A Neurobiological Model of Insomnia

Pharmacokinetics, safety, and efficacy of daridorexant in Japanese subjects: Results from phase 1 and 2 studies

Daridorexant is a dual orexin receptor antagonist for the treatment of insomnia. We report results from the first two randomised, double-blind clinical studies of daridorexant in Japanese subjects. In the Phase 1 study, daridorexant (10, 25, 50 mg) or placebo were administered in the morning for 4 days in 24 young (mean age 26.9 years) and 24 older (mean age 69.7 years) healthy Japanese adults. Daridorexant reached a peak plasma concentration within 1.0 h across every dose and age group. For all doses, the mean plasma concentration of daridorexant showed a similar change between the age groups. Exposure parameters increased dose-dependently with minimal/no accumulation upon repeated dosing. The terminal half-life was ~8 h. In the Phase 2, four-period, four-way crossover study, 47 Japanese subjects (mean age 50.4 years) with insomnia disorder were randomised to receive four treatments (daridorexant 10, 25, 50 mg, placebo) during four treatment periods, each consisting of two treatment nights (5-12 day washout between treatment periods). Subjects continued their fourth treatment for 12 further days. A statistically significant dose-response relationship (multiple-comparison procedure-modelling, p < 0.0001) was found in the reduction of polysomnography-measured wake after sleep onset (WASO; primary endpoint) and latency to persistent sleep (secondary endpoint) from baseline to days 1/2. Statistically significant dose-response relationships were also observed for secondary subjective endpoints from baseline to days 1/2 (sWASO, latency to sleep onset). All daridorexant doses were well tolerated, with no treatment discontinuations and no next-morning residual effects. These results supported further investigation of daridorexant in Japanese patients with insomnia disorder.

The Prevalence of Insomnia Among Patients With Chronic Tinnitus in the General Population of the Kingdom of Saudi Arabia

BACKGROUND

 Tinnitus is a perception of sound without external sound stimulation. Subjective tinnitus is the most common type and is unrelated to external sounds. It is a symptom, not an illness, and is often linked to various psychological factors like anxiety and depression. Insomnia is a personal sense of difficulty falling asleep and issues with sleep initiation, length, consolidation, or quality while having ample chance to sleep, which impairs one's ability to function during the day. Sleep problems are prevalent in individuals with chronic tinnitus.

OBJECTIVE

 We aimed to assess insomnia prevalence in chronic tinnitus patients in Saudi Arabia.

METHOD

 Our study, an online cross-sectional survey, included 434 Saudi participants with chronic insomnia, utilizing a Google Forms questionnaire (Google LLC, Mountain View, California, United States).

RESULTS

 A total of 434 participants responded to the online survey. The most represented age group was 18-25 years, and 319 (73.5%) of the respondents were female. Approximately one-third (34.6%, n=150) were from the southern region. In the sample, 184 (42.4%) participants had bilateral tinnitus, and 105 (24.2%) had had tinnitus for over two years. Around 62.7% of the participants suffered from insomnia due to tinnitus. In terms of sleep quality, 174 (40.1%) participants took over 40 minutes to fall asleep, 85 (19.5%) were often afraid to sleep due to disturbed sleep, and 63 (14.5%) frequently used sleep pills.

CONCLUSION

 Our study of over 400 Saudi chronic tinnitus patients revealed that a large percentage of tinnitus patients have insomnia, influenced by geographic region and tinnitus duration. Our findings offer valuable insights, emphasizing the necessity for additional research to inform interventions aimed at enhancing the quality of life of individuals with chronic tinnitus.

Daytime sleepiness in insomnia: Are we focusing on what truly matters?

Insomnia, the most prevalent sleep disorder, is commonly associated with other mental and somatic disorders, making it a significant health concern. It is characterized by nighttime symptoms and daytime dysfunction, with sleepiness being a potential criterion for the latter. Sleepiness is a normal physiological state that is typically experienced near usual bedtime, in normal circumstances. In insomnia, it seems somewhat logical the idea that there is significant daytime sleepiness. However, the topic has been the subject of various discussions in sleep medicine, with studies yielding contradictory and inconsistent results. In this article, we aim to critically examine daytime sleepiness in individuals with insomnia disorder and propose an alternative approach to addressing it, both in clinical practice and research settings. It is crucial to further investigate the role of daytime sleepiness in insomnia, particularly by focusing on sleepiness perception as a more relevant dimension to explore in majority of patients. It is plausible that certain insomnia phenotypes are objectively sleepy during the day, but more studies are necessary, particularly with well-defined clinical samples. The implications of assessing sleepiness perception in insomnia for clinical practice are discussed, and new avenues for research are suggested.

A flexible and dissolving traditional Chinese medicine microneedle patch for sleep-aid intervention

About a quarter of the world's population suffers from insomnia, and the number of the insomniacs is gradually increasing. However, the current drug therapy and non-drug therapy sleep-aid methods have certain limitations. In general, the sleep-aid effect of drug therapy is better than that of Non-drug therapy, but western medicine may lead to some side effects and drug abuse. Although the side effects of Chinese Herbal Medicine (CHM) are relatively small, making the herbal decoction is complex and time-consuming. Therefore, exploring a novel sleep-aid method is very significant. In this paper, a flexible and dissolving Traditional Chinese Medicine (TCM) microneedle patch is proposed for sleep-aid intervention. The TCM microneedle patch is a micrometer-scale intrusive object, and the herbal extracts are carried by the patch. The materials, design method, and fabrication process of the microneedle patch have been described in detail. Besides, the mechanical characteristics of the microneedle patch, sleep-aid effect evaluation method, and experimental scheme have been presented. Three microneedle tips with radii of 5 μm, 15 μm, and 22 μm are selected for simulation analysis. Abaqus simulation results indicate that the smaller the radius of the microneedle tip, the smaller the piercing force. Considering that the microneedle should easily penetrate the skin without buckling, that is, the piercing force should be larger than the buckling force, thus 15 μm, instead of 5 μm or 22 μm, is more suitable to be adopted as the radius of the microneedle tip. For the microneedle with the radius of 15 μm, the piercing force is 0.033 N, and the difference between the piercing force and buckling force is 0.036 N. Experimental results demonstrate that the fracture force of the microneedle is about 0.29 N, which is far larger than the piercing force and buckling force. The single-lead EEG signals of the frontal lobe are used to evaluate the sleep-aid effect of the TCM microneedle patch. After sleep-aid intervention on the Anmian and Yintang acupoints using the patches, for most subjects, the ratios of the low-frequency brain wave energies to the high-frequency brain wave energies are increased obviously, indicating that the proposed sleep-aid method is effective.

Chronic insomnia, REM sleep instability and emotional dysregulation: A pathway to anxiety and depression?

The world-wide prevalence of insomnia disorder reaches up to 10% of the adult population. Women are more often afflicted than men, and insomnia disorder is a risk factor for somatic and mental illness, especially depression and anxiety disorders. Persistent hyperarousals at the cognitive, emotional, cortical and/or physiological levels are central to most theories regarding the pathophysiology of insomnia. Of the defining features of insomnia disorder, the discrepancy between minor objective polysomnographic alterations of sleep continuity and substantive subjective impairment in insomnia disorder remains enigmatic. Microstructural alterations, especially in rapid eye movement sleep ("rapid eye movement sleep instability"), might explain this mismatch between subjective and objective findings. As rapid eye movement sleep represents the most highly aroused brain state during sleep, it might be particularly prone to fragmentation in individuals with persistent hyperarousal. In consequence, mentation during rapid eye movement sleep may be toned more as conscious-like wake experience, reflecting pre-sleep concerns. It is suggested that this instability of rapid eye movement sleep is involved in the mismatch between subjective and objective measures of sleep in insomnia disorder. Furthermore, as rapid eye movement sleep has been linked in previous works to emotional processing, rapid eye movement sleep instability could play a central role in the close association between insomnia and depressive and anxiety disorders.

Neurocognitive consequences of adolescent sleep disruptions and their relationship to psychosis vulnerability: a longitudinal cohort study

Adolescence is a key period for neurocognitive maturation where deviation from normal developmental trajectories may be tied to adverse mental health outcomes. Cognitive disruptions have been noted in populations at risk for psychosis and are known to accompany periods of sleep deprivation. This study aims to assess the role of cognition as a mediator between sleep disruptions and psychosis risk. A cohort of 3801 high school students (51% female, mean age = 12.8, SD = 0.45 years) was recruited from 31 Montreal high schools. Measures of sleep, psychotic-like experiences, inhibition, working memory, perceptual reasoning, and delayed recall were collected from participants on a yearly basis over the five years of their high school education. A multi-level model mediation analysis was performed controlling for sex and time squared. Response inhibition was shown to be associated with, and to mediate (B = -0.005, SD = 0.003, p = 0.005*) the relationship between sleep disruptions (B = -0.011, SD = 0.004, p < 0.001*) and psychotic-like experiences (B = 0.411, SD = 0.170, p = 0.005*). Spatial working memory deficits on a given year were associated with a higher frequency of psychotic-like experiences that same year (B = -0.046, SD = 0.018, p = 0.005*) and the following year (B = -0.051, SD = 0.023, p = 0.010*), but were not associated with sleep disturbances. No significant associations were found between our variables of interest and either delayed recall or perceptual reasoning at the within person level. Findings from this large longitudinal study provide evidence that the association between sleep disruptions and psychosis risk is specifically mediated by inhibitory rather than general cognitive impairments. The association of spatial working memory, response inhibition, and sleep disruptions with psychotic-like experiences suggests that these factors may represent potential targets for preventative interventions.

Social interaction anxiety and sleep quality in youth: Individual difference in childhood adversity and cardiac vagal control

BACKGROUND

Social interaction anxiety and sleep problems are prevalent during adolescence. Social interaction anxiety undermines sleep quality, however, little is known whether the association between social interaction anxiety and sleep quality is moderated by environmental factors such as childhood adversity and individual factors such as cardiac vagal control. This study sought to investigate the moderating effects of childhood adversity and cardiac vagal control on the link between social interaction anxiety and sleep quality.

METHOD

The Social Interaction Anxiety Scale, the Pittsburgh Sleep Quality Index and the Childhood Trauma Questionnaire were administered to 274 adolescents, who received 3-min resting ECG recording to assess respiratory sinus arrhythmia (RSA) as an index of cardiac vagal control.

RESULTS

Social interaction anxiety was negatively associated with sleep quality, and this association was moderated by childhood adversity and cardiac vagal control. In specific, social interaction anxiety was negatively associated with sleep quality among adolescents with low childhood adversity regardless of cardiac vagal control. Sleep quality was generally disrupted when adolescents exposed to high childhood adversity, but the negative association between social interaction anxiety and sleep quality among adolescents with high childhood adversity could be amortized by high cardiac vagal control.

LIMITATIONS

Cross-sectional design precluded establishing causality among variables.

CONCLUSION

These findings suggest that high cardiac vagal control reflecting better self-regulation might buffer the negative effect of social interaction anxiety on sleep quality particularly among adolescents exposed to early life stress.

Identifying the insomnia-related psychological issues associated with hyperarousal: A network perspective

Hyperarousal, recognized as a fundamental characteristic of insomnia for decades, has yielded limited evidence concerning its direct psychological associations. This study aimed to explore the psychological factors linked to hyperarousal within the framework of interrelated variables. Two independent samples, comprising n = 917 and n = 652 young adults, were included in the study. Employing the first dataset as a discovery sample and the second dataset as a replication sample, network analyses were conducted using 26 variables derived from 17 scales. The objective was to estimate the direct and indirect associations between psychological issues, including hyperarousal and insomnia. Additionally, linear regression analysis was employed to assess the convergence of findings obtained from the network analysis. Network analyses in both samples converged to reveal direct associations between insomnia severity and several psychological factors, including negative sleep beliefs, physical fatigue, insomnia response to stress, hyperarousal, self-reported depression, and mental fatigue. Notably, the nodes with relative importance within the network include trait anxiety, depressive rumination, hyperarousal, perfectionism sub-dimension of concern over mistakes, and private self-consciousness. Hyperarousal is one of the key factors linking insomnia with a variety of psychological issues, including emotion-related factors (rumination, perveived stress), sleep-related factors (dysfunctional sleep beliefs and attitudes, insomnia response to stress, fatigue, chronotype), and self-related factors (self-consciousness, perfectionism). The results suggest that forthcoming strategies for enhancing the treatment efficacy of insomnia could consider supplementary interventions that specifically address hyperarousal, other factors directly linked to insomnia, or the hub nodes within the network.

Animal models of human insomnia

Insomnia disorder (chronic sleep continuity disturbance) is a debilitating condition affecting 5%-10% of the adult population worldwide. To date, researchers have attempted to model insomnia in animals through breeding strategies that create pathologically short-sleeping individuals or with drugs and environmental contexts that directly impose sleeplessness. While these approaches have been invaluable for identifying insomnia susceptibility genes and mapping the neural networks that underpin sleep-wake regulation, they fail to capture concurrently several of the core clinical diagnostic features of insomnia disorder in humans, where sleep continuity disturbance is self-perpetuating, occurs despite adequate sleep opportunity, and is often not accompanied by significant changes in sleep duration or architecture. In the present review, we discuss these issues and then outline ways animal models can be used to develop approaches that are more ecologically valid in their recapitulation of chronic insomnia's natural aetiology and pathophysiology. Conditioning of self-generated sleep loss with these methods promises to create a better understanding of the neuroadaptations that maintain insomnia, including potentially within the infralimbic cortex, a substrate at the crossroads of threat habituation and sleep.

The orexin story and orexin receptor antagonists for the treatment of insomnia

Insomnia is present in up to one third of the adult population worldwide, and it can present independently or with other medical conditions such as mental, metabolic, or cardiovascular diseases, which highlights the importance of treating this multifaceted disorder. Insomnia is associated with an abnormal state of hyperarousal (increased somatic, cognitive, and cortical activation) and orexin has been identified as a key promotor of arousal and vigilance. The current standards of care for the treatment of insomnia recommend non-pharmacological interventions (cognitive behavioural therapy) as first-line treatment and, if behavioural interventions are not effective or available, pharmacotherapy. In contrast to most sleep medications used for decades (benzodiazepines and 'Z-drugs'), the new orexin receptor antagonists do not modulate the activity of γ-aminobutyric acid receptors, the main inhibitory mechanism of the central nervous system. Instead, they temporarily block the orexin pathway, causing a different pattern of effects, e.g., less morning or next-day effects, motor dyscoordination, and cognitive impairment. The pharmacokinetic/pharmacodynamic properties of these drugs are the basis of the different characteristics explained in the package inserts, including the recommended starting dose. Orexin receptor antagonists seem to be devoid of any dependence and tolerance-inducing effects, rendering them a viable option for longer-term treatment. Safety studies did not show exacerbation of existing respiratory problems, but more real-world safety and pharmacovigilance experience is needed. This review provides an overview of the orexin history, the mechanism of action, the relation to insomnia, and key features of available drugs mediating orexin signalling.

What is sleep exactly? Global and local modulations of sleep oscillations all around the clock

Wakefulness, non-rapid eye-movement (NREM) and rapid eye-movement (REM) sleep differ from each other along three dimensions: behavioral, phenomenological, physiological. Although these dimensions often fluctuate in step, they can also dissociate. The current paradigm that views sleep as made of global NREM and REM states fail to account for these dissociations. This conundrum can be dissolved by stressing the existence and significance of the local regulation of sleep. We will review the evidence in animals and humans, healthy and pathological brains, showing different forms of local sleep and the consequences on behavior, cognition, and subjective experience. Altogether, we argue that the notion of local sleep provides a unified account for a host of phenomena: dreaming in REM and NREM sleep, NREM and REM parasomnias, intrasleep responsiveness, inattention and mind wandering in wakefulness. Yet, the physiological origins of local sleep or its putative functions remain unclear. Exploring further local sleep could provide a unique and novel perspective on how and why we sleep.

Altered functional connectivity of the thalamus in patients with insomnia disorder after transcutaneous auricular vagus nerve stimulation therapy

The pathogenesis of insomnia is related to the dysfunction of the thalamus. Transcutaneous auricular vagus nerve stimulation (taVNS) has proved to be effective in treating insomnia. However, whether taVNS alleviates insomnia through modulating thalamus-related functional connectivity remains unclear. To elucidate the instant modulating effects of taVNS on the resting state functional connectivity (RSFC) of the thalamus, 20 patients with insomnia disorder were recruited to receive taVNS treatment and their resting state functional magnetic resonance imaging (fMRI) data were collected immediately before and after stimulation. The fMRI data were compared with 20 age- and gender-matched healthy subjects who received no stimulation and had RSFC fMRI data collected once. RSFC analyses of the thalamus were performed in both groups. In addition to assessing the group differences between ID patients and healthy controls regarding the RSFC of the thalamus, we examined the taVNS-induced changes of RSFC of the thalamus in ID patients. Before taVNS treatment, the ID patients showed increased RSFC of the thalamus with the right insula and inferior frontal gyrus than healthy controls. After taVNS treatment, the RSFC between the thalamus and the right angular gyrus, left anterior cingulate gyrus, and precuneus were significantly decreased in patients. This study provides insights into the instant brain effects involving the thalamus-related functional connectivity of taVNS performed on insomnia disorder patients.

Does poor sleep quality lead to increased low back pain the following day?

OBJECTIVES

This study explored the relationship between sleep quality and next-day pain intensity for people with low back pain and investigated whether there was any evidence that this relationship was causal.

METHODS

We conducted a secondary analysis of an observational study that investigated sleep quality in people with low back pain. People with low back pain were recruited from primary care and the community. Sleep quality was measured with subjective (self-report) and objective (polysomnography (PSG)) measures. PSG analysis classifies sleep into stages, of which slow-wave sleep (SWS) is thought to have a key role in maintaining or increasing pain intensity. We drew directed acyclic graphs to identify possible confounders of the relationship between both measures of sleep quality, and pain intensity. We constructed two linear regression models to explore the effect of subjective and objective sleep quality on next-day pain intensity before and after confounder adjustment.

RESULTS

Thirty-nine participants were included in the study. For participants with low back pain, self-reported better quality sleep β=-0.38 (95% CI -0.63 to -0.13), or spending a greater proportion of time in SWS β=-0.12 (95% CI -0.22 to -0.02) was associated with lower next day pain intensity. After confounder adjustment, the effect reduced and was no longer significant for either self-reported β=-0.18 (95% CI -0.46 to 0.10), or SWS β=-0.08 (95% CI -0.18 to 0.03).

CONCLUSIONS

Sleep quality, whether measured by self-report or proportion of time in SWS, was associated with next day pain intensity for people with low back pain. However, this relationship is likely to be confounded and therefore not likely to be causal.

Understanding neuron-glia crosstalk and biological clocks in insomnia

According to the World Health Organization, about one-third of the population experiences insomnia symptoms, and about 10-15% suffer from chronic insomnia, the most common sleep disorder. Sleeping difficulties associated with insomnia are often linked to chronic sleep deprivation, which has a negative health impact partly due to disruption in the internal synchronisation of biological clocks. These are regulated by clock genes and modulate most biological processes. Most studies addressing circadian rhythm regulation have focused on the role of neurons, yet glial cells also impact circadian rhythms and sleep regulation. Chronic insomnia and sleep loss have been associated with glial cell activation, exacerbated neuroinflammation, oxidative stress, altered neuronal metabolism and synaptic plasticity, accelerated age-related processes and decreased lifespan. It is, therefore, essential to highlight the importance of glia-neuron interplay on sleep/circadian regulation and overall healthy brain function. Hence, in this review, we aim to address the main neurobiological mechanisms involved in neuron-glia crosstalk, with an emphasis on microglia and astrocytes, in both healthy sleep, chronic sleep deprivation and chronic insomnia.

Effects of Continuous Positive Airway Pressure on Sleep State Misperception in Patients With Obstructive Sleep Apnea

BACKGROUND

Little is known regarding the effects of continuous positive airway pressure (CPAP) on sleep misperception in obstructive sleep apnea (OSA).

METHODS

Sleep state perception was measured by subtracting the objective total sleep time from the subjective sleep duration. Sleep underestimation and overestimation were defined as ± 60 minutes sleep perception. Insomnia and depressive symptoms were assessed using questionnaires. Finally, nonparametric statistical analyses were performed.

RESULTS

Of the 339 patients with OSA included in the study, 90 (26.5%) and 45 (13.3%) showed sleep underestimation and overestimation, respectively. Overall, a significant underestimation of sleep was noted during CPAP titration comparing to a diagnostic PSG (P < 0.001). OSA patients with insomnia or depressive symptoms did not show any changes in sleep perception between diagnostic and CPAP titration studies, whereas those without insomnia or depressed mood showed significantly underestimated sleep duration during CPAP titration. Patients with OSA and either underestimated or overestimated misperception showed perceptual improvements during CPAP titration regardless of the presence of insomnia or depressive symptoms. However, of 204 patients with normal sleep perception, 138 (67.6%) and 10 (4.9%) had underestimation and overestimation of sleep during CPAP titration.

CONCLUSION

CPAP titration may improve sleep perception with moderate to severe OSA who have sleep misperception. However, CPAP titration may result in sleep misperception especially underestimation of sleep in those who have normal sleep perception.

Strength of excitation and insomnia as mediated by mood dimensions

BACKGROUND

The main goal of our study was to demonstrate the relationship between the strength of excitation (SE) as one of the basic central nervous system (CNS) properties and insomnia, and to determine the role of the mood components as mediators of this relationship. We hypothesized that SE directly and indirectly via arousal-related mood dimensions may be related to insomnia.

PARTICIPANTS AND PROCEDURE

The study involved 149 people, 85 women and 64 men, aged 18 to 60 (M = 30.11, SD = 11.43) selected from the general population using snowball sampling. The basic properties of the CNS were diagnosed using Pavlovian Temperament Survey. Mood was assessed using the Polish adaptation of UWIST Mood Adjective Checklist. To evaluate insomnia symptoms Athens Insomnia Scale in its Polish adaptation was used.

RESULTS

SE negatively correlated with insomnia (no significant correlations between strength of inhibition and mobility and insomnia). All CNS properties positively correlated with hedonic tone (HT) and energetic arousal (EA), and negatively with tense arousal (TA) as mood dimensions. HT and EA were negatively correlated with insomnia but TA positively correlated with insomnia. Both EA and TA served as mediators in the relationship between SE and insomnia.

CONCLUSIONS

The results indicated the relationship between SE and insomnia as well as between SE and EA and TA as mood dimensions related to arousal. Mediation analysis suggests that both EA and TA may serve as mediators of the relationship between SE and insomnia. However, the results of the mediation analysis require careful interpretation.

Insomnia

Insomnia is highly prevalent in clinical practice, occurring in up to 50% of primary care patients. Insomnia can present independently or alongside other medical conditions or mental health disorders and is a risk factor for the development and exacerbation of these other disorders if not treated. In 2016, the American College of Physicians recommended that insomnia be specifically targeted for treatment. The recommended first-line treatment for insomnia, whether the underlying cause has been identified or not, is cognitive behavioural therapy for insomnia (CBT-I). Currently, there is no global consensus regarding which pharmacological treatment has the best efficacy or risk-benefit ratio. Both CBT-I and pharmacological intervention are thought to have similar acute effects, but only CBT-I has shown durable long-term effects after treatment discontinuation. Administering a combined treatment of CBT-I and medication could decrease the latency to treatment response, but might diminish the durability of the positive treatment effects of CBT-I.

A Meta-Analysis of Mindfulness-Based Therapies for Insomnia and Sleep Disturbance Moving Toward Processes of Change

MBTs are increasingly being investigated as a viable treatment of insomnia or sleep disturbance. To date, 13 trials published since 2010 suggest that MBTs are efficacious for improving symptoms of insomnia and sleep quality relative to psychological placebos and inactive control conditions with medium to large effects. Limited evidence suggests that these effects are sustained at 3-month follow-up. Despite this, limited data were collected evaluating the empirically supported mechanisms or processes of change. The authors propose a testable model in the psychological process model of sleep that they hope will advance the next generation of research into MBTs for insomnia.

Sex differences in prevalence and clinical correlates of insomnia in Chinese patients with chronic schizophrenia

OBJECTIVE

It is generally recognized that there are sex differences in many aspects of schizophrenia. The main purpose of this study was to investigate the sex differences in the prevalence and clinical correlates of insomnia in patients with chronic schizophrenia.

METHODS

A total of 957 patients who met the DSM-IV diagnostic criteria for schizophrenia were recruited in this cross-sectional study (male/female = 630/327). Demographic, clinical, and insomnia data were collected using self-reported questionnaires. Fasting blood samples were collected to evaluate the status of blood lipids. Psychopathological symptoms were evaluated using the Positive and Negative Syndrome Scale (PANSS).

RESULTS

The prevalence rate of insomnia in female patients with schizophrenia was significantly higher than that in male patients (17.3% for males and 26.3% for females; χ² = 10.74, p = 0.001). Regression analysis showed that in male patients, insomnia was independently associated with severe PANSS positive symptoms, severe PANSS depressive factor, and high levels of low-density lipoprotein levels, while in female patients, insomnia was associated with low education level, high PANSS depressive factor, and high levels of apolipoprotein B levels.

CONCLUSION

This study illustrates that insomnia is more frequent in female than male schizophrenia patients, and that there are differences in the clinical correlates of insomnia by sex, suggesting that sex differences should be considered in prevention and treatment strategies for coexisting insomnia in schizophrenia patients.

Real-Time fMRI Neurofeedback Training Changes Brain Degree Centrality and Improves Sleep in Chronic Insomnia Disorder: A Resting-State fMRI Study

Background

Chronic insomnia disorder (CID) is considered a major public health problem worldwide. Therefore, innovative and effective technical methods for studying the pathogenesis and clinical comprehensive treatment of CID are urgently needed.

Methods

Real-time fMRI neurofeedback (rtfMRI-NF), a new intervention, was used to train 28 patients with CID to regulate their amygdala activity for three sessions in 6 weeks. Resting-state fMRI data were collected before and after training. Then, voxel-based degree centrality (DC) method was used to explore the effect of rtfMRI-NF training. For regions with altered DC, we determined the specific connections to other regions that most strongly contributed to altered functional networks based on DC. Furthermore, the relationships between the DC value of the altered regions and changes in clinical variables were determined.

Results

Patients with CID showed increased DC in the right postcentral gyrus, Rolandic operculum, insula, and superior parietal gyrus and decreased DC in the right supramarginal gyrus, inferior parietal gyrus, angular gyrus, middle occipital gyrus, and middle temporal gyrus. Seed-based functional connectivity analyses based on the altered DC regions showed more details about the altered functional networks. Clinical scores in Pittsburgh sleep quality index, insomnia severity index (ISI), Beck depression inventory, and Hamilton anxiety scale decreased. Furthermore, a remarkable positive correlation was found between the changed ISI score and DC values of the right insula.

Conclusions

This study confirmed that amygdala-based rtfMRI-NF training altered the intrinsic functional hubs, which reshaped the abnormal functional connections caused by insomnia and improved the sleep of patients with CID. These findings contribute to our understanding of the neurobiological mechanism of rtfMRI-NF in insomnia treatment. However, additional double-blinded controlled clinical trials with larger sample sizes need to be conducted to confirm the effect of rtfMRI-NF from this initial study.

Factors associated with insomnia among frontline nurses during COVID-19: a cross-sectional survey study

BACKGROUND

Research predominantly suggests that nurses are at high risk of developing psychopathology. The empirical data show that the occurrence rate of problem-related sleep quality among clinical nurses is high. Therefore, this study was conducted to address the lack of information on the relationship between the coronavirus disease 2019 (COVID-19) pandemic and insomnia.

METHODS

A convenience sample of nurses (n = 680) completed an online survey that included the Insomnia severity index, the COVID-19-related psychological distress scale, the general health questionnaire, neuroticism, dysfunctional beliefs, attitudes about sleep scale, and difficulties in emotion regulation scale.

RESULTS

The results showed that 35.8% (n = 253) of nurses were classified as individuals with moderate to severe clinical insomnia. The results showed that the psychological distress generated by COVID-19 predicted insomnia (β = .47, SE = 0.02, P < .001, t = 13.27, 95% CI 0.31-0.46). Additionally, the association is mediated by psychopathology vulnerabilities, emotion dysregulation, dysfunctional beliefs about sleep, and neuroticism. Moreover, female nurses exhibited higher levels of insomnia (Cohen's d = .37), neuroticism (Cohen's d = 30), psychopathology vulnerability (Cohen's d = .26), and COVID-19-related psychological distress (Cohen's d = .23).

CONCLUSION

The present study's findings help to explain how pandemic consequences can be associated with insomnia. Additionally, the findings make a significant contribution to better understanding the role of neuroticism, emotion dysregulation, beliefs, and psychopathology vulnerability in the development of insomnia among nurses. The findings suggest the potential influence of cognitive behavioral therapy for insomnia (CBT-I) and transdiagnostic integrated therapies that could be incorporated into therapeutic programs designed to develop as a way of inhibiting or preventing insomnia among clinical nurses.

Factors associated with sleep state misperception in patients with obstructive sleep apnea

PURPOSE

Little is known regarding the prevalence of sleep state misperception and the factors related to this in patients with obstructive sleep apnea (OSA).

METHODS

This retrospective study included patients with OSA defined by an apnea-hypopnea index (AHI) of ≥ 5 and used the Insomnia Severity Index (ISI), the Epworth sleepiness scale, the Patient Health Questionnaire-9, and the Generalized Anxiety Disorder-7. Underestimation and overestimation of sleep state perception were defined as < 80% and > 120%, respectively, of the ratio between subjective and objective total sleep time. An ISI score > 14 indicated clinically significant insomnia and an AHI ≥ 30 indicated severe OSA. A multinomial logistic regression was conducted with the category of sleep state perception as an outcome variable.

RESULTS

Of the 707 patients with OSA, underestimation and overestimation of sleep state perception were noted in 22.5% and 10.6% of subjects, respectively. The median absolute differences (and percentages of the ratio) between subjective and objective total sleep time were 116 min (66.9%) and 87 min (127.3%) in the underestimated and overestimated perception groups, respectively. In the adjusted model, the underestimated group was more likely to have an ISI score > 14 (OR = 1.812, P = .006). The overestimated group was more likely to be older (OR = 1.025, P = .025) and has severe OSA (OR = 1.729, P = .035).

CONCLUSIONS

There are two patterns of sleep state misperception in patients with OSA: underestimation associated with comorbid insomnia symptoms and overestimation associated with severe OSA. These findings enhance understanding of the pathophysiology of sleep state misperception in patients with OSA.

Improved Regional Homogeneity in Chronic Insomnia Disorder After Amygdala-Based Real-Time fMRI Neurofeedback Training

BACKGROUND

Chronic insomnia disorder (CID) is a highly prevalent sleep disorder, which influences people's daily life and is even life threatening. However, whether the resting-state regional homogeneity (ReHo) of disrupted brain regions in CID can be reshaped to normal after treatment remains unclear.

METHODS

A novel intervention real-time functional magnetic resonance imaging neurofeedback (rtfMRI-NF) was used to train 28 CID patients to regulate the activity of the left amygdala for three sessions in 6 weeks. The ReHo methodology was adopted to explore its role on resting-state fMRI data, which were collected before and after training. Moreover, the relationships between changes of clinical variables and ReHo value of altered regions were determined.

RESULTS

Results showed that the bilateral dorsal medial pre-frontal cortex, supplementary motor area (SMA), and left dorsal lateral pre-frontal cortex had decreased ReHo values, whereas the bilateral cerebellum anterior lobe (CAL) had increased ReHo values after training. Some clinical scores markedly decreased, including Pittsburgh Sleep Quality Index, Insomnia Severity Index, Beck Depression Inventory, and Hamilton Anxiety Scale (HAMA). Additionally, the ReHo values of the left CAL were positively correlated with the change in the Hamilton depression scale score, and a remarkable positive correlation was found between the ReHo values of the right SMA and the HAMA score.

CONCLUSION

Our study provided an objective evidence that amygdala-based rtfMRI-NF training could reshape abnormal ReHo and improve sleep in patients with CID. The improved ReHo in CID provides insights into the neurobiological mechanism for the effectiveness of this intervention. However, larger double-blinded sham-controlled trials are needed to confirm our results from this initial study.

Insomnia subtypes characterised by objective sleep duration and NREM spectral power and the effect of acute sleep restriction: an exploratory analysis

Insomnia disorder (ID) is a heterogeneous disorder with proposed subtypes based on objective sleep duration. We speculated that insomnia subtyping with additional power spectral analysis and measurement of response to acute sleep restriction may be informative in overall assessment of ID. To explore alternative classifications of ID subtypes, insomnia patients (n = 99) underwent two consecutive overnight sleep studies: (i) habitual sleep opportunity (polysomnography, PSG) and, (ii) two hours less sleep opportunity (electroencephalography, EEG), with the first night compared to healthy controls (n = 25). ID subtypes were derived from data-driven classification of PSG, EEG spectral power and interhemispheric EEG asymmetry index. Three insomnia subtypes with different sleep duration and NREM spectral power were identified. One subtype (n = 26) had shorter sleep duration and lower NREM delta power than healthy controls (short-sleep delta-deficient; SSDD), the second subtype (n = 51) had normal sleep duration but lower NREM delta power than healthy controls (normal-sleep delta-deficient; NSDD) and a third subtype showed (n = 22) no difference in sleep duration or delta power from healthy controls (normal neurophysiological sleep; NNS). Acute sleep restriction improved multiple objective sleep measures across all insomnia subtypes including increased delta power in SSDD and NSDD, and improvements in subjective sleep quality for SSDD (p = 0.03), with a trend observed for NSDD (p = 0.057). These exploratory results suggest evidence of novel neurophysiological insomnia subtypes that may inform sleep state misperception in ID and with further research, may provide pathways for personalised care.

What Does Sleeping Brain Tell About Stress? A Pilot Functional Near-Infrared Spectroscopy Study Into Stress-Related Cortical Hemodynamic Features During Sleep

People with mental stress often experience disturbed sleep, suggesting stress-related abnormalities in brain activity during sleep. However, no study has looked at the physiological oscillations in brain hemodynamics during sleep in relation to stress. In this pilot study, we aimed to explore the relationships between bedtime stress and the hemodynamics in the prefrontal cortex during the first sleep cycle. We tracked the stress biomarkers, salivary cortisol, and secretory immunoglobulin A (sIgA) on a daily basis and utilized the days of lower levels of measured stress as natural controls to the days of higher levels of measured stress. Cortical hemodynamics was measured using a cutting-edge wearable functional near-infrared spectroscopy (fNIRS) system. Time-domain, frequency-domain features as well as nonlinear features were derived from the cleaned hemodynamic signals. We proposed an original ensemble algorithm to generate an average importance score for each feature based on the assessment of six statistical and machine learning techniques. With all channels counted in, the top five most referred feature types are Hurst exponent, mean, the ratio of the major/minor axis standard deviation of the Poincaré plot of the signal, statistical complexity, and crest factor. The left rostral prefrontal cortex (RLPFC) was the most relevant sub-region. Significantly strong correlations were found between the hemodynamic features derived at this sub-region and all three stress indicators. The dorsolateral prefrontal cortex (DLPFC) is also a relevant cortical area. The areas of mid-DLPFC and caudal-DLPFC both demonstrated significant and moderate association to all three stress indicators. No relevance was found in the ventrolateral prefrontal cortex. The preliminary results shed light on the possible role of the RLPCF, especially the left RLPCF, in processing stress during sleep. In addition, our findings echoed the previous stress studies conducted during wake time and provides supplementary evidence on the relevance of the dorsolateral prefrontal cortex in stress responses during sleep. This pilot study serves as a proof-of-concept for a new research paradigm to stress research and identified exciting opportunities for future studies.

Association of white matter volume with sleep quality: a voxel-based morphometry study

Many studies have focused on the gray matter volume associated with sleep quality, little is known about the relationship between white matter volume and sleep quality. Brain white structure is a crucial component in the structural neuroanatomy. Therefore, in this study, we investigated the association between white matter volume and sleep quality. Data were collected using the Pittsburgh Sleep Quality Index and voxel-based morphometry among 352 college students. Results showed that the global PSQI score was negatively associated with the white matter volume, including in the right middle occipital gyrus, the left superior temporal gyrus, the right the precentral gyrus, the left supramarginal gyrus, the left middle frontal gyrus, the left precunes, and the right superior frontal gyrus. Results also indicated that the white matter volume in specific regions negatively associated with the factor of PSQI. These specific brain regions may be replicated in brain areas related to sleep quality. In summary, we suggested that exploring brain white structure are related to sleep could help to expound the mechanisms by which sleep quality are associated with brain function, behavior and cognition, as well as potentially the networks and systems responsible for variations in sleep themselves.

Abnormal functional connectivity of the salience network in insomnia

The salience network plays an important role in detecting stimuli related to behavior and integrating neural processes. The aim of this study was to investigate changes in functional connectivity of the salience network in insomnia patients. Independent component analysis combined with a dual regression approach was used to examine functional connectivity differences in the salience network between patients with insomnia (n = 33) and healthy controls (n = 33). Pearson correlation analysis was used to analyze the relationship between differences in functional connectivity and the clinical characteristics of insomnia patients. Compared to healthy controls, insomnia patients showed increased functional connectivity in the dorsal anterior cingulate cortex within the salience network, as well as greater connectivity between the salience network and other brain regions including the dorsolateral prefrontal cortex, superior frontal gyrus, sensorimotor area and brain stem. The correlation analysis showed that increased functional connectivity between the salience network and left dorsolateral prefrontal cortex was positively correlated with Pittsburgh Sleep Quality Index score. Increased functional connectivity between salience network and several brain regions may be related to hyperarousal in insomnia patients. The connectivity between salience network and dorsolateral prefrontal cortex may potentially be used as a neuroimaging biomarker of sleep quality.

The gray matter volume of bilateral inferior temporal gyrus in mediating the association between psychological stress and sleep quality among Chinese college students

The role of brain regions in the relationship between psychological stress and sleep quality is unclear. This study investigates the neuroanatomical basis of the association between psychological stress and sleep quality. Data were collected using the Pittsburgh Sleep Quality Index, the Psychosomatic Tension Relaxation Inventory, and voxel-based morphometry among 318 healthy students. The results showed that psychological stress was negatively correlated with sleep quality. According to the mediation analysis results, the correlation between psychological stress and sleep quality was partially mediated by the region of the bilateral inferior temporal gyrus. These findings suggest that there is a strong link between sleep quality and psychological stress, highlighting the gray matter volume of the bilateral inferior temporal gyrus related to emotional processing, which plays an essential role in improving sleep quality.

Is there any relation between arterial stiffness and insomnia? A challenging question

PURPOSE

Insomnia is a common sleep disorder which has high comorbidity with a number of cardiovascular diseases (CVD). As a possible risk factor for the CVDs, arterial stiffness may be assessed non-invasively by pulse wave velocity (PWV) and augmentation index (AI). The aim of this study was to evaluate any relation between insomnia and arterial stiffness.

METHODS

Patients with insomnia were included in the study after the exclusion of other sleep disorders by polysomnography. Sleep quality and the degree of insomnia symptoms were evaluated by the Pittsburgh sleep quality index (PSQI) and insomnia severity index (ISI), respectively. PWV and AI were assessed by Mobil-O-Graph arteriograph system.

RESULTS

Consecutive patients with insomnia (n = 72, 56 women, mean age 55.8 ± 9.1 years) were included. Patients were grouped as those with severe ISI scores (22-28) and those with mild to moderate ISI scores (8-21). Despite no significant difference in characteristics and clinical data, patients with severe ISI scores had significantly higher total PSQI scores and NREM-2 with significantly lower REM duration. They also had significantly higher systolic blood pressure, mean blood pressure, pulse pressure, PWV, and AI compared to patients with mild and moderate ISI scores. Correlation analysis revealed that PWV and AI were significantly correlated with the ISI score and PSQI score.

CONCLUSION

There is a close relation between arterial stiffness and insomnia suggesting a risk for CVD in patients with insomnia.

Sleep-Related Cognitive Processes and the Incidence of Insomnia Over Time: Does Anxiety and Depression Impact the Relationship?

Aim: According to the Cognitive Model of Insomnia, engaging in sleep-related cognitive processes may lead to sleep problems over time. The aim was to examine associations between five sleep-related cognitive processes and the incidence of insomnia, and to investigate if baseline anxiety and depression influence the associations. Methods: Two thousand three hundred and thirty-three participants completed surveys on nighttime and daytime symptoms, depression, anxiety, and cognitive processes at baseline and 6 months after the first assessment. Only those without insomnia at baseline were studied. Participants were categorized as having or not having incident insomnia at the next time point. Baseline anxiety and depression were tested as moderators. Results: Three cognitive processes predicted incident insomnia later on. Specifically, more safety behaviors and somatic arousal at Time 1 increased the risk of developing insomnia. When investigating changes in the cognitive processes over time, reporting an increase of worry and safety behaviors also predicted incident insomnia. Depressive symptoms moderated the association between changes in worry and incident insomnia. Conclusion: These findings provide partial support for the hypothesis that cognitive processes are associated with incident insomnia. In particular, safety behaviors, somatic arousal, and worry increase the risk for incident insomnia. Preventative interventions and future research are discussed.

Functional MRI of arousals in nonrapid eye movement sleep

Arousals commonly occur during human sleep and have been associated with several sleep disorders. Arousals are characterized as an abrupt electroencephalography (EEG) frequency change to higher frequencies during sleep. However, the human brain regions involved in arousal are not yet clear. Simultaneous EEG and functional magnetic resonance imaging (fMRI) data were recorded during the early portion of the sleep period in healthy young adults. Arousals were identified based on the EEG data, and fMRI signal changes associated with 83 arousals from 19 subjects were analyzed. Subcortical regions, including the midbrain, thalamus, basal ganglia, and cerebellum, were activated with arousal. Cortices, including the temporal gyrus, occipital gyrus, and frontal gyrus, were deactivated with arousal. The activations associated with arousal in the subcortical regions were consistent with previous findings of subcortical involvement in behavioral arousal and consciousness. Cortical deactivations may serve as a mechanism to direct incoming sensory stimuli to specific brain regions, thereby monitoring environmental perturbations during sleep.

Managing Insomnia Using Lucid Dreaming Training: A Pilot Study

Objectives/Background: Despite Cognitive Behavioral Therapy for Insomnia (CBT-I) being considered the first-line treatment for insomnia, it is not without its challenges. As such it is worthwhile to consider, and test, alternative or adjuvant management options. Methods/Participants: The aim of the present study was to examine whether Lucid Dreaming Training for insomnia (LDT-I) impacted on insomnia, depressive and anxious symptomology in an open label trial of 48 adults with Insomnia Disorder. Participants completed the Insomnia Severity Index, General Anxiety Disorder-7 and Patient Health Questionnaire at baseline then one month following LDT-I. Training consisted of four modules delivered over a period of two consecutive weeks. Results: The results suggest, albeit preliminarily, that LDT-I may have a place within the non-pharmacological management of insomnia, as there were significant reductions in insomnia severity (t(46) = 8.16,p <.001), anxious symptomology (t(46) = 4.75,p <.001) and depressive symptomology (t(46) = 5.87,p <.001). Further, the effect size in terms of pre-post reductions on ISI scores was large (d_z 1.17). Conclusions: Whilst the results are promising, further testing of LDT-I is needed to inform its place amongst the non-pharmacological treatments for insomnia.

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.

Misperception of sleep duration in mild traumatic brain injury/concussion: a preliminary report

Background: Polysomnographic (PSG) findings of persons with mild traumatic brain injury (mTBI)/concussion show longer total sleep time than patients themselves report; the reason for this is not entirely clear.Objective: This study aimed to elucidate the socio-demographic, brain-injury-related, and clinical characteristics that underlie accuracy of sleep duration reporting in mTBI/concussion.Methods: Thirty-seven participants diagnosed with mTBI/concussion (57% male, 47.54 ± 11.3 years old) underwent clinical and neuroimaging examinations, full-night PSG, and estimated sleep duration following PSG.Results: Mean self-reported sleep duration was 342 ± 93.6 minutes and PSG-measured sleep duration was 382 ± 76.8 minutes. Measurements were moderately correlated (rho = 0.46, p = .004). Age associated with self- and PSG-measured sleep duration (rho = 0.34 and rho = 0.84, respectively, p < .05). Self-reported sleep duration was uniquely associated with insomnia severity (rho = -0.48, p = .002). In the fully adjusted multivariable regression analysis, several clinical characteristics of patients explained 30% of the discrepancy between self- and PSG-measured sleep duration.Conclusion: The observed results indicate that persons with mTBI do not accurately assess their sleep duration and, therefore, PSG is warranted in clinical situations where sleep duration is of concern.

Nonclinical pharmacology of daridorexant: a new dual orexin receptor antagonist for the treatment of insomnia

Dual orexin receptor antagonists (DORAs) represent a novel type of sleep medication that provide an alternative to the traditionally used positive allosteric gamma-aminobutyric acid (GABA)-A receptor modulators. Daridorexant is a new DORA that exhibited in phase 3 trials in insomnia not only a beneficial effect on sleep variables, measured objectively and assessed subjectively, but also an improvement in daytime functioning. Daridorexant was discovered through a tailored research program aimed at identifying an optimized sleep-promoting molecule with pharmacokinetic properties appropriate for covering the whole night while avoiding next-morning residual activity at efficacious doses. By specific binding to both orexin receptors, daridorexant inhibits the actions of the wake-promoting orexin (also called hypocretin) neuropeptides. This mechanism avoids a more widespread inhibition of neuronal pathways and associated side effects that are intrinsic to positive allosteric GABA-A receptor modulators. Here, we review the general pharmacology of daridorexant, based on nonclinical pharmacology studies of daridorexant, unpublished or already described, or based on work with other DORAs. Some unique features of daridorexant will be highlighted, such as the promotion of natural and surmountable sleep, the preservation of memory and cognition, the absence of tolerance development or risk of physical dependence, and how it can benefit daytime functioning.

Self-reported difficulty initiating sleep and early morning awakenings are associated with nocturnal diastolic non-dipping in older white Swedish men

Chronically blunted nocturnal blood pressure (BP) dipping has been shown to increase the future risk of cardiovascular diseases. In the present cross-sectional study, we investigated whether self-reported insomnia symptoms were associated with an altered 24-h BP profile and blunted nocturnal BP dipping (night-to-day BP ratio > 0.90) in older men. For the analysis, we used 24-h ambulatory blood pressure data and reports of insomnia symptoms (difficulty initiating sleep, DIS; and early morning awakenings, EMA) from 995 Swedish men (mean age: 71 years). Compared to men without DIS, those reporting DIS (10% of the cohort) had a higher odds ratio of diastolic non-dipping (1.85 [1.15, 2.98], P = 0.011). Similarly, men who reported EMA (19% of the cohort) had a higher odds ratio of diastolic non-dipping than those without EMA (1.57 [1.09, 2.26], P = 0.015). Despite a slightly higher nocturnal diastolic BP among men with EMA vs. those without EMA (+ 1.4 mmHg, P = 0.042), no other statistically significant differences in BP and heart rate were found between men with and those without insomnia symptoms. Our findings suggest that older men reporting difficulty initiating sleep or early morning awakenings may have a higher risk of nocturnal diastolic non-dipping. Our findings must be replicated in larger cohorts that also include women.

Assessment of nonnegative matrix factorization algorithms for electroencephalography spectral analysis

BACKGROUND

Nonnegative matrix factorization (NMF) has been successfully used for electroencephalography (EEG) spectral analysis. Since NMF was proposed in the 1990s, many adaptive algorithms have been developed. However, the performance of their use in EEG data analysis has not been fully compared. Here, we provide a comparison of four NMF algorithms in terms of accuracy of estimation, stability (repeatability of the results) and time complexity of algorithms with simulated data. In the practical application of NMF algorithms, stability plays an important role, which was an emphasis in the comparison. A Hierarchical clustering algorithm was implemented to evaluate the stability of NMF algorithms.

RESULTS

In simulation-based comprehensive analysis of fit, stability, accuracy of estimation and time complexity, hierarchical alternating least squares (HALS) low-rank NMF algorithm (lraNMF_HALS) outperformed the other three NMF algorithms. In the application of lraNMF_HALS for real resting-state EEG data analysis, stable and interpretable features were extracted.

CONCLUSION

Based on the results of assessment, our recommendation is to use lraNMF_HALS, providing the most accurate and robust estimation.

Effect of suvorexant on event-related oscillations and EEG sleep in rats exposed to chronic intermittent ethanol vapor and protracted withdrawal

STUDY OBJECTIVES

Insomnia is a prominent complaint in patients with alcohol use disorders (AUD). However, despite the importance of sleep in the maintenance of sobriety, treatment options for sleep disturbance associated with a history of AUD are currently limited. Recent clinical trials have demonstrated that suvorexant, a dual Hct/OX receptor antagonist, normalizes sleep in patients with primary insomnia; yet, its potential for the treatment of sleep pathology associated with AUD has not been investigated in either preclinical or clinical studies.

METHODS

This study employed a model whereby ethanol vapor exposure or control conditions were administered for 8 weeks to adult rats. Waking event-related oscillations (EROs) and EEG sleep were evaluated at baseline before exposure and again following 24 hr of withdrawal from the exposure. Subsequently, the ability of vehicle (VEH) and two doses (10, 30 mg/kg IP) of suvorexant to modify EROs, sleep, and the sleep EEG was investigated.

RESULTS

After 24 hr following EtOH withdrawal, the ethanol-treated group had increases in waking ERO θ and β activity, more fragmented sleep (shorter duration and increased frequency of slow wave (SW) and rapid eye movement [REM] sleep episodes), and increased θ and β power in REM and SW sleep. Suvorexant induced a dose-dependent decrease in the latency to REM and SW sleep onsets but also produced REM and SW sleep fragmentation and increased β energy in waking EROs when compared with VEH.

CONCLUSIONS

Taken together, these studies suggest that suvorexant has overall sleep-promoting effects, but it may exacerbate some aspects of sleep and EEG pathology.

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?).

Surveillance During REM Sleep for the First-Night Effect

We experience disturbed sleep in a new place, and this effect is known as the first-night effect (FNE) in sleep research. We previously demonstrated that the FNE is associated with a surveillance system in one brain hemisphere during NREM sleep, which manifests as interhemispheric asymmetry in sleep depth in the default-mode network (DMN) and increased vigilance toward monitoring external stimuli. This surveillance system may be useful for protecting vulnerable sleepers from abnormal events in unfamiliar environments. The present study investigated whether a similar surveillance system is exhibited during rapid eye movement (REM) sleep. The impacts of the FNE could be different between the phasic period, in which eyes move rapidly, and the tonic period, in which eye movement ceases, of REM sleep; without the FNE, vigilance to external stimuli is generally reduced during the phasic period but not the tonic period. Thus, REM sleep was split into phasic and tonic periods. First, we replicated previous findings showing interhemispheric asymmetry in delta activity in the DMN associated with the FNE during NREM sleep. However, during REM sleep, interhemispheric asymmetry in delta activity or theta activities, two oscillatory activities during REM sleep, was not found during the phasic or tonic periods. Next, we tested whether vigilance, as measured by evoked brain responses (P2) to deviant tones, associated with the FNE was increased in one hemisphere during REM sleep. The P2 amplitudes during the phasic period were augmented by the FNE on day 1 and were significantly larger than those on day 2 when the FNE was not present. In contrast, the P2 amplitudes during the tonic period were not different across days. The P2 amplitudes showed no interhemispheric asymmetry during the phasic or tonic periods. These results suggest that while the surveillance system exhibits interhemispheric asymmetry in sleep depth and vigilance during NREM sleep, this system shows no interhemispheric asymmetry in oscillatory activities and exhibits increased vigilance in both hemispheres only during the phasic period of REM sleep. Therefore, the surveillance system associated with the FNE may involve different mechanisms during NREM and REM sleep.

Stroop Task-Related Brain Activity in Patients With Insomnia: Changes After Cognitive-Behavioral Therapy for Insomnia

Objective/Background: In the present study, we compared differences in brain activity during the Stroop task between patients with chronic insomnia disorder (CID) and good sleepers (GS). Furthermore, we evaluated changes in Stroop task-related brain activity after cognitive-behavioral therapy for insomnia (CBT-I). Participants/Methods: The final analysis included 21 patients with CID and 25 GS. All participants underwent functional magnetic resonance imaging (fMRI) while performing the color-word Stroop task. CBT-I, consisting of 5 sessions, was administered to 14 patients with CID in the absence of medication. After CBT-I, fMRI was repeated in the patients with CID while performing the same task. Sleep-related questionnaires and sleep variables from a sleep diary were also obtained before and after CBT-I. Results: No significant differences in behavioral performance in the Stroop task or task-related brain activation were observed between the CID and GS groups. No changes in behavioral performance or brain activity were found after CBT-I. However, clinical improvement in the Insomnia Severity Index (ISI) score was significantly associated with changes in the Stroop task-related regional blood oxygen level-dependent signals in the left supramarginal gyrus. Conclusions: Our findings suggest that cognitive impairment in patients with CID was not detectable by the Stroop task or Stroop task-related brain activation on fMRI. Moreover, there was no altered brain activity during the Stroop task after CBT-I. However, the ISI score reflected changes in the neural correlates of cognitive processes in patients with CID after CBT-I.

Childhood high-frequency EEG activity during sleep is associated with incident insomnia symptoms in adolescence

BACKGROUND

Insomnia has been associated in cross-sectional studies with increased beta (15-35 Hz) electroencephalogram (EEG) power during nonrapid eye movement (NREM) sleep, an index of cortical hyperarousal. However, it is unknown whether this cortical hyperarousal is present before individuals with insomnia develop the disorder. To fill this gap, we examined the association of childhood sleep high-frequency EEG activity with incident insomnia symptoms (i.e., absence of insomnia symptoms in childhood but presence in adolescence).

METHODS

We studied a case-control subsample of 45 children (6-11 years) from the Penn State Child Cohort, a population-based random sample of 421 children, who were followed up after 8 years as adolescents (13-20 years). We examined low-beta (15-25 Hz) and high-beta (25-35 Hz) relative power at central EEG derivations during NREM sleep and, in secondary analyses, during sleep onset latency, sleep onset, and REM sleep. Incident insomnia symptoms were defined as the absence of parent-reported difficulty falling and/or staying asleep during childhood and a self-report of these insomnia symptoms during adolescence.

RESULTS

Childhood high-beta power during NREM sleep was significantly increased in children who developed insomnia symptoms in adolescence (n = 25) as compared to normal sleeping controls (n = 20; p = .03). Multivariable-adjusted logistic regression models showed that increased childhood high-beta EEG power during NREM sleep was associated with a threefold increased odds (95% CI = 1.12-7.98) of incident insomnia symptoms in adolescence. No other significant relationships were observed for other sleep/wake states or EEG frequency bands.

CONCLUSIONS

Increased childhood high-frequency EEG power during NREM sleep is associated with incident insomnia symptoms in adolescence. This study indicates that cortical hyperarousal during sleep may be a premorbid neurophysiological sign of insomnia, which may mediate the increased risk of psychiatric disorders associated with insomnia.

The impact of cognitive behavioural therapy for insomnia on objective sleep parameters: A meta-analysis and systematic review

It is well-established that cognitive behavioural therapy for insomnia (CBT-I) improves self-reported sleep disturbance, however the impact on objective sleep is less clear. This meta-analysis aimed to quantify the impact of multi-component CBT-I on objective measures of sleep, indexed via polysomnography (PSG) and actigraphy. Fifteen studies met inclusion criteria. Following appraisal for risk of bias, extracted data were meta-analysed using random-effects models. The quality of the literature was generally high, although reporting of methodological detail varied markedly between studies. Meta-analyses found no evidence that CBT-I reliably improves PSG-defined sleep parameters. Actigraphy evidence was more mixed; with a small effect for reduction in sleep onset latency (Hedge's g = -0.28 [95% confidence interval (CI) -0.51 to -0.05], p = 0.018) and a moderate effect for reduction in total sleep time (TST) (Hedge's g = -0.51 [95% CI -0.75 to -0.26], p < 0.001). In contrast, and consistent with recent meta-analyses, CBT-I was associated with robust improvements in diary measures of sleep initiation and maintenance (Hedge's g range = 0.50 to 0.79) but not TST. While the literature is small and still developing, the sleep benefits of CBT-I are more clearly expressed in the subjective versus objective domain.