, or road traffic noises occurred with maximum levels of 45-77 dBA. The polysomnogram and the electrocardiogram were recorded during all nights. In case of awakenings, the HR alterations consisted of monophasic elevations for >1 min, with mean maximum HR elevations of 30 bpm. Though obviously triggered by the noise events, the awakenings per se rather than the acoustical parameters determined the extent and pattern of the response. Without awakenings, HR responses were biphasic and consisted of initial accelerations with maximum HR elevations of about 9 bpm followed by decelerations below the baseline. These alterations were clearly influenced by the acoustic parameters (traffic mode, maximum level, rate of rise) as well as by the momentary sleep stage.

CONCLUSIONS

Cardiac responses did not habituate to traffic noise within the night and may therefore play a key role in promoting traffic noise induced cardiovascular disease. If so, these consequences are more likely for responses accompanied by awakenings than for situations without awakenings.

Sleep and sleepiness in relation to stress and displaced work hours

Sleep is an important factor in relation to accidents, long-term health and mortality. Our group has had a long-term commitment to research on sleep regulation and its consequences. Over the years we have demonstrated pronounced effects of night work on sleep and alertness, including electroencephalographically determined sleep during work. We have also demonstrated that experimental displacement of sleep will result in short sleep at daytime and increased physiological sleepiness at night and developed mathematical models for prediction of sleep duration, as well as of sleepiness and risk of sleep-related accidents. We have also looked at the concept of sleep quality and found it dependent on sleep duration, sleep continuity and content of sleep stages 3 and 4. Sleep is also clearly disturbed in patients on long-term sick leave for burnout or in non-patients with high burnout scores, in particular sleep fragmentation is increased and sleep efficiency and sleep stages 3 and 4 (SWS--deep sleep) decreased. The fragmentation in turn seems related to endocrine changes. Present work is focused on bringing this work together, connecting the links from stress to sleep to metabolic changes to disease and long-term sickness absence.

Characterization of the sleep EEG in acutely depressed men using detrended fluctuation analysis

OBJECTIVE

The aim of the present paper is to study the fluctuations of the sleep EEG over various time scales during a specific pathological condition: major depressive episode. Focus is made on scaling behaviour, which is the signature of the absence of characteristic time scale, and the presence of long-range correlations associated to physiological constancy preservation, variability reduction and mostly adaptability.

METHODS

Whole night sleep electroencephalogram signals were recorded in 24 men: 10 untreated patients with a major depressive episode (41.70+/-8.11 years) and 14 healthy subjects (42.43+/-5.67 years). Scaling in these time series was investigated with detrended fluctuation analysis (time range: 0.16-2.00s). Scaling exponents (alpha) were determined in stage 2, slow wave sleep (stages 3 and 4) and during REM sleep. Forty-five epochs of 20s were chosen randomly in each of these stages.

RESULTS

The median values of alpha were lower in patients during stage 2 and SWS.

CONCLUSIONS

Major depressive episodes are characterized by a modification in the correlation structure of the sleep EEG time series. The finding which shows decreasing rate of the temporal correlations being different within the two groups in stage 2 and SWS provides an electrophysiologic argument that the underlying neuronal dynamics are modified during acute depression.

SIGNIFICANCE

The observed modifications in scaling behaviour in acutely depressed patients could be an explanation of the sleep fragmentation and instability found during major depressive episode.

Hypertension research in sleep apnea

Obstructive sleep apnea (OSA) is characterized by repetitive partial and total collapse of the upper airway that induces stressful arousals throughout sleep to reestablish breathing. Although estimates vary, prevalence has been reported as high as 20% in the adult population. OSA is common in several chronic diseases, the most common of which is obesity. Evidence is strong that OSA increases the risk of hypertension and both fatal and nonfatal cardiovascular events. Several mechanisms linking OSA to hypertension have been proposed, with increased sympathetic activation implicated as the prime mediator. This review summarizes recent data on the influence of OSA on blood pressure, the effect of standard OSA therapy on improving blood pressure, and the potential of lifestyle modification for further decreasing hypertension risk. Challenges confronting the investigation of blood pressure outcomes in response to treatment in OSA patients are discussed.

Burnout and risk of cardiovascular disease: evidence, possible causal paths, and promising research directions

Burnout is characterized by emotional exhaustion, physical fatigue, and cognitive weariness, resulting from prolonged exposure to work-related stress. The authors review the accumulated evidence suggesting that burnout and the related concept of vital exhaustion are associated with increased risk of cardiovascular disease and cardiovascular-related events. The authors present evidence supporting several potential mechanisms linking burnout with ill health, including the metabolic syndrome, dysregulation of the hypothalamic-pituitary-adrenal axis along with sympathetic nervous system activation, sleep disturbances, systemic inflammation, impaired immunity functions, blood coagulation and fibrinolysis, and poor health behaviors. The association of burnout and vital exhaustion with these disease mediators suggests that their impact on health may be more extensive than currently indicated.

Hyperarousal, depression and quality of life - validity and reliability of the Swedish version of the Hyperarousal Scale

AIM

Research focusing on hyperarousability in association with general sensitivity to stress has increased. This study aimed to: (i) describe values for self-reported hyperarousal behaviour traits, depression, sleeplessness behaviour and health-related quality of life [The Short Form 36 Health Survey Questionnaire (SF-36)] in a gender-stratified random sample from the Swedish population; and (ii) test the validity and reliability of the Swedish version of the Hyperarousal Behavioural Trait Scale (H-scale).

METHODS

In this study, 402 women and 391 men from Sweden were included. A test-retest study was performed on 297 subjects.

RESULTS

The total mean score on the H-scale was 29.5 (SD 10.0, 95% CI 28.8-30.2). Compared to men, women scored higher on the H-scale (total score, sub-scales and many items), whereas no evidence of an age trend was seen. The H-scale has proven to be a valid and reliable scale. Pearson's correlation coefficient showed similar magnitude and direction between the H-scale and the Zung's Self-rating Depression Scale, as between the H-scale and the Vicious Cycle of Sleeplessness Behaviour Scale, Vitality, Mental Health and the Mental Component Summary index on the SF-36 respectively. The Cronbach's alpha for the H-scale was 0.84 and estimated stability test-retest point of time varies between 0.73 and 0.80.

CONCLUSIONS

This study indicates gender differences in response style in association with altered health-related quality of life. The H-scale is a valid and reliable self-reported scale for measuring hyperarousal behavioural trait research outcome in clinical practice.

Sleep loss: a novel risk factor for insulin resistance and Type 2 diabetes

Chronic sleep loss as a consequence of voluntary bedtime restriction is an endemic condition in modern society. Although sleep exerts marked modulatory effects on glucose metabolism, and molecular mechanisms for the interaction between sleeping and feeding have been documented, the potential impact of recurrent sleep curtailment on the risk for diabetes and obesity has only recently been investigated. In laboratory studies of healthy young adults submitted to recurrent partial sleep restriction, marked alterations in glucose metabolism including decreased glucose tolerance and insulin sensitivity have been demonstrated. The neuroendocrine regulation of appetite was also affected as the levels of the anorexigenic hormone leptin were decreased, whereas the levels of the orexigenic factor ghrelin were increased. Importantly, these neuroendocrine abnormalities were correlated with increased hunger and appetite, which may lead to overeating and weight gain. Consistent with these laboratory findings, a growing body of epidemiological evidence supports an association between short sleep duration and the risk for obesity and diabetes. Chronic sleep loss may also be the consequence of pathological conditions such as sleep-disordered breathing. In this increasingly prevalent syndrome, a feedforward cascade of negative events generated by sleep loss, sleep fragmentation, and hypoxia are likely to exacerbate the severity of metabolic disturbances. In conclusion, chronic sleep loss, behavioral or sleep disorder related, may represent a novel risk factor for weight gain, insulin resistance, and Type 2 diabetes.

Disorders of glucose metabolism in sleep apnea

Sleep is a complex behavioral state that occupies one-third of the human life span. Although viewed as a passive condition, sleep is a highly active and dynamic process. The sleep-related decrease in muscle tone is associated with an increase in resistance to airflow through the upper airway. Partial or complete collapse of the airway during sleep can lead to the occurrence of apneas and hypopneas during sleep that define the syndrome of sleep apnea. Sleep apnea has become pervasive in Western society, affecting approximately 5% of adults in industrialized countries. Given the pandemic of obesity, the prevalence of Type 2 diabetes mellitus and metabolic syndrome has also increased dramatically over the last decade. Although the role of sleep apnea in cardiovascular disease is uncertain, there is a growing body of literature that implicates sleep apnea in the pathogenesis of altered glucose metabolism. Intermittent hypoxemia and sleep fragmentation in sleep apnea can trigger a cascade of pathophysiological events, including autonomic activation, alterations in neuroendocrine function, and release of potent proinflammatory mediators such as tumor necrosis factor-alpha and interleukin-6. Epidemiologic and experimental evidence linking sleep apnea and disorders of glucose metabolism is reviewed and discussed here. Although the cause-and-effect relationship remains to be determined, the available data suggest that sleep apnea is independently associated with altered glucose metabolism and may predispose to the eventual development of Type 2 diabetes mellitus.