Sleep characteristics as predictor variables of stress systems markers in insomnia disorder

Functional MRI-based biomarkers of insomnia with objective short sleep duration phenotype

BACKGROUND

Insomnia disorder with objective short sleep duration (ISS) phenotype is a more serious biological subtype than insomnia with objective normal sleep duration (INS) phenotype, and the neuroimaging data is helpful to understand the pathophysiology of the ISS phenotype. This study was to compare the amplitude of low-frequency fluctuation (ALFF), regional homogeneity (ReHo), and functional connectivity (FC) between the ISS phenotype and the INS phenotype.

METHODS

In this cross-sectional study, 55 patients with insomnia disorder were recruited, and 22 of them were defined as the ISS phenotype by the objective cardiopulmonary coupling (CPC) technique. The blood oxygen level-dependent (BOLD) sequences of all participants were obtained using the 3.0 T magnetic resonance imaging system. We analyzed and compared the ALFF, ReHo, and FC between the ISS phenotype and the INS phenotype. We also conducted Pearson's correlation analysis between significant neuroimaging biomarkers and the CPC parameters.

RESULTS

The differences were not significant in ALFF (PFWE-corr＞0.05) or ReHo (PFWE-corr＞0.05) between the ISS phenotype and the INS phenotype. For the FC analysis, the ISS phenotype had a Hub-node of the left inferior occipital gyrus (IOG.L), with significantly decreased connections (p＜0.001) in the bilateral occipital, parietal, and temporal regions. The significant FCs were closely related to sleep parameters.

CONCLUSION

The left inferior occipital gyrus (IOG.L), as a Hub-node with decreased functional connections, may be a potential fMRI-based biomarker of the ISS phenotype.

Changed nocturnal levels of stress-related hormones couple with sleep-wake states in the patients with chronic insomnia disorder: A clinical pilot study

OBJECTIVES

To explore the relationship between nocturnal levels of stress-related hormones and different sleep-wake states in chronic insomnia disorder (CID) patients.

METHODS

Thirty-three CID patients and 34 good sleepers were enrolled and completed assessment of sleep log, Pittsburgh Sleep Quality Index and Insomnia Severity Index. During a-overnight polysomnography monitoring, the patients' vein bleeds were continually collected at different time points (pre-sleep, deep-sleep, 5-min or 30-min waking, and morning waking-up). The control subjects' bleeds were collected only at 22:00 and morning waking-up. The serum hormones were detected using enzyme-linked immunosorbent assay.

RESULTS

Compared with at pre-sleep, the level of cortisol was significantly higher at morning waking-up respectively in two-group subjects (Ps < 0.001), with insignificant inter-group differences in cortisol, corticotropin releasing hormone and copeptin at the two time-points. In the patients, the nocturnal secretion curves of three hormones were similar, with the highest concentration at morning waking-up, followed by 30-min waking, 5-min waking, pre-sleep, and deep-sleep. The patients' cortisol (Z = 79.192, P < 0.001) and copeptin (Z = 12.333, P = 0.015) levels were statistically different at different time-points, with higher cortisol at morning waking-up relative to deep-sleep, pre-sleep and 5-min waking (Ps < 0.05), and at 30-min waking relative to deep-sleep and pre-sleep (Ps < 0.05), and higher copeptin at morning waking-up relative to deep-sleep (P < 0.05).

CONCLUSIONS

In CID, the nocturnal wakes were instantaneously accompanied by high level, and deep sleep was accompanied by the lowest levels, of stress-related hormones, especially in cortisol, supporting the insomniac hypothesis of increased nocturnal pulse-release of cortisol.

Preliminary investigation of the interactive role of physiological arousal and insomnia complaints in gray matter volume alterations in chronic widespread pain

STUDY OBJECTIVES

Brain regions involved in insomnia and chronic pain are overlapping and diffuse. The interactive role of physiological arousal in associations between insomnia symptoms and neural regions is unknown. This preliminary study examined whether arousal interacted with sleep in associations with gray matter volume of frontal (dorsolateral prefrontal cortex, anterior cingulate cortex) and temporal (right/left hippocampus) regions in adults with chronic widespread pain and insomnia complaints.

METHODS

Forty-seven adults with chronic widespread pain and insomnia (mean age = 46.00, standard deviation = 13.88, 89% women) completed 14 daily diaries measuring sleep onset latency (SOL), wake time after sleep onset, and total sleep time (TST), as well as Holter monitor assessments of heart rate variability (measuring physiological arousal), and magnetic resonance imaging. Multiple regressions examined whether average SOL, wake time after sleep onset, or TST were independently or interactively (with arousal/heart rate variability) associated with dorsolateral prefrontal cortex, anterior cingulate cortex, and left/right hippocampus gray matter volumes.

RESULTS

Shorter TST was associated with lower right hippocampus volume. TST also interacted with arousal in its association with right hippocampal volume, Specifically, shorter TST was associated with lower volume at highest and average arousal levels. SOL interacted with arousal in its association with anterior cingulate cortex volume, such that, among individuals with lowest arousal, longer SOL was associated with lower volume.

CONCLUSIONS

Preliminary findings highlight the interactive roles of physiological arousal and insomnia symptoms in associations with neural structure in chronic widespread pain and insomnia. Individuals with the highest physiological arousal may be particularly vulnerable to the impact of shorter TST on hippocampal volume loss. Reducing SOL may only impact anterior cingulate cortex volume in those with lower physiological arousal.

CITATION

Curtis AF, Nair N, Hayse B, et al. Preliminary investigation of the interactive role of physiological arousal and insomnia complaints in gray matter volume alterations in chronic widespread pain. J Clin Sleep Med. 2024;20(2):293-302.

Insomnia nosology: a systematic review and critical appraisal of historical diagnostic categories and current phenotypes

Insomnia nosology has significantly evolved since the Diagnostic and Statistical Manual (DSM)-III-R first distinguished between 'primary' and 'secondary' insomnia. Prior International Classification of Sleep Disorders (ICSD) nosology 'split' diagnostic phenotypes to address insomnia's heterogeneity and the DSM nosology 'lumped' them into primary insomnia, while both systems assumed causality for insomnia secondary to health conditions. In this systematic review, we discuss the historical phenotypes in prior insomnia nosology, present findings for currently proposed insomnia phenotypes based on more robust approaches, and critically appraise the most relevant ones. Electronic databases PsychINFO, PubMED, Web of Science, and references of eligible articles, were accessed to find diagnostic manuals, literature on insomnia phenotypes, including systematic reviews or meta-analysis, and assessments of the reliability or validity of insomnia diagnoses, identifying 184 articles. The data show that previous insomnia diagnoses lacked reliability and validity, leading current DSM-5-TR and ICSD-3 nosology to 'lump' phenotypes into a single diagnosis comorbid with health conditions. However, at least two new, robust insomnia phenotyping approaches were identified. One approach is multidimensional-multimethod and provides evidence for self-reported insomnia with objective short versus normal sleep duration linked to clinically relevant outcomes, while the other is multidimensional and provides evidence for two to five clusters (phenotypes) based on self-reported trait, state, and/or life-history data. Some approaches still need replication to better support whether their findings identify true phenotypes or simply different patterns of symptomatology. Regardless, these phenotyping efforts aim at improving insomnia nosology both as a classification system and as a mechanism to guide treatment.

From improved sleep regularity to reduced sleep complaints and mental health conditions: a population-based interventional study using a smartphone-based virtual agent

STUDY OBJECTIVES

To explore the effect of sleep regularity on sleep complaints and mental health conditions (i.e. insomnia, fatigue, anxiety, and depressive symptoms) in a population-based interventional study using a smartphone-based virtual agent.

METHODS

A populational cohort based on the Kanopée application, which provided interactions with a virtual companion to collect data on sleep and make personalized recommendations to improve sleep over 17 days. A pre-intervention sleep diary and interview were used for cross-sectional analysis (n = 2142), and a post-intervention sleep diary and interview were used for longitudinal analysis (n = 732). The intra-individual mean (IIM) and standard deviation (ISD) of total sleep time (TST) were calculated to measure sleep quantity and sleep regularity.

RESULTS

The mean age at baseline was 49 years, 65% were female, 72% reported insomnia, 58% fatigue, 36% anxiety, and 17% depressive symptoms. Before the intervention, irregular and short sleep was associated with a higher likelihood of insomnia (Relative risk [RR] = 1.26 [1.21-1.30] for irregular TST and RR = 1.19 [1.15-1.23] for short TST), fatigue, anxiety, and depressive symptoms. After the intervention, the IIM of the TST increased while the ISD of the TST and sleep complaints and mental health conditions decreased. More regular TST was associated with reduced insomnia and depressive symptoms (RR = 1.33 [1.10-1.52] and RR = 1.55 [1.13-1.98], respectively).

CONCLUSIONS

Our results reveal a longitudinal association between sleep regularity and sleep complaints and mental health conditions. Policymakers, health professionals, and the general population should be aware that, beyond its positive effect on sleep health, regular sleep could promote mental health.

Association Between Insomnia Symptoms and Trajectory With the Risk of Stroke in the Health and Retirement Study

BACKGROUND AND OBJECTIVES

Insomnia is a common condition affecting more than a third of the US population. However, the link between insomnia symptoms and stroke is understudied and the underlying mechanism remains unclear. This study aimed to investigate the relationship between insomnia symptoms and the incidence of stroke.

METHODS

The Health and Retirement Study, a survey of Americans older than 50 years and their spouses, from 2002 to 2020 was used as the data source. Only those who were stroke-free at baseline were included in this study. The exposure variable was insomnia symptoms and was derived from self-reported sleep-related factors including difficulty initiating sleep, difficulty maintaining sleep, waking up too early, and nonrestorative sleep. Repeated-measures latent class analysis was used to identify insomnia trajectories over time. To investigate the relationship between insomnia symptoms and stroke events reported during the follow-up period, Cox proportional hazards regression models were used. Mediation analyses of comorbidities were performed using causal mediation within a counterfactual framework.

RESULTS

A total of 31,126 participants were included with a mean follow-up of 9 years. The mean age was 61 years (SD = 11.1) and 57% were females. Insomnia symptom trajectories remained constant over time. Compared with those with no insomnia symptoms, an increased risk of stroke was observed for those with insomnia symptom scores ranging from 1 to 4 and 5 to 8 (hazard ratio (HR) = 1.16, 95% confidence interval (CI) 1.02-1.33) and (HR = 1.51, 95% CI 1.29-1.77), respectively, indicating a dose-response relationship. The association was stronger in participants younger than 50 years (HR = 3.84, 95% CI 1.50-9.85) than in those aged 50 years and older (HR = 1.38, 95% CI 1.18-1.62), comparing those with insomnia symptoms ranging from 5 to 8 with those with no insomnia symptoms. This association was mediated by diabetes, hypertension, heart disease, and depression.

DISCUSSION

Insomnia symptoms were associated with an increased risk of stroke, especially in adults younger than 50 years, and the risk was mediated by certain comorbidities. Increased awareness and management of insomnia symptoms may contribute to the prevention of stroke occurrence.

Associations of social isolation and loneliness with the onset of insomnia symptoms among middle-aged and older adults in the United States: A population-based cohort study

There is an inconsistent conclusion regarding the relationship of social isolation and loneliness with poor sleep. We investigated the associations of social isolation and loneliness with new-onset insomnia symptoms in a nationally-representative sample of 9,430 adults aged ≥50 who were free of any insomnia symptoms/sleep disorders at baseline (wave 12/13) and followed up to 4 years from the Health and Retirement Study. Social isolation was measured by Steptoe's Social Isolation Index. Loneliness was measured by the revised 3-item UCLA-Loneliness Scale. Insomnia symptoms were quantified using the modified Jenkins Sleep Questionnaire. During a mean follow-up of 3.52 years, 1,522 (16.1%) participants developed at least one insomnia symptom. Cox models showed that loneliness was associated with the onset of difficulties initiating or maintaining sleep, early-morning awakening, nonrestorative sleep, and at least one of these symptoms after adjusting for potential covariates; while social isolation was not associated with the onset of difficulties maintaining sleep, early-morning awakening, or at least one insomnia symptom after adjusting for health indicators. These results are consistent in sensitivity analyses and stratified analyses by age, sex, race/ethnicity, and obesity. Public health interventions aimed at fostering close emotional relationships may reduce the burden of poor sleep among middle-aged and older adults.

Insomnia Severity is Associated with Morning Cortisol and Psychological Health

Studies suggest associations between cortisol and sleep, and cortisol shows a profound diurnal rhythm. The evidence about the relationship between chronic insomnia and cortisol is mixed. Chronic insomnia is associated with the risk of mental health disorders. The aim of this study was to evaluate the association of insomnia severity and objective sleep pattern with morning cortisol level and psychological health. The instruments used were the Insomnia Severity Index (ISI), polysomnography, Beck Depression Inventory (BDI), and Profile of Mood States (POMS). Serum cortisol was analyzed by chemiluminescence. The data revealed significant positive correlations of ISI with morning cortisol level (r = 0.37, p  = 0.03), BDI score (r = 0.44, p  < 0.01), and POMS-tension anxiety (r = 0.39, p  = 0.02). Sleep stages N2 and N3 were correlated with POMS-fatigue (r = 0.46, p  < 0.01; r = -0.37, p  = 0.04). Sleep stage N3 was also negatively correlated with POMS-tension-anxiety (r = -0.36, p  = 0.04). Higher insomnia severity was associated with higher morning cortisol, depression, and tension-anxiety. Sleep stage N2 was associated with higher fatigue and N3 was associated with lower tension-anxiety and fatigue.

Cognitive-behavioral therapy for insomnia with objective short sleep duration phenotype: A systematic review with meta-analysis

Cognitive-behavioral therapy for insomnia (CBT-I) has been recommended as the first-line therapy for this condition. However, insomnia disorder with objective short sleep duration (ISS) phenotype is a distinct subtype from insomnia with normal sleep duration (INS) phenotype, and it may have a differential therapeutic response. We searched PubMed, EMBASE, Cochrane Library, and ClinicalTrials.gov using the PICOS principle for studies that examined the efficacy of cognitive-behavioral therapy for those with the ISS phenotype versus the INS phenotype, and identified nine studies with 612 patients with insomnia disorder. This included 270 patients with the ISS phenotype and 342 patients with the INS phenotype. The main outcome was that CBT-I had a better efficacy for the INS phenotype compared with the ISS phenotype, with about 30% higher response and about 20% higher remission. Similar results were indicated in the secondary outcomes. The therapeutic response of the ISS phenotype was significantly different from that of the INS phenotype. In the future, research is needed to clarify how to optimally treat insomnia disorder with the ISS phenotype in prospective randomized clinical trials, and to understand whether decreasing physiologic arousal will be necessary to improve results.

The evolving role of quantitative actigraphy in clinical sleep medicine

Actigraphy has a consolidated role in Insomnia and Circadian Rhythm Sleep-Wake Disorders (CRSWD) and recent studies have highlighted the use of actigraphy for narcolepsy and REM sleep behaviour disorder (RBD). This review aims at summarising the results of studies published over the last decade regarding the use of actigraphy. Thirty-five studies proved eligible, and results were analysed separately for insomnia, narcolepsy and RBD. Actigraphy showed to consistently differentiate insomnia patients from healthy controls. Furthermore, the application of advanced analytical techniques has been shown to provide both unique insights into the physiology of insomnia and sleep misperception and to improve the specificity of actigraphy in detecting wakefulness within sleep periods. Regarding narcolepsy, several studies showed that actigraphy can detect peculiar sleep/wake disruption and the effects of pharmacological treatments. Finally, although the number of studies in RBD patients is still limited, the available evidence indicates a reduced amplitude of the activity pattern, sleep-wake rhythm dysregulation and daytime sleepiness. Therefore, the potential use of these markers as predictors of phenoconversion should be further explored. In conclusion, quantitative actigraphy presents a renewed interest when considering the possibility of using actigraphy in clinical sleep medicine to diagnose, monitor, and follow sleep disorders other than CRSWD.

Insomnia with objective short sleep duration is associated with hypertension

Insomnia with objective short sleep duration has been proposed as the most biologically severe phenotype of the disorder associated with cardiometabolic morbidity in population-based samples. In this study, we investigated the association between insomnia with objective short sleep duration and hypertension in a large clinical sample. We studied 348 patients diagnosed with chronic insomnia disorder based on International Classification of Sleep Disorders Third Edition criteria and 150 normal sleepers. Objective short sleep duration was defined by the median total sleep time of the sample (< 7 hr) measured with 1-night polysomnography. Hypertension was defined based on blood pressure levels, antihypertensive medication use and/or a physician diagnosis. After adjusting for potential confounders, patients with chronic insomnia disorder who slept < 7 hr were associated with 2.8-fold increased odds of hypertension compared with normal sleepers who slept ≥ 7 hr (odds ratio = 2.81, 95% confidence interval = 1.068-7.411) or < 7 hr (odds ratio = 2.75, 95% confidence interval = 1.005-7.542), whereas patients with chronic insomnia disorder who slept ≥ 7 hr (odds ratio = 1.52, 95% confidence interval = 0.537-4.285) or normal sleepers who slept < 7 hr (odds ratio = 1.07, 95% confidence interval = 0.294-3.904) were not significantly associated with increased odds of hypertension compared with normal sleepers who slept ≥ 7 hr. Linear regression analyses showed that, for every hour decrease in total sleep time, systolic and diastolic blood pressure increased by 1.014 mmHg (p = 0.045) and 0.923 mmHg (p = 0.015), respectively, in patients with chronic insomnia disorder but not in normal sleepers. Our findings further support that insomnia with objective short sleep duration is a risk factor for hypertension, and objective short sleep duration may be a useful marker of the biological severity of chronic insomnia disorder in clinical practice.

Sleep Immune Cross Talk and Insomnia

Sleep and immunity have bidirectional relationships. In this chapter, we review the links between sleep and immunity, focusing on immune changes occurring in the insomnia disorder. During physiological sleep, there is a decrease of pro-inflammatory cytokines (IL-1, IL-6 and TNF-α) and a decrease of anti-inflammatory cytokines (IL-4, IL-10). Examinations of ratios of pro-inflammatory and anti-inflammatory cytokines allow to identify rather a pro-inflammatory activity at the beginning of the night and confirm then anti-inflammatory during the second part of the night. Immune cells, as NK-cells, decrease in the blood, due to their migration to secondary lymphoid organs, but their activity increases. Inversely, a short sleep duration appears associated with increased inflammatory processes and increased risk of infection.Only few studies have investigated changes in immunity in patients with insomnia disorder. These studies suggest that insomnia disorder is related to deregulation of the immune system, with an increase in the level of pro-inflammatory cytokines and change in rate of secretion and a decrease in the level of lymphocyte. Insomnia treatments, particularly cognitive behavioral therapy (CBT-I), seems to have a restorative effect not only on sleep, but also on the associated inflammation. Melatonin also seems to reduce inflammation in patients suffering from insomnia disorder.More studies are necessary to better understand the pathophysiology of changes in immune system in patients suffering from insomnia disorders and their clinical implications.

Causal association between sleep traits and the risk of coronary artery disease in patients with diabetes

Background and aims

The association between sleep traits and coronary artery disease (CAD) in patients with diabetes has been reported in previous observational studies. However, whether these potential relationships are causal remains unclear. We aim to assess the causal relationship between sleep traits and CAD in diabetic.

Methods

Genetic instrumental variables associated with five sleep-related traits (insomnia, sleep duration, ease of getting up, morningness and snoring) were extracted from corresponding genome-wide association studies (GWAS). The associations of genetic variants with CAD were based on 15,666 individuals with diabetes (3,968 CAD cases and 11,696 controls). The primary analysis was derived using the inverse variance weighting method. Further sensitivity analysis was conducted to confirm the robustness and consistency of the main results.

Results

Genetic liability to insomnia was significantly related to the increased risk of CAD in individuals with diabetes [odds ratio (OR): 1.163; 95% CI: 1.072-1.254; p = 0.001]. Suggestive evidence was found for the borderline associations between both sleep duration (OR: 0.629; 95% CI: 0.380-1.042, p = 0.072) and snoring (OR: 1.010, 95% CI: 1.000-1.020, p = 0.050) with CAD risk. However, no consistent evidence was found for the association between ease of getting up and morningness with the risk of CAD in diabetic. Similar results can be verified in most sensitivity analyses.

Conclusions

We provide consistent evidence for the causal effect of insomnia on the increased risk of CAD in individuals with diabetes. The management of sleep health should be emphasized to prevent CAD in diabetic patients.

Role of Oxidative Stress and Inflammation in Insomnia Sleep Disorder and Cardiovascular Diseases: Herbal Antioxidants and Anti-inflammatory Coupled with Insomnia Detection using Machine Learning

Insomnia is well-known as trouble in sleeping and enormously influences human life due to the shortage of sleep. Reactive Oxygen Species (ROS) accrue in neurons during the waking state, and sleep has a defensive role against oxidative damage and dissipates ROS in the brain. In contrast, insomnia is the source of inequity between ROS generation and removal by an endogenous antioxidant defense system. The relationship between insomnia, depression, and anxiety disorders damages the cardiovascular systems' immune mechanisms and functions. Traditionally, polysomnography is used in the diagnosis of insomnia. This technique is complex, with a long time overhead. In this work, we have proposed a novel machine learning-based automatic detection system using the R-R intervals extracted from a single-lead electrocardiograph (ECG). Additionally, we aimed to explore the role of oxidative stress and inflammation in sleeping disorders and cardiovascular diseases, antioxidants' effects, and the psychopharmacological effect of herbal medicine. This work has been carried out in steps, which include collecting the ECG signal for normal and insomnia subjects, analyzing the signal, and finally, automatic classification. We used two approaches, including subjects (normal and insomnia), two sleep stages, i.e., wake and rapid eye movement, and three Machine Learning (ML)-based classifiers to complete the classification. A total number of 3000 ECG segments were collected from 18 subjects. Furthermore, using the theranostics approach, the role of mitochondrial dysfunction causing oxidative stress and inflammatory response in insomnia and cardiovascular diseases was explored. The data from various databases on the mechanism of action of different herbal medicines in insomnia and cardiovascular diseases with antioxidant and antidepressant activities were also retrieved. Random Forest (RF) classifier has shown the highest accuracy (subjects: 87.10% and sleep stage: 88.30%) compared to the Decision Tree (DT) and Support Vector Machine (SVM). The results revealed that the suggested method could perform well in classifying the subjects and sleep stages. Additionally, a random forest machine learning-based classifier could be helpful in the clinical discovery of sleep complications, including insomnia. The evidence retrieved from the databases showed that herbal medicine contains numerous phytochemical bioactives and has multimodal cellular mechanisms of action, viz., antioxidant, anti-inflammatory, vasorelaxant, detoxifier, antidepressant, anxiolytic, and cell-rejuvenator properties. Other herbal medicines have a GABA-A receptor agonist effect. Hence, we recommend that the theranostics approach has potential and can be adopted for future research to improve the quality of life of humans.

Biomarker associations with insomnia and secondary sleep outcomes in persons with and without HIV in the POPPY-Sleep substudy: a cohort study

STUDY OBJECTIVES

We investigated associations between inflammatory profiles/clusters and sleep measures in people living with HIV and demographically-/lifestyle-similar HIV-negative controls in the Pharmacokinetic and clinical Observations in PeoPle over fiftY (POPPY)-Sleep substudy.

METHODS

Primary outcome was insomnia (Insomnia Severity Index [ISI]>15). Secondary sleep outcomes included 7-day actigraphy (e.g. mean/standard deviation of sleep duration/efficiency), overnight oximetry (e.g. oxygen desaturation index [ODI]) and patient-reported measures (Patient-Reported Outcomes Measurement Information System (PROMIS) sleep questionnaires). Participants were grouped using Principal Component Analysis of 31 biomarkers across several inflammatory pathways followed by cluster analysis. Between-cluster differences in baseline characteristics and sleep outcomes were assessed using Kruskal-Wallis/logistic regression/Chi-squared/Fisher's exact tests.

RESULTS

Of the 465 participants included (74% people with HIV, median [interquartile range] age 54 [50-60] years), only 18% had insomnia and secondary sleep outcomes suggested generally good sleep (e.g. ODI 3.1/hr [1.5-6.4]). Three clusters with distinct inflammatory profiles were identified: "gut/immune activation" (n = 47), "neurovascular" (n = 209), and "reference" (relatively lower inflammation; n = 209). The "neurovascular" cluster included higher proportions of people with HIV, obesity (BMI>30 kg/m2), and previous cardiovascular disease, mental health disorder, and arthritis of knee/hip relative to the other two clusters. No clinically relevant between-cluster differences were observed in proportions with insomnia (17%, 18%, 20%) before (p = .76) or after (p = .75) adjustment for potential confounders. Few associations were observed among actigraphy, oximetry, and PROMIS measures.

CONCLUSIONS

Although associations could exist with other sleep measures or biomarker types not assessed, our findings do not support a strong association between sleep and inflammation in people with HIV.

Sleep disruption induces activation of inflammation and heightens risk for infectious disease: Role of impairments in thermoregulation and elevated ambient temperature

Thermoregulation and sleep are tightly coordinated, with evidence that impairments in thermoregulation as well as increases in ambient temperature increase the risk of sleep disturbance. As a period of rest and low demand for metabolic resources, sleep functions to support host responses to prior immunological challenges. In addition by priming the innate immune response, sleep prepares the body for injury or infection which might occur the following day. However when sleep is disrupted, this phasic organization between nocturnal sleep and the immune system becomes misaligned, cellular and genomic markers of inflammation are activated, and increases of proinflammatory cytokines shift from the nighttime to the day. Moreover, when sleep disturbance is perpetuated due to thermal factors such as elevated ambient temperature, the beneficial crosstalk between sleep and immune system becomes further imbalanced. Elevations in proinflammatory cytokines have reciprocal effects and induce sleep fragmentation with decreases in sleep efficiency, decreases in deep sleep, and increases in rapid eye movement sleep, further fomenting inflammation and inflammatory disease risk. Under these conditions, sleep disturbance has additional potent effects to decrease adaptive immune response, impair vaccine responses, and increase vulnerability to infectious disease. Behavioral interventions effectively treat insomnia and reverse systemic and cellular inflammation. Further, insomnia treatment redirects the misaligned inflammatory- and adaptive immune transcriptional profiles with the potential to mitigate risk of inflammation-related cardiovascular, neurodegenerative, and mental health diseases, as well as susceptibility to infectious disease.

Sympathetic neural responses to sleep disorders and insufficiencies

Short sleep duration and poor sleep quality are associated with cardiovascular risk, and sympathetic nervous system (SNS) dysfunction appears to be a key contributor. The present review will characterize sympathetic function across several sleep disorders and insufficiencies in humans, including sleep deprivation, insomnia, narcolepsy, and obstructive sleep apnea (OSA). We will focus on direct assessments of sympathetic activation, e.g., plasma norepinephrine and muscle sympathetic nerve activity, but include heart rate variability (HRV) when direct assessments are lacking. The review also highlights sex as a key biological variable. Experimental models of total sleep deprivation and sleep restriction are converging to support several epidemiological studies reporting an association between short sleep duration and hypertension, especially in women. A systemic increase of SNS activity via plasma norepinephrine is present with insomnia and has also been confirmed with direct, regionally specific evidence from microneurographic studies. Narcolepsy is characterized by autonomic dysfunction via both HRV and microneurographic studies but with opposing conclusions regarding SNS activation. Robust sympathoexcitation is well documented in OSA and is related to baroreflex and chemoreflex dysfunction. Treatment of OSA with continuous positive airway pressure results in sympathoinhibition. In summary, sleep disorders and insufficiencies are often characterized by sympathoexcitation and/or sympathetic/baroreflex dysfunction, with several studies suggesting women may be at heightened risk.

Validation of the Thyrotoxicosis-associated Insomnia Model Induced by Thyroxine through Sympathetic Stimulation: Face, Construct and Predictive Perspectives

Insomnia has become a common central nervous system disease. At present, the pathogenesis of insomnia is not clear. Animal models can help us understand the pathogenesis of the disease and can be used in transformational medicine. Therefore, it is very necessary to establish an appropriate model of insomnia. Clinical data show that insomnia patients with high levels of thyroxine and often accompanied by cardiovascular problems, a common mechanism underlying all of these physiological disruptions is the sympathetic nervous system. Combined with the characteristics of chronic onset of clinical insomnia, an insomnia model induced by long-term intraperitoneal injection of thyroid hormone has been created in our laboratory. In this paper, the insomnia-like state of the model was evaluated based on three validity criteria. Face validity has been demonstrated in metabolism, the Morris water maze, electrocardiogram (ECG) and electroencephalogram (EEG). Structure validity has been proved by the results of targeted metabolomics. After treatment with diazepam, a commonly used clinical anti-insomnia drug, the above physiological and pathological disorders were reversed. The results of comprehensive analysis show that the established thyrotoxicosis-associated insomnia model meets the validity requirement to establish an appropriate animal model of insomnia. The model presented in this article might help to study pathogenetic mechanisms of clinical insomnia, as well as to test promising methods of insomnia treatment.

Hypothalamic-pituitary-adrenal (HPA) axis response to exogenous corticotropin-releasing hormone (CRH) is attenuated in men with chronic insomnia

Although insomnia is by far the most common sleep disorder, our understanding of its neurobiology is limited. Insomnia, particularly when associated with objective sleep disturbance, has been associated with activation of the hypothalamic-pituitary-adrenal axis. The objective of this experimental study was to compare the response of the hypothalamic-pituitary-adrenal axis to ovine corticotropin-releasing hormone, a stress test, in men with insomnia versus controls. Circulating adrenocorticotropic hormone and cortisol levels were assayed before (-30 min, -15 min), at (0 min) and after (+5 min, +15 min, +30 min, +60 min, +90 min, +120 min) exogenous ovine corticotropin-releasing hormone administration in 23 men (11 insomnia, 12 controls), who underwent four consecutive nights of in-lab polysomnography. Men with insomnia compared with controls demonstrated markedly and significantly shorter total sleep time (368.4 ± 8.99 min versus 411.61 ± 8.61 min; p < 0.01) and lower sleep efficiency (76.77 ± 1.80% versus 86.04 ± 1.72%; p < 0.01) on polysomnography, and showed decreased adrenocorticotropic hormone and cortisol levels after ovine corticotropin-releasing hormone administration. Adrenocorticotropic hormone levels at 15 min and 30 min were significantly lower in men with insomnia than in controls (p < 0.05). Similarly, the peak levels of cortisol at +60 min, and the total and net area under the curve levels of this hormone were significantly lower in men with insomnia than controls (all p < 0.01). Adrenocorticotropic hormone and cortisol response to ovine corticotropin-releasing hormone administration was attenuated in men with insomnia associated with objective sleep disturbance, suggesting that objectively defined insomnia subtypes have a disrupted hypothalamic-pituitary-adrenal axis function and highlight the need to develop treatments targeting the underlying hypothalamic-pituitary-adrenal axis dysregulation.

Genetically Predicted Insomnia in Relation to 14 Cardiovascular Conditions and 17 Cardiometabolic Risk Factors: A Mendelian Randomization Study

Background

This Mendelian randomization study aims to investigate causal associations between genetically predicted insomnia and 14 cardiovascular diseases (CVDs) as well as the potential mediator role of 17 cardiometabolic risk factors.

Methods and Results

Using genetic association estimates from large genome‐wide association studies and UK Biobank, we performed a 2‐sample Mendelian randomization analysis to estimate the associations of insomnia with 14 CVD conditions in the primary analysis. Then mediation analysis was conducted to explore the potential mediator role of 17 cardiometabolic risk factors using a network Mendelian randomization design. After correcting for multiple testing, genetically predicted insomnia was consistent significantly positively associated with 9 of 14 CVDs, those odds ratios ranged from 1.13 (95% CI, 1.08–1.18) for atrial fibrillation to 1.24 (95% CI, 1.16–1.32) for heart failure. Moreover, genetically predicted insomnia was consistently associated with higher body mass index, triglycerides, and lower high‐density lipoprotein cholesterol, each of which may act as a mediator in the causal pathway from insomnia to several CVD outcomes. Additionally, we found very little evidence to support a causal link between insomnia with abdominal aortic aneurysm, thoracic aortic aneurysm, total cholesterol, low‐density lipoprotein cholesterol, glycemic traits, renal function, and heart rate increase during exercise. Finally, we found no evidence of causal associations of genetically predicted body mass index, high‐density lipoprotein cholesterol, or triglycerides on insomnia.

Conclusions

This study provides evidence that insomnia is associated with 9 of 14 CVD outcomes, some of which may be partially mediated by 1 or more of higher body mass index, triglycerides, and lower high‐density lipoprotein cholesterol.

Trait positive affect buffers the association between experimental sleep disruption and inflammation

BACKGROUND

Sleep disturbances and insufficient sleep are highly prevalent. Both clinical sleep disorders and multiple forms of experimental sleep loss predict heightened inflammation. As such, it is necessary to investigate potential protective factors. Given that trait positive affect (PA) is associated with reduced inflammation, and buffers the proinflammatory effects of stress, it is possible that high trait positive affect might protect individuals from an inflammatory response to sleep disruption. The present study tested this hypothesis in an experimental sleep disruption paradigm with assessment of cellular inflammation.

METHODS

Data were drawn from good sleeping adults (n = 79) who participated in a randomized, within-subjects crossover experiment comparing the effects of two nights of sleep disruption versus two nights of uninterrupted sleep. Stimulated monocytic production of intracellular proinflammatory cytokines tumor necrosis factor (TNF) and interleukin-6 (IL-6) were assayed using flow cytometric methods and indexed as the percentage of monocytes expressing TNF, IL-6, or co-expressing both. Hypotheses were evaluated using linear mixed effects models.

RESULTS

Controlling for negative affect, body mass index, age, and sex, PA significantly moderated the associations between sleep condition and stimulated monocyte production of IL-6 (b = -1.03, t = -2.02, p = .048) and its co-expression with TNF (b = -0.93, t = -2.00, p = .049), such that inflammatory responses were blunted among those high in PA with increases principally among those low in PA. The effect on TNF was similar in terms of effect size, but marginally significant.

CONCLUSIONS

Activation of cellular inflammation in response to sleep disruption is buffered by PA independent of negative affect. Interventions that promote PA might protect persons from the inflammatory activation following sleep loss, with the potential to mitigate the adverse health consequences of sleep disturbance.

Autonomic dysregulation and sleep homeostasis in insomnia

STUDY OBJECTIVES

Insomnia is common in older adults, and is associated with poor health, including cognitive impairment and cardio-metabolic disease. Although the mechanisms linking insomnia with these comorbidities remain unclear, age-related changes in sleep and autonomic nervous system (ANS) regulation might represent a shared mechanistic pathway. In this study, we assessed the relationship between ANS activity with indices of objective and subjective sleep quality in older adults with insomnia.

METHODS

Forty-three adults with chronic insomnia and 16 age-matched healthy sleeper controls were studied. Subjective sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI), objective sleep quality by electroencephalogram spectral components derived from polysomnography, and ANS activity by measuring 24-h plasma cortisol and norepinephrine (NE).

RESULTS

Sleep cycle analysis displayed lower slow oscillatory (SO: 0.5-1.25 Hz) activity in the first cycle in insomnia compared to controls. In insomnia, 24-h cortisol levels were higher and 24-h NE levels were lower than controls. In controls, but not in insomnia, there was a significant interaction between NE level during wake and SO activity levels across the sleep cycles, such that in controls but not in insomnia, NE level during wake was positively associated with the amount of SO activity in the first cycle. In insomnia, lower 24-h NE level and SO activity in the first sleep cycle were associated with poorer subjective sleep quality.

CONCLUSION

Dysregulation of autonomic activity may be an underlying mechanism that links objective and subjective measures of sleep quality in older adults with insomnia, and potentially contribute to adverse health outcomes.

Links between objective sleep and sleep variability measures and inflammatory markers in adults with bipolar disorder

Premature mortality and increased physical comorbidity associated with bipolar disorder (BD) may be related to accelerated biological aging. Sleep disturbances and inflammation may be key mechanisms underlying accelerated aging in adults with BD. To our knowledge, these relationships have not been examined rigorously. This cross-sectional study included 50 adults with BD and 73 age- and sex-comparable non-psychiatric comparison (NC) subjects, age 26-65 years. Participants were assessed with wrist-worn actigraphy for total sleep time (TST), percent sleep (PS), and bed/wake times for 7 consecutive nights as well as completing scales for subjective sleep quality. Within-individual variability in sleep measures included intra-individual standard deviation (iSD) and atypicality of one evening's sleep. Blood-based inflammatory biomarkers included interleukin (IL)-6, C-reactive protein (CRP), and tumor necrosis factor-alpha (TNF-α). Linear regression analyses tested relationships of mean and iSD sleep variables with inflammatory marker levels; time-lagged analyses tested the influence of the previous evening's sleep on inflammation. BD participants had worse subjective sleep quality, as well as greater TST iSD and wake time iSD compared to the NC group. In all participants, higher TST iSD and lower mean PS were associated with higher IL-6 levels (p = 0.04, η_p² = 0.042; p = 0.05, η_p² = 0.039, respectively). Lower mean PS was associated with higher CRP levels (p = 0.05, η_p² = 0.039). Atypicality of the previous night's TST predicted next day IL-6 levels (p = 0.05, η_p² = 0.04). All of these relationships were present in both BD and NC groups and remained significant even after controlling for sleep medications. Overall, sleep measures and their variability may influence inflammatory markers in all adults. Thus, sleep may be linked to the inflammatory processes believed to underlie accelerated aging in BD.

Are Anti-Inflammatory Cytokines Associated with Cognitive Impairment in Patients with Insomnia Comorbid with Depression? A Pilot Study

BACKGROUND

To distinguish insomnia comorbid with depression (ICD) from chronic insomnia disorder (CID) by exploring the relationship between serum levels of frequently overlooked anti-inflammatory cytokines and cognitive function.

METHODS

A total of 42 ICD patients, 63 CID patients, and 42 healthy control subjects were enrolled in the study. The Pittsburgh Sleep Quality Index and Hamilton Depression Rating Scale were used to assess sleep quality and depression severity, respectively. The Chinese-Beijing version of Montreal Cognitive Assessment scale (MoCA-C) and Nine-Box Maze Test (NBMT) were used to assess cognitive function. Serum levels of anti-inflammatory interleukins (IL-1RA, IL-4, IL-5, IL-10, IL-13, and IL-28A), transforming growth factor (TGF)-β1, granulocyte-macrophage colony-stimulating factor, interferon-γ, and the chemokine regulated upon activation, normal T cell expressed and secreted (RANTES) were measured by enzyme-linked immunosorbent assay.

RESULTS

The ICD group had significantly more errors in the spatial reference task (H=2.55, P_s=0.03) and spatial working memory task (H=5.67, P_s<0.01) of the NBMT, as well as lower levels of IL-1RA (H=-2.85, P_s=0.01), IL-4 (H=-3.28, P_s<0.01), IL-5 (H=-3.35, P_s<0.01), IL-10 (H=-4.46, P_s<0.01), and IL-28A (H=-2.75, P_s=0.02) than control subjects. Compared with the CID group, the ICD group had significantly more errors in the spatial reference memory task (H=-2.84, P_s=0.01) of the NBMT, and lower levels of IL-5 (H=3.41, P_s<0.01), IL-10 (H=5.30, P_s<0.01), IL-13 (H=3.89, P_s<0.01), and GM-CSF (H=2.72, P_s=0.02). A partial correlation analysis showed that the level of one or more of IL-4, IL-5, IL-10, IL-13, and TGF-β1 was positively correlated with cognitive function (MoCA-C score and/or performance in spatial memory task) in ICD patients.

CONCLUSION

ICD is a distinct condition that can be distinguished from CID based on immune dysfunction and specific types of cognitive dysfunction.

Associations of Sleep Insufficiency and Chronotype with Inflammatory Cytokines in College Students

PURPOSE

Sleep insufficiency and circadian rhythm disturbances in college students have become prominent. Current findings show that sleep insufficiency is closely related to inflammation. Studies on the correlation between chronotype and inflammatory factors are still lacking. Therefore, this research intended to examine the relationships between sleep duration, chronotype and inflammatory cytokines in young adults, and to estimate the correlation between chronotype and inflammatory cytokines stratified by sleep duration.

PATIENTS AND METHODS

We conducted a cross-sectional study in April and May 2019. Participants were recruited from two colleges located in central China. The Pittsburgh Sleep Quality Index (PSQI) and the Morning and Evening Questionnaire-5 (MEQ-5) were administered to assess sleep duration and chronotype. Sleep duration less than 7 hours was defined as insufficient sleep. Fasting venous blood was collected to measure plasma levels of inflammatory markers including IL-1β, IL-6, TNF-α and IL-10.

RESULTS

A total of 723 participants were included in this study, with a mean age of 18.68 years (standard deviation=0.99). After adjusting for confounding factors, the results of generalized linear model showed that sleep insufficiency was positively correlated with IL-1β, TNF-α and IL-10; and evening-types (E-types) were positively associated with the levels of IL-1β and IL-6 (p<0.05). Compared to the control group (sleep sufficiency and M-types), there were positive interaction effects of sleep insufficiency and neutral-types (N-types) on the levels of IL-1β, IL-6, TNF-α and IL-10 (p<0.05). The hierarchical regression model showed that N-types and E-types were positively correlated to the levels of IL-1β, IL-6, TNF-α and IL-10 among college students with sleep insufficiency (p<0.05).

CONCLUSION

The levels of inflammatory markers were higher among college students with sleep insufficiency and E-types. N-types and E-types were positively correlated with IL-1β, IL-6, TNF-α and IL-10 among college students with sleep insufficiency.

An exploration of employee dreams: The dream-based overnight carryover of emotional experiences at work

OBJECTIVE

We sought to explore the manner in which daily challenge and hindrance stressors at work may be associated with mood the next day, through the mediating mechanisms of presleep rumination and moods experienced while asleep during dreams.

METHODS

A daily diary study in which 94 adults with full-time jobs completed 2 surveys per day for 2 work weeks. Each morning, participants reported the degree to which they engaged in rumination before sleep the previous night, the affective tone of their dreams, and their mood at that moment. Each evening participants reported their experiences of challenge and hindrance stressors at work that day.

RESULTS

Hindrance stressors were positively related to next-morning negative affect via the effects of rumination and negative affect in dreams. Challenge stressors negatively related to positive affect in the morning, via rumination and lowered positive affect in dreams. These results occurred above and beyond the effects of sleep quantity, sleep quality, and several other time-based control variables.

CONCLUSIONS

Dreams play an important role in how work stressors which are experienced in a given workday are associated with mood the next morning.

Treating sleep disorders to improve blood pressure control and cardiovascular prevention: a dream come true?-a narrative review

Hypertension is one of the primary risk factors for heart disease and stroke, the leading causes of death worldwide. Current evidence supports the treatment of high blood pressure (BP) values in order to obtain a substantial reduction of cardiovascular burden. Sleep plays an important role in maintaining nocturnal BP control and nocturnal hypertension which, in turn, can be affected by the presence of sleep disorders. Whilst respiratory disturbances have been extensively studied and their causal role in the development of nocturnal hypertension has been demonstrated in both cross sectional and prospective studies, less is known about the impact of other sleep disorders such as insomnia. In this review, we aim to describe the role of sleep disorders in the development of nocturnal and diurnal hypertension. Furthermore, we aim to discuss the potential impact of the treatment of such sleep disorders on BP values as an adjunct treatment for patients with hypertension.

The Effects of Dietary Nutrition on Sleep and Sleep Disorders

Sleep disorder significantly affects the life quality of a large number of people but is still an underrecognized disease. Dietary nutrition is believed to play a significant impact on sleeping wellness. Many nutritional supplements have been used trying to benefit sleep wellness. However, the relationship between nutritional components and sleep is complicated. Nutritional factors vary dramatically with different diet patterns and depend significantly on the digestive and metabiotic functions of each individual. Moreover, nutrition can profoundly affect the hormones and inflammation status which directly or indirectly contribute to insomnia. In this review, we summarized the role of major nutritional factors, carbohydrates, lipids, amino acids, and vitamins on sleep and sleep disorders and discussed the potential mechanisms.

Both objective and paradoxical insomnia elicit a stress response involving mitokine production

Chronic insomnia is the most common sleep disorder in the elderly population. From 9 to 50% of patients suffer of paradoxical insomnia, with the same symptoms and ailments, though characterized by normal sleep patterns. We have investigated the level of parameters related to stress in a group of post-menopausal female patients (age range 55-70 years) suffering by either objective or paradoxical insomnia, in particular we have measured 24-hours urinary cortisol, allostatic load index, Perceived Stress Scale (PSS) score, and, for the first time, mitokines (mitochondrial stress response molecules) such as FGF21, GDF15 and Humanin (HN). Results show that the two groups are different as far as sleep efficiency score, as expected, but not for stress parameters, that in some cases resulted within the normality range, although quite close to the top threshold (such as cortisol) or much higher with respect to normality ranges (such as PSS). Therefore, the consequences of paradoxical insomnia on the expression of these parameters are the same as objective insomnia. As far as the level of mitokines, we showed that FGF21 and HN in particular resulted altered (decreased and increased, respectively) with respect to control population, however with no difference between the two groups of patients.

Onset of regular cannabis use and young adult insomnia: an analysis of shared genetic liability

STUDY OBJECTIVES

Estimate the genetic and environmental influences on the relationship between onset of regular cannabis use and young adult insomnia.

METHODS

In a population-based twin cohort of 1882 twins (56% female, mean age = 22.99, SD = 2.97) we explored the genetic/environmental etiology of the relationship between onset of regular cannabis use and insomnia-related outcomes via multivariate twin models.

RESULTS

Controlling for sex, current depression symptoms, and prior diagnosis of an anxiety or depression disorder, adult twins who reported early onset for regular cannabis use (age 17 or younger) were more likely to have insomnia (β = 0.07, p = 0.024) and insomnia with short sleep on weekdays (β = 0.08, p = 0.003) as young adults. We found significant genetic contributions for the onset of regular cannabis use (a2 = 76%, p < 0.001), insomnia (a2 = 44%, p < 0.001), and insomnia with short sleep on weekdays (a2 = 37%, p < 0.001). We found significant genetic correlations between onset of regular use and both insomnia (rA = 0.20, p = 0.047) and insomnia with short sleep on weekdays (rA = 0.25, p = 0.008) but no significant environmental associations between these traits.

CONCLUSIONS

We found common genetic liabilities for early onset of regular cannabis use and insomnia, implying pleiotropic influences of genes on both traits.

Sleep and inflammation: partners in sickness and in health

The discovery of reciprocal connections between the central nervous system, sleep and the immune system has shown that sleep enhances immune defences and that afferent signals from immune cells promote sleep. One mechanism by which sleep is proposed to provide a survival advantage is in terms of supporting a neurally integrated immune system that might anticipate injury and infectious threats. However, in modern times, chronic social threats can drive the development of sleep disturbances in humans, which can contribute to the dysregulation of inflammatory and antiviral responses. In this Review, I describe our current understanding of the relationship between sleep dynamics and host defence mechanisms, with a focus on cytokine responses, the neuroendocrine and autonomic pathways that connect sleep with the immune system and the role of inflammatory peptides in the homeostatic regulation of sleep. Furthermore, I discuss the therapeutic potential of harnessing these reciprocal mechanisms of sleep-immune regulation to mitigate the risk of inflammatory and infectious diseases.

Acute and Chronic Insomnia: What Has Time and/or Hyperarousal Got to Do with It?

Nearly one-third of the population reports new onset or acute insomnia in a given year. Similarly, it is estimated that approximately 10% of the population endorses sleep initiation and maintenance problems consistent with diagnostic criteria for chronic insomnia. For decades, acute and chronic insomnia have been considered variations of the same condition or disorder, only really differentiated in terms of chronicity of symptoms (days/weeks versus months). Whether or not acute and chronic insomnia are part of the same phenomena is an important question, one that has yet to be empirically evaluated. The goal of the present theoretical review was to summarize the definitions of acute and chronic insomnia and discuss the role that hyperarousal may have in explaining how the pathophysiology of acute and chronic insomnia is likely different (i.e., what biopsychological factors precipitate and/or perpetuate acute insomnia, chronic insomnia, or both?).

Objective Short Sleep Duration is Related to the Peripheral Inflammasome Dysregulation in Patients with Chronic Insomnia

OBJECTIVE

Insomnia with objective short sleep duration (IOSSD) is associated with an increased risk of cardiovascular morbidity, diabetes, neurocognitive impairment, and mortality. Inflammation is believed to be one of the main links between IOSSD and these diseases. The role of nucleotide-binding domain and leucine-rich repeat protein-3 (NLRP3) inflammasome in inducing activation of inflammatory signaling in IOSSD is not clear. In this study, we investigated the expression of NLRP3 inflammasome in patients with IOSSD to clarify this issue.

METHODS

Thirty-six patients with insomnia and 20 age- and sex-matched healthy controls were sequentially recruited. Subjects were categorized into three groups: IOSSD (sleep duration < 6h, n=20), insomnia with objective normal sleep duration (IONSD, sleep duration ≥ 6h, n=16) and healthy controls (n=20). Objective sleep parameters were measured by overnight polysomnography. Peripheral NLRP3 inflammasome protein levels [NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), caspase l] and cytokines [interleukin (IL)-1β and IL-18] were assessed by Western blotting and ELISA, respectively.

RESULTS

IOSSD group showed significantly increased protein expressions of ASC and caspase-1 compared to IONSD and healthy controls and significantly increased IL-18 levels compared to healthy controls. On correlation analysis, total sleep time showed an inverse correlation with NLRP3, ASC, IL-18, and IL-1β levels. Wake after sleep onset (WASO) showed a positive correlation with NLRP3, ASC, caspase-1, and IL-1β levels. N3 sleep ratio showed a significant negative correlation with NLRP3, ASC, and IL-18 levels.

CONCLUSION

The current study demonstrated upregulation of NLRP3 inflammasome in IOSSD. Short sleep duration, decreased slow wave sleep, and sleep fragmentation may contribute to dysregulation of NLRP3 inflammasome.

Objective sleep duration is associated with cognitive deficits in primary insomnia: BDNF may play a role

Study Objectives

Objective sleep duration has been linked to insomnia severity. However, cognitive functions of people with insomnia with different sleep durations have been seldom addressed. Brain-derived neurotrophic factor (BDNF) has an important role in cognitive function and has been linked to clinical insomnia recently. The present study aimed to evaluate the comprehensive cognitive functions in people with primary insomnia with different objective sleep durations, and further examine the involvement of peripheral BDNF.

Methods

Fifty-seven people with insomnia were subdivided into short sleep duration (SSD, sleep time < 6 hr) group and normal sleep duration (NSD, sleep time ≥ 6 hr) group based on polysomnography data. Twenty-nine healthy controls (HC) were matched on age, gender, and education. Cognitive function was assessed using a comprehensive and sensitive neuropsychological test battery. Both objective and subjective insomnia statuses were estimated. Serum BDNF level was measured using enzyme-linked immune sorbent assay.

Results

Compared with HC, the SSD group showed impaired neuropsychological performances in spatial span, brief visuospatial memory test, fluency, managing emotions, and continuous performance tests. In contrast, NSD had bad performance only in brief visuospatial memory test and continuous performance tests, and relatively better than SSD group in the latter test. People with SSD insomnia but not NSD had decreased BDNF levels compared with HC, and neuropsychological performance was positively correlated with BDNF levels only in SSD group.

Conclusions

Primary insomnia was associated with impaired neuropsychological performance, and the impairment might be related to decreased objective sleep duration. In addition, decreased peripheral BDNF might mediate the impaired cognitive functions of people with insomnia with SSD.

Maternal tiredness and cytokine concentrations in mid-pregnancy

OBJECTIVE

Sleep disturbances relate to altered levels of inflammatory mediators in general population, but not much is known about the associations between sleep disturbances and inflammatory mediators during pregnancy. The present exploratory study investigated whether insomnia, tiredness, general sleep quality, and insufficient sleep duration during pregnancy relate to the concentrations of maternal peripheral circulating cytokines. As sleep disturbances are frequently observed in mood disorders, the results were controlled for symptoms of depression and anxiety.

METHODS

137 participants were randomly drawn from a representative FinnBrain Birth Cohort. Serum concentrations of selected cytokines were analyzed using Multiplex bead arrays from blood samples drawn at the gestational week 24. The sleep disturbances were evaluated using the Basic Nordic Sleep Questionnaire. Depressive and anxiety symptoms were measured with the Edinburgh Postnatal Depression Scale and the anxiety subscale of the self-rated Symptom Checklist 90, respectively.

RESULTS

Enhanced tiredness was associated with cytokine concentrations of IL-2, IL-10, IL-12, IL-13, and TNF-α. The observed associations resembled a reversed U-shaped curve rather than being linear. Having a good general sleep quality was associated with higher logarithmic cytokine concentrations of IL-2, IL-4, IL-6, IL-10, IL-12, IL-13, and IFN-γ. There was no evidence for associations between insomnia or sleep loss and cytokines.

CONCLUSIONS

Maternal subjective tiredness and good general sleep quality were associated with altered levels of immunological markers during pregnancy. The association was independent from symptoms of depression and anxiety.

Clinical Pain-related Outcomes and Inflammatory Cytokine Response to Pain Following Insomnia Improvement in Adults With Knee Osteoarthritis

OBJECTIVES

Clinical insomnia is known to affect pain, but mechanisms are unclear. Insomnia can dysregulate inflammatory pathway, and inflammation plays a mediating role in pain. It is unclear whether insomnia-related alterations in inflammation can be modified with insomnia improvement, and if such alterations parallel improvement in pain. The current study objective was to provide proof of concept for the role of insomnia in inflammation and pain by testing whether improving insomnia would reduce pain and related physical function, and, concurrently, modulate inflammatory responses.

MATERIALS AND METHODS

Thirty adults with osteoarthritis knee pain and insomnia (Insomnia Severity Index >10) provided baseline measures of osteoarthritis and laboratory pain, and serial blood samples for inflammatory biomarkers, interleukin 6, and tumor necrosis factor α, before and after pain testing. To manipulate insomnia, participants were randomly assigned to a 6-week cognitive-behavioral therapy for insomnia (n=16); or wait-list control (n=14). At 8-weeks (time 2), all measures were repeated. To directly test insomnia improvement effects, participants were grouped by insomnia status at time 2 after confirming baseline equivalency on all outcomes.

RESULTS

Compared with those maintaining insomnia at time 2 (Insomnia Severity Index ≥8; n=18), those whose insomnia improved at time 2 (n=12) had significantly improved physical functioning, decline in knee pain during transfer activities, and attenuated increase in interleukin 6 and less decrease in tumor necrosis factor α across the pain testing session.

DISCUSSION

These findings suggest further exploration of inflammatory pathways linking clinical insomnia, and its improvement, to chronic pain.

Mothers' postpartum sleep disturbance is associated with the ability to sustain sensitivity toward infants

BACKGROUND/OBJECTIVE

Infancy is a period of rapid development when the quality of caregiving behavior may be particularly consequential for children's long-term functioning. During this critical period for caregiving behavior, parents experience changes in their sleep that may affect their ability to provide sensitive care. The current study investigated the association of mothers' sleep disturbance with both levels and trajectories of maternal sensitivity during interactions with their infants.

METHODS

At 18 weeks postpartum, mothers and their infants were observed during a home-based 10-minute "free play" interaction. Mothers' nighttime sleep was objectively measured using actigraphy and subjectively measured using sleep diaries. Maternal sensitivity was coded in two-minute intervals in order to characterize changes in sensitivity across the free play interaction. We used exploratory factor analysis to reduce the dimensionality of the objective and subjective measures of mothers' sleep, identifying a subjective sleep disturbance and an objective sleep continuity factor.

RESULTS

Using multi-level modeling, we found that mothers with poorer objective sleep continuity evidenced decreasing sensitivity toward their infants across the interaction. Mothers' self-reports of sleep disturbance were not associated with maternal sensitivity.

CONCLUSIONS

Although future research is necessary to identify the mechanisms that may explain the observed association between poor sleep continuity and the inability to sustain sensitivity toward infants, mothers' postpartum sleep continuity may be one factor to consider when designing interventions to improve the quality of caregiving.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov, NCT01846585.

The Sleep-Immune Crosstalk in Health and Disease

Sleep and immunity are bidirectionally linked. Immune system activation alters sleep, and sleep in turn affects the innate and adaptive arm of our body's defense system. Stimulation of the immune system by microbial challenges triggers an inflammatory response, which, depending on its magnitude and time course, can induce an increase in sleep duration and intensity, but also a disruption of sleep. Enhancement of sleep during an infection is assumed to feedback to the immune system to promote host defense. Indeed, sleep affects various immune parameters, is associated with a reduced infection risk, and can improve infection outcome and vaccination responses. The induction of a hormonal constellation that supports immune functions is one likely mechanism underlying the immune-supporting effects of sleep. In the absence of an infectious challenge, sleep appears to promote inflammatory homeostasis through effects on several inflammatory mediators, such as cytokines. This notion is supported by findings that prolonged sleep deficiency (e.g., short sleep duration, sleep disturbance) can lead to chronic, systemic low-grade inflammation and is associated with various diseases that have an inflammatory component, like diabetes, atherosclerosis, and neurodegeneration. Here, we review available data on this regulatory sleep-immune crosstalk, point out methodological challenges, and suggest questions open for future research.

Sleep characteristics and inflammatory biomarkers among midlife women

Study Objectives

Research suggests that sleep disturbances are associated with elevated levels of inflammation. Some evidence indicates that women may be particularly vulnerable; increased levels of inflammatory biomarkers with sleep disturbances are primarily observed among women. Midlife, which encompasses the menopause transition, is typically reported as a time of poor sleep. We tested whether poorer objectively measured sleep characteristics were related to a poorer inflammatory profile in midlife women.

Methods

Two hundred ninety-five peri- and postmenopausal women aged 40-60 completed 3 days of wrist actigraphy, physiologic hot flash monitoring, questionnaires (e.g. Berlin sleep apnea risk questionnaire], and a blood draw for the assessment of inflammatory markers, including C-reactive protein (CRP), interleukin-6 (IL-6), and von Willebrand factor (VWF) antigen. Associations of objective (actigraphy) sleep with inflammatory markers were tested in regression models. Sleep efficiency was inverse log transformed. Covariates included age, race/ethnicity, education, body mass index, sleep apnea risk, homeostatic model assessment (a measure of insulin resistance), systolic blood pressure, low-density lipoprotein cholesterol, and physical activity.

Results

In separate models controlling for age, race/ethnicity, and education, lower sleep efficiency was associated with higher IL-6 [b(SE) = .02 (.10), p = .003] and VWF [b(SE) = .02 (.08), p = .002]. More minutes awake after sleep onset was associated with higher VWF [b(SE) = .12 (.06), p = .01]. Findings persisted in multivariable models.

Conclusions

Lower sleep efficiency and more minutes awake after sleep onset were independently associated with higher circulating levels of VWF. Lower sleep efficiency was associated with higher circulating levels of IL-6. These findings suggest that sleep disturbances are associated with greater circulating inflammation in midlife women.

Sleep Architecture and Hypothalamic-Pituitary-Adrenal Activity in Paradoxical and Psychophysiological Insomnia

Introduction:

There are controversial reports about association between sleep and Hypothalamic-Pituitary-Adrenal (HPA) activity. Studies have reported the influence of insomnia on HPA hormones. However, they usually ignored the heterogeneity of insomnia symptoms, so subtypes of the disorder have not been considered in the reports. The present study aimed to investigate the final and intermediate products of HPA system among a group of psychophysiological and paradoxical insomniac patients in comparison to a group of normal sleepers.

Methods:

We investigated the awakening serum level of Adrenocorticotropic Hormone (ACTH) and cortisol after one night Polysomnography (PSG) in 17 subjects with psychophysiological insomnia, 19 subjects with paradoxical insomnia and 17 subjects with normal sleep profile. Groups were matched for age and Body Mass Index (BMI). Serum levels of ACTH and cortisol were measured by Enzyme-Linked Immunosorbent Assay (ELISA) method.

Results:

Although, a tendency toward elevation of both ACTH and cortisol was observed among patients with paradoxical insomnia compared to both control and psychophysiological insomnia, the differences were not significant comparing three groups. According to regression analysis, higher Non-Rapid Eye Movement sleep (NREM) arousal and Pulse Transit Time (PTT) significantly predicted higher level of ACTH.

Conclusion:

These findings could suggest the personality traits hypothesis for paradoxical insomnia. Both cortical and subcortical arousal could lead to more HPA activity and higher ACTH level. Further studies are recommended to confirm the hypothesis.

Insomnia and hypertension: A systematic review

Insomnia is a prevalent sleep disorder that is associated with a multitude of health consequences. Particularly, insomnia has been associated with cardiovascular disease and its precursors, such as hypertension and blood pressure (BP) non-dipping. The present systematic review aimed to summarize the evidence on the concurrent and prospective associations between insomnia and hypertension and/or BP. Using electronic search engines (PubMed, SCOPUS, PsycINFO), 5,618 articles published from January 1970 to December 2017 were identified, and 64 met the inclusion criteria (26 to 162,121 participants; age range: 18-100; 46.4% male). Insomnia was based on diagnostic or non-diagnostic criteria. Hypertension was based on self-or physician-reports, antihypertensive medication use, and/or measured BP. Findings indicate that when insomnia is frequent, chronic, and/or accompanied with short sleep duration or objective markers of arousal, there is a strong association with hypertension/BP. Based on limited studies, hypertension did not significantly predict future insomnia in middle-aged adults, but did in older adults. Based on a majority of case-control studies, no differences in BP were found between participants with and without insomnia. Further research is needed to identify putative pathophysiological mechanisms underlying the link between insomnia and hypertension. The impact of insomnia therapy on BP should also be further examined in the future.

Altered ultradian cortisol rhythmicity as a potential neurobiologic substrate for chronic insomnia

Chronic insomnia is highly prevalent and associated with significant morbidity (i.e., confers risk for multiple psychiatric and medical disorders, such as depression and hypertension). Therefore, it is essential to identify factors that perpetuate this disorder. One candidate factor in the neurobiology of chronic insomnia is hypothalamic-pituitary-adrenal-axis dysregulation, and in particular, alterations in circadian cortisol rhythmicity. Cortisol secretory patterns, however, fluctuate with both a circadian and an ultradian rhythm (i.e., pulses every 60-120 min). Ultradian cortisol pulses are thought to be involved in the maintenance of wakefulness during the day and their relative absence at night may allow for the consolidation of sleep and/or shorter nocturnal awakenings. It is possible that the wakefulness that occurs in chronic insomnia may be associated with the aberrant occurrence of cortisol pulses at night. While cortisol pulses naturally occur with transient awakenings, it may also be the case that cortisol pulsatility becomes a conditioned phenomenon that predisposes one to awaken and/or experience prolonged nocturnal awakenings. The current review summarizes the literature on cortisol rhythmicity in subjects with chronic insomnia, and proffers the suggestion that it may be abnormalities in the ultradian rather than circadian cortisol that is associated with the pathophysiology of insomnia.

Use of Actigraphy for the Evaluation of Sleep Disorders and Circadian Rhythm Sleep-Wake Disorders: An American Academy of Sleep Medicine Systematic Review, Meta-Analysis, and GRADE Assessment

INTRODUCTION

The purpose of this systematic review is to provide supporting evidence for a clinical practice guideline on the use of actigraphy.

METHODS

The American Academy of Sleep Medicine commissioned a task force of experts in sleep medicine. A systematic review was conducted to identify studies that compared the use of actigraphy, sleep logs, and/or polysomnography. Statistical analyses were performed to determine the clinical significance of using actigraphy as an objective measure of sleep and circadian parameters. Finally, the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) process was used to assess the evidence for making recommendations.

RESULTS

The literature search resulted in 81 studies that met inclusion criteria; all 81 studies provided data suitable for statistical analyses. These data demonstrate that actigraphy provides consistent objective data that is often unique from patient-reported sleep logs for some sleep parameters in adult and pediatric patients with suspected or diagnosed insomnia, circadian rhythm sleep-wake disorders, sleep-disordered breathing, central disorders of hypersomnolence, and adults with insufficient sleep syndrome. These data also demonstrate that actigraphy is not a reliable measure of periodic limb movements in adult and pediatric patients. The task force provided a detailed summary of the evidence along with the quality of evidence, the balance of benefits and harms, patient values and preferences, and resource use considerations.

Glucocorticoid and inflammatory reactivity to a repeated physiological stressor in insomnia disorder

Despite known associations of insomnia disorder with alterations in cytokine and glucocorticoid (GC) production, neither the sensitivity of immune cells to a GC signal nor the reactivity of the hypothalamus-pituitary-adrenal (HPA) axis and inflammatory system to stress, or adaptation of these systems to repeated stress have been assessed in patients with insomnia. To investigate potential dysregulation in stress reactivity and adaptation to repeated exposure, a physiological stressor (the cold pressor test; CPT) was repeatedly administered to N = 20 participants with insomnia disorder (based on DSM-V, 18 females, age 30 ± 2.5 years) and N = 20 sex-matched healthy controls following an at-home actigraphy and in-laboratory PSG. HPA and inflammatory markers (serum cortisol, plasma interleukin [IL]-6) were measured at baseline/resting levels and following each of the three CPTs. In addition, sensitivity of monocytes to the synthetic GC dexamethasone was assessed in-vitro at baseline levels in order to examine the cortisol-IL-6 interplay at the cell level. Compared to healthy controls, individuals with insomnia disorder exhibited shorter sleep duration as assessed by actigraphy and PSG (p ≤ 0.05). HPA, but not inflammatory reactivity to the repeated CPT challenge was greater in insomnia disorder (p ≤ 0.05 for group effect), due to greater cortisol responses to the initial CPT (p ≤ 0.05). There were no between-group differences in the ability of the HPA to adapt to stress repetition nor in basal/resting levels of cortisol, IL-6, and GC sensitivity. These findings suggest that insomnia disorder potentiates HPA axis reactivity to initial/novel stressors, which may constitute a pathway underlying adverse health consequences in the long term.

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Insomnia disorder potentiates HPA, but not inflammatory reactivity to a novel stressor.

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The ability of the HPA axis to adapt to the repeated exposure to the same stressor is unchanged in insomnia.

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Basal/resting levels of cortisol, IL-6, and their interplay at cell level (i.e., GC sensitivity of monocytes) are unchanged in insomnia.