Sleep–wake physiology

Postbiotics Made From Selected Lactic Acid Bacteria Improves Chronic Restraint Stress-Induced Anhedonia and Sleep Disorders

Sleep disorders have become one of the most prevalent neuropsychiatric disorders in recent years. This study aimed to investigate the effects of postbiotics derived from selected lactic acid bacteria on anhedonia and sleep disorders in chronic restraint stress (CRS)-induced mice, as well as their potential mechanisms. Mice were orally administered normal saline, low, medium, or high doses of postbiotics for 30 days, with CRS applied from days 1 to 21. The medium dose of postbiotics significantly increased the sucrose preference index, and the high dose of postbiotics significantly increased sleep duration. Postbiotic treatment effectively restored the diversity and composition of the gut microbiota to levels comparable to those observed in the vehicle (Veh) group. Furthermore, low and medium doses of postbiotics significantly reduced serum corticosterone levels, and medium and high doses significantly reduced serum IL-1β levels. Additionally, postbiotics administration significantly increased glutamate and GABA levels in both the prefrontal cortex and hypothalamus, as well as GABA levels in the feces. These results indicate that postbiotics alleviate CRS-induced anhedonia and sleep disorders in a dose-dependent manner. This effect may be mediated through the restoration of homeostasis in the MGB axis, HPA axis, inflammation pathways, and neurotransmitter balance.

Sleep and circadian disturbances in children with neurodevelopmental disorders

Sleep is essential for brain development and overall health, particularly in children with neurodevelopmental disorders (NDDs). Sleep disruptions can considerably impact brain structure and function, leading to dysfunction of neurotransmitter systems, metabolism, hormonal balance and inflammatory processes, potentially contributing to the pathophysiology of NDDs. This Review examines the prevalence, types and mechanisms of sleep disturbances in children with NDDs, including autism spectrum disorder, attention-deficit hyperactivity disorder and various genetic syndromes. Common sleep disorders in these populations include insomnia, hypersomnia, circadian rhythm disorders, sleep-related breathing disorders and parasomnias, with underlying factors often involving genetic, neurobiological, environmental and neurophysiological influences. Sleep problems such as insomnia, night awakenings and sleep fragmentation are closely linked to both internalizing symptoms such as anxiety and depression, and externalizing behaviours such as hyperactivity and aggression. Assessment of sleep in children with NDDs presents unique challenges owing to communication difficulties, comorbid conditions and altered sensory processing. The Review underscores the importance of further research to unravel the complex interactions between sleep and neurodevelopment, advocating for longitudinal studies and the identification of predictive biomarkers. Understanding and addressing sleep disturbances in NDDs is crucial for improving developmental outcomes and the overall quality of life for affected individuals and their families.

GABALAGEN Alleviates Stress-Induced Sleep Disorders in Rats

(1) Background: Gamma-aminobutyric acid (GABA) is an amino acid and the primary inhibitory neurotransmitter in the brain. GABA has been shown to reduce stress and promote sleep. GABALAGEN (GBL) is the product of fermented fish collagen by Lactobacillus brevis BJ20 and Lactobacillus plantarum BJ21, naturally enriched with GABA through the fermentation process and characterized by low molecular weight. (2) Methods: The present study evaluated the GABAA affinity of GBL through receptor binding assay. The sedative effects of GBL were investigated through electroencephalography (EEG) analysis in an animal model of electro foot shock (EFS) stress-induced sleep disorder, and then we examined the expression of orexin and the GABAA receptor in the brain region using immunohistochemistry and an enzyme-linked immunosorbent assay (ELISA). (3) Results: We found that on the binding assay, GBL displayed high affinity to the GABAA receptor. Also, after treatment with GBL, the percentage of the total time in rapid eye movement (REM) and non-rapid eye movement (NREM) sleep was significantly and dose-dependently increased in EFS-induced rats. Consistent with behavioral results, the GBL-treated groups showed that the expression of GABAA receptor immune-positive cells in the VLPO was markedly and dose-dependently increased. Also, the GBL-treated groups showed that the expression of the orexin-A level in LH was significantly decreased. (4) Conclusions: GBL showed efficacy and potential to be used as an anti-stress therapy to treat sleep deprivation through the stimulation of GABAA receptors and the consequent inhibition of orexin activity.

The effect of emotional freedom techniques on anxiety depression and sleep in older people living with HIV: a randomized controlled trial

OBJECTIVE

To investigate the effect of Emotional Freedom Techniques on anxiety, depression and sleep in older people living with HIV (PLWH).

METHODS

70 older PLWH experiencing anxiety, depression, and sleep disorders were randomly divided into control and experimental groups using a random number table system (RNT), with 35 participants in each group. The experimental group received Emotional Freedom Techniques once a day for 15-20 min as part of their routine care and health counselling, and the intervention lasted for 2 weeks. The control group received standard nursing care and health guidance. The two groups were assessed using the Pittsburgh Sleep Quality Index (PSQI) and the Hospital Anxiety and Depression Scale (HADS) to measure changes in anxiety, depression, and sleep quality before and after the intervention.

RESULTS

There are totally 67 participants in the trial. In the EFT group (n = 33), PSQI scores decreased from 12.36 ± 2.409 to 9.15 ± 2.476(mean ± SD P < 0.001), HA scores decreased from 12.39 ± 2.344 to 9.12 ± 2.176(mean ± SD P < 0.001), HD scores decreased from 11.58 ± 1.969 to 8.94 ± 2.015 (mean ± SD P < 0.001), compared with no change in the usual care group (n = 34). The EFT group showed significantly lower post-intervention scores than the control group on all scales (P < 0.001), indicating the effectiveness of the intervention.

CONCLUSION

Emotional Freedom Techniques can effectively alleviate anxiety and depression in older PLWH and improve their sleep quality.

Post-Lunch Napping as a Strategy to Enhance Physiological Performance and Cognitive Function in Elite Volleyball Players

Background and Objectives: Volleyball demands high levels of anaerobic strength, flexibility, agility, and mental focus. Adequate sleep has been shown to enhance athletic performance and cognitive function. This study investigates the impact of post-lunch naps of varying durations (25 and 45 min) on the physiological performance and cognitive focus of elite volleyball players. Materials and Methods: Sixteen elite volleyball players (8 male, 8 female) with at least 7 years of competitive experience participated in a randomized crossover study. They underwent three experimental conditions: no nap (No-Nap), a 25-min nap (N25), and a 45-min nap (N45). Physical performance was measured through counter-movement jumps (CMJ) and volleyball agility tests, while cognitive function was assessed using the D2 attention test. Statistical analysis included repeated measures ANOVA to examine the differences between nap conditions and gender-specific responses. Results: Significant improvements in both physical performance and cognitive focus were observed in the N25 and N45 conditions compared to the No-Nap condition (indicating the effectiveness of short naps in enhancing both physical and mental performance). Males outperformed females in most physical metrics, while females scored higher on the D2 attention test (suggesting possible gender-specific responses to napping). The 25-min nap showed slightly better results in terms of sleep quality and subsequent performance (confirming that shorter naps may be more beneficial). Conclusions: Post-lunch naps, especially of 25 or 45 min, enhance both physiological and cognitive performance in elite volleyball players. These findings suggest that integrating short naps into athletes' training regimens can improve performance and focus, with potential gender-specific benefits. Further research is needed to explore long-term effects and variations across other sports.

A translationally informed approach to vital signs for psychiatry: a preliminary proof of concept

The nature of data obtainable from the commercial smartphone - bolstered by a translational model emphasizing the impact of social and physical zeitgebers on circadian rhythms and mood - offers the possibility of scalable and objective vital signs for major depression. Our objective was to explore associations between passively sensed behavioral smartphone data and repeatedly measured depressive symptoms to suggest which features could eventually lead towards vital signs for depression. We collected continuous behavioral data and bi-weekly depressive symptoms (PHQ-8) from 131 psychiatric outpatients with a lifetime DSM-5 diagnosis of depression and/or anxiety over a 16-week period. Using linear mixed-effects models, we related depressive symptoms to concurrent passively sensed behavioral summary features (mean and variability of sleep, activity, and social engagement metrics), considering both between- and within-person associations. Individuals with more variable wake-up times across the study reported higher depressive symptoms relative to individuals with less variable wake-up times (B [95% CI] = 1.53 [0.13, 2.93]). On a given week, having a lower step count (-0.16 [-0.32, -0.01]), slower walking rate (-1.46 [-2.60, -0.32]), lower normalized location entropy (-3.01 [-5.51, -0.52]), more time at home (0.05 [0.00, 0.10]), and lower distances traveled (-0.97 [-1.72, -0.22]), relative to one's own typical levels, were each associated with higher depressive symptoms. With replication in larger samples and a clear understanding of how these components are best combined, a behavioral composite measure of depression could potentially offer the kinds of vital signs for psychiatric medicine that have proven invaluable to assessment and decision-making in physical medicine. Clinical Trials Registration: The data that form the basis of this report were collected as part of clinical trial number NCT03152864.

Distinct lateral hypothalamic CaMKIIα neuronal populations regulate wakefulness and locomotor activity

For nearly a century, evidence has accumulated indicating that the lateral hypothalamus (LH) contains neurons essential to sustain wakefulness. While lesion or inactivation of LH neurons produces a profound increase in sleep, stimulation of inhibitory LH neurons promotes wakefulness. To date, the primary wake-promoting cells that have been identified in the LH are the hypocretin/orexin (Hcrt) neurons, yet these neurons have little impact on total sleep or wake duration across the 24-h period. Recently, we and others have identified other LH populations that increase wakefulness. In the present study, we conducted microendoscopic calcium imaging in the LH concomitant with EEG and locomotor activity (LMA) recordings and found that a subset of LH neurons that express Ca2+/calmodulin-dependent protein kinase IIα (CaMKIIα) are preferentially active during wakefulness. Chemogenetic activation of these neurons induced sustained wakefulness and greatly increased LMA even in the absence of Hcrt signaling. Few LH CaMKIIα-expressing neurons are hypocretinergic or histaminergic while a small but significant proportion are GABAergic. Ablation of LH inhibitory neurons followed by activation of the remaining LH CaMKIIα neurons induced similar levels of wakefulness but blunted the LMA increase. Ablated animals showed no significant changes in sleep architecture but both spontaneous LMA and high theta (8 to 10 Hz) power during wakefulness were reduced. Together, these findings indicate the existence of two subpopulations of LH CaMKIIα neurons: an inhibitory population that promotes locomotion without affecting sleep architecture and an excitatory population that promotes prolonged wakefulness even in the absence of Hcrt signaling.

Understanding zebrafish sleep and wakefulness physiology as an experimental model for biomedical research

Sleep is a globally observable fact, or period of reversible distracted rest, that can be distinguished from arousal by various behavioral criteria. Although the function of sleep is an evolutionarily conserved behavior, its mechanism is not yet clear. The zebrafish (Danio rerio) has become a valuable model for neurobehavioral studies such as studying learning, memory, anxiety, and depression. It is characterized by a sleep-like state and circadian rhythm, making it comparable to mammals. Zebrafish are a good model for behavioral studies because they share genetic similarities with humans. A number of neurotransmitters are involved in sleep and wakefulness. There is a binding between melatonin and the hypocretin system present in zebrafish. The full understanding of sleep and wakefulness physiology in zebrafish is still unclear among researchers. Therefore, to make a clear understanding of the sleep/wake cycle in zebrafish, this article covers the mechanism involved behind it, and the role of the neuromodulator system followed by the mechanism of the HPA axis.

The complexities of the sleep-pain relationship in adolescents: A critical review

Chronic pain is a common and disabling condition in adolescents. Disturbed sleep is associated with many detrimental effects in adolescents with acute and chronic pain. While sleep and pain are known to share a reciprocal relationship, the sleep-pain relationship in adolescence warrants further contextualization within normally occurring maturation of several biopsychological processes. Since sleep and pain disorders begin to emerge in early adolescence and are often comorbid, there is a need for a comprehensive picture of their interrelation especially related to temporal relationships and mechanistic drivers. While existing reviews provide a solid foundation for the interaction between disturbed sleep and pain in youth, we will extend this review by highlighting current methodological challenges for both sleep and pain assessments, exploring the recent evidence for directionality in the sleep-pain relationship, reviewing potential mechanisms and factors underlying the relationship, and providing direction for future investigations. We will also highlight the potential role of digital technologies in advancing the understanding of the sleep and pain relationship. Ultimately, we anticipate this information will facilitate further research and inform the management of pain and poor sleep, which will ultimately improve the quality of life in adolescents and reduce the risk of pain persisting into adulthood.

A Review on Pathophysiological Aspects of Sleep Deprivation

Sleep deprivation (SD) (also referred as insomnia) is a condition in which individuals fail to get enough sleep due to excessive yawning, facing difficulty to learn new concepts, experiencing forgetfulness as well as depressed mood. This could occur due to several possible reasons, including medications and stress (caused by shift work). Despite the fact that sleep is important for normal physiology, it currently affects millions of people around the world, especially the US (70 million) and Europe (45 million). Due to increased work demand nowadays, lots of people are experiencing sleep deprivation hence, this could be the reason for several car accidents followed by death and morbidity. This review highlighted the impact of SD on neurotransmitter release and functions, theories (Flip-flop theory, oxidative stress theory, neuroinflammation theory, neurotransmitter theory, and hormonal theory) associated with SD pathogenesis; apart from this, it also demonstrates the molecular pathways underlying SD (PI3K and Akt, NF-κB, Nrf2, and adenosine pathway. However, this study also elaborates on the SD-induced changes in the level of neurotransmitters, hormonal, and mitochondrial functions. Along with this, it also covers several molecular aspects associated with SD as well. Through this study, a link is made between SD and associated causes, which will further help to develop a potential therapeutic strategy against SD.

The role of ovarian hormones in the pathophysiology of perimenopausal sleep disturbances: A systematic review

Sleep disturbance is a common clinical concern throughout the menopausal transition. However, the pathophysiology and causes of these sleep disturbances remain poorly understood, making it challenging to provide appropriate therapy. Our goal was to i) review the literature about the influence of ovarian hormones on sleep in perimenopausal women, ii) summarize the potential underlying pathophysiology of menopausal sleep disturbances and iii) evaluate the implications of these findings for the therapeutic approach to sleep disturbances in the context of menopause. A systematic literature search using the databases Embase, MEDLINE and Cochrane Library was conducted. Keywords relating to ovarian hormones, sleep disturbances and menopause were used. Ultimately, 86 studies were included. Study Quality Assessment Tools of the National Institutes of Health were used for quality assessment. Results from good-quality studies demonstrated that the postmenopausal decline in estrogen and progesterone contributes to sleep disturbances in women and that timely treatment with estrogen and/or progesterone therapy improved overall sleep quality. Direct and indirect effects of both hormones acting in the central nervous system and periphery, as well as via secondary effects (e.g. reduction in vasomotor symptoms), can contribute to improvements in sleep. To strengthen external validity, studies examining neurobiological pathways are needed.

Cross talk mechanism of disturbed sleep patterns in neurological and psychological disorders

The incidence and prevalence of sleep disorders continue to increase in the elderly populace, particularly those suffering from neurodegenerative and neuropsychiatric disorders. This not only affects the quality of life but also accelerates the progression of the disease. There are many reasons behind sleep disturbances in such patients, for instance, medication use, nocturia, obesity, environmental factors, nocturnal motor disturbances and depressive symptoms. This review focuses on the mechanism and effects of sleep dysfunction in neurodegenerative and neuropsychiatric disorders. Wherein we discuss disturbed circadian rhythm, signaling cascade and regulation of genes during sleep deprivation. Moreover, we explain the perturbation in brainwaves during disturbed sleep and the ocular perspective of neurodegenerative and neuropsychiatric manifestations in sleep disorders. Further, as the pharmacological approach is often futile and carries side effects, therefore, the non-pharmacological approach opens newer possibilities to treat these disorders and widens the landscape of treatment options for patients.

Neurobiology of dream activity and effects of stimulants on dreams

The sleep-wake cycle is the result of the activity of a multiple neurobiological network interaction. Dreaming feature is one interesting sleep phenomena that represents sensorial components, mostly visual perceptions, accompanied with intense emotions. Further complexity has been added to the topic of the neurobiological mechanism of dreams generation by the current data that suggests the influence of drugs on dream generation. Here, we discuss the review on some of the neurobiological mechanism of the regulation of dream activity, with special emphasis on the effects of stimulants on dreaming.

Butyrylcholinesterase is a potential biomarker for Sudden Infant Death Syndrome

Background

Autonomic dysfunction has been implicated in the pathophysiology of the Sudden Infant Death Syndrome (SIDS). Butyrylcholinesterase (BChE) is an enzyme of the cholinergic system, a major branch of the autonomic system, and may provide a measure of autonomic (dys)function. This study was undertaken to evaluate BChE activity in infants and young children who had died from Sudden Infant Death or Sudden Unexpected Death.

Methods

In this case-control study we measured BChE activity and total protein in the eluate of 5μL spots punched from the dried blood spots taken at birth as part of the newborn screening program. Results for each of 67 sudden unexpected deaths classified by the coroner (aged 1 week-104 weeks) = Cases, were compared to 10 date of birth - and gender-matched surviving controls (Controls), with five cases reclassified to meet criteria for SIDS, including the criterion of age 3 weeks to 1 year.

Findings

Conditional logistic regression showed that in groups where cases were reported as “SIDS death” there was strong evidence that lower BChE specific activity (BChEsa) was associated with death (OR=0·73 per U/mg, 95% CI 0·60-0·89, P=0·0014), whereas in groups with a “Non-SIDS death” as the case there was no evidence of a linear association between BChEsa and death (OR=1·001 per U/mg, 95% CI 0·89-1·13, P=0·99).

Interpretation

BChEsa, measured in dried blood spots taken 2-3 days after birth, was lower in babies who subsequently died of SIDS compared to surviving controls and other Non-SIDS deaths. We conclude that a previously unidentified cholinergic deficit, identifiable by abnormal -BChEsa, is present at birth in SIDS babies and represents a measurable, specific vulnerability prior to their death.

Funding

All funding provided by a crowd funding campaign https://www.mycause.com.au/p/184401/damiens-legacy

Is paradoxical sleep setting up innate and acquired complex sensorimotor and adaptive behaviours?: A proposed function based on literature review

We summarize here the progress in identifying the neuronal network as well as the function of paradoxical sleep and the gaps of knowledge that should be filled in priority. The core system generating paradoxical sleep localized in the brainstem is now well identified, and the next step is to clarify the role of the forebrain in particular that of the hypothalamus including the melanin-concentrating hormone neurons and of the basolateral amygdala. We discuss these two options, and also the discovery that cortical activation during paradoxical sleep is restricted to a few limbic cortices activated by the lateral supramammillary nucleus and the claustrum. Such activation nicely supports the findings recently obtained showing that neuronal reactivation occurs during paradoxical sleep in these structures, and induces both memory consolidation of important memory and forgetting of less relevant ones. The question that still remains to be answered is whether paradoxical sleep is playing more crucial roles in processing emotional and procedural than other types of memories. One attractive hypothesis is that paradoxical sleep is responsible for erasing negative emotional memories, and that this function is not properly functioning in depressed patients. On the other hand, the presence of a muscle atonia during paradoxical sleep is in favour of a role in procedural memory as new types of motor behaviours can be tried without harm during the state. In a way, it also fits with the proposed role of paradoxical sleep in setting up the sensorimotor system during development.

Translational Approaches to Influence Sleep and Arousal

Sleep disorders are widespread in society and are prevalent in military personnel and in Veterans. Disturbances of sleep and arousal mechanisms are common in neuropsychiatric disorders such as schizophrenia, post-traumatic stress disorder, anxiety and affective disorders, traumatic brain injury, dementia, and substance use disorders. Sleep disturbances exacerbate suicidal ideation, a major concern for Veterans and in the general population. These disturbances impair quality of life, affect interpersonal relationships, reduce work productivity, exacerbate clinical features of other disorders, and impair recovery. Thus, approaches to improve sleep and modulate arousal are needed. Basic science research on the brain circuitry controlling sleep and arousal led to the recent approval of new drugs targeting the orexin/hypocretin and histamine systems, complementing existing drugs which affect GABA_A receptors and monoaminergic systems. Non-invasive brain stimulation techniques to modulate sleep and arousal are safe and show potential but require further development to be widely applicable. Invasive viral vector and deep brain stimulation approaches are also in their infancy but may be used to modulate sleep and arousal in severe neurological and psychiatric conditions. Behavioral, pharmacological, non-invasive brain stimulation and cell-specific invasive approaches covered here suggest the potential to selectively influence arousal, sleep initiation, sleep maintenance or sleep-stage specific phenomena such as sleep spindles or slow wave activity. These manipulations can positively impact the treatment of a wide range of neurological and psychiatric disorders by promoting the restorative effects of sleep on memory consolidation, clearance of toxic metabolites, metabolism, and immune function and by decreasing hyperarousal.

Involvement of adenosine signaling pathway in migraine pathophysiology: A systematic review of clinical studies

OBJECTIVE

To systematically review clinical studies investigating the involvement of adenosine and its receptors in migraine pathophysiology.

BACKGROUND

Adenosine is a purinergic signaling molecule, clinically used in cardiac imaging during stress tests. Headache is a frequent adverse event after intravenous adenosine administration. Migraine headache relief is reported after intake of adenosine receptor antagonist, caffeine. These findings suggest a possible involvement of adenosine signaling in migraine pathophysiology and its potential as a drug target.

METHODS

A search through PubMed and EMBASE was undertaken for clinical studies investigating the role of adenosine and its receptors in migraine, published until September 2021.

RESULTS

A total of 2510 studies were screened by title and abstract. Of these, seven clinical studies were included. The main findings were that adenosine infusion induced headache, and plasma adenosine levels were elevated during ictal compared to interictal periods in migraine patients.

CONCLUSION

The present systematic review emphasizes a potentially important role of adenosine signaling in migraine pathogenesis. Further randomized and placebo-controlled clinical investigations applying adenosine receptors modulators in migraine patients are needed to further understand the adenosine involvement in migraine.

Agomelatine for the treatment of generalized anxiety disorder: focus on its distinctive mechanism of action

Generalized anxiety disorder (GAD), the most frequently diagnosed form of anxiety, is usually treated by cognitive-behavioural approaches or medication; in particular, benzodiazepines (acutely) and serotonin or serotonin/noradrenaline reuptake inhibitors (long term). Efficacy, compliance, and acceptability are, however, far from ideal, reinforcing interest in alternative options. Agomelatine, clinically employed in the treatment of major depression, expresses anxiolytic properties in rodents and was effective in the treatment of GAD (including severely ill patients) in several double-blind, short-term (12 weeks) and relapse-prevention (6 months) studies. At active doses, the incidence of adverse effects was no higher than for placebo. Agomelatine possesses a unique binding profile, behaving as a melatonin (MT₁/MT₂) receptor agonist and 5-HT_2C receptor antagonist, yet recognizing neither monoamine transporters nor GABA_A receptors. Extensive evidence supports a role for 5-HT_2C receptors in the induction of anxious states, and their blockade likely plays a primary role in mediating the anxiolytic actions of agomelatine, including populations in the amygdala and bed nucleus of stria terminalis, as well as the hippocampus. Recruitment of MT receptors in the suprachiasmatic nucleus, thalamic reticular nucleus, and hippocampus appears to fulfil a complimentary role. Downstream of 5-HT_2C and MT receptors, modulation of stress-sensitive glutamatergic circuits and altered release of the anxiogenic neuropeptides, corticotrophin-releasing factor, and vasopressin, may be implicated in the actions of agomelatine. To summarize, agomelatine exerts its anxiolytic actions by mechanisms clearly distinct from those of other agents currently employed for the management of GAD.

PLAIN LANGUAGE SUMMARY

How agomelatine helps in the treatment of anxiety disorders.

INTRODUCTION

• Anxiety disorders have a significant negative impact on quality of life.• The most common type of anxiety disorder, called generalized anxiety disorder (GAD), is associated with nervousness and excessive worry.• These symptoms can lead to additional symptoms like tiredness, sleeplessness, irritability, and poor attention.• GAD is generally treated through either cognitive-behavioural therapy or medication. However, widely used drugs like benzodiazepines and serotonin reuptake inhibitors have adverse effects.• Agomelatine, a well-established antidepressant drug, has shown anxiety-lowering ('anxiolytic') properties in rats and has been shown to effectively treat GAD with minimal side effects.• However, exactly how it acts on the brain to manage GAD is not yet clear.• Thus, this review aims to shed light on agomelatine's mechanism of action in treating GAD.

METHODS

• The authors reviewed studies on how agomelatine treats anxiety in animals.• They also looked at clinical studies on the effects of agomelatine in people with GAD.

RESULTS

• The study showed that agomelatine 'blocks' a receptor in nerve cells, which plays a role in causing anxiety, called the 5-HT_2C receptor.• Blocking this receptor, especially in specific brain regions such as nerve cells of the amygdala, bed nucleus of stria terminalis, and hippocampus, produced the anxiety reduction seen during agomelatine treatment.• Agomelatine also activates the melatonin (MT) receptor, which is known to keep anxiety in check, promote sleep, and maintain the sleep cycle.• Agomelatine should thus tackle sleep disturbances commonly seen in patients with GAD.• Beyond 5-HT_2C and MT receptors, signalling molecules in nerve cells that are known to be involved in anxiety disorders (called 'neurotransmitters' and 'neuropeptides') are also affected by agomelatine.

CONCLUSION

• Agomelatine's anxiolytic effects are caused by mechanisms that are distinct from those of other medications currently used to treat GAD.• This explains its therapeutic success and minimal adverse side effects.

Neurophysiological Aspects of REM Sleep Behavior Disorder (RBD): A Narrative Review

REM sleep without atonia (RSWA) is the polysomnographic (PSG) hallmark of rapid eye movement (REM) sleep behavior disorder (RBD), a feature essential for the diagnosis of this condition. Several additional neurophysiological aspects of this complex disorder have also recently been investigated in depth, which constitute the focus of this narrative review, together with RSWA. First, we describe the complex neural network underlying REM sleep and its muscle atonia, focusing on the disordered mechanisms leading to RSWA. RSWA is then described in terms of its polysomnographic features, and the methods (visual and automatic) currently available for its scoring and quantification are exposed and discussed. Subsequently, more recent and advanced neurophysiological features of RBD are described, such as electroencephalography during wakefulness and sleep, transcranial magnetic stimulation, and vestibular evoked myogenic potentials. The role of the assessment of neurophysiological features in the study of RBD is then carefully discussed, highlighting their usefulness and sensitivity in detecting neurodegeneration in the early or prodromal stages of RBD, as well as their relationship with other proposed biomarkers for the diagnosis, prognosis, and monitoring of this condition. Finally, a future research agenda is proposed to help clarify the many still unclear aspects of RBD.

Neurophysiological Aspects of REM Sleep Behavior Disorder (RBD): A Narrative Review

REM sleep without atonia (RSWA) is the polysomnographic (PSG) hallmark of rapid eye movement (REM) sleep behavior disorder (RBD), a feature essential for the diagnosis of this condition. Several additional neurophysiological aspects of this complex disorder have also recently been investigated in depth, which constitute the focus of this narrative review, together with RSWA. First, we describe the complex neural network underlying REM sleep and its muscle atonia, focusing on the disordered mechanisms leading to RSWA. RSWA is then described in terms of its polysomnographic features, and the methods (visual and automatic) currently available for its scoring and quantification are exposed and discussed. Subsequently, more recent and advanced neurophysiological features of RBD are described, such as electroencephalography during wakefulness and sleep, transcranial magnetic stimulation, and vestibular evoked myogenic potentials. The role of the assessment of neurophysiological features in the study of RBD is then carefully discussed, highlighting their usefulness and sensitivity in detecting neurodegeneration in the early or prodromal stages of RBD, as well as their relationship with other proposed biomarkers for the diagnosis, prognosis, and monitoring of this condition. Finally, a future research agenda is proposed to help clarify the many still unclear aspects of RBD.

Sleep Apnea and Serum Serotonin Level Pre- and Post-PAP Therapy: A Preliminary Study

Introduction

The high prevalence of obstructive sleep apnea (OSA), which impairs quality of life for numerous patients and leads to various OSA complications, has contributed to the continued interest in this disorder. The role of serotonin (5-HT) in many physiological processes, studies on its connection with the circadian system, and relationship to changes in sleep architecture are insufficient to assess the interaction of this neurotransmitter with nocturnal hypoxia. The aim of this study was to determine changes in sleep patterns and serum serotonin levels before and after positive airway pressure (PAP) therapy in patients with OSA.

Methods

The study involved 30 OSA patients (27 men and 3 women) who were treated with PAP for 3 months. Polysomnography using the GRASS TELEFACTOR (USA) and blood collection were conducted before and after PAP courses. Determination of serum serotonin was performed by high-performance liquid chromatography (HPLC). PAP therapy was performed using an automatic Prisma 20A (Germany) continuous positive airway pressure (CPAP) device.

Results

The use of PAP for 3 months revealed a significant improvement as measured by sleep data and serotonin levels (before: apnea index [AI] 17.2 eV/h, after: 2.4 eV/h p = 0.001; SpO₂ < 90% − 45.7 min vs. 6.2 min p = 0.001; serotonin 20.3 ng/mL vs. 26.03 ng/mL p = 0.036].

Conclusion

Our results demonstrate an improvement in sleep patterns. There was an increase in serum serotonin levels in OSA patients following PAP therapy, which could be an effect of intermittent hypoxia decline, and could be used as criteria for the effectiveness of PAP and an improvement in sleep quality.

Understanding the Associations of Prenatal Androgen Exposure on Sleep Physiology, Circadian Proteins, Anthropometric Parameters, Hormonal Factors, Quality of Life, and Sex Among Healthy Young Adults: Protocol for an International, Multicenter Study

Background

The ratio of the second finger length to the fourth finger length (2D:4D ratio) is considered to be negatively correlated with prenatal androgen exposure (PAE) and positively correlated with prenatal estrogen. Coincidentally, various brain regions are sensitive to PAE, and their functions in adults may be influenced by the prenatal actions of sex hormones.

Objective

This study aims to assess the relationship between PAE (indicated by the 2D:4D ratio) and various physiological (sex hormone levels and sleep-wake parameters), psychological (mental health), and sexual parameters in healthy young adults.

Methods

This study consists of two phases. In phase 1, we will conduct a survey-based study and anthropometric assessments (including 2D:4D ratio and BMI) in healthy young adults. Using validated questionnaires, we will collect self-reported data on sleep quality, sexual function, sleep chronotype, anxiety, and depressive symptoms. In phase 2, a subsample of phase 1 will undergo polysomnography and physiological and genetic assessments. Sleep architecture data will be obtained using portable polysomnography. The levels of testosterone, estradiol, progesterone, luteinizing hormone, follicle-stimulating hormone, prolactin, melatonin, and circadian regulatory proteins (circadian locomotor output cycles kaput [CLOCK], timeless [TIM], and period [PER]) and the expression levels of some miRNAs will be measured using blood samples. The rest and activity cycle will be monitored using actigraphy for a 7-day period.

Results

In Poland, 720 participants were recruited for phase 1. Among these, 140 completed anthropometric measurements. In addition, 25 participants joined and completed phase 2 data collection. Recruitment from other sites will follow.

Conclusions

Findings from our study may help to better understand the plausible role of PAE in sleep physiology, mental health, and sexual quality of life in young adults.

International Registered Report Identifier (IRRID)

DERR1-10.2196/29199

Why It Is Important to Consider the Effects of Analgesics on Sleep: A Critical Review

We review the known physiological mechanisms underpinning all of pain processing, sleep regulation, and pharmacology of analgesics prescribed for chronic pain. In particular, we describe how commonly prescribed analgesics act in sleep-wake neural pathways, with potential unintended impact on sleep and/or wake function. Sleep disruption, whether pain- or drug-induced, negatively impacts quality of life, mental and physical health. In the context of chronic pain, poor sleep quality heightens pain sensitivity and may affect analgesic function, potentially resulting in further analgesic need. Clinicians already have to consider factors including efficacy, abuse potential, and likely side effects when making analgesic prescribing choices. We propose that analgesic-related sleep disruption should also be considered. The neurochemical mechanisms underlying the reciprocal relationship between pain and sleep are poorly understood, and studies investigating sleep in those with specific chronic pain conditions (including those with comorbidities) are lacking. We emphasize the importance of further work to clarify the effects (intended and unintended) of each analgesic class to inform personalized treatment decisions in patients with chronic pain. © 2021 American Physiological Society. Compr Physiol 11:1-31, 2021.

Clinical evaluation of the pharmacological impact of ashwagandha root extract on sleep in healthy volunteers and insomnia patients: A double-blind, randomized, parallel-group, placebo-controlled study

ETHNOPHARMACOLOGICAL RELEVANCE

Ashwagandha (Withania somnifera (L.) Dunal.) is long known for its sleep-inducing effects. Ashwagandha can be proposed as an alternative to the recommended present treatments for insomnia. This study aimed to evaluate the pharmacological effect of Ashwagandha root extract on sleep in healthy subjects and also in the subjects having insomnia.

MATERIAL AND METHODS

We performed a randomized, parallel-group, stratified design, placebo-controlled study. A total of 80 eligible participants, 40 in Arm-A (healthy) and 40 in Arm-B (insomnia) were assigned to two groups, either Ashwagandha or placebo and studied for 8-weeks. The assessment was done based on the sleep parameters (Sleep Onset Latency, Total Sleep Time, Wake After Sleep Onset, Total time in bed, and Sleep Efficiency), Pittsburgh Sleep Quality Index and Hamilton Anxiety scale-A questionnaire, mental alertness on rising assessment, and sleep quality questionnaire. Safety and adverse events along with the concomitant medication were also assessed.

RESULTS

In both healthy and insomnia subjects, there was a significant improvement in the sleep parameters in the Ashwagandha root extract supplemented group. The improvement was found more significant in insomnia subjects than healthy subjects. Repeat measure Analysis of variance (ANOVA) confirmed the significant improvement in SOL (p 0.013), HAM-A outcomes (p < 0.05), mental alertness (p 0.01), and sleep quality (p < 0.05) of the insomnia patients. A two-way ANOVA was used to confirm the outcomes that denoted sleep onset latency (p < 0.0001) and sleep efficiency (p < 0.0001) as the most improved parameters, followed by TST (p < 0.002) and WASO(p < 0.040). All these parameters (SOL, TST, WASO, TIB, SE, PSQI, HAM-A, Mental Alertness, and Sleep quality) were also statistically assessed for the significant improvement within the group both for the treatment, and the placebo groups in the healthy and the insomnia datasets. Obtained results suggest statistically significant (p < 0.0001) changes between the baseline values and the end of the study results except for the HAM-A and the mental alertness scoresn the healthy subject group.

CONCLUSION

The present study confirms that Ashwagandha root extract can improve sleep quality and can help in managing insomnia. Ashwagandha root extract was well tolerated by all the participants irrespective of their health condition and age. Additional clinical trials are required to generalize the outcome.

Sleep disorders in autoimmune encephalitis

Sleep disorders in people with autoimmune encephalitis have received little attention, probably overshadowed by the presence of other neurological and psychiatric symptoms in this group of conditions. However, sleep disorders are frequent, often severe, and usually persist beyond the acute disease stage, interfering with patients' recovery and quality of life. Because autoimmune encephalitis can affect any brain network involved in sleep initiation and regulation, all types of sleep disorders can occur, with varying distinct associations, frequency, and intensity. Anti-IgLON5 and anti-NMDA receptor encephalitis exemplify two diseases in which sleep disorders are prominent. In anti-IgLON5 disease, sleep disorders were the core symptoms that led to the description of this disease, whereas in anti-NMDA receptor encephalitis, sleep disorders vary according to the disease stage along with other neuropsychiatric symptoms. Comprehensive, systematic, multicentre studies are needed to characterise sleep disorders and their mechanisms in autoimmune encephalitis.

The Paraventricular Nucleus of the Thalamus Is an Important Node in the Emotional Processing Network

The paraventricular nucleus of the thalamus (PVT) has for decades been acknowledged to be an important node in the limbic system, but studies of emotional processing generally fail to incorporate it into their investigational framework. Here, we propose that the PVT should be considered as an integral part of the emotional processing network. Through its distinct subregions, cell populations, and connections with other limbic nuclei, the PVT participates in both major features of emotion: arousal and valence. The PVT, particularly the anterior PVT, can through its neuronal activity promote arousal, both as part of the sleep-wake cycle and in response to novel stimuli. It is also involved in reward, being both responsive to rewarding stimuli and itself affecting behavior reflecting reward, likely via specific populations of cells distributed throughout its subregions. Similarly, neuronal activity in the PVT contributes to depression-like behavior, through yet undefined subregions. The posterior PVT in particular demonstrates a role in anxiety-like behavior, generally promoting but also inhibiting this behavior. This subregion is also especially responsive to stressors, and it functions to suppress the stress response following chronic stress exposure. In addition to participating in unconditioned or primary emotional responses, the PVT also makes major contributions to conditioned emotional behavior. Neuronal activity in response to a reward-predictive cue can be detected throughout the PVT, and endogenous activity in the posterior PVT strongly predicts approach or seeking behavior. Similarly, neuronal activity during conditioned fear retrieval is detected in the posterior PVT and its activation facilitates the expression of conditioned fear. Much of this involvement of the PVT in arousal and valence has been shown to occur through the same general afferents and efferents, including connections with the hypothalamus, prelimbic and infralimbic cortices, nucleus accumbens, and amygdala, although a detailed functional map of the PVT circuits that control emotional responses remains to be delineated. Thus, while caveats exist and more work is required, the PVT, through its extensive connections with other prominent nuclei in the limbic system, appears to be an integral part of the emotional processing network.

Rapid Eye Movement Sleep Sawtooth Waves Are Associated with Widespread Cortical Activations

Sawtooth waves (STW) are bursts of frontocentral slow oscillations recorded in the scalp electroencephalogram (EEG) during rapid eye movement (REM) sleep. Little is known about their cortical generators and functional significance. Stereo-EEG performed for presurgical epilepsy evaluation offers the unique possibility to study neurophysiology in situ in the human brain. We investigated intracranial correlates of scalp-detected STW in 26 patients (14 women) undergoing combined stereo-EEG/polysomnography. We visually marked STW segments in scalp EEG and selected stereo-EEG channels exhibiting normal activity for intracranial analyses. Channels were grouped in 30 brain regions. The spectral power in each channel and frequency band was computed during STW and non-STW control segments. Ripples (80-250 Hz) were automatically detected during STW and control segments. The spectral power in the different frequency bands and the ripple rates were then compared between STW and control segments in each brain region. An increase in 2-4 Hz power during STW segments was found in all brain regions, except the occipital lobe, with large effect sizes in the parietotemporal junction, the lateral and orbital frontal cortex, the anterior insula, and mesiotemporal structures. A widespread increase in high-frequency activity, including ripples, was observed concomitantly, involving the sensorimotor cortex, associative areas, and limbic structures. This distribution showed a high spatiotemporal heterogeneity. Our results suggest that STW are associated with widely distributed, but locally regulated REM sleep slow oscillations. By driving fast activities, STW may orchestrate synchronized reactivations of multifocal activities, allowing tagging of complex representations necessary for REM sleep-dependent memory consolidation.SIGNIFICANCE STATEMENT Sawtooth waves (STW) present as scalp electroencephalographic (EEG) bursts of slow waves contrasting with the low-voltage fast desynchronized activity of REM sleep. Little is known about their cortical origin and function. Using combined stereo-EEG/polysomnography possible only in the human brain during presurgical epilepsy evaluation, we explored the intracranial correlates of STW. We found that a large set of regions in the parietal, frontal, and insular cortices shows increases in 2-4 Hz power during scalp EEG STW, that STW are associated with a strong and widespread increase in high frequencies, and that these slow and fast activities exhibit a high spatiotemporal heterogeneity. These electrophysiological properties suggest that STW may be involved in cognitive processes during REM sleep.

Migraine and Sleep in Children: A Bidirectional Relationship

Migraine and sleep disorders in children exhibit a bidirectional relationship. This relationship is based on shared pathophysiology. Migraine involves activation of the trigeminal vascular system. Nociceptive neurons that innervate the dura release various vasoactive peptides. Calcitonin gene-related peptide is the most active of these peptides. Neural pathways that are involved in sleep generation are divided into those responsible for circadian rhythm, wake promotion, non-rapid eye movement, and rapid eye movement sleep activation. Sleep state switches are a critical component of these systems. The cerebral structures, networks, and neurochemical systems that are involved in migraine align closely with those responsible for the regulation of sleep. Neurochemical systems that are involved with both the pathogenesis of migraine and regulation of sleep include adenosine, melatonin, orexin, and calcitonin gene-related peptide. Sleep disorders represent the most common comorbidity with migraine in childhood. The prevalence of parasomnias, obstructive sleep apnea, and sleep-related movement disorders is significantly greater in children migraineurs. Infantile colic is a precursor of childhood migraine. Treatment of comorbid sleep disorders is important for the appropriate management of children with migraine. Sleep-based behavioral interventions can be of substantial benefit. These interventions are particularly important in children due to limited evidence for effective migraine pharmacotherapy.

Hypnotic Effects of Lactobacillus fermentum PS150TM on Pentobarbital-Induced Sleep in Mice

The bidirectional communication between the gastrointestinal tract and the central nervous system appears to be functionally linked to the intestinal microbiome, namely the microbiome-gut-brain axis (MGBA). Probiotics with health benefits on psychiatric or neurological illnesses are generally called psychobiotics, and some of them may also be able to improve sleep by targeting the MGBA. This study aimed to investigate the effects of a psychobiotic strain, Lactobacillus fermentum PS150TM (PS150TM), on sleep improvement by using a pentobarbital-induced sleep mouse model. Compared with the vehicle control group, the oral administration of PS150TM, but not the other L. fermentum strains, significantly decreased the sleep latency and increased the sleep duration of mice, suggesting strain-specific sleep-improving effects of PS150TM. Moreover, the ingestion of diphenhydramine, an antihistamine used to treat insomnia, as a drug control group, only increased the sleep duration of mice. We also found that the sleep-improving effects of PS150TM are time- and dose-dependent. Furthermore, the oral administration of PS150TM could attenuate a caffeine-induced sleep disturbance in mice, and PS150TM appeared to increase the expression of the gene encoding the adenosine 1 receptor in the hypothalamus of mice, as assessed by quantitative real-time polymerase chain reaction. Taken together, our results present a potential application of PS150TM as a dietary supplement for sleep improvement.