Chronic insomnia and activity of the stress system: a preliminary study

Association Between Sleep Reactivity, Pre-Sleep Arousal State, and Neuroendocrine Hormones in Patients with Chronic Insomnia Disorder

Purpose

The purpose of this study was to look into the relationship between pre-sleep arousal state, sleep reactivity, and serum levels of neuroendocrine hormones (cortisol, copeptin, and corticotropin-releasing hormone) in patients with chronic insomnia disorders (CID), and whether the effects of sleep reactivity and pre-sleep arousal on insomnia are related to the levels of these neuroendocrine hormones.

Patients and Methods

This study included 61 CID patients and 27 healthy controls (HC) whose base data were matched to those of the CID patients. The Pittsburgh Sleep Quality Index(PSQI), Pre-Sleep Arousal Scale (PSAS), and the Ford Insomnia Response to Stress Test (FIRST) were used to evaluate the participants' sleep, stress, and neuropsychological function. We measured the participants' serum concentration levels of cortisol, copeptin, and corticotropin-releasing hormone (CRH), using quantitative sandwich enzyme-linked immunosorbent assays.

Results

The CID group had significantly greater serum levels of copeptin, CRH, and cortisol, as well as higher FIRST and PSAS scores than the HC group. The partial correlation analysis revealed a substantial and positive association among cortisol, CRH, copeptin PSQI, PSAS, and FIRST after adjusting for sex, age, depression, and cognition. Principal component analysis showed that PSQI, FIRST, and PSAS, as well as cortisol, CRH, and copeptin, were all loaded on factor 1.

Conclusion

Patients with CID showed increased sleep reactivity and pre-sleep arousal, which correlated with serum levels of cortisol, copeptin, and CRH. Changes in neuroendocrine hormone levels may influence how pre-sleep arousal and sleep reactivity affect the development of insomnia.

Associations between insomnia and cardiovascular diseases: a meta-review and meta-analysis of observational and Mendelian randomization studies

STUDY OBJECTIVES

Observational studies suggest associations between insomnia and cardiovascular diseases (CVDs), but the causal mechanism remains unclear. We investigated the potential causal associations between insomnia and CVDs by a combined systematic meta-review and meta-analysis of observational and Mendelian randomization studies.

METHODS

We searched PubMed, Web of Science, and Embase for English-language articles from inception to July 11, 2023. Two reviewers independently screened the articles to minimize potential bias. We summarized the current evidence on the associations of insomnia with coronary artery disease, atrial fibrillation, heart failure, myocardial infarction, hypertension, and stroke risk by combining meta-analyses of observational and Mendelian randomization studies.

RESULTS

Four meta-analyses of observational studies and 9 Mendelian randomization studies were included in the final data analysis. A systematic meta-review of observational studies provided strong evidence that insomnia is an independent risk factor for many CVDs, including atrial fibrillation, myocardial infarction, and hypertension. A meta-analysis of Mendelian randomization studies revealed that insomnia may be potentially causally related to coronary artery disease (odds ratio [OR] = 1.14, 95% confidence interval [CI] = 1.10-1.19, I2 = 97%), atrial fibrillation (OR = 1.02, 95% CI = 1.01-1.04, I2 = 94%), heart failure (OR = 1.04, 95% CI = 1.03-1.06, I2 =97%), hypertension (OR = 1.16, 95% CI = 1.13-1.18, I2 = 28%), large artery stroke (OR = 1.14, 95% CI = 1.05-1.24, I2 = 0%), any ischemic stroke (OR = 1.09, 95% CI = 1.03-1.14, I2 = 60%), and primary intracranial hemorrhage (OR = 1.16, 95% CI = 1.05-1.27, I2 = 0%). No evidence suggested that insomnia is causally associated with cardioembolic or small vessel stroke.

CONCLUSIONS

Our results provide strong evidence supporting a possible causal association between insomnia and CVD risk. Strategies to treat insomnia may be promising targets for preventing CVDs.

CITATION

Zhang X, Sun Y, Ye S, et al. Associations between insomnia and cardiovascular diseases: a meta-review and meta-analysis of observational and Mendelian randomization studies. J Clin Sleep Med. 2024;20(12):1975-1984.

Insomnia disorder is associated with 24-hour cortical hyperarousal

OBJECTIVE

Cortical hyperarousal has been proposed as a primary underlying mechanism for insomnia disorder. However, most evidence comes from nighttime sleep and whether patients with insomnia disorder have cortical hyperarousal through the 24-h sleep/wake cycle is not resolved.

METHODS

We included 49 patients with insomnia disorder and 49 age-and sex-matched normal sleepers. All participants underwent an over-night polysomnography followed by a Multiple Sleep Latency Test during daytime. Nighttime and daytime delta, theta, alpha, sigma and beta relative power at central electroencephalogram derivations during wakefulness and non-rapid eye movement (NREM) sleep were calculated. Insomnia disorder was defined based on the International Classification of Sleep Disorders Third Edition criteria. Insomnia with objective short sleep duration was defined as patients with insomnia who slept <7 h based on nighttime polysomnography recording.

RESULTS

Compared to normal sleepers, patients with insomnia disorder had significantly higher nighttime (P = 0.040) and daytime (P = 0.021) relative electroencephalogram power in beta during NREM sleep and marginally significantly lower relative electroencephalogram power in theta (P = 0.060) during nighttime wakefulness. Furthermore, linear trend association was observed across normal sleepers, and patients with insomnia who slept ≥7 h and insomnia who slept <7 h in relative electroencephalogram power in beta during nighttime and daytime NREM sleep, and relative electroencephalogram power in theta during nighttime wakefulness (all P for trend <0.05).

CONCLUSION

Increased high-frequency electroencephalogram power during nighttime and daytime sleep suggests that insomnia is a disorder of 24-h cortical hyperarousal. Decreasing both nighttime and daytime cortical arousal levels should be our therapeutic target for insomnia.

Insomnia and risk of mortality in older adults

Existing evidence linking insomnia to all-cause mortality in older individuals remains inconclusive. We conducted a retrospective study of a large cohort of veterans aged 65-80 years old identified from the Corporate Data Warehouse, a large data repository derived from the Veterans Health Administration integrated medical records. Veterans' enrollees with and without International Classification of Diseases, Ninth and Tenth Revision, codes corresponding to insomnia diagnosis between 1 January 2010 and 30 March 2019 were assessed for eligibility. The primary outcome was all-cause mortality. A total of 36,269 veterans, 9584 with insomnia and 26,685 without insomnia, were included in the analysis. Baseline mean (SD) age was 72.6 (4.2) years. During a mean follow-up of 6.0 (2.9) years of the propensity score matched sample, the mortality rate was 34.8 [95% confidence interval: 33.2-36.6] deaths per 1000 person-years among patients with insomnia compared with 27.8 [95% confidence interval: 26.6-29.1] among patients without insomnia. In a Cox proportional hazards model, insomnia was significantly associated with higher mortality (hazard ratio: 1.39; [95% confidence interval: 1.27-1.52]). Patients with insomnia also had a higher risk of non-fatal cardiovascular events (hazard ratio: 1.21; [95% confidence interval: 1.06-1.37]). Secondary stratified analyses by sex, race, ethnicity and hypertension showed no evidence of effect modification. A higher risk of mortality (hazard ratio: 1.51; [95% confidence interval: 1.33-1.71]) was observed when depression was present compared with absent (hazard ratio: 1.26; [95% confidence interval: 1.12-1.44]; p = 0.02). In this cohort study, insomnia was associated with increased risk-adjusted mortality and non-fatal cardiovascular events in older individuals.

An integrated multi-omics analysis identifies novel regulators of circadian rhythm and sleep disruptions under unique light environment in Antarctica

Light is the dominant zeitgeber for biological clocks, and its regulatory mechanism for sleep-wake activity has been extensively studied. However, the molecular pathways through which the unique Antarctic light environment, with polar days in summer and polar nights in winter, affects human sleep and circadian rhythm remain largely unidentified, although previous studies have observed delayed circadian rhythm and sleep disruptions among expeditioners during polar nights. In this study, we conducted comprehensive dynamic research on the expeditioners residing in Antarctica for over one year. By integrating the phenotypic changes with multi-omics data, we tried to identify the novel candidate regulators and their correlation networks involved in circadian and sleep disorders under abnormal light exposure. We found that during the austral winter, expeditioners exhibited delayed bedtime and getting up time, reduced sleep efficiency, and increased sleep fragmentation. Meanwhile, serum dopamine metabolite levels significantly increased, while serotonin metabolites and antioxidants decreased. These changes were accompanied by altered expression of genes and proteins associated with neural functions, cellular activities, transcriptional regulation, and so on. Through the correlation and causal mediation analysis, we identified several potential pathways modulating human sleep-wake activity, involving genes and proteins related to neural function, glucose metabolism, extracellular matrix homeostasis, and some uncharacterized lncRNAs. Based on the identified causal mediators, LASSO regression analysis further revealed a novel candidate gene, Shisa Family Member 8 (SHISA8), as a potential key regulatory hub in this process. These findings shed light on the probable molecular mechanisms of sleep disorders in Antarctica and suggest SHISA8 as a novel candidate target for medical intervention in sleep disorders under unique light environments.

Genetically predicted smoking and body mass index mediate the relationship between insomnia and myocardial infarction

Objective

This study aimed to investigate the causal relationship between insomnia and the risk of myocardial infarction (MI) and explore potential mediators such as smoking initiation, alcohol consumption and body mass index (BMI) using mendelian randomization (MR) analysis.

Methods

Data from 1,207,228 individuals of European ancestry were obtained from the UK Biobank and 23andMe for insomnia-related genetic associations. Genetic instruments for MI, smoking initiation, alcohol consumption, and BMI were derived from large-scale genome-wide association studies. Univariate MR analysis mainly utilized the inverse variance weighting method, and multivariable MR analysis assessed the mediation effects of smoking initiation and BMI.

Results

The univariate MR analysis revealed a 96% increased risk of MI in individuals with insomnia [odds ratio (OR) = 1.96; 95% CI: 1.67, 2.31]. Smoking initiation and BMI were identified as potential mediators. The multivariable MR analysis indicated smoking initiation accounted for 29% of the total effect (95% CI: 13%, 61%), while BMI accounted for 15% (95% CI: 7%, 27%), with a combined mediation proportion of 54% (95% CI: 31%, 91%).

Conclusions

The results of this MR analysis demonstrate that insomnia increases the risk of MI. Quitting smoking and losing weight may reduce this risk; however, there is still a portion of the impact of insomnia on MI that cannot be explained. Therefore, further investigation into other potentially modifiable intermediate factors is necessary.

Sleep disturbances and psychomotor retardation in the prediction of cognitive impairments in patients with major depressive disorder

BACKGROUND

Symptoms of depression and comorbid anxiety are known risk factors for cognitive impairment in major depressive disorder (MDD). Understanding their relationships is crucial for developing targeted interventions to mitigate cognitive impairments in MDD patients. We expect that the severity of sleep disturbances and other depressive symptoms will be positively correlated with the degree of cognitive impairments. We also hypothesize that anxiety symptoms, especially psychic anxiety, is a key factor in predicting cognitive performance in MDD patients and may indirectly contribute to cognitive impairment by affecting sleep disturbances and other potential factors.

AIM

To determine which dimension of the depressive and anxiety symptoms predicts cognitive impairment during a depressive episode.

METHODS

A comprehensive neurocognitive test battery assessed executive function, attention, processing speed, and memory in 162 medication-free MDD patients and 142 matched healthy controls. The 24-item Hamilton Depression Rating Scale was used to assess depressive symptoms, and the 14-item Hamilton Anxiety Scale was used to assess anxiety symptoms. Linear regression analyses and mediation analyses were conducted to evaluate the impact of depressive and anxiety symptoms, as well as their interactions, on cognitive impairments.

RESULTS

Among the depressive symptoms, sleep disturbances were associated with poorer executive function (P = 0.004), lower processing speed (P = 0.047), and memory impairments (P < 0.001), and psychomotor retardation (PR) was associated with lower processing speed in patients with MDD (P = 0.019). Notably, PR was found to mediate the impact of sleep disturbances on the processing speed. Regarding anxiety symptoms, psychic anxiety, rather than somatic anxiety, was associated with cognitive impairments in all aspects. Sleep disturbances mediated the effect of psychic anxiety on executive function [β = -0.013, BC CI (-0.027, -0.001)] and memory [β = -0.149, BC CI (-0.237, -0.063)], while PR mediated its effect on processing speed (β = -0.023, BC CI (-0.045, -0.004)].

CONCLUSION

Sleep disturbances may be a key predictor of poorer executive function, lower processing speed, and memory loss, while PR is crucial for lower processing speed during a depressive episode. Psychic anxiety contributes to all aspects of cognitive impairments, mediated by sleep disturbances and PR.

Worse sleep architecture but not self-reported insomnia and sleepiness is associated with higher cortisol levels in menopausal women

OBJECTIVE

Worsening of sleep quality during menopause is well recognized. However, the underlying hormonal regulation is insufficiently described. In this study, we evaluated associations between sleep and cortisol levels.

STUDY DESIGN

Seventeen perimenopausal and 18 postmenopausal women were enrolled in a three-night sleep study. Diurnal blood sampling was performed during the third night and the following day.

MAIN OUTCOME MEASURES

Self-reported insomnia and sleepiness were evaluated with the Basic Nordic Sleep Questionnaire and sleep architecture with all-night polysomnography. Diurnal cortisol samples were collected at 20-min intervals. Correlation analyses and generalized linear models adjusted by age, body mass index, vasomotor symptoms and depressive symptoms were conducted.

RESULTS

In correlation analyses, self-reported insomnia and sleepiness were not associated with cortisol levels. Lower sleep efficiency, slow-wave sleep and stage 1 percentages, number of slow-wave sleep and of rapid-eye-movement (REM) periods, longer slow-wave sleep latency and higher wake after sleep onset percentage were associated with higher cortisol levels (all p < 0.05). Further, lower slow-wave sleep percentage and longer slow-wave sleep latency correlated with steeper daytime cortisol slope (i.e. day cortisol decrease, both p < 0.05). In adjusted generalized linear models, lower sleep efficiency and number of rapid-eye-movement periods as well as higher wake after sleep onset percentage correlated with higher cortisol levels; lower slow-wave sleep percentage correlated with higher cortisol awakening response.

CONCLUSIONS

Worse sleep architecture but not worse self-reported insomnia and sleepiness was associated with higher cortisol levels. This is important for understanding sleep in women, especially during the menopausal period.

The relationships between the family impact and distress of the coronavirus disease-19 pandemic, parent insomnia, infant temperamental negative affectivity, and parent-reported infant sleep: a path analysis

Study Objectives

The coronavirus disease 2019 (COVID-19) pandemic impact on infant sleep (IS) is understudied. The purpose of this study was to examine the relationships between family impact and distress from COVID-19 pandemic stressors, parental insomnia symptoms, infant temperamental negative affectivity, and parent-reported IS.

Methods

Parents from the Phoenix metropolitan area with a full-term healthy infant (<1 year) were recruited from February 27, 2021, to August 7, 2021. A sample of 70 parents (baby age 5.5 ± 3.5 months; parental age: 31.7 ± 5.0 years) completed the COVID-19 Exposure and Family Impact Survey (CEFIS) Impact and Distress scales, the Insomnia Severity Index (ISI), the Infant Behavioral Questionnaire-Revised Negative Affectivity subscale (IBQ-R-NA), and the Brief Infant Sleep Questionnaire-Revised (BISQ-R). Based on the transactional model of IS, path analyses were conducted to identify the direct effect of CEFIS scores and the indirect effects of parental ISI and infant IBQ-R-NA scores on BISQ-R scores.

Results

The parent sample was predominantly female (94.3%), white (72.9%), and married or in a domestic partnership (98.6%). Although COVID-19 pandemic impact and distress were not directly related to parent-reported IS, pandemic distress was negatively related to parent-reported IS indirectly through infant negative affectivity, including BISQ-R total score (β = -0.14, 95% CI [-0.32, -0.01]) and IS subscale score (β = -0.12, 95% CI [-0.27, -0.01]).

Conclusions

Heightened COVID-19 pandemic family distress was related to poorer parent-reported IS through greater parent-reported infant negative affectivity, suggesting the importance of addressing family stress and emotional regulation during crises.

Insomnia with objective but not subjective short sleep duration is associated with incident cardiovascular and/or cerebrovascular disease

STUDY OBJECTIVES

Insomnia with objective short sleep duration (ISSD) has been associated with cardiometabolic outcomes (ie, hypertension or diabetes). We examined whether ISSD, based on objective or subjective sleep measures, is associated with more serious health problems, such as incident cardiovascular and/or cerebrovascular disease (CBVD).

METHODS

1,258 men and women from the Penn State Adult Cohort (56.9% women, aged 48.3 ± 12.95 years) without CBVD at baseline were followed up for 9.21 ± 4.08 years. The presence of CBVD was defined as a history of diagnosis or treatment of heart disease and/or stroke. Insomnia was defined as a complaint of insomnia with a duration ≥ 1 year. Poor sleep was defined as a complaint of difficulty falling asleep, staying asleep, nonrestorative sleep, or early morning awakening. Objective short sleep duration was defined as < 6 hours' sleep based on polysomnography. Subjective short sleep duration was based on the median self-reported percentage of sleep time (ie, < 7 hours).

RESULTS

Compared with normal sleepers with normal sleep duration, the highest risk of incident CBVD was in the ISSD group (odds ratio = 2.46, 95% confidence interval = 1.04-5.79), and the second highest was in normal sleepers with short sleep duration (odds ratio = 1.68, 95% confidence interval = 1.11-2.54). The risk of incident CBVD was not significantly increased in poor sleepers or those with insomnia with normal sleep duration. Finally, insomnia with subjective short sleep duration was not associated with increased incident CBVD.

CONCLUSIONS

These data add to the cumulative evidence that ISSD, based on objective but not subjective measures, is the more severe biological phenotype of the disorder associated with incident CBVD.

CITATION

Pejovic S, Vgontzas AN, Fernandez-Mendoza J, et al. Insomnia with objective but not subjective short sleep duration is associated with incident cardiovascular and/or cerebrovascular disease. J Clin Sleep Med. 2024;20(7):1049-1057.

A meta-analysis of the association between insomnia with objective short sleep duration and risk of hypertension

The aim of this meta-analysis was to examine the association between insomnia with objective short sleep duration (ISSD) with prevalent and incident hypertension in cross-sectional and longitudinal studies, respectively. Data were collected from 6 cross-sectional studies with 5914 participants and 2 longitudinal studies with 1963 participants. Odds ratios (ORs) for prevalent and risk ratios (RRs) for incident hypertension were calculated through meta-analyses of adjusted data from individual studies. Compared to normal sleepers with objective normal sleep duration (NNSD), ISSD was significantly associated with higher pooled OR for prevalent hypertension (pooled OR = 2.67, 95%CI = 1.45-4.90) and pooled RR for incident hypertension (pooled RR = 1.95, 95%CI = 1.19-3.20), respectively. Compared to insomnia with objective normal sleep duration, ISSD was associated with significantly higher pooled OR of prevalent hypertension (pooled OR = 1.94, 95%CI = 1.29-2.92) and pooled RR for incident hypertension (pooled RR = 2.07, 95%CI = 1.47-2.90), respectively. Furthermore, normal sleepers with objective short sleep duration were not associated with either prevalent (pooled OR = 1.21, 95%CI = 0.84-1.75) or incident (pooled RR = 0.97, 95%CI = 0.81-1.17) hypertension compared to NNSD. Our findings suggest that ISSD is a more severe phenotype of the disorder associated with a higher risk of hypertension. Objective short sleep duration might be a valid and clinically useful index of insomnia's impact on cardiovascular health.

Salivary α-amylase as a marker of sleep disorders: A theoretical review

Sleep disorders are commonplace in our modern societies. Specialized hospital departments are generally overloaded, and sleep assessment is an expensive process in terms of equipment, human resources, and time. Biomarkers would usefully complement current measures in the screening and follow-up of sleep disorders and their daytime repercussions. Among salivary markers, a growing body of literature suggests that salivary α-amylase (sAA) may be a cross-species marker of sleep debt. However, there is no consensus as to the direction of variation in sAA with sleep disorders. Herein, after describing the mechanisms of sAA secretion and its relationship with stress, studies assessing the relationship between sAA and sleep parameters are reviewed. Finally, the influence of confounding factors is discussed, along with methodological considerations, to better understand the fluctuations in sAA and facilitate future studies in the field.

Edward O. Bixler, PhD: from the Apollo project and chimpanzees to sleep epidemiology

What an honor to write about Dr. Edward O. Bixler's contributions to the sleep field. In 1967, Dr. Bixler published a case report on a chimpanzee with implanted brain electrodes while working at an Air Force base in New Mexico. A few years later, in 1971, he published on the sleep effects of flurazepam in individuals with insomnia together with Dr. Anthony Kales, data that he had collected when the Sleep Research & Treatment Center (SRTC) was housed at the University of California Los Angeles. Dr. Bixler, a meticulous scientist, learned from Dr. Kales, a devoted clinician, to study "the whole patient, and all aspects of sleep," a legacy that continued when the SRTC moved to Penn State in Hershey. Indeed, Dr. Bixler's tenure at Penn State from 1971 until 2019 kept the science of the SRTC focused on that premise and helped translate scientific evidence into clinical care. He not only contributed early to the pharmacology of sleep and the effects of hypnotics, but he was also a pioneer in "sleep epidemiology." His "Prevalence of sleep disorders in the Los Angeles metropolitan area" study of 1979 was the first rigorous epidemiological study on sleep disturbances. Starting in 1990, he established the Penn State Adult Cohort to estimate the prevalence and natural history of sleep-disordered breathing and other sleep disorders in adults. Inspired by life-course epidemiology, he established in 2001 the Penn State Child Cohort to estimate the same phenomena in children. This Living Legend paper captures and highlights Dr. Bixler's enduring legacy to sleep science.

In Vitro Assessment of Cortisol Release Inhibition, Bioaccessibility and Bioavailability of a Chemically Characterized Scutellaria lateriflora L. Hydroethanolic Extract

Excess cortisol release is associated with numerous health concerns, including psychiatric issues (i.e., anxiety, insomnia, and depression) and nonpsychiatric issues (i.e., osteoporosis). The aim of this study was to assess the in vitro inhibition of cortisol release, bioaccessibility, and bioavailability exerted by a chemically characterized Scutellaria lateriflora L. extract (SLE). The treatment of H295R cells with SLE at increasing, noncytotoxic, concentrations (5-30 ng/mL) showed significant inhibition of cortisol release ranging from 58 to 91%. The in vitro simulated gastric, duodenal, and gastroduodenal digestions, induced statistically significant reductions (p < 0.0001) in the bioactive polyphenolic compounds that most represented SLE. Bioavailability studies on duodenal digested SLE, using Caco-2 cells grown on transwell inserts and a parallel artificial membrane permeability assay, indicated oroxylin A glucuronide and oroxylin A were the only bioactive compounds able to cross the Caco-2 cell membrane and the artificial lipid membrane, respectively. The results suggest possible applications of SLE as a food supplement ingredient against cortisol-mediated stress response and the use of gastroresistant oral dosage forms to partially prevent the degradation of SLE bioactive compounds. In vivo studies and clinical trials remain necessary to draw a conclusion on the efficacy and tolerability of this plant extract.

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.

Mechanisms of cognitive behavioural therapy for insomnia

Although much is known now about behavioural, cognitive and physiological consequences of insomnia, little is known about changes after cognitive behavioural therapy for insomnia on these particular factors. We here report baseline findings on each of these factors in insomnia, after which we address findings on their changes after cognitive behavioural therapy. Sleep restriction remains the strongest determinant of insomnia treatment success. Cognitive interventions addressing dysfunctional beliefs and attitudes about sleep, sleep-related selective attention, worry and rumination further drive effectiveness of cognitive behavioural therapy for insomnia. Future studies should focus on physiological changes after cognitive behavioural therapy for insomnia, such as changes in hyperarousal and brain activity, as literature on these changes is sparse. We introduce a detailed clinical research agenda on how to address this topic.

Bifidobacterium breve CCFM1025 Improves Sleep Quality via Regulating the Activity of the HPA Axis: A Randomized Clinical Trial

Psychobiotics, a newly identified category of probiotics primarily targeting the gut-brain axis, exhibit tremendous potential in improving sleep quality. In this study, the clinical trial was registered in advance (identifier: NO. ChiCTR2300067806). Forty participants who were diagnosed with stress-induced insomnia were chosen and randomly divided into two groups: one received CCFM1025 at a dose of 5 × 109 CFU (n = 20), while the other was administered a placebo (n = 20), over a period of four weeks. The results revealed that compared to the placebo group (pre: M = 10.10, SD = 2.292; post: M = 8.650, SD = 2.793; pre vs. post: F (1, 38) = 15.41, p = 0.4316), the CCFM1025-treated group exhibited a significant decrease in Pittsburgh Sleep Quality Index (PSQI) scores from baseline (pre: M = 11.60, SD = 3.169; post: M = 7.750, SD = 3.697, F (1, 38) = 15.41, p = 0.0007). Furthermore, the administration of CCFM1025 was associated with a more pronounced reduction in stress marker concentrations. This effect could potentially be linked to changes in serum metabolites induced by the probiotic treatment, notably daidzein. In conclusion, B. breve CCFM1025 demonstrates promise as a psychobiotic strain for enhancing sleep quality.

Exogenous Ketosis Improves Sleep Efficiency and Counteracts the Decline in REM Sleep after Strenuous Exercise

INTRODUCTION

Available evidence indicates that ketone bodies may improve sleep quality. Therefore, we determined whether ketone ester (KE) intake could counteract sleep disruptions induced by strenuous exercise.

METHODS

Ten well-trained cyclists with good sleep quality participated in a randomized crossover design consisting of two experimental sessions each involving a morning endurance training and an evening high-intensity interval training ending 1 h before sleep, after which polysomnography was performed overnight. Postexercise and 30 min before sleeping time, subjects received either 25 g of KE (EX KE ) or a placebo drink (EX CON ). A third session without exercise but with placebo supplements (R CON ) was added to evaluate the effect of exercise per se on sleep.

RESULTS

Blood d -β-hydroxybutyrate concentrations transiently increased to ~3 mM postexercise and during the first part of the night in EX KE but not in EX CON or R CON . Exercise significantly reduced rapid eye movement sleep by 26% ( P = 0.001 vs R CON ) and increased wakefulness after sleep onset by 95% ( P = 0.004 vs R CON ). Interestingly, KE improved sleep efficiency by 3% ( P = 0.040 vs EX CON ) and counteracted the exercise-induced decrease in rapid eye movement sleep ( P = 0.011 vs EX CON ) and the increase in wakefulness after sleep onset ( P = 0.009 vs EX CON ). This was accompanied by a KE-induced increase in dopamine excretion ( P = 0.033 vs EX CON ), which plays a pivotal role in sleep regulation. In addition, exercise increased sleep spindle density by 36% ( P = 0.005 vs R CON ), suggesting an effect on neural plasticity processes during sleep.

CONCLUSIONS

These data indicate that KE ingestion improves sleep efficiency and quality after high-intensity exercise. We provide preliminary evidence that this might result from KE-induced increases in dopamine signaling.

[Frailty phenotype and risk factor for disturbed sleep]

Regardless of the nature of its operationalization, frailty has significant negative consequences for the person concerned and the community. Even if a generally accepted definition of frailty is still missing, there is no doubt about the existence of this phenomenon. Pathophysiologically, a dysfunctional interaction between multiple complex systems is discussed. Therapeutic interventions show that frailty is a dynamic state that can be improved. The pathophysiological characteristics of frailty and sleep disturbances show numerous similarities. In addition, the risk of frailty is increased in individuals with sleep disturbances. As the majority of sleep disorders can usually be well treated, screening for sleep disorders should be integrated into a comprehensive concept of management of frailty.

Acute or Chronic Exposure to Corticosterone Promotes Wakefulness in Mice

Elevated glucocorticoid levels triggered by stress potentially contribute to sleep disturbances in stress-induced depression. However, sleep changes in response to elevated corticosterone (CORT), the major glucocorticoid in rodents, remain unclear. Here, we investigated the effects of acute or chronic CORT administration on sleep using electroencephalogram (EEG) and electromyography (EMG) recordings in freely moving mice. Acute CORT exposure rapidly promoted wakefulness, marked by increased episodes and enhanced EEG delta power, while simultaneously suppressing rapid eye movement (REM) and non-rapid eye movement (NREM) sleep, with the latter marked by decreased mean duration and reduced delta power. Prolonged 28-day CORT exposure led to excessive wakefulness and REM sleep, characterized by higher episodes, and decreased NREM sleep, characterized by higher episodes and reduced mean duration. EEG theta activity during REM sleep and delta activity during NREM sleep were attenuated following 28-day CORT exposure. These effects persisted, except for REM sleep amounts, even 7 days after the drug withdrawal. Elevated plasma CORT levels and depressive phenotypes were identified and correlated with observed sleep changes during and after administration. Fos expression significantly increased in the lateral habenula, lateral hypothalamus, and ventral tegmental area following acute or chronic CORT treatment. Our findings demonstrate that CORT exposure enhanced wakefulness, suppressed and fragmented NREM sleep, and altered EEG activity across all stages. This study illuminates sleep alterations during short or extended periods of heightened CORT levels in mice, providing a neural link connecting insomnia and depression.

Insomnia with objective, but not subjective, short sleep duration is associated with increased risk of incident hypertension: the Sleep Heart Health Study

STUDY OBJECTIVES

Insomnia with objective short sleep duration has been associated with higher risk of cardiometabolic morbidity. In this study, we examined the association between insomnia with objective short sleep duration, also based on subjective sleep duration, with incident hypertension in the Sleep Heart Health Study.

METHODS

We analyzed data from 1,413 participants free of hypertension or sleep apnea at baseline from the Sleep Heart Health Study, with a median follow-up duration of 5.1 years. Insomnia symptoms were defined based on difficulty falling asleep, difficulty returning to sleep, early morning awakening, or sleeping pill use more than half the days in a month. Objective short sleep duration was defined as polysomnography-measured total sleep time < 6 hours. Incident hypertension was defined based on blood pressure measures and/or use of antihypertensive medications at follow-up.

RESULTS

Individuals with insomnia who slept objectively < 6 hours had significantly higher odds of incident hypertension compared to normal sleepers who slept ≥ 6 hours (odds ratio = 2.00, 95% confidence interval = 1.09-3.65) or < 6 hours (odds ratio = 2.00, 95% confidence interval = 1.06-3.79) or individuals with insomnia who slept ≥ 6 hours (odds ratio = 2.79, 95% confidence interval = 1.24-6.30). Individuals with insomnia who slept ≥ 6 hours or normal sleepers who slept < 6 hours were not associated with increased risk of incident hypertension compared to normal sleepers who slept ≥ 6 hours. Finally, individuals with insomnia who self-reported sleeping < 6 hours were not associated with significantly increased odds of incident hypertension.

CONCLUSIONS

These data further support that the insomnia with objective short sleep duration phenotype based on objective, but not subjective measures, is associated with increased risk of developing hypertension in adults.

CITATION

Dai Y, Chen B, Chen L, et al. Insomnia with objective, but not subjective, short sleep duration is associated with increased risk of incident hypertension: the Sleep Heart Health Study. J Clin Sleep Med. 2023;19(8):1421-1428.

Efficacy of hydrotherapy, spa therapy, and balneotherapy on sleep quality: a systematic review

The purpose of this article was to review and assess the results obtained from human studies on the effects of hydrotherapy, balneotherapy, and spa therapy on sleep disorders. In this study, databases such as Pubmed, Embase, Web of Science, Google Scholar, Cochrane, Scopus, and sciences direct database were searched from the beginning to September 2022. All human studies that examined the effect of hydrotherapy, balneotherapy, and spa therapy on sleep disorders were published in the form of a full article in English. In the end, only 18 of the 189 articles met the criteria for analysis. Most studies have shown that balneotherapy, spa therapy, and hydrotherapy may by affecting some hormones such as histamine, serotonin, sympathetic nerves, and regulating body temperature led to increased quality and quantity of sleep. Also, the results obtained from Downs and Black show that 3 studies were rated as very good, 7 studies as good, 7 studies as fair, and 1 study as weak. The results of studies also showed that hydrotherapy leads to an improvement in the PSQI score index. Nevertheless, more clinical trials are needed to determine the mechanism of action of hydrotherapy on sleep disorders.

Association between insomnia and the incidence of myocardial infarction: A systematic review and meta-analysis

BACKGROUND

Insomnia has been closely associated with cardiovascular disease (CVD) including myocardial infarction (MI). Our study aims to assess the eligibility of insomnia as a potential risk factor for MI.

METHODS

PubMed, Scopus, and Web of Science were searched using terms; such as "Insomnia" and "MI." Only observational controlled studies with data on the incidence of MI among insomniacs were included. Revman software version 5.4 was used for the analysis.

RESULTS

Our pooled analysis showed a significant association between insomnia and the incidence of MI compared with noninsomniacs (relative risk [RR] = 1.69, 95% confidence interval [CI] = 1.41-2.02, p < .00001). Per sleep duration, we detected the highest association between ≤5 h of sleep, and MI incidence compared to 7-8 h of sleep (RR = 1.56, 95% CI = 1.41-1.73). Disorders of initiating and maintaining sleep were associated with increased MI incidence (RR = 1.13, 95% CI = 1.04-1.23, p = .003). However, subgroup analysis of nonrestorative sleep and daytime dysfunction showed an insignificant association with MI among both groups (RR = 1.06, 95% CI = 0.91-1.23, p = .46). Analysis of age, follow-up duration, sex, and comorbidities showed a significant association in insomniacs.

CONCLUSION

Insomnia and ≤5 h of sleep are highly associated with increased incidence of MI; an association comparable to that of other MI risk factors and as such, it should be considered as a risk factor for MI and to be incorporated into MI prevention guidelines.

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.

The Interrelated Multifactorial Actions of Cortisol and Klotho: Potential Implications in the Pathogenesis of Parkinson's Disease

The pathogenesis of Parkinson's disease (PD) is complex, multilayered, and not fully understood, resulting in a lack of effective disease-modifying treatments for this prevalent neurodegenerative condition. Symptoms of PD are heterogenous, including motor impairment as well as non-motor symptoms such as depression, cognitive impairment, and circadian disruption. Aging and stress are important risk factors for PD, leading us to explore pathways that may either accelerate or protect against cellular aging and the detrimental effects of stress. Cortisol is a much-studied hormone that can disrupt mitochondrial function and increase oxidative stress and neuroinflammation, which are recognized as key underlying disease mechanisms in PD. The more recently discovered klotho protein, considered a general aging-suppressor, has a similarly wide range of actions but in the opposite direction to cortisol: promoting mitochondrial function while reducing oxidative stress and inflammation. Both hormones also converge on pathways of vitamin D metabolism and insulin resistance, also implicated to play a role in PD. Interestingly, aging, stress and PD associate with an increase in cortisol and decrease in klotho, while physical exercise and certain genetic variations lead to a decrease in cortisol response and increased klotho. Here, we review the interrelated opposite actions of cortisol and klotho in the pathogenesis of PD. Together they impact powerful and divergent mechanisms that may go on to influence PD-related symptoms. Better understanding of these hormones in PD would facilitate the design of effective interventions that can simultaneously impact the multiple systems involved in the pathogenesis of PD.

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.

Temporal relations between peripheral and central arousals in good and poor sleepers

Good sleepers and patients with insomnia symptoms (poor sleepers) were tracked with two measures of arousal; conventional polysomnography (PSG) for electroencephalogram (EEG) assessed cortical arousals, and a peripheral arterial tonometry device was used for the detection of peripheral nervous system (PNS) arousals associated with vasoconstrictions. The relationship between central (cortical) and peripheral (autonomic) arousals was examined by evaluating their close temporal dynamics. Cortical arousals almost invariably were preceded and followed by peripheral activations, while large peripheral autonomic arousals were followed by cortical arousals only half of the time. The temporal contiguity of these two types of arousals was altered in poor sleepers, and poor sleepers displayed a higher number of cortical and peripheral arousals compared with good sleepers. Given the difference in the number of peripheral autonomic arousals between good and poor sleepers, an evaluation of such arousals could become a means of physiologically distinguishing poor sleepers.

Association of insomnia phenotypes based on polysomnography-measured sleep duration with suicidal ideation and attempts

OBJECTIVE

To assess the association of insomnia phenotypes, being insomnia with short sleep duration (ISSD) and insomnia with normal sleep duration (INSD), with suicidality in a randomly selected population-based sample.

METHODS

Data were analyzed from the Penn State Adult Cohort. Participants (N = 1741, 52.5 years, 57.4% female) were randomly recruited from the general population between January 1990 through March 1999 and mortality data were available through December 2018. Insomnia symptoms were defined as self-reports of moderate-to-severe difficulties initiating or maintaining sleep, early morning awakening and non-restorative sleep, or having chronic insomnia (n = 719). Short sleep duration was defined as <6 hours of in-lab polysomnography-measured sleep duration (n = 879). Suicidality (SAI; n = 102) was ascertained by a lifetime history of suicidal ideation (SI; n = 84), suicide attempts (SA; n = 48) or death by suicide (DBS; n = 10).

RESULTS

Compared to normal sleepers who slept ≥6 hours, participants with ISSD and INSD were associated with 1.72-fold and 2.22-fold increased odds of SAI, respectively; these associations were significant for SI, with 2.09-fold and 2.24-fold increased odds, respectively, but not for SA, after adjusting for physical and mental health comorbidities. ISSD and INSD differed in SAI age of onset and hospitalizations after SA.

CONCLUSIONS

The results of this cohort study suggest that both INSD and ISSD phenotypes are associated with increased suicidal ideation, while the INSD phenotype has an earlier age of onset and is more likely to experience hospitalizations after attempting suicide. These results highlight the importance of targeting insomnia symptoms to help prevent suicide.

The Effects of Insomnia and Sleep Loss on Cardiovascular Disease

Sleep loss has negative impacts on quality of life, mood, cognitive function and heath. Insomnia or difficulty sleeping is also a prevalent issue, affecting up to 35% of the population at some point in their lives. Insomnia is linked to poor mood, increased use of health care resources, and decreased quality of life as well as possible links to cardiovascular risk factors and disease. Studies have shown an increase in cortisol levels, decreased immunity, and increased markers of sympathetic activity in sleep-deprived healthy subjects and those with chronic insomnia. The literature also shows that subjective complaints consistent with chronic insomnia and shortened sleep time, both independently and in combination, can be associated with the development of diabetes, hypertension, and cardiovascular disease. In this article, we will explore the relationship and strength of association between insufficient sleep and insomnia with these health conditions.

Emotional Dysregulation, Anxiety Symptoms and Insomnia in Individuals with Alcohol Use Disorder

Alcohol craving is associated with insomnia symptoms, and insomnia is often reported as a reason for alcohol relapse. The current study examined associations between emotional regulation, anxiety, and insomnia among a group of 338 patients with alcohol use disorder (AUD). Because insomnia most often develops after stressful experiences, it was expected that anxiety symptoms would mediate the association between emotional dysregulation and insomnia severity. It was also expected that an insomnia diagnosis would moderate the association between emotional dysregulation and anxiety symptoms, namely that higher anxiety levels would be found in individuals with insomnia than in those without insomnia. Insomnia severity was assessed with a total score based on the Athens Insomnia Scale (AIS). Additionally, an eight-point cut-off score on the AIS was used to classify participants as with (n = 107) or without (n = 231) an insomnia diagnosis. Moreover, participants completed the Emotion Regulation Scale (DERS; total score) and the Brief Symptoms Inventory (BSI; anxiety). Individuals with insomnia did not differ from those without insomnia in age (p = 0.86), duration of problematic alcohol use (p < 0.34), mean days of abstinence (p = 0.17), nor years of education (p = 0.41). Yet, individuals with insomnia endorsed higher anxiety (p < 0.001) and higher emotional dysregulation (p < 0.001). Anxiety symptoms fully mediated the association between emotional dysregulation and insomnia severity (p < 0.001). Furthermore, insomnia diagnosis positively moderated the association between emotional dysregulation and anxiety (p < 0.001). Our results suggest that emotional dysregulation can lead to insomnia via anxiety symptoms. Treating anxiety symptoms and emotional dysregulation could help to prevent or alleviate symptoms of insomnia in people with AUD. Moreover, treating insomnia in people with AUD may also have a positive effect on anxiety symptoms.

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.

Analysis of self-reported mental health problems among the self-employed compared with paid workers in the Republic of Korea

Background

Methods

Results

Conclusions

Basal Cortisol Levels Are Increased in Patients with Mild Cognitive Impairment: Role of Insomnia and Short Sleep Duration

BACKGROUND

Mild cognitive impairment (MCI) is frequent in elderly and a risk factor for dementia. Both insomnia and increased cortisol levels are risk factors for MCI.

OBJECTIVE

We examined cross-sectionally whether increased cortisol levels are associated with short sleep duration (SSD) and/or the insomnia short sleep duration (ISS) phenotype, in elderly with MCI.

METHODS

One hundred twenty-four participants with MCI and 84 cognitively non-impaired controls (CNI)≥60 years underwent medical history, physical examination, neuropsychiatric evaluation, neuropsychological testing, 3-day actigraphy, assessment of subjective insomnia symptoms, and a single morning plasma cortisol level. The short sleep phenotypes were defined by sleep efficiency below the median of the entire sample (i.e.,≤81%) with at least one insomnia symptom (ISS) or without (SSD). ANOVA models were used to compare the various sleep phenotypes to those who did not present either short sleep or insomnia symptoms [non-insomnia (NI)].

RESULTS

MCI participants had higher cortisol levels compared to the CNI group (p = 0.009). MCI participants with insomnia (n = 44) or SSD (n = 38) had higher cortisol levels compared to the NI group (n = 42; p = 0.014 and p = 0.045, respectively). Furthermore, MCI participants with ISS phenotype but not those with insomnia with normal sleep duration had higher cortisol levels compared to NI (p = 0.011 and p = 0.4, respectively). Both linear trend analyses showed that cortisol reached the highest levels in the ISS phenotype.

CONCLUSION

The ISS and SSD phenotypes are associated with increased cortisol levels in elderly with MCI. Improving sleep quality and duration and decreasing cortisol levels may delay further cognitive decline.

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.

Insomnia with physiological hyperarousal is associated with lower weight: a novel finding and its clinical implications

Previous studies on the association of insomnia with body mass index (BMI) have been controversial. Physiological hyperarousal, the key pathological mechanism of insomnia, may be an important reason for different findings. We explored whether insomnia with physiological hyperarousal measured by the multiple sleep latency test (MSLT) is associated with body-weight differences. A total of 185 normal sleepers and 440 insomniacs were included in this study. Insomnia was defined by standard diagnostic criteria with symptoms lasting ≥6 months. All subjects underwent one night of laboratory polysomnography followed by a standard MSLT. We used the median MSLT value (i.e., ≥14 min) to define physiological hyperarousal. BMI was based on measured height (cm) and weight (kg) during the subjects' sleep laboratory visit. BMI > 25 kg/m² was defined as overweight, while BMI < 18.5 kg/m² was defined as underweight. After controlling for confounders, the odds of lower weight rather than overweight were significantly increased among insomnia patients with increased MSLT: insomnia with MSLT 14-17 min and MSLT > 17 min increased the odds of lower weight by approximately 89% (OR = 1.89, 95% CI 1.00-4.85) and 273% (OR = 3.73, 95% CI 1.51-9.22) compared with normal sleepers, respectively. In contrast, insomnia in patients with MSLT 11-14 min and 8-11 min was not different from normal sleepers in terms of body weight. Insomnia associated with physiological hyperarousal, the most severe phenotype of chronic insomnia, is associated with higher odds of lower weight and underweight compared with normal sleepers. This is a novel finding consistent with previous physiologic data and has significant clinical implications.

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.

Effect of Aquatic Exercise on Sleep Efficiency of Adults With Chronic Musculoskeletal Pain

BACKGROUND

Aerobic exercise improves sleep for people who have difficulty in sleeping soundly, but most research to date has focused on land-based exercise. There has been only very limited research into the effect of aquatic exercise on people with chronic musculoskeletal (MSK) pain. The purpose of this study is to examine the effect of a 6-week aquatic exercise program on sleep efficiency among adults with chronic MSK pain.

METHODS

A total of 30 adults with chronic MSK pain were recruited by convenience sampling and assigned into intervention and control groups by a trained research assistant. Their sleep efficiency, sleep quality, activity level, stress level, and pain level were measured with ActiGraph GT3X accelerometer before and after the intervention group completed a 6-week, biweekly program of aquatic exercise.

RESULTS

Following intervention, the intervention group had significantly longer total true sleep time (by 27.6 min, P = .006); greater sleep efficiency (+3.01%, P = .005); and less pain (-1.33/10, P = .026). The control group had significantly shorter total true sleep time by 5.8 minutes (P = .036) while changes in the other outcomes were not significant.

CONCLUSIONS

Six weeks of moderate-intensity aquatic exercise may improve sleep efficiency and reduce pain for persons suffering chronic MSK pain.

Morning and evening salivary cortisol levels in patients with chronic widespread pain and those at high risk

BACKGROUND

Hypothalamic-Pituitary-Adrenal (HPA) axis dysregulation has been implicated in chronic widespread pain (CWP); the hallmark of fibromyalgia (FM). This is the first study to compare HPA axis changes in individuals with CWP and those at high risk of symptom development.

METHODS

We sought to determine differences in morning and evening salivary cortisol levels in FM (n = 19), those at-risk (n = 20) and pain-free controls (n = 17). Risk factors included non-CWP pain, somatic symptoms, illness behaviour and sleep disturbance. We conducted the study in the absence of centrally acting medication, to address limitations of previous research.

RESULTS

Repeated measures ANOVA revealed significant main effects of group (p = 0.003), and time of day (p = 0.002), with no significant interaction. Cortisol levels were higher in FM (p = 0.027) and at-risk (p = 0.003) groups, compared to controls, but there was no significant difference between FM and at-risk groups. The main effect of group remained significant with sleep problems (p = 0.021) and life events (p = 0.007), but was not significant with anxiety (p = 0.076) or depression (p = 0.098) scores as covariates. With sleep problems as a covariate, cortisol levels remained significantly higher only in the at-risk group (p = 0.017).

CONCLUSIONS

This study indicates elevated salivary cortisol in FM and those at high risk, and identifies anxiety, depression and sleep problems as potential contributing factors. The results shed light on the dynamic relationship between stress, mood and sleep disorders and the brain's resilience to pain.

SIGNIFICANCE

This study examines neurobiological changes in chronic widespread pain and high risk individuals. One strength of the study is the absence of centrally acting medication. We found high salivary cortisol common to Fibromyalgia and those at risk and identified contributing factors. Our results offer insight into the early mechanistic changes underlying Fibromyalgia development and open up possibilities for early diagnosis and prevention.

At the intersection of sleep deficiency and opioid use: mechanisms and therapeutic opportunities

Due to the ongoing opioid epidemic, innovative scientific perspectives and approaches are urgently needed to reduce the unprecedented personal and societal burdens of nonmedical and recreational opioid use. One promising opportunity is to focus on the relationship between sleep deficiency and opioid use. In this review, we examine empirical evidence: (1) at the interface of sleep deficiency and opioid use, including hypothesized bidirectional associations between sleep efficiency and opioid abstinence; (2) as to whether normalization of sleep deficiency might directly or indirectly improve opioid abstinence (and vice versa); and (3) regarding mechanisms that could link improvements in sleep to opioid abstinence. Based on available data, we identify candidate sleep-restorative therapeutic approaches that should be examined in rigorous clinical trials.

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.

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.

The Weight of Racial Discrimination: Examining the Association Between Racial Discrimination and Change in Adiposity Among Emerging Adult Women Enrolled in a Behavioral Weight Loss Program

BACKGROUND

Non-Hispanic Black (NHB) emerging adult (EA) women are at disproportionate risk for obesity but experience limited benefit from behavioral weight loss (BWL) programs. Race-related stress could play a role; the goal of this study was to examine the association between racial discrimination (RD) and early (3 months) changes in adiposity, and to explore potential protective factors, among EA in an adapted BWL program.

METHODS

This is an ancillary study of non-Hispanic White (NHW) and NHB EA women enrolled in an adapted BWL trial (N = 49; 55.1% NHB; Age 21.2 (2.1); BMI = 33.0 + 4.3 kg/m²). At baseline, group- and personal-level RD (RD-group and RD-personal), racial identity (NHB women only), vigilant coping, and social support were assessed via validated questionnaires. Weight and waist circumference were measured objectively at 0 and 3 months.

RESULTS

NHW women manifested greater reductions in waist circumference relative to NHB women (p = .004). RD-personal did not predict change in waist circumference at 3 months (p = .402); however, the association between RD-group and change in waist circumference was statistically significant (p = .015), such that reporting greater group-level discrimination predicted a smaller decrease in waist circumference; the model explained 22% of the variance. Social support and vigilant coping were not statistically significant in the model. Among NHB women only, higher racial identity-centrality predicted greater reduction in waist circumference (p = .019).

CONCLUSION

Findings suggest racial discrimination could contribute to greater cardiometabolic risk during this developmental period. Future research should examine how experiences of racial discrimination unfold in the daily lives of NHB women to inform mechanistic interventions to enhance health and well-being.

TRIAL REGISTRATION

NCT02736981. Low Intensity Weight Loss for Young Adults.

The association of insomnia disorder characterised by objective short sleep duration with hypertension, diabetes and body mass index: A systematic review and meta-analysis

Insomnia disorder with objective short sleep duration (less than 6 h of objective sleep or sleep efficiency less than 85%) has been considered as a biologically severe subtype of insomnia associated with a higher risk of cardiometabolic disease morbidity. This systematic review and meta-analysis firstly compared insomnia disorder with objective short and normal sleep duration, and subsequently, objective short sleep duration with and without insomnia disorder, and their associations with hypertension, type 2 diabetes and body mass index. A systematic search of five databases yielded 2345 non-duplicated articles, of which 11 individual studies were used for the qualitative review and 10 individual studies for the meta-analysis. The sample size varied from 30 to 4994 participants. A higher risk of hypertension (RR 1.54, 95% CI: [1.30; 1.82] p < 0.0001) and type 2 diabetes (RR 1.63 [1.37; 1.94], p < 0.0001) was associated with insomnia disorder with objective short sleep compared to normal sleep duration, but not for body mass index. Comparisons between insomnia disorder with objective short sleep and objective short sleep without insomnia disorder showed no significant differences. However, the majority of these studies were cross-sectional, and there is a need for more cohort study data.