Sleeping to fuel the immune system: mammalian sleep and resistance to parasites

Effect of melatonin supplementation upon parental care and nestling growth in arctic-breeding songbirds

Arctic-breeding birds exhibit around-the-clock activity, and these activity cycles are postulated to maximize reproductive success during the short breeding season characteristic of high-latitude regions. Two closely related species of arctic-breeding songbirds, Lapland longspurs (Calcarius lapponicus; ground-nesting) and snow buntings (Plectrophenax nivalis; cavity-nesting) exhibit extended activity cycles throughout the polar day (71° N) except for 4-5 h of daily quiescence. Ground-nesting Lapland longspurs experience higher levels of nest predation than cavity-nesting snow buntings, and this difference is reflected in elevated nest vigilance in male longspurs compared with snow buntings. In this study, we examined the effect of melatonin supplementation upon male parental care, corresponding measures of nestling growth, and ability to reduce activity (and increase sleep). A pharmacological dose of melatonin in captive snow buntings dampened the amplitude of activity rhythms over the polar day with no detectable phase-shifting compared with control-implanted birds. Melatonin treatment reduced nest visits and overall time spent on the nest by male snow buntings compared with controls. There was no significant increase in time spent by female snow buntings on the nest to compensate for this, and there was no significant effect on offspring growth rates. There were no effects of melatonin supplementation on longspur adults or offspring, suggesting behavioral insensitivity to exogenous melatonin treatment. These differences in sensitivity underscore the importance of nest defense in ground-nesting longspurs compared with cavity-nesting snow buntings, which participate minimally in nest defense.

Self-control and bed procrastination as mediators between mindfulness and sleep quality among college students during the COVID-19 pandemic

In recent years, sleep problems among college students have become increasingly prominent, especially in the context of the COVID-19 pandemic, and their sleep quality has deteriorated dramatically, severely affecting their physical and mental health. Numerous research studies have investigated the relationship between mindfulness and sleep quality; however, it is still unclear what psychological process underlies this relationship. In the current study, college students' bed procrastination and self-control as mediating factors in the association between mindfulness and sleep quality were investigated. Using the convenience sampling method, 763 Chinese college students (mean age = 19.48 years, SD = 2.06) were recruited to complete self-reported questionnaires that included the Mindful Attention Awareness Scale, Self-Control Scale, Bed Procrastination Scale, and Sleep Quality Scale. All statistical analyses were performed using SPSS 23.0 software. Results showed that (a) mindfulness was positively associated with sleep quality; (b) both self-control and bed procrastination mediated the relationship between mindfulness and sleep quality, and (c) self-control and bed procrastination sequentially mediated the relationship between mindfulness and sleep quality. These findings collectively suggest a potential mechanism for how mindfulness influences sleep quality, providing a therapeutic target for mindfulness-based interventions aimed at helping college students improve sleep quality.

Factors associated with survival after early at-home NIV initiation in ALS patients

BACKGROUND

The initiation of early non-invasive ventilation (NIV) often involves a careful balance between tolerance and effectiveness. In amyotrophic lateral sclerosis (ALS) patients, the establishment of a strategy, including the decision to focus on adhering to a cut-off, setting specific targets, or correcting all events, is crucial.

OBJECTIVE

To identify factors at 1 month after early at-home NIV initiation that are associated with improved survival in ALS patients. We explored the impacts of adherence (ADH), quality of treatment, and NIV parameters at 1 month after early at-home NIV initiation on patient survival.

METHODS

We conducted a retrospective study of 184 ALS patients at the Bordeaux ALS Centre for whom NIV was initiated between September 2017 and June 2021, and we collected data for a minimum period of 2 years after the last patient included. The primary outcome was the risk of death according to baseline characteristics of our population and the NIV parameters and monitoring during the early NIV initiation period. The secondary outcomes were association with NIV ADH during the early NIV initiation period on prognosis, and NIV ADH cut-off for good versus poor prognosis.

RESULTS

Among the 178 ALS patients analysed, we found that quality of NIV treatment and device settings did not significantly influence prognosis. However, low ADH was significantly associated with a higher risk of death. The use of NIV for > 5 h/day during the early NIV initiation period was linked to a decreased risk of death [hazard ratio = 0.4; 95% confidence interval: 0.27-0.9].

CONCLUSION

The use of NIV for > 5 h/day during the early NIV initiation period was associated with increased survival.

Shifted levels of sleep and activity under darkness as mechanisms underlying ectoparasite resistance

Parasites harm host fitness and are pervasive agents of natural selection to evolve host defense strategies Host defensive traits in natural populations typically show genetic variation, which may be maintained when parasite resistance imposes fitness costs on the host in the absence of parasites. Previously we demonstrated significant evolutionary responses to artificial selection for increasing behavioral immunity to Gamasodes queenslandicus mites in replicate lines of Drosophila melanogaster. Here, we report transcriptional shifts in metabolic processes between selected and control fly lines based on RNA-seq analyses. We also show decreased starvation resistance and increased use of nutrient reserves in flies from mite-resistant lines. Additionally, mite-resistant lines exhibited increased behavioral activity, such as, reduced sleep and elevated oxygen consumption under conditions of darkness. The link between resistance and sleep was confirmed in an independent panel of D. melanogaster genetic lines exhibiting variable sleep durations, showing a positive correlation between mite resistance and reduced sleep. Experimentally restraining the activity of artificially selected mite-resistant flies during exposure to parasites under dark conditions reduced their resistance advantage relative to control flies. The results suggest that ectoparasite resistance in this system involves increased dark-condition activity and metabolic gene expression at the expense of nutrient reserves and starvation resistance.

Effects of acute exposure to hypoxia on sleep structure in healthy adults: A systematic review

The sleep quality of lowlanders in hypoxic environments has become increasingly important with an increase in highland and alpine activities. This study aimed to identify the effects of acute exposure to hypoxia on the sleep structure of lowlanders and to analyze the changes in sleep indicators at varying levels of hypoxia. This review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Twenty-three studies were screened and included in the quantitative analysis. The results showed that acute exposure to hypoxia reduced sleep quality in lowlanders. Post-sleep arousal events and the percentage of N1 were significantly increased, whereas total sleep time, sleep efficiency, and the percentage of N3 and rapid eye movement sleep were significantly decreased in hypoxic environments. Acute exposure to hypoxia had the greatest negative impact on wakefulness after sleep onset (WASO). In addition, a larger decrease in sleep efficiency and higher increase in the percentages of N1 and WASO were observed when lowlanders were exposed to higher levels of hypoxia. This study clarifies the quantitative effects of acute hypoxic exposure on sleep in lowlanders based on original studies and explains the sleep disorders faced by lowlanders in hypoxic environments.

REM Sleep Loss-Induced Elevated Noradrenaline Plays a Significant Role in Neurodegeneration: Synthesis of Findings to Propose a Possible Mechanism of Action from Molecule to Patho-Physiological Changes

Wear and tear are natural processes for all living and non-living bodies. All living cells and organisms are metabolically active to generate energy for their routine needs, including for survival. In the process, the cells are exposed to oxidative load, metabolic waste, and bye-products. In an organ, the living non-neuronal cells divide and replenish the lost or damaged cells; however, as neuronal cells normally do not divide, they need special feature(s) for their protection, survival, and sustenance for normal functioning of the brain. The neurons grow and branch as axons and dendrites, which contribute to the formation of synapses with near and far neurons, the basic scaffold for complex brain functions. It is necessary that one or more basic and instinct physiological process(es) (functions) is likely to contribute to the protection of the neurons and maintenance of the synapses. It is known that rapid eye movement sleep (REMS), an autonomic instinct behavior, maintains brain functioning including learning and memory and its loss causes dysfunctions. In this review we correlate the role of REMS and its loss in synaptogenesis, memory consolidation, and neuronal degeneration. Further, as a mechanism of action, we will show that REMS maintains noradrenaline (NA) at a low level, which protects neurons from oxidative damage and maintains neuronal growth and synaptogenesis. However, upon REMS loss, the level of NA increases, which withdraws protection and causes apoptosis and loss of synapses and neurons. We propose that the latter possibly causes REMS loss associated neurodegenerative diseases and associated symptoms.

Physical activity and sleep relate to antibody maintenance following naturalistic infection and/or vaccination in older adults

Health behaviours such as being physically active and having good quality sleep have been associated with decreased susceptibility to infection and stronger antibody responses to vaccination. Less is known about how such factors might influence the maintenance of immunity following naturalistic infection and/or prior vaccination, particularly among older adults who may have formed initial antibodies some time ago. This analysis explored antibody levels against a range of common infectious diseases in 104 older adults (60 women) aged 65+ years, and whether these relate to self-reported physical activity (PA) and sleep. PA and sleep were measured subjectively through standardized questions. Antibody levels to a range of common pathogens, including pneumococcal (Pn) and meningococcal (Men) serotypes, Haemophilus influenza type b, diphtheria, and tetanus were assayed using Multiplex technology. Higher PA at baseline related to higher antibody levels against three Pn serotypes and MenY, and higher PA at one month with higher levels against six Pn serotypes. Longer time in bed related to higher antibody levels against Pn4, and longer sleep related to higher levels against Pn19f. More difficulty staying awake in the day related to lower antibodies against Pn19a, Pn19f, MenA and MenY, and more frequent daytime napping related to lower levels against three Pn serotypes and MenY. Using clinically protective antibody thresholds as an outcome showed similar results for PA, but effects for sleep became non-significant, with the exception of time in bed. This extends beyond existing literature demonstrating associations between PA and sleep and peak antibody response to vaccination to antibody maintenance. Longitudinal research with objective measures of health behaviours is warranted.

Sleep and Neuroimmunomodulation for Maintenance of Optimum Brain Function: Role of Noradrenaline

Immune function and sleep are two normal physiological processes to protect the living organism from falling sick. There is hardly any disease in which they remain unaffected, though the quantum of effect may differ. Therefore, we propose the existence of a strong correlation between sleep (quality or quantity) and immune response. This may be supported by the fact that sleep loss modulates many of the immunological molecules, which includes interferons; however, not much is known about their mechanism of action. Sleep is divided into rapid eye movement sleep (REMS) and non-REMS. For practical reasons, experimental studies have been conducted mostly by inducing loss of REMS. It has been shown that withdrawal of noradrenaline (NA) is a necessity for generation of REMS. Moreover, NA level increases in the brain upon REMS loss and the elevated NA is responsible for many of the sleep loss-associated symptoms. In this review, we describe how sleep (and its disturbance/loss) modulates the immune system by modulating the NA level in the brain or vice versa to maintain immune functions, physiological homeostasis, and normal healthy living. The increased levels of NA during REMS loss may cause neuroinflammation possibly by glial activation (as NA is a key modulator of microglia). Therefore, maintaining sleep hygiene plays a crucial role for a normal healthy living.

Infection increases activity via Toll dependent and independent mechanisms in Drosophila melanogaster

Host behavioural changes are among the most apparent effects of infection. ‘Sickness behaviour’ can involve a variety of symptoms, including anorexia, depression, and changed activity levels. Here, using a real-time tracking and behavioural profiling platform, we show that in Drosophila melanogaster, several systemic bacterial infections cause significant increases in physical activity, and that the extent of this activity increase is a predictor of survival time in some lethal infections. Using multiple bacteria and D. melanogaster immune and activity mutants, we show that increased activity is driven by at least two different mechanisms. Increased activity after infection with Micrococcus luteus, a Gram-positive bacterium rapidly cleared by the immune response, strictly requires the Toll ligand spätzle. In contrast, increased activity after infection with Francisella novicida, a Gram-negative bacterium that cannot be cleared by the immune response, is entirely independent of both Toll and the parallel IMD pathway. The existence of multiple signalling mechanisms by which bacterial infections drive increases in physical activity implies that this effect may be an important aspect of the host response.

Sickness behaviours are often observed during infection. Animals have been shown to change their feeding, mating, social and resting (sleeping) behaviours in response to infection. We show here that fruit-flies infected with bacteria respond by increasing their physical activity and decreasing the amount of time spent sleeping. This increase in activity is seen in some, but not all, bacterial infections, and appears to be driven by at least two different mechanisms: with some bacteria, activating the immune response is the only requirement to induce increased activity, while other bacteria induce increased activity independently of known immune detection pathways. The biological role of increased activity is unclear; flies in the wild may be driven to flee sites where infection risk or pathogen burden is high. Alternatively, increased activity could serve a less direct anti-microbial function. For example, active animals may be more likely to encounter potential mates or food resource.

Effects of quilts on comfortable indoor temperatures and human thermal responses during sleep

Quilts play a vital role in the thermal comfort of sleeping people. This study aims to investigate the comfortable indoor temperatures and thermal responses when people sleep in different quilts. The experiment tested three kinds of quilts (down, silk, and polyester), and each kind of quilt involved six filling weights. Sixteen participants (eight males and eight females) conducted whole-night sleeping trials to acquire skin temperatures, bedding temperatures, and thermal perceptual responses. The lower and upper limits of air temperatures ( T lower $$ {T}_{lower} $$ and T upper $$ {T}_{upper} $$ ) for comfortable sleeping were obtained. The results indicated that thermal sensation votes were in the range from 0.1 (close to "neutral") to 1.3 (close to "slightly warm") when participants felt comfortable and preferred "no change" in thermal preference. The corresponding comfortable mean skin and bedding temperatures were 34.6 ~ 35.2°C and 31.2 ~ 32.7°C, respectively. T lower $$ {T}_{lower} $$ and T upper $$ {T}_{upper} $$ had good linear correlations with bedding insulations. For the same bedding insulation, the T lower $$ {T}_{lower} $$ and T upper $$ {T}_{upper} $$ were highest for using silk quilts, followed by down and polyester quilts. The comfort ranges of air temperatures and quilt insulations were finally determined. The findings may benefit understanding the thermal requirement of quilts and help people select and design quilts to achieve thermal comfort.

A survey of bedroom ventilation types and the subjective sleep quality associated with them in Danish housing

We performed a survey of the types of bedroom ventilation in Danish dwellings (January-February 2020) and the associated subjective sleep quality. Five hundred and seventeen people responded. Their median age was 33 years old and 55.4% of them were males. We used an online questionnaire and collected information on the type of bedroom ventilation, bedroom airing behaviour by the respondents, the bedroom environment, building surroundings and location, and sleep disturbance caused by stuffy air, noise, and the thermal environment. Subjective sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI); its median among respondents was >5 indicating reduced sleep quality. 35.4% of the bedrooms had mechanical, 24.6% exhaust, and 40.0% natural ventilation. Sleeping in a bedroom with mechanical ventilation tended to reduce sleep disturbance. The absence of mechanical ventilation and the presence of carpet in the bedroom were all associated with stuffy air causing sleep disturbance, which was the second most sleep disturbing factor. PSQI increased significantly with increased sleep disturbance. People who reported that their sleep was disturbed by stuffy air or "too warm" conditions opened windows frequently during the day or night, but no association was found between PSQI and bedroom airing behaviours. Our results are valid for the heating season and the survey would have to be repeated in the non-heating season to permit generalization of the findings. The results present associations and are qualitative, so field measurements are necessary to validate the present observations and provide further explanations.

Differential Effect of Light and Dark Period Sleep Fragmentation on Composition of Gut Microbiome and Inflammation in Mice

Bi-directional interactions amongst the gut microbiota, immune system, and brain function are thought to be critical mediators of health and disease. The role sleep plays in mediating these interactions is not known. We assessed the effects of sleep fragmentation (SF) on the microbiota–gut–brain axis. Male C57BL/6NCrl mice (4 to 5 per cage, fed standard lab chow) experienced SF via mechanical stimulation at 2 min intervals during the light (SF) and dark (DD, dark disturbances) periods. Home cage (HC) controls were undisturbed. After 10 days, fecal samples were collected at light onset, midday, light offset, and midnight. Samples were also collected after 10 days without SF. Subsequently, the mice were randomized across groups and allowed 20 additional days of recovery followed by 10 days of SF or DD. To assess effects on the microbiota, 16S rRNA sequencing was used, and mesenteric lymph nodes (MLNs) and cortex and medial prefrontal cortex were analyzed using cytokine arrays. SF and DD produced significant alterations in the microbiota compared to HC, and DD had greater impact than SF on some organisms. SF produced marked suppression in MLNs of chemokines that regulate inflammation (CCL3, CCL4 and their receptor CCR5) and maintain the immune mucosal barrier (Cxcl13) at the same time that cortical cytokines (IL-33) indicated neuroinflammation. DD effects on immune responses were similar to HC. These data suggest that SF alters the microbiome and suppresses mucosal immunity at the same time that mediators of brain inflammation are upregulated. The translational implications for potential application to clinical care are compelling.

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.

Toxoplasma gondii: A possible etiologic agent for Alzheimer's disease

Toxoplasma gondii (T. gondii) is one of the most pervasive neurotropic pathogens causing different lesions in a wide variety of mammals as intermediate hosts, including humans. It is estimated that one-third of the world population is infected with T. gondii; however, for a long time, there has been much interest in the examination of the possible role of this parasite in the development of mental disorders, such as Alzheimer's disease (AD). T. gondii may play a role in the progression of AD using mechanisms, such as the induction of the host's immune responses, inflammation of the central nervous system (CNS), alteration in the levels of neurotransmitters, and activation of indoleamine-2,3-dyoxigenase. This paper presents an appraisal of the literature, reports, and studies that seek to the possible role of T. gondii in the development of AD. For achieving the purpose of the current study, a search of six English databases (PubMed, ScienceDirect, Web of Science, Scopus, ProQuest, and Google Scholar) was performed. The results support the involvement of T. gondii in the induction and development of AD. Indeed, T. gondii can be considered a risk factor for the development of AD and requires the special attention of specialists and patients. Furthermore, the results of this study may contribute to prevent or delay the progress of AD worldwide. Therefore, it is required to carry out further studies in order to better perceive the parasitic mechanisms in the progression of AD.

Pervasive effects of Wolbachia on host activity

Heritable symbionts have diverse effects on the physiology, reproduction and fitness of their hosts. Maternally transmitted Wolbachia are one of the most common endosymbionts in nature, infecting about half of all insect species. We test the hypothesis that Wolbachia alter host behaviour by assessing the effects of 14 different Wolbachia strains on the locomotor activity of nine Drosophila host species. We find that Wolbachia alter the activity of six different host genotypes, including all hosts in our assay infected with wRi-like Wolbachia strains (wRi, wSuz and wAur), which have rapidly spread among Drosophila species in about the last 14 000 years. While Wolbachia effects on host activity were common, the direction of these effects varied unpredictably and sometimes depended on host sex. We hypothesize that the prominent effects of wRi-like Wolbachia may be explained by patterns of Wolbachia titre and localization within host somatic tissues, particularly in the central nervous system. Our findings support the view that Wolbachia have wide-ranging effects on host behaviour. The fitness consequences of these behavioural modifications are important for understanding the evolution of host-symbiont interactions, including how Wolbachia spread within host populations.

Sleep, inflammation and cognitive function in middle-aged and older adults: A population-based study

BACKGROUND

Sleep plays a key role in preserving cognitive function. However, the optimal strategies of sleep for cognition and the underlying mechanism are not well-established.

METHODS

A cross-sectional study was performed using the China Health and Retirement Longitudinal Study (CHARLS), 2011-2012 survey. Self-reported nighttime sleep and afternoon napping data were collected. Fasting blood collected was analyzed for the high-sensitivity C-reactive protein (CRP) and white blood cell.

RESULTS

Both nighttime sleep and afternoon napping were significantly associated with cognition after adjusting for confounders (p < 0.05). Precisely, participants with nighttime sleep of 6.1-7h had the highest cognition scores (p < 0.05). Participants with less than 30 min afternoon napping had the highest cognition scores (p < 0.05). The synergistic effect of nighttime sleep and afternoon napping was not significant (p > 0.05). Nighttime sleep and afternoon napping were significantly related to the white blood cell, but not the high-sensitivity CRP. The white blood cell mediated the association between sleep and cognition (p < 0.05).

CONCLUSION

Nighttime sleep of six to seven hours and afternoon napping of less than 30 minutes are associated with optimal cognitive function in middle-aged and older people, respectively. Sleep influences cognition partly via the inflammatory profile.

Comfort driven design of innovative products: A personalized mattress case study

BACKGROUND

Human-centred design asks for wellbeing and comfort of the customer/worker when interacting with a product. Having a good perception-model and an objective method to evaluate the experienced (dis)comfort by the product user is needed for performing a preventive comfort evaluation as early as possible in the product development plan. The mattress of a bed is a typical product whose relevance in everyday life of people is under-evaluated. Fortunately, this behaviour is quickly changing, and the customer wants to understand the product he/she buys and asks for more comfortable and for scientifically assessed products. No guidelines for designing a personalized mattress are available in the literature.

OBJECTIVES

This study deals with the experience of designing an innovative product whose product-development-plan is focused on the customer perceived comfort: a personalized mattress. The research question is: which method can be used to innovate or create a comfort-driven human-centred product?

METHODS

Virtual prototyping was used to develop a correlated numerical model of the mattress. A comfort model for preventively assessing the perceived comfort was proposed and experimentally tested. Mattress testing sessions with subjects were organized, and collected data were compared with already tested mattresses. Brainstorming and multi-expert methods were used to propose, realize, and test an archetype of a new mattress for final comfort assessment.

RESULTS

A new reconfigurable mattress was developed, resulting in two patents. The mattress design shows that personalized products can be tuned according to the anthropometric data of the customer in order to improve the comfort experience during sleep.

CONCLUSIONS

A "comfort-driven design guideline" was proposed; this method has been based on the use of virtual prototyping, virtual optimization and physical prototyping and testing. It allowed to improve an existing product in a better way and to bring innovation in it.

Sleep Disturbance during Infection Compromises Tfh Differentiation and Impacts Host Immunity

Although the influence of sleep quality on the immune system is well documented, the mechanisms behind its impact on natural host immunity remain unclear. Meanwhile, it has been suggested that neuroimmune interactions play an important role in this phenomenon. To evaluate the impact of stress-induced sleep disturbance on host immunity, we used a murine model of rapid eye movement sleep deprivation (RSD) integrated with a model of malaria blood-stage infection. We demonstrate that sleep disturbance compromises the differentiation of T follicular helper cells, increasing host susceptibility to the parasite. Chemical inhibition of glucocorticoid (Glcs) synthesis showed that abnormal Glcs production compromised the transcription of Tfh-associated genes resulting in impaired germinal center formation and humoral immune response. Our data demonstrate that RSD-induced abnormal activation of the hypothalamic-pituitary-adrenal axis drives host susceptibility to infection. Understanding the impact of sleep quality in natural resistance to infection may provide insights for disease management.

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REM sleep deprivation (RSD) worsens malaria induced by Plasmodium yoelii infection

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RSD decreases germinal center formation and impairs specific antibody production

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Exacerbated glucocorticoid production impairs T lymphocyte differentiation

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The relationship between sleep and immunity is a target for malaria management

Toxoplasma gondii IgG associations with sleep-wake problems, sleep duration and timing

Background:

Evidence links Toxoplasmagondii (T. gondii), a neurotropic parasite, with schizophrenia, mood disorders and suicidal behavior, all of which are associated and exacerbated by disrupted sleep. Moreover, low-grade immune activation and dopaminergic overstimulation, which are consequences of T. gondii infection, could alter sleep patterns and duration.

Methods:

Sleep data on 833 Amish participants [mean age (SD) = 44.28 (16.99) years; 59.06% women] were obtained via self-reported questionnaires that assessed sleep problems, duration and timing. T. gondii IgG was measured with ELISA. Data were analyzed using multivariable logistic regressions and linear mixed models, with adjustment for age, sex and family structure.

Results:

T. gondii seropositives reported less sleep problems (p < 0.005) and less daytime problems due to poor sleep (p < 0.005). Higher T. gondii titers were associated with longer sleep duration (p < 0.05), earlier bedtime (p< 0.005) earlier mid-sleep time (p < 0.05).

Conclusions:

It seems unlikely that sleep mediates the previously reported associations between T. gondii and mental illness. Future longitudinal studies with objective measures are necessary to replicate our findings.

Puppet resting behavior in the Tibetan antelope (Pantholops hodgsonii)

Rest contributes a large part of animals' daily life, and animals usually rest in two ways, standing or in recumbence. Small or medium sized ungulates bed to rest in most cases, and standing rest is very rare and hardly seen. Here we described a standing rest behavior of Tibetan antelopes (Pantholops hodgsonii) living on the Tibet Plateau which has not been reported before. We named the standing rest behavior Puppet behavior, since the antelope stand still for a certain time. Of the 304 individuals observed, 48.3% (98/203) of adult and sub-adult males expressed the Puppet behavior, whereas only 6.3% (6/96) of females did, indicating an obvious sexual difference. Puppet behavior occurred more frequently at noon and in the afternoon on sunny and cloudy days, meaning that daytime and weather were both influential factors. Puppet behavior was usually accompanied with rumination and sometimes ended with leg-shaking. Our results suggest that Puppet behavior may be an adaptive form of rest, which may serve a thermoregulatory and anti-predation function, and may be simpler and safer than recumbent rest.

Sleep research goes wild: new methods and approaches to investigate the ecology, evolution and functions of sleep

Despite being a prominent aspect of animal life, sleep and its functions remain poorly understood. As with any biological process, the functions of sleep can only be fully understood when examined in the ecological context in which they evolved. Owing to technological constraints, until recently, sleep has primarily been examined in the artificial laboratory environment. However, new tools are enabling researchers to study sleep behaviour and neurophysiology in the wild. Here, we summarize the various methods that have enabled sleep researchers to go wild, their strengths and weaknesses, and the discoveries resulting from these first steps outside the laboratory. The initial studies to 'go wild' have revealed a wealth of interindividual variation in sleep, and shown that sleep duration is not even fixed within an individual, but instead varies in response to an assortment of ecological demands. Determining the costs and benefits of this inter- and intraindividual variation in sleep may reveal clues to the functions of sleep. Perhaps the greatest surprise from these initial studies is that the reduction in neurobehavioural performance resulting from sleep loss demonstrated in the laboratory is not an obligatory outcome of reduced sleep in the wild.This article is part of the themed issue 'Wild clocks: integrating chronobiology and ecology to understand timekeeping in free-living animals'.

Relevance of deprivation studies in understanding rapid eye movement sleep

Rapid eye movement sleep (REMS) is a unique phenomenon essential for maintaining normal physiological processes and is expressed at least in species higher in the evolution. The basic scaffold of the neuronal network responsible for REMS regulation is present in the brainstem, which may be directly or indirectly influenced by most other physiological processes. It is regulated by the neurons in the brainstem. Various manipulations including chemical, elec-trophysiological, lesion, stimulation, behavioral, ontogenic and deprivation studies have been designed to understand REMS genesis, maintenance, physiology and functional significance. Although each of these methods has its significance and limitations, deprivation studies have contributed significantly to the overall understanding of REMS. In this review, we discuss the advantages and limitations of various methods used for REMS deprivation (REMSD) to understand neural regulation and physiological significance of REMS. Among the deprivation strategies, the flowerpot method is by far the method of choice because it is simple and convenient, exploits physiological parameter (muscle atonia) for REMSD and allows conducting adequate controls to overcome experimental limitations as well as to rule out nonspecific effects. Notwithstanding, a major criticism that the flowerpot method faces is that of perceived stress experienced by the experimental animals. Nevertheless, we conclude that like most methods, particularly for in vivo behavioral studies, in spite of a few limitations, given the advantages described above, the flowerpot method is the best method of choice for REMSD studies.

Disciplined sleep for healthy living: Role of noradrenaline

Sleep is essential for maintaining normal physiological processes. It has been broadly divided into rapid eye movement sleep (REMS) and non-REMS (NREMS); one spends the least amount of time in REMS. Sleep (both NREMS and REMS) disturbance is associated with most altered states, disorders and pathological conditions. It is affected by factors within the body as well as the environment, which ultimately modulate lifestyle. Noradrenaline (NA) is one of the key molecules whose level increases upon sleep-loss, REMS-loss in particular and it induces several REMS-loss associated effects and symptoms. The locus coeruleus (LC)-NAergic neurons are primarily responsible for providing NA throughout the brain. As those neurons project to and receive inputs from across the brain, they are modulated by lifestyle changes, which include changes within the body as well as in the environment. We have reviewed the literature showing how various inputs from outside and within the body integrate at the LC neuronal level to modulate sleep (NREMS and REMS) and vice versa. We propose that these changes modulate NA levels in the brain, which in turn is responsible for acute as well as chronic psycho-somatic disorders and pathological conditions.

Pathogen-Host Defense in the Evolution of Depression: Insights into Epidemiology, Genetics, Bioregional Differences and Female Preponderance

Significant attention has been paid to the potential adaptive value of depression as it relates to interactions with people in the social world. However, in this review, we outline the rationale of why certain features of depression including its environmental and genetic risk factors, its association with the acute phase response and its age of onset and female preponderance appear to have evolved from human interactions with pathogens in the microbial world. Approaching the relationship between inflammation and depression from this evolutionary perspective yields a number of insights that may reveal important clues regarding the origin and epidemiology of the disorder as well as the persistence of its risk alleles in the modern human genome.

Adolescent Alcohol Exposure Persistently Impacts Adult Neurobiology and Behavior

Adolescence is a developmental period when physical and cognitive abilities are optimized, when social skills are consolidated, and when sexuality, adolescent behaviors, and frontal cortical functions mature to adult levels. Adolescents also have unique responses to alcohol compared with adults, being less sensitive to ethanol sedative-motor responses that most likely contribute to binge drinking and blackouts. Population studies find that an early age of drinking onset correlates with increased lifetime risks for the development of alcohol dependence, violence, and injuries. Brain synapses, myelination, and neural circuits mature in adolescence to adult levels in parallel with increased reflection on the consequence of actions and reduced impulsivity and thrill seeking. Alcohol binge drinking could alter human development, but variations in genetics, peer groups, family structure, early life experiences, and the emergence of psychopathology in humans confound studies. As adolescence is common to mammalian species, preclinical models of binge drinking provide insight into the direct impact of alcohol on adolescent development. This review relates human findings to basic science studies, particularly the preclinical studies of the Neurobiology of Adolescent Drinking in Adulthood (NADIA) Consortium. These studies focus on persistent adult changes in neurobiology and behavior following adolescent intermittent ethanol (AIE), a model of underage drinking. NADIA studies and others find that AIE results in the following: increases in adult alcohol drinking, disinhibition, and social anxiety; altered adult synapses, cognition, and sleep; reduced adult neurogenesis, cholinergic, and serotonergic neurons; and increased neuroimmune gene expression and epigenetic modifiers of gene expression. Many of these effects are specific to adolescents and not found in parallel adult studies. AIE can cause a persistence of adolescent-like synaptic physiology, behavior, and sensitivity to alcohol into adulthood. Together, these findings support the hypothesis that adolescent binge drinking leads to long-lasting changes in the adult brain that increase risks of adult psychopathology, particularly for alcohol dependence.

Detrimental role of prolonged sleep deprivation on adult neurogenesis

Adult mammalian brains continuously generate new neurons, a phenomenon called adult neurogenesis. Both environmental stimuli and endogenous factors are important regulators of adult neurogenesis. Sleep has an important role in normal brain physiology and its disturbance causes very stressful conditions, which disrupt normal brain physiology. Recently, an influence of sleep in adult neurogenesis has been established, mainly based on sleep deprivation studies. This review provides an overview on how rhythms and sleep cycles regulate hippocampal and subventricular zone neurogenesis, discussing some potential underlying mechanisms. In addition, our review highlights some interacting points between sleep and adult neurogenesis in brain function, such as learning, memory, and mood states, and provides some insights on the effects of antidepressants and hypnotic drugs on adult neurogenesis.

Sleep and vigilance linked to melanism in wild barn owls

Understanding the function of variation in sleep requires studies in the natural ecological conditions in which sleep evolved. Sleep has an impact on individual performance and hence may integrate the costs and benefits of investing in processes that are sensitive to sleep, such as immunity or coping with stress. Because dark and pale melanic animals differentially regulate energy homeostasis, immunity and stress hormone levels, the amount and/or organization of sleep may covary with melanin-based colour. We show here that wild, cross-fostered nestling barn owls (Tyto alba) born from mothers displaying more black spots had shorter non-REM (rapid eye movement) sleep bouts, a shorter latency until the occurrence of REM sleep after a bout of wakefulness and more wakefulness bouts. In male nestlings, the same sleep traits also correlated with their own level of spotting. Because heavily spotted male nestlings and the offspring of heavily spotted biological mothers switched sleep-wakefulness states more frequently, we propose the hypothesis that they could be also behaviourally more vigilant. Accordingly, nestlings from mothers displaying many black spots looked more often towards the nest entrance where their parents bring food and towards their sibling against whom they compete. Owlets from heavily spotted mothers might invest more in vigilance, thereby possibly increasing associated costs due to sleep fragmentation. We conclude that different strategies of the regulation of brain activity have evolved and are correlated with melanin-based coloration.

Sleep and dreaming are for important matters

Recent studies in sleep and dreaming have described an activation of emotional and reward systems, as well as the processing of internal information during these states. Specifically, increased activity in the amygdala and across mesolimbic dopaminergic regions during REM sleep is likely to promote the consolidation of memory traces with high emotional/motivational value. Moreover, coordinated hippocampal-striatal replay during NREM sleep may contribute to the selective strengthening of memories for important events. In this review, we suggest that, via the activation of emotional/motivational circuits, sleep and dreaming may offer a neurobehavioral substrate for the offline reprocessing of emotions, associative learning, and exploratory behaviors, resulting in improved memory organization, waking emotion regulation, social skills, and creativity. Dysregulation of such motivational/emotional processes due to sleep disturbances (e.g., insomnia, sleep deprivation) would predispose to reward-related disorders, such as mood disorders, increased risk-taking and compulsive behaviors, and may have major health implications, especially in vulnerable populations.

Extreme sleep durations and increased C-reactive protein: effects of sex and ethnoracial group

STUDY OBJECTIVES

We hypothesize that extremes of sleep duration are associated with elevated C-reactive protein (CRP), a pro-inflammatory marker for cardiovascular disease risk.

DESIGN

Cross-sectional.

SETTING

Population-based research.

PARTICIPANTS

Nationally representative sample of 2007-2008 National Health and Nutrition Examination Survey participants (n = 5,587 adults).

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Associations between CRP and self-reported total sleep time (TST) were examined. Explanatory models considered contributions of sex, age, race/ethnicity, body mass index (BMI), and BMI squared (BMI2). Models also explored the role of insomnia symptoms, sleep apnea, active medical illness, and antidiabetic/antihypertensive treatment. Differential patterns among race/ethnicity groups were examined using interactions and stratified analyses. Nonlinear relationships between CRP and TST were assessed using polynomial and multinomial regression models (< 5, 5, 6, 7, 8, 9, and > 9 h). Linear and squared terms were significant in all models in the complete sample, with notable differences by sex and ethnoracial group. Overall, in models adjusted for sociodemographics and BMI, different patterns were observed for non-Hispanic white (elevated CRP for < 5 h and > 9 h), black/African-American (elevated CRP for < 5 h and 8 h), Hispanic/Latino (elevated CRP for > 9 h), and Asian/ Other (higher in 9 and > 9 h and lower in 5 h and 6 h) groups. Ethnoracial groups also demonstrated patterning by sex.

CONCLUSION

In a representative sample of American adults, elevated CRP was associated with extreme sleep durations. Sex, race/ethnicity, sleep disorders, and medical comorbidity influenced these associations. Differences in CRP along these dimensions should be considered in future research on sleep related disparities influencing cardiometabolic disease risk.

Sleep-wake state tradeoffs, impulsivity and life history theory

Evolutionary ecological theory predicts that sleep-wake state tradeoffs may be related to local environmental conditions and should therefore correlate to alterations in behavioral life history strategies. It was predicted that firefighters who slept more and reported better quality sleep on average would exhibit lower impulsivity inclinations related to slower life history trajectories. UPPS impulsivity scores and self-reported sleep averages were analyzed and indicated a negative association between sleep variables and urgency and a positive association with premeditation. Perseverance, and in some cases premeditation, however, disclosed an unpredicted marginally significant positive association between increased and emergency nighttime waking-related sleep deprivation. Sensation seeking was not associated with sleep variables, but was strongly associated with number of biological children. This research contributes to understanding the implications of human sleep across ecological and behavioral contexts and implies further research is necessary for constructing evolutionarily oriented measures of impulsivity inclination and its meaning in the context of life history strategies.

Sleep and Immune Function

Scientists are only beginning to fully understand the purpose of sleep and its underlying mechanisms. Lack of sleep is associated with many diseases, including infection, and with increased mortality. Lack of proper sleep is an important problem in the intensive care unit, and interventions have been designed to improve it. Sleep is associated with immune function, and this relationship is partially based on the physiological basis of sleep, sleep architecture, the sleep-wake cycle, cytokines and the hypothalamic-pituitary axis.

Nocturia: current status and future perspectives

PURPOSE OF REVIEW

Nocturia is a bothersome and highly prevalent condition characterized by the need to wake to void at night. Nocturia is equally common in men and women, and although its prevalence increases with age, a significant proportion of younger people are also affected. Nocturia leads to fragmentation of sleep and consequently to a serious decline in daytime functioning and in quality of life and health. Its impact should not be underestimated by clinicians and therefore a review on nocturia is timely and relevant.

RECENT FINDINGS

Traditionally, nocturia is regarded as a symptom of benign prostatic enlargement and/or overactive bladder syndrome, with treatment therefore directed toward increasing the capacity of the bladder to hold urine. Such treatments have proven ineffective in many patients because nocturnal polyuria, an overproduction of urine at night, has been found to be present in the majority of patients. Nocturia can be attributed to some underlying pathological factors but it can also be a distinct clinical entity with specific pathogenesis. Frequency-volume charts are recommended for routine use in clinical practice, to determine whether nocturia is a result of excessive urine production at night, or of small voided volumes due to bladder problems, or a combination of these factors. Desmopressin, a synthetic analogue of the antidiuretic hormone, should be considered in patients with nocturia where nocturnal polyuria is present.

SUMMARY

Contrary to popular and medical misconception nocturia is an important condition leading to general morbidity and with serious impact on overall quality of life and health. We advise clinicians to pay attention to nocturia and diagnostics should be offered. Treatment modalities are available and have to be discussed with the patient.

Deficiency of corticotropin-releasing hormone type-2 receptor alters sleep responses to bacterial lipopolysaccharide in mice

In response to infectious stimuli, enhanced non-rapid eye movement sleep (NREMS) occurs, which is driven by pro-inflammatory cytokines. Those cytokines further elicit the release of corticotropin-releasing hormone (CRH), resulting in the activation of the hypothalamic-pituitary-adrenocortical axis. Signals of CRH are mediated by two receptor types, namely CRH-R1 and -R2. The role of CRH-R1 in wake-promoting effects of CRH has been rather clarified, whereas the involvement of CRH-R2 in sleep-wake regulation is poorly understood. To investigate whether CRH-R2 interferes with sleep responses to immune challenge, this study examined effects of bacterial lipopolysaccharide (LPS) on sleep in CRH-R2 deficient (KO) mice. CRH-R2 KO mice and control littermates (CL) were implanted with electrodes for recording electroencephalogram (EEG) and electromyogram. After recovery, LPS was applied by intraperitoneal injection at doses of 0.1, 1.0, or 10 μg at dark onset. In response to LPS injection NREMS of both genotypes was enhanced in a dose-dependent manner. However, CRH-R2 KO mice showed a larger increase, in particular after 10 μg of LPS compared to CL mice. During postinjection, reduced delta power for NREMS was detected in both genotypes after each dose, but the highest dose evoked a marked elevation of EEG activity in a limited frequency band (4 Hz). However, the EEG power of lower frequencies (1-2 Hz) increased more in CRH-R2 KO than in CL mice. The results indicated that CRH-R2 KO mice show greater NREMS responses to LPS, providing evidence that CRH-R2 participates in sleep-wake regulation via an interaction with the activated immune system.

Sleep duration, sleep quality, and biomarkers of inflammation in a Taiwanese population

PURPOSE

Short and long sleep duration and sleep quality are associated with health including all-cause mortality, cardiovascular disease, diabetes, and obesity. Inflammation may play a role in mediating these associations.

METHODS

We examined associations between inflammation and self-reported sleep characteristics in 1020 respondents of the 2000 and 2006 Social Environment and Biomarkers of Aging Study, a nationally representative survey of Taiwanese adults ages 53 and over. Regression models were used to estimate cross-sectional relationships between inflammation (interleukin-6, C-reactive protein, fibrinogen, e-selectin, soluble intercellular adhesion molecule-1, albumin, and white blood cell count) and a modified Pittsburgh Sleep Quality Index, index subcomponents, and self-reported sleep duration. Change in inflammatory markers between 2000 and 2006 was also used to predict long or short sleep duration in 2006.

RESULTS

Inflammation was not related to the overall index of sleep quality. However, longer sleep (>8 hr) was associated with higher levels of inflammation. These associations remained after adjustment for waist circumference, self-reported health decline, diabetes, arthritis/rheumatism, heart disease, and depressive symptoms. Increases in inflammation between 2000 and 2006 were associated with long but not short sleep duration in 2006 for several markers.

CONCLUSIONS

Long sleep duration may be a marker of underlying inflammatory illness in older populations. Future studies should explore whether inflammation explains observed relationships between long sleep and mortality.

Impairment of the mitochondrial electron transport chain due to sleep deprivation in mice

It has been demonstrated that sleep deprivation is associated with altered expression of genes related to metabolic processes, response to stress and inflammation, circadian sleep/wake cycles, regulation of cell proliferation and various signaling pathways. However, the molecular mechanisms underlying these changes remain poorly understood. Thus, the present study aims to characterize the function of the mitochondrial electron transport chain in the brain using an animal model of paradoxical sleep deprivation (PSD). The question of whether sleep recovery (rebound) can reverse changes found after PSD is also addressed. Adult male inbred C57BL/6J mice were randomly distributed into three groups: home-cage control, PSD and sleep rebound groups. The PSD and rebound groups were subjected to PSD for 72 h. After this sleep deprivation period, the rebound group was returned to its home cage and allowed to sleep in an undisturbed and spontaneous fashion for 24h. The mitochondrial complex I-III, complex II, succinate dehydrogenase and complex II-III activities were then measured by spectrophotometric methods in sub-mitochondrial particles extracted from the prefrontal cortex, hippocampus, striatum and hypothalamus. Our results showed a significant decrease in the activity of complex I-III in the PSD and rebound groups as compared to the control group. The complex II and II-III activity were particularly decreased in the hypothalamus of the sleep rebound group. These results are consistent with the involvement of sleep in energy metabolism and corroborate previous experiments demonstrating the importance of the hypothalamus in sleep regulation.

Impact of nocturia on bone fracture and mortality in older individuals: a Japanese longitudinal cohort study

PURPOSE

We evaluated the association of nocturia with fracture and death in a large, community based sample of Japanese individuals 70 years old or older.

MATERIALS AND METHODS

The baseline in this population based study was determined in 2003 by an extensive health interview with each participant. In this study we followed 784 individuals with a mean ± SD age of 76.0 ± 4.6 years (range 70 to 97). Information on mortality and fracture during the study period was provided by the National Health Insurance system and details on fractures were collected from medical records. We compared the risk of bone fracture and death with or without nocturia in a multivariate Cox proportional hazard model.

RESULTS

Nocturia (2 or greater voids per night) was present in 359 of the 784 participants (45.7%). Fracture was observed in 41 cases, including 32 fall related cases. For all fractures and fall related fractures with nocturia the HR was 2.01 (95% CI 1.04-3.87) and 2.20 (95% CI 1.04-4.68, each p = 0.04). Death occurred in 53 cases. The mortality rate in individuals with nocturia was significantly higher than in those without nocturia. For mortality in patients with nocturia the age-gender adjusted HR was 1.91 (95% CI 1.07-3.43, p = 0.03). Even when further adjusted for diabetes, smoking status, history of coronary disease, renal disease and stroke, tranquilizers, hypnotics and diuretics, the positive relationship was unchanged (HR 1.98, 95% CI 1.09-3.59, p = 0.03).

CONCLUSIONS

During a 5-year observation period elderly individuals with nocturia were at greater risk for fracture and death than those without nocturia.

Thinking beyond the bladder: antidiuretic treatment of nocturia

Nocturia is a bothersome and highly prevalent urological condition characterised by the need to wake to void at night. Contrary to popular misconception, nocturia is equally common in men and women, and although its prevalence increases with age, a significant proportion of younger people are also affected. Nocturia leads to repeated fragmentation of sleep and consequently to a serious decline in daytime functioning and in overall quality of life and health. As such, its impact should not be underestimated by clinicians. Traditionally, nocturia has been regarded as a symptom of benign prostatic enlargement and/or overactive bladder syndrome, with treatment therefore directed towards increasing the capacity of the bladder to hold urine. Such treatments have proven largely ineffective in many patients, likely because nocturnal polyuria (NP), a condition that results in overproduction of urine at night, has been found to be present in the majority of nocturia patients. As such, the traditional belief that nocturia is attributable to some other underlying pathological factors, is now being replaced by the acknowledgment that it can be a distinct clinical entity with specific pathogenesis. Frequency-volume charts are an invaluable tool, recommended for routine use in clinical practice, to determine whether nocturia is a result of excessive urine production at night, or of small voided volumes (indicating bladder storage problems), or indeed a combination of these factors. Given the specific antidiuretic action of desmopressin, a synthetic analogue of the body's own antidiuretic hormone, it should be considered as first-line therapy for patients with nocturia where NP is present.

Sleep triggered by an immune response in Drosophila is regulated by the circadian clock and requires the NFkappaB Relish

Background

Immune challenge impacts behavior in many species. In mammals, this adaptive behavior is often manifested as an increase in sleep. Sleep has therefore been proposed to benefit the host by enhancing immune function and thereby overcome the challenge. To facilitate genetic studies on the relationship between sleep and immune function, we characterized the effect of the immune response on sleep in Drosophila melanogaster. Behavioral features of sleep as well as the innate immune response signaling pathways are well characterized in flies and are highly conserved in mammals.

Results

An immune response induced by infection with Gram-negative bacteria or by aseptic injury increased sleep in flies. The increase in sleep occurred during the morning hours after treatment and the magnitude of the effect was dependent on the time-of-day of inoculation or injury such that night-time treatment had a stronger effect than that during the daytime. This pattern persisted in constant darkness, indicating a role of the circadian clock. Mutants of the circadian clock gene, period, eliminated the increase in sleep observed in the morning, but instead showed enhanced sleep immediately after injury or infection.

Null mutants of the Nuclear Factor κB (NFκB) Relish, which is central to the innate immune response, do not increase sleep in response to injury or infection at any time of day. Instead, they maintain a normal sleep pattern until they die. Expression of a full-length Relish transgene in the fat bodies of Relish mutants restored the morning increase in sleep during an immune response. Fat bodies are a major site of immune signalling in flies and have a key role in host defense.

Conclusions

These data demonstrate that an immune response increases sleep in flies in a manner that is gated by the circadian clock and that requires the NFκB Relish. These findings support a role of sleep in a recovery process and demonstrate a conserved feature of the Drosophila model of sleep.

Sleep viewed as a state of adaptive inactivity

Sleep is often viewed as a vulnerable state that is incompatible with behaviours that nourish and propagate species. This has led to the hypothesis that sleep has survived because it fulfills some universal, but as yet unknown, vital function. I propose that sleep is best understood as a variant of dormant states seen throughout the plant and animal kingdoms and that it is itself highly adaptive because it optimizes the timing and duration of behaviour. Current evidence indicates that ecological variables are the main determinants of sleep duration and intensity across species.