Low-grade neuroinflammation due to chronic sleep deprivation results in anxiety and learning and memory impairments

Sleep Duration and Hypertension: Epidemiological Evidence and Underlying Mechanisms

While the contribution of several physiological systems to arterial blood pressure regulation has been studied extensively, the role of normal and disrupted sleep as a modifiable determinant of blood pressure control, and in the pathophysiology of hypertension, has only recently emerged. Several sleep disorders, including sleep apnea and insomnia, are thought to contribute to the development of hypertension, although less attention is paid to the relationship between sleep duration and blood pressure independent of sleep disorders per se. Accordingly, this review focuses principally on the physiology of sleep and the consequences of abnormal sleep duration both experimentally and at the population level. Clinical implications for patients with insomnia who may or may not have abbreviated sleep duration are explored. As a corollary, we further review studies of the effects of sleep extension on blood pressure regulation. We also discuss epidemiological evidence suggesting that long sleep may also be associated with hypertension and describe the parabolic relationship between total sleep time and blood pressure. We conclude by highlighting gaps in the literature regarding the potential role of gut microbial health in the cross-communication of lifestyle patterns (exercise, diet, and sleep) with blood pressure regulation. Additionally, we discuss populations at increased risk of short sleep, and specifically the need to understand mechanisms and therapeutic opportunities in women, pregnancy, the elderly, and in African Americans.

Are Changes in Sleep Quality/Quantity or Baseline Sleep Parameters Related to Changes in Clinical Outcomes in Patients With Nonspecific Chronic Low Back Pain?: A Systematic Review

OBJECTIVES

Sleep disturbance is prevalent among patients with chronic low back pain (CLBP). This systematic review aimed to summarize the evidence regarding the: (1) temporal relations between changes in sleep quality/quantity and the corresponding changes in pain and/or disability; and (2) role of baseline sleep quality/quantity in predicting future pain and/or disability in patients with CLBP.

METHODS

Four databases were searched from their inception to February 2021. Two reviewers independently screened the abstract and full text, extracted data, assessed the methodological quality of the included studies, and evaluated the quality of evidence of the findings using the Grading of Recommendations Assessment Development and Evaluation (GRADE).

RESULTS

Of 1995 identified references, 6 articles involving 1641 participants with CLBP were included. Moderate-quality evidence substantiated that improvements in self-reported sleep quality and total sleep time were significantly correlated with the corresponding LBP reduction. Low-quality evidence showed that self-reported improvements in sleep quality were related to the corresponding improvements in CLBP-related disability. There was conflicting evidence regarding the relation between baseline sleep quality/quantity and future pain/disability in patients with CLBP.

DISCUSSION

This is the first systematic review to accentuate that improved self-reported sleep quality/quantity may be associated with improved pain/disability, although it remains unclear whether baseline sleep quality/quantity is a prognostic factor for CLBP. These findings highlight the importance of understanding the mechanisms underlying the relation between sleep and CLBP, which may inform the necessity of assessing or treating sleep disturbance in people with CLBP.

Synergistic gene regulation by thyroid hormone and glucocorticoid in the hippocampus

The hippocampus is considered the center for learning and memory in the brain, and its development and function is greatly affected by the thyroid and stress axes. Thyroid hormone (TH) and glucocorticoids (GC) are known to have a synergistic effect on developmental programs across several vertebrate species, and their effects on hippocampal structure and function are well-documented. However, there are few studies that focus on the processes and genes that are cooperatively regulated by the two hormone axes. Cross-regulation of the thyroid and stress axes in the hippocampus occurs on multiple levels such that TH can regulate the expression of the GC receptor (GR) while GC can modulate tissue sensitivity to TH by controlling the expression of TH receptor (TR) and enzymes involved in TH biosynthesis. Thyroid hormone and GC are also known to synergistically regulate the transcription of genes associated with neuronal function and development. Synergistic gene regulation by TH and GC may occur through the direct, cooperative action of TR and GR on common target genes, or by indirect mechanisms involving gene regulatory cascades activated by TR and GR. In this chapter, we describe the known physiological effects and underlying molecular mechanisms of TH and GC synergistic gene regulation in the hippocampus.

Sleep Disruption Worsens Seizures: Neuroinflammation as a Potential Mechanistic Link

Sleep disturbances, such as insomnia, obstructive sleep apnea, and daytime sleepiness, are common in people diagnosed with epilepsy. These disturbances can be attributed to nocturnal seizures, psychosocial factors, and/or the use of anti-epileptic drugs with sleep-modifying side effects. Epilepsy patients with poor sleep quality have intensified seizure frequency and disease progression compared to their well-rested counterparts. A better understanding of the complex relationship between sleep and epilepsy is needed, since approximately 20% of seizures and more than 90% of sudden unexpected deaths in epilepsy occur during sleep. Emerging studies suggest that neuroinflammation, (e.g., the CNS immune response characterized by the change in expression of inflammatory mediators and glial activation) may be a potential link between sleep deprivation and seizures. Here, we review the mechanisms by which sleep deprivation induces neuroinflammation and propose that neuroinflammation synergizes with seizure activity to worsen neurodegeneration in the epileptic brain. Additionally, we highlight the relevance of sleep interventions, often overlooked by physicians, to manage seizures, prevent epilepsy-related mortality, and improve quality of life.

Effect of chronic sleep deprivation and sleep recovery on hippocampal CA3 neurons, spatial memory and anxiety-like behavior in rats

Sleep deprivation-induced degenerative changes in the brain lead to the impairment of memory, anxiety, and quality of life. Several studies have reported the effects of sleep deprivation on CA1 and dentate gyrus regions of the hippocampus; in contrast, there is less known about the impact of chronic sleep deprivation (CSD) and sleep recovery on CA3 neurons and behavior. Hence, the present study aimed to understand the effect of CSD and sleep recovery on hippocampal CA3 neurons and spatial memory, and anxiety-like behavior in rats. Sixty male rats (Sprague Dawley) were grouped as control, environmental control (EC), CSD, 5 days sleep recovery (CSD + 5D SR), and 21 days sleep recovery (CSD + 21D SR). CSD, CSD + 5D SR and, CSD + 21D SR group rats were sleep deprived for 21 days (18 h/day). After CSD, the CSD + 5D SR and CSD + 21D SR rats were sleep recovered for 5- and 21-days respectively. Oxidative stress, dendritic arborization of CA3 neurons, spatial memory, and anxiety-like behavior was assessed. Spatial memory, basal, and apical dendritic branching points/intersections in hippocampal CA3 neurons were reduced, and anxiety-like behavior and oxidative stress increased significantly in the CSD group compared to control (p < 0.001). The CSD + 21D SR showed a significant improvement in spatial memory, reduction in anxiety-like behavior, and oxidative stress when compared to the CSD group (p < 0.05). The basal and apical dendritic branching points/intersections in hippocampal CA3 neurons were increased after CSD + 21D SR, however, it was not significant (p > 0.05). Even though the CSD + 21D SR showed a significant improvement in all the parameters, it did not reach the control level. There was an improvement in all the parameters after CSD + 5D SR but this was not significant compared to the CSD group (p > 0.05). Overall results indicate that the CSD-induced impairment of spatial memory and anxiety-like behavior was associated with oxidative stress and reduced dendritic arborization of hippocampal CA3 neurons. The CSD + 21D SR significantly reduced the damage caused by CSD, but it was not sufficient to reach the control level.

Role of sleep deprivation in immune-related disease risk and outcomes

Modern societies are experiencing an increasing trend of reduced sleep duration, with nocturnal sleeping time below the recommended ranges for health. Epidemiological and laboratory studies have demonstrated detrimental effects of sleep deprivation on health. Sleep exerts an immune-supportive function, promoting host defense against infection and inflammatory insults. Sleep deprivation has been associated with alterations of innate and adaptive immune parameters, leading to a chronic inflammatory state and an increased risk for infectious/inflammatory pathologies, including cardiometabolic, neoplastic, autoimmune and neurodegenerative diseases. Here, we review recent advancements on the immune responses to sleep deprivation as evidenced by experimental and epidemiological studies, the pathophysiology, and the role for the sleep deprivation-induced immune changes in increasing the risk for chronic diseases. Gaps in knowledge and methodological pitfalls still remain. Further understanding of the causal relationship between sleep deprivation and immune deregulation would help to identify individuals at risk for disease and to prevent adverse health outcomes.

Propofol protects hippocampal neurons in sleep-deprived rats by inhibiting mitophagy and autophagy

Background

Sleep deprivation (SD) causes a disturbance in the cognitive function of rats. While propofol has a powerful sedative and hypnotic effect and is an antioxidant, its effect on the cognitive function of rats following SD remains unknown. The purpose of this study was to explore the protective effects of propofol on excessive autophagy and mitophagy in the hippocampus of rats after SD.

Methods

Adult male rats were intraperitoneally injected with 30 mg/kg of propofol after 96 hours of SD. Then we evaluated the effect of propofol on the cognitive function of sleep deprived rats by the Morris water maze. Transmission electron microscopy, Western blotting, PCR, immunohistochemistry, autophagy enhancer and autophagy inhibitor were used to study the effect of propofol on hippocampal neurons of rat with excessive autophagy and mitophagy.

Results

The behavioral experimental results of the Morris water maze showed that propofol improved the learning and memory ability of sleep-deprived rats. The expression of Beclin1, PINK1, parkin, p62, and LC3 protein increased significantly after sleep deprivation. While the intervention of propofol could significantly reduce the expression of these proteins, rapamycin treatment eliminated this effect.

Conclusions

Our findings showed that propofol could reduce the impairment of learning and memory in sleep-deprived rats by inhibiting excessive autophagy and mitophagy in hippocampal neurons. This strategy may provide an application basis for the clinical use of propofol in patients with chronic insomnia.

Short-Term Sleep Fragmentation Dysregulates Autophagy in a Brain Region-Specific Manner

In this study, we investigated autophagy, glial activation status, and corticotropin releasing factor (CRF) signaling in the brains of mice after 5 days of sleep fragmentation (SF). Three different brain regions including the striatum, hippocampus, and frontal cortex were selected for examination based on roles in sleep regulation and sensitivity to sleep disruption. For autophagy, we monitored the levels of various autophagic induction markers including beclin1, LC3II, and p62 as well as the levels of lysosomal associated membrane protein 1 and 2 (LAMP1/2) and the transcription factor EB (TFEB) which are critical for lysosome function and autophagy maturation stage. For the status of microglia and astrocytes, we determined the levels of Iba1 and GFAP in these brain regions. We also measured the levels of CRF and its cognate receptors 1 and 2 (CRFR1/2). Our results showed that 5 days of SF dysregulated autophagy in the striatum and hippocampus but not in the frontal cortex. Additionally, 5 days of SF activated microglia in the striatum but not in the hippocampus or frontal cortex. In the striatum, CRFR2 but not CRFR1 was significantly increased in SF-experienced mice. CRF did not alter its mRNA levels in any of the three brain regions assessed. Our findings revealed that autophagy processes are sensitive to short-term SF in a region-specific manner and suggest that autophagy dysregulation may be a primary initiator for brain changes and functional impairments in the context of sleep disturbances and disorders.

Does Modern Lifestyle Favor Neuroimmunometabolic Changes? A Path to Obesity

Factors linked to modern lifestyles, such as physical inactivity, Western diet, and poor sleep quality have been identified as key contributors to the positive energy balance (PEB). PEB rises adipose tissue hypertrophy and dysfunction over the years, affecting cells and tissues that are metabolically critical for energy homeostasis regulation, especially skeletal muscle, hypothalamic-pituitary-adrenal axis, and gut microbiota. It is known that the interaction among lifestyle factors and tissue metabolic dysfunction increases low-grade chronic systemic inflammation, leading to insulin resistance and other adverse metabolic disorders. Although immunometabolic mechanisms are widely discussed in obesity, neuroimmunoendocrine pathways have gained notoriety, as a link to neuroinflammation and central nervous system disorders. Hypothalamic inflammation has been associated with food intake dysregulation, which comprises homeostatic and non-homeostatic mechanisms, promoting eating behavior changes related to the obesity prevalence. The purpose of this review is to provide an updated and integrated perspective on the effects of Western diet, sleep debt, and physical exercise on the regulation of energy homeostasis and low-grade chronic systemic inflammation. Subsequently, we discuss the intersection between systemic inflammation and neuroinflammation and how it can contribute to energy imbalance, favoring obesity. Finally, we propose a model of interactions between systemic inflammation and neuroinflammation, providing new insights into preventive and therapeutic targets for obesity.

Butanol Extract of Tinospora cordifolia Alleviates Acute Sleep Deprivation-Induced Impairments in Cognitive Functions and Neuromuscular Coordination in Middle-Aged Female Rats

Sleep deprivation due to present-day lifestyle and late-hours work commitments are associated with a broad spectrum of neurobehavioral complications. Moreover, women, as they age, become prone to the cumulative effects of menopause such as sleep disturbances, adiposity, and inflammation which are attributed to a compromised immuno-neuro-endocrine axis. So far, no effective therapeutic remedy is available to mitigate the adverse effects of SD. The current study was aimed to elucidate the neuroprotective potential of n-Butanol fraction obtained from hydroalcoholic extract of Tinospora cordifolia stem (B-TCE). Four groups of female rats are (1) Vehicle-undisturbed sleep, (2) Vehicle-sleep deprived (between 6 a.m. and 6 p.m.), (3) B-TCE oral feeding for 2 weeks and sleep deprivation, and (4) B-TCE alone undisturbed sleep group. Novel Object Recognition test was used to study cognitive impairments and Rotarod for motor coordination. Rats were then sacrificed to study the expression of various marker proteins in the hippocampus and piriform cortex regions of the brain by western blotting. SD was observed to impair the exploratory behavior and neuromuscular coordination, whereas, B-TCE pre-treatment was observed to ameliorate these behavioral functions'- impairments and further suppressed the changes in the expression of markers for synaptic plasticity, inflammation, cell survival, and apoptosis pathways. The current data suggest that B-TCE may be effective in the management of acute SD-associated impairments in learning and memory functions and neuromuscular coordination.

H2S Attenuates Sleep Deprivation-Induced Cognitive Impairment by Reducing Excessive Autophagy via Hippocampal Sirt-1 in WISTAR RATS

Sleep deprivation (SD) is widespread in society causing serious damage to cognitive function. Hydrogen sulfide (H2S), the third gas signal molecule, plays important regulatory role in learning and memory functions. Inhibition of excessive autophagy and upregulation of silent information regulator 1 (Sirt-1) have been reported to prevent cognitive dysfunction. Therefore, this present work was to address whether H2S attenuates the cognitive impairment induced by SD in Wistar rats and whether the underlying mechanisms involve in inhibition of excessive autophagy and upregulation of Sirt-1. After treatment with SD for 72 h, the cognitive function of Wistar rats was evaluated by Y-maze, new object recognition, object location, and Morris water maze tests. The results shown that SD-caused cognitive impairment was reversed by treatment with NaHS (a donor of H2S). NaHS also prevented SD-induced hippocampal excessive autophagy, as evidenced by the decrease in autophagosomes, the down-regulation of Beclin1, and the up-regulation of p62 in the hippocampus of SD-exposed Wistar rats. Furthermore, Sirtinol, an inhibitor of Sirt-1, reversed the inhibitory roles of NaHS in SD-induced cognitive impairment and excessive hippocampal autophagy in Wistar rats. Taken together, our results suggested that H2S improves the cognitive function of SD-exposed rats by inhibiting excessive hippocampal autophagy in a hippocampal Sirt-1-dependent way.

Neurobehavioral alterations in a mouse model of chronic partial sleep deprivation

The night shift paradigm induces a state of chronic partial sleep deprivation (CPSD) and enhances the vulnerability to neuronal dysfunction. However, the specific neuronal impact of CPSD has not been thoroughly explored to date. In the current study, the night shift condition was mimicked in female Swiss albino mice. The classical sleep deprivation model, i.e., Modified Multiple Platform (MMP) method, was used for 8 h/day from Monday to Friday with Saturday and Sunday as a weekend off for nine weeks. Following nine weeks of night shift schedule, their neurobehavioral profile and physiological parameters were assessed along with the activity of the mitochondrial complexes, oxidative stress, serotonin levels, and inflammatory markers in the brain. Mice showed an overall hyperactive behavioral profile including hyperlocomotion, aggression, and stereotyped behavior accompanied by decreased activity of mitochondrial enzymes and serotonin levels, increased oxidative stress and inflammatory markers in whole brain homogenates. Collectively, the study points towards the occurrence of a hyperactive behavioral profile akin to mania and psychosis as a potential consequence of CPSD.

Melatonin ameliorates anxiety-like behaviors induced by sleep deprivation in mice: Role of oxidative stress, neuroinflammation, autophagy and apoptosis

Increasing evidence suggests there is a relationship between anxiety disorders and sleep deprivation (SD). However, underlying molecular mechanism remains elusive and currently there is no effective therapy to negate the effects of SD. We established a mouse model of acute SD with or without melatonin supplementation. We found that melatonin supplementation suppressed an increase of corticosterone level caused by SD. Behavioral data indicated that 72 h SD exposure induced anxiety-like behaviors, as evidenced by the reduced central area travels in OFT. Immunohistochemical staining and western blot analysis revealed that SD promoted neuronal loss by inducing pro-apoptotic protein Bax and cleaved-caspase-3 and autophagic proteins (LC3II, ATG5 and Beclin1) and reducing the levels of the anti-apoptotic protein Bcl-2. In contrast, the aforementioned SD-inductions were reversed by supplementation using 20 mg/kg and 40 mg/kg melatonin in SD mice. Meanwhile, we observed that melatonin reduced activated gliosis via attenuation of Iba1, and inhibited increase of anti-inflammatory cytokines (IL-4 and IL-10) and the decrease of pro-inflammatory cytokines (IL-6 and TNF-α). Furthermore, melatonin supplementation inverted the SD-induced the decline of antioxidant enzyme activities (T-AOC and CAT etc) and the increase of p-P65 and p-IκB proteins in the hippocampus. On the whole, our findings revealed that melatonin attenuated SD-induced anxiety-like behavior via ameliorating oxidative stress, activation of NF-κB pathway, neuroinflammation, apoptosis and excessive autophagy.

Comparison effects of chronic sleep deprivation on juvenile and young adult mice

Sleeplessness leads to a spectrum of neuropsychiatric disorders, affecting both juveniles and young adults. Studies have shown different sleep patterns at different stages of development. However, the molecular mechanisms underlying the effects of the same chronic sleep deprivation (CSD) on behaviours of juveniles and young adults remain elusive. Here, we aimed to evaluate the effects of CSD (6 days, 19 h per day) on anxiety-like behaviour, cognitive performance and molecular alterations in juvenile and young adult mice. Change in body weight suggested impaired physical development in CSD animals, specifically juveniles gaining weight at a lower rate and young adults losing weight. Behavioural performance indicated that CSD had little effect on spatial memory, but induced analogous anxiety-like phenotypes in both juveniles and young adults, as evidenced by no significant difference in the Y-maze experiment (Y-M) or the Morris water maze experiment (MWM), as well as the decreased open-arm distance percentage in the elevated plus maze experiment (EPM). In addition, CSD reduced the N-methyl-D-aspartic receptor subunit 2B (NR2B) and postsynaptic density protein 95 (PSD95) levels in juveniles, but these were increased in young adults. In conclusion, our results suggested that although CSD resulted in analogous anxiety-like behaviours in both juvenile and young adult mice, the underlying mechanisms might be different, which was indicated by the opposite change of synaptic proteins under CSD. These findings may help to better understand the important role of sleep and have constructive significance for human health.

Neuroprotective effects of garlic extract on dopaminergic neurons of substantia nigra in a rat model of Parkinson's disease: motor and non-motor outcomes

Parkinson's disease (PD) is a common and severe neurodegenerative disorder associated with a selective loss of dopaminergic neurons in substantia nigra pars compacta. The crucial role of oxidative stress and inflammation in PD onset and progression is evident. It has been proven that garlic extract (GE) protects the cells from oxidative stress, inflammation, mitochondrial dysfunction and apoptosis. That is, we aimed to investigate if GE reveals protective features on the preclinical model of PD. The study has been designed to evaluate both preventive (GE administered before 6-OHDA injection) and therapeutic (GE administered after 6-OHDA injection) effects of GE on the animal model. Forty male Wistar rats were divided into 4 groups including control, lesion, treatment I (received GE before 6-OHDA injection) and treatment II (received GE both before and after 6-OHDA injection). At the end of treatment, hanging, rotarod, open field and passive avoidance tests as well as immunohistochemistry were performed to evaluate the neuroprotective effects of garlic against PD. Our immunohistochemistry analysis revealed that the tyrosine hydroxylase positive cells (TH⁺) in GE treated groups were significantly higher (p˂0.001) than the lesion group. The motor deficiency significantly improved in hanging, rotarod, open-field and apomorphine-induced rotational tests. We observed an attenuation in memory impairment induced by PD on GE treated group. Therefore, we found that GE protects dopaminergic neurons in 6-OHDA-induced neurotoxicity and ameliorates movement disorders and behavioral deficits.

The old guard: Age-related changes in microglia and their consequences

Among all major organs, the brain is one of the most susceptible to the inexorable effects of aging. Throughout the last decades, several studies in human cohorts and animal models have revealed a plethora of age-related changes in the brain, including reduced neurogenesis, oxidative damage, mitochondrial dysfunction and cell senescence. As the main immune effectors and first responders of the nervous tissue, microglia are at the center of these events. These cells experience irrevocable changes as a result from cumulative exposure to environmental triggers, such as stress, infection and metabolic dysregulation. The age-related immunosenescent phenotype acquired by microglia is characterized by profound modifications in their transcriptomic profile, secretome, morphology and phagocytic activity, which compromise both their housekeeping and defensive functions. As a result, aged microglia are no longer capable of establishing effective immune responses and sustaining normal synaptic activity, directly contributing to age-associated cognitive decline and neurodegeneration. This review discusses how lifestyle and environmental factors drive microglia dysfunction at the molecular and functional level, also highlighting possible interventions to reverse aging-associated damage to the nervous and immune systems.

Homeostatic state of microglia in a rat model of chronic sleep restriction

Chronic sleep restriction (CSR) negatively impacts brain functions. Whether microglia, the brain's resident immune cells, play any role is unknown. We studied microglia responses to CSR using a rat model featuring slowly rotating wheels (3 h on/1 h off), which was previously shown to induce both homeostatic and adaptive responses in sleep and attention. Adult male rats were sleep restricted for 27 or 99 h. Control rats were housed in locked wheels. After 27 and/or 99 h of CSR, the number of cells immunoreactive for the microglia marker ionized calcium-binding adaptor molecule-1 (Iba1) and the density of Iba1 immunoreactivity were increased in 4/10 brain regions involved in sleep/wake regulation and cognition, including the prelimbic cortex, central amygdala, perifornical lateral hypothalamic area, and dorsal raphe nucleus. CSR neither induced mitosis in microglia (assessed with bromodeoxyuridine) nor impaired blood-brain barrier permeability (assessed with Evans Blue). Microglia appeared ramified in all treatment groups and, when examined quantitatively in the prelimbic cortex, their morphology was not affected by CSR. After 27 h, but not 99 h, of CSR, mRNA levels of the anti-inflammatory cytokine interleukin-10 were increased in the frontal cortex. Pro-inflammatory cytokine mRNA levels (tumor necrosis factor-α, interleukin-1β, and interleukin-6) were unchanged. Furthermore, cortical microglia were not immunoreactive for several pro- and anti-inflammatory markers tested, but were immunoreactive for the purinergic P2Y12 receptor. These results suggest that microglia respond to CSR while remaining in a physiological state and may contribute to the previously reported homeostatic and adaptive responses to CSR.

Association of Atopic Dermatitis Severity With Learning Disability in Children

IMPORTANCE

Recent population-based data indicate that atopic dermatitis (AD) is associated with learning disability (LD) in children, but the association between AD severity and LD is unknown.

OBJECTIVE

To evaluate the association of AD severity with learning problems in children with AD.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study analyzed data of US participants enrolled in the Pediatric Eczema Elective Registry (PEER) between November 1, 2004, and November 30, 2019. Participants were children aged 2 to 17 years at registry enrollment with physician-confirmed diagnosis of AD and had completed 10 years of follow-up in PEER.

EXPOSURES

Atopic dermatitis severity measured by both the Patient-Oriented Eczema Measure (POEM) score and self-report. The POEM scores ranged from 0 to 28, with strata of clear or almost clear skin (0-2), mild (3-7), moderate (8-16), severe (17-24), and very severe (25-28). Self-reported AD severity was categorized as clear skin or no symptoms, mild, moderate, or severe.

MAIN OUTCOMES AND MEASURES

Learning disability diagnosed by a health care practitioner, as reported by the participants or their caregivers.

RESULTS

Among the 2074 participants with AD (1116 girls [53.8%]; median [interquartile range (IQR)] age, 16.1 [13.9-19.5] years at 10-year follow-up), 169 (8.2%) reported a diagnosis of an LD. Children with an LD vs those without an LD were more likely to have worse AD severity, as measured by the median (IQR) total POEM score (5 [1-10] vs 2 [0-6]; P < .001), POEM severity category (moderate AD: 50 of 168 [29.8%] vs 321 of 1891 [17.0%]; severe to very severe AD: 15 of 168 [8.9%] vs 85 of 1891 [4.5%]; P < .001); and self-report (moderate AD: 49 of 168 [29.2%] vs 391 of 1891 [20.7%]; severe AD: 11 of 168 [6.5%] vs 64 of 1891 [3.4%]; P < .001). In multivariable logistic regression models adjusted for sex, age, race/ethnicity, annual household income, age of AD onset, family history of AD, and comorbid conditions, participants with mild AD (odds ratio [OR], 1.72; 95% CI, 1.11-2.67), moderate AD (OR, 2.09; 95% CI, 1.32-3.30), and severe to very severe AD (OR, 3.10; 95% CI, 1.55-6.19) on the POEM were all significantly more likely to have reported an LD than those with clear or almost clear skin.

CONCLUSIONS AND RELEVANCE

This cross-sectional study found that worse AD severity was associated with greater odds of reported LD, independent of socioeconomic characteristics, AD onset age, and other related disorders. Although additional prospective and mechanistic studies are needed to clarify the association of AD with learning, the findings suggest that children with more severe AD should be screened for learning difficulties to initiate appropriate interventions that can mitigate the consequences of an LD.

Sleep, Narcolepsy, and Sodium Oxybate

Sodium oxybate (SO) has been in use for many decades to treat narcolepsy with cataplexy. It functions as a weak GABAB agonist but also as an energy source for the brain as a result of its metabolism to succinate and as a powerful antioxidant because of its capacity to induce the formation of NADPH. Its actions at thalamic GABAB receptors can induce slow-wave activity, while its actions at GABAB receptors on monoaminergic neurons can induce or delay REM sleep. By altering the balance between monoaminergic and cholinergic neuronal activity, SO uniquely can induce and prevent cataplexy. The formation of NADPH may enhance sleep’s restorative process by accelerating the removal of the reactive oxygen species (ROS), which accumulate during wakefulness. SO improves alertness in normal subjects and in patients with narcolepsy. SO may allay severe psychological stress - an inflammatory state triggered by increased levels of ROS and characterized by cholinergic supersensitivity and monoaminergic deficiency. SO may be able to eliminate the inflammatory state and correct the cholinergic/ monoaminergic imbalance.

Sleep disturbance induces depressive behaviors and neuroinflammation by altering the circadian oscillations of clock genes in rats

Sleep loss leads to a spectrum of mood disorders such as anxiety disorders, bipolar disorder and depression in many individuals. However, the underlying mechanisms are largely unknown. In this study, sleep-disturbed animals were tested for anxiety and depressive behaviors. We then studied the effects of SD on hypothalamic-pituitary-adrenal (HPA) axis function by measuring serum and CSF levels of corticosterone (CORT), and at the end of the experiment, brains were collected to measure the circadian oscillations of clock genes expression in the hypothalamus, glial cell activation and inflammatory cytokine alterations. Our results indicated that SD for 3 days resulted in anxiety- and depressive-like behaviors. SD exaggerated cortisol response to HPA axis, significantly altered the circadian oscillations of clock genes, decreased the expression of tight junction protein ZO-1 and Claudin 5 and increased the number of GFAP-positive cells and Iba-1-positive cells and caused subsequent elevation of pro-inflammatory cytokines IL-6, IL-1β and TNFα. These findings demonstrated that SD for 3 days induced anxiety- and depression-like behaviors in rats in company with altering the circadian oscillations of clock genes and inducing neuroinflammation, indicating the underlying mechanism of sleep loss induced neuronal dysfunction.

The effect of sleep medications on prospective and retrospective memory: a population-based study

Sleep medications, especially benzodiazepines, are known to cause motor and cognitive impairments as side-effects from their use. However, an evaluation of the effects of sleep medications in general on prospective and retrospective memory remains to be seen. Thus, the effects of the different types of sleep medicines were assessed using the total score and the 8 subscales of the Prospective and Retrospective Memory Questionnaire (PRMQ) in a representative sample from the Municipality of São Paulo. The effects of each type of medication on these same parameters were evaluated afterwards. Each analysis was performed controlling for different covariates to observe their degree of interference on the observed results. Impairment due to use of sleep aid medication was observed in 6 of the 8 subscales, as well in the overall score of the PRMQ when compared to non-users. Prospective subscales were particularly affected, even when controlling for highly interfering covariates such as depression and anxiety, and objective sleep variables related to sleep architecture and wakefulness in the night. Few effects were detected between the various types of medication even when controlling for covariates, suggesting that a sample with higher power is necessary to conduct a more detailed analysis. Using pharmacological aids to improve sleep may impair prospective and (to some extent) retrospective memory. Therefore, the relationship between sleep impairment, memory deficits and medication use must be considered by physicians.

The Treatment of Sleep Dysfunction in Neurodegenerative Disorders

Sleep dysfunction is highly prevalent across the spectrum of neurodegenerative conditions and is a key determinant of quality of life for both patients and their families. Mounting recent evidence also suggests that such dysfunction exacerbates cognitive and affective clinical features of neurodegeneration, as well as disease progression through acceleration of pathogenic processes. Effective assessment and treatment of sleep dysfunction in neurodegeneration is therefore of paramount importance; yet robust therapeutic guidelines are lacking, owing in part to a historical paucity of effective treatments and trials. Here, we review the common sleep abnormalities evident in neurodegenerative disease states and evaluate the latest evidence for traditional and emerging interventions, both pharmacological and nonpharmacological. Interventions considered include conservative measures, targeted treatments of specific clinical sleep pathologies, established sedating and alerting agents, melatonin, and orexin antagonists, as well as bright light therapy, behavioral measures, and slow-wave sleep augmentation techniques. We conclude by providing a suggested framework for treatment based on contemporary evidence and highlight areas that may emerge as major therapeutic advances in the near future.

The sleep and circadian problems of Huntington's disease: when, why and their importance

Introduction

Mounting evidence supports the existence of an important feedforward cycle between sleep and neurodegeneration, wherein neurodegenerative diseases cause sleep and circadian abnormalities, which in turn exacerbate and accelerate neurodegeneration. If so, sleep therapies bear important potential to slow progression in these diseases.

Findings

This cycle is challenging to study, as its bidirectional nature renders cause difficult to disentangle from effect. Likewise, well-controlled intervention studies are often impractical in the setting of established neurodegenerative disease. It is this that makes understanding sleep and circadian abnormalities in Huntington’s disease (HD) important: as a monogenic fully penetrant neurodegenerative condition presenting in midlife, it provides a rare opportunity to study sleep and circadian abnormalities longitudinally, prior to and throughout disease manifestation, and in the absence of confounds rendered by age and comorbidities. It also provides potential to trial sleep therapies at a preclinical or early disease stage. Moreover, its monogenic nature facilitates the development of transgenic animal models through which to run parallel pre-clinical studies. HD, therefore, provides a key model condition through which to gain new insights into the sleep-neurodegeneration interface.

Conclusions

Here, we begin by summarising contemporary knowledge of sleep abnormalities in HD, and consider how well these parallel those of Alzheimer’s and Parkinson’s as more common neurodegenerative conditions. We then discuss what is currently known of the sleep-neurodegeneration cyclical relationship in HD. We conclude by outlining key directions of current and future investigation by which to advance the sleep-neurodegeneration field via studies in HD.

Microglia dynamics in sleep/wake states and in response to sleep loss

Sleep has an essential role for optimal brain function, but the cellular substrates for sleep regulation are not fully understood. Microglia, the immune cells of the brain, have gained increasingly more attention over the last two decades for their important roles in various brain functions that extend beyond their well-known immune function, including brain development, neuronal protection, and synaptic plasticity. Here we review recent advances in understanding: i) morphological and phenotypic dynamics of microglia including process motility/growth and gene/protein expression, and ii) microglia-neuron interactions including phagocytosis and contact at synapses which alters neuronal circuit activity, both under physiological state in the adult brain. We discuss how the microglia-neuron interactions particularly at synapses could influence microglia and neuronal activities across circadian cycles and sleep/wake states. We also review recent findings on how microglia respond to sleep loss. We conclude by pointing out key questions and proposing suggestions for future research to better understand the role of microglia in sleep regulation, sleep homeostasis, and the function of sleep.

Sleep loss disrupts pericyte-brain endothelial cell interactions impairing blood-brain barrier function

Sleep loss in the rat increases blood-brain barrier permeability to circulating molecules by disrupting interendothelial tight junctions. Despite the description of the ultrastructure of cerebral microvessels and the evidence of an apparent pericyte detachment from capillary wall in sleep restricted rats the effect of sleep loss on pericytes is unknown. Here we characterized the interactions between pericytes and brain endothelial cells after sleep loss using male Wistar rats. Animals were sleep-restricted 20 h daily with 4 h sleep recovery for 10 days. At the end of the sleep restriction, brain microvessels (MVs) were isolated from cerebral cortex and hippocampus and processed for Western blot and immunocytochemistry to evaluate markers of pericyte-endothelial cell interaction (connexin 43, PDGFR-β), tight junction proteins, and proinflammatory mediator proteins (MMP9, A_2A adenosine receptor, CD73, NFκB). Sleep restriction reduced PDGFR-β and connexin 43 expression in MVs; in addition, scanning electron microscopy micrographs showed that pericytes were detached from capillary walls, but did not undergo apoptosis (as depicted by a reduced active caspase-3 expression). Sleep restriction also decreased tight junction protein expression in MVs and increased BBB permeability to low- and high-molecular weight tracers in in vivo permeability assays. Those alterations seemed to depend on a low-grade inflammatory status as reflected by the increased expression of phosphorylated NFκB and A_2A adenosine receptor in brain endothelial cells from the sleep-restricted rats. Our data show that pericyte-brain endothelial cell interaction is altered by sleep restriction; this evidence is essential to understand the role of sleep in regulating blood-brain barrier function.

Sleep deprivation and its association with diseases- a review

Sleep deprivation, a consequence of multiple health problems or a cause of many major health risks, is a significant public health concern in this era. In the recent years, numerous reports have been added to the literature to provide explanation and to answer previously unanswered questions on this important topic but comprehensive updates and reviews in this aspect remain scarce. The present study identified 135 papers that investigated the association between sleep deprivation and health risks, including cardiovascular, respiratory, neurological, gastrointestinal, immunology, dermatology, endocrine, and reproductive health. In this review, we aimed to provide insight into the association between sleep deprivation and the development of diseases. We reviewed the latest updates available in the literature and particular attention was paid to reports that detailed all possible causal relationships involving both extrinsic and intrinsic factors that may be relevant to this topic. Various mechanisms by which sleep deprivation may affect health were presented and discussed, and this review hopes to serve as a platform for ideas generation for future research.

The spleen mediates chronic sleep restriction-mediated enhancement of LPS-induced neuroinflammation, cognitive deficits, and anxiety-like behavior

Chronic sleep restriction promotes neuroinflammation and cognitive deficits in neurodegenerative and neurobehavioral diseases. The spleens of mice exposed to chronic and repeated psychological stress serve as a reservoir of inflammatory myeloid cells that are released into the blood and brain following secondary acute stress. Here, we tested whether chronic and repeated short-term sleep restriction (CRSR) would exacerbate lipopolysaccharide (LPS)-induced neuroinflammation, cognitive deficits, and anxiety-like behavior in a spleen-dependent manner. LPS was administered to aged mice 14 days after exposure to CRSR consisting of three cycles of 7 days of sleep restriction with 7-day intervals in between. CRSR increased plasma proinflammatory cytokine levels, blood-brain barrier permeability, hippocampal proinflammatory cytokine levels, and transition of microglia to the M1 phenotype 24 h after LPS treatment. This in turn led to cognitive deficits and anxiety-like behavior. Interestingly, removal of the spleen 14 days prior to CRSR abrogated the enhancement of LPS-induced increases in systemic inflammation, neuroinflammation, cognitive deficits, and anxiety-like behavior. These data indicate that the spleen was essential for CRSR-induced exacerbation of LPS-induced brain damage.

Interactive Impact of Sleep Duration and Sleep Quality on the Risk of Developing Metabolic Syndrome in Korean Adults

Sleep quality is important for the normal functioning of hormonal and metabolic processes in the body; however, few studies have considered the effects of both sleep duration and sleep quality on predicting metabolic syndrome risk. We examined the interactive impact of sleep duration and sleep quality on the risk of developing metabolic syndrome using logistic regression analysis with a threshold based on hours of sleep. Data were collected from 411 adults in South Korea and, according to the estimated threshold of 6 h of sleep (95% Confidence Interval, CI = 5–7 h), participants were classified as short (<6 h) or adequate-long (≥6 h) sleepers. The two groups differed significantly on various health measures. While short sleepers were more likely than adequate-long sleepers to experience adverse health conditions, which increased their risk of developing metabolic syndrome, they were not influenced by sleep quality. For adequate-long sleepers, however, a decrease in sleep quality was associated with an increased risk of developing metabolic syndrome (odds ratio = 1.24, 95% CI = 1.07–1.43). Our results suggest that both sleep duration and sleep quality are crucial determinants of the development of metabolic syndrome and that it is important to maintain at least 6 h of sleep.

Impact of sleep disturbances on neurodegeneration: Insight from studies in animal models

Chronic short sleep or extended wake periods are commonly observed in most industrialized countries. Previously neurobehavioral impairment following sleep loss was considered to be a readily reversible occurrence, normalized upon recovery sleep. Recent clinical studies suggest that chronic short sleep and sleep disruption may be risk factors for neurodegeneration. Animal models have been instrumental in determining whether disturbed sleep can injure the brain. We now understand that repeated periods of extended wakefulness across the typical sleep period and/or sleep fragmentation can have lasting effects on neurogenesis and select populations of neurons and glia. Here we provide a comprehensive overview of the advancements made using animal models of sleep loss to understand the extent and mechanisms of chronic short sleep induced neural injury.

Resilience to acute sleep deprivation is associated with attenuation of hippocampal mediated learning impairment

BACKGROUND

Sleep deprivation is a universal issue that affects individuals in different ways. While some individuals experience a deficit in performance, others experience resiliency as they maintain high levels of physical and mental activity. Sleep loss is known to cause cognitive dysfunction in areas such as learning and memory, but little is known about neural mechanisms that contribute to resilience to this adverse effect.

METHODS

An existing database of a learning paradigm in sleep deprived and non-sleep deprived 16 to 18-month old C57BL/6 mice was used to identify fast learners and slow learners based on an R2 value representing the learning curve of each individual mouse.

RESULTS

Results showed that sleep deprived mice had more slow learners compared to fast learners whereas non-sleep-deprived mice showed the opposite. Hippocampal immunohistochemistry and digital imaging analysis showed sleep deprived, fast learners expressed lower levels of monocyte chemoattractant protein-1 and histone deacetylase 2 and higher levels of synaptophysin and brain-derived neurotrophic factor compared to sleep-deprived slow learners.

CONCLUSIONS

These observations provide evidence to suggest that sleep-deprived mice that performed well in a cognitive assay show less hippocampal mediated learning impairment and provide the rationale for further investigations into neurobiological resilience to sleep deprivation with increasing age.

The role of sleep and wakefulness in myelin plasticity

Myelin plasticity is gaining increasing recognition as an essential partner to synaptic plasticity, which mediates experience-dependent brain structure and function. However, how neural activity induces adaptive myelination and which mechanisms are involved remain open questions. More than two decades of transcriptomic studies in rodents have revealed that hundreds of brain transcripts change their expression in relation to the sleep-wake cycle. These studies consistently report upregulation of myelin-related genes during sleep, suggesting that sleep represents a window of opportunity during which myelination occurs. In this review, we summarize recent molecular and morphological studies detailing the dependence of myelin dynamics after sleep, wake, and chronic sleep loss, a condition that can affect myelin substantially. We present novel data about the effects of sleep loss on the node of Ranvier length and provide a hypothetical mechanism through which myelin changes in response to sleep loss. Finally, we discuss the current findings in humans, which appear to confirm the important role of sleep in promoting white matter integrity.

Aquaporin 4 deletion exacerbates brain impairments in a mouse model of chronic sleep disruption

AIMS

As a normal physiological process, sleep has recently been shown to facilitate clearance of macromolecular metabolic wastes from the brain via the glymphatic system. The aim of the present study was to investigate pathophysiological roles of astroglial aquaporin 4 (AQP4), a functional regulator of glymphatic clearance, in a mouse model of chronic sleep disruption (SD).

METHODS

Adult AQP4 null mice and wild-type (WT) mice were given 7 days of SD using the improved rotating rod method, and then received behavioral, neuropathological, and neurochemical analyses.

RESULTS

Aquaporin 4 deletion resulted in an impairment of glymphatic transport and accumulation of β-amyloid and Tau proteins in the brain following SD. AQP4 null SD mice exhibited severe activation of microglia, neuroinflammation, and synaptic protein loss in the hippocampus, as well as decreased working memory, compared with WT-SD mice.

CONCLUSION

These results demonstrate that AQP4-mediated glymphatic clearance ameliorates brain impairments caused by abnormal accumulation of metabolic wastes following chronic SD, thus serving as a potential target for sleep-related disorders.

Coordinated transcriptional regulation by thyroid hormone and glucocorticoid interaction in adult mouse hippocampus-derived neuronal cells

The hippocampus is a well-known target of thyroid hormone (TH; e.g., 3,5,3’-triiodothyronine—T₃) and glucocorticoid (GC; e.g., corticosterone—CORT) action. Despite evidence that TH and GC play critical roles in neural development and function, few studies have identified genes and patterns of gene regulation influenced by the interaction of these hormones at a genome-wide scale. In this study we investigated gene regulation by T₃, CORT, and T₃ + CORT in the mouse hippocampus-derived cell line HT-22. We treated cells with T₃, CORT, or T₃ + CORT for 4 hr before cell harvest and RNA isolation for microarray analysis. We identified 9 genes regulated by T₃, 432 genes by CORT, and 412 genes by T₃ + CORT. Among the 432 CORT-regulated genes, there were 203 genes that exhibited an altered CORT response in the presence of T₃, suggesting that T₃ plays a significant role in modulating CORT-regulated genes. We also found 80 genes synergistically induced, and 73 genes synergistically repressed by T₃ + CORT treatment. We performed in silico analysis using publicly available mouse neuronal chromatin immunoprecipitation-sequencing datasets and identified a considerable number of synergistically regulated genes with TH receptor and GC receptor peaks mapping within 1 kb of chromatin marks indicative of hormone-responsive enhancer regions. Functional annotation clustering of synergistically regulated genes reveal the relevance of proteasomal-dependent degradation, neuroprotective effect of growth hormones, and neuroinflammatory responses as key pathways to how TH and GC may coordinately influence learning and memory. Taken together, our transcriptome data represents a promising exploratory dataset for further study of common molecular mechanisms behind synergistic TH and GC gene regulation, and identify specific genes and their role in processes mediated by cross-talk between the thyroid and stress axes in a mammalian hippocampal model system.

The Sleep-Immune Crosstalk in Health and Disease

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