Measuring individual vulnerability to sleep loss—the CHICa scale

The aim of this project was to construct a psychometrically satisfying scale to describe subjective reactions to sleep deprivation. First, on the basis of a literature review, a list of items was generated which reflected the negatively affected mood and reduced wellbeing associated with sleep loss. Additionally, psychology students were asked to describe their cognitive and emotional symptoms following a night with curtailed sleep. As a result, 69 items were included in the experimental set. University students (n = 102, females, mean age 22.5 ± 1.9 years) completed the form several times during 1 week in June (while preparing for examinations) and on a free day in September; a total of 460 forms were collected. The final, 26‐item version of the scale was validated in a sleep deficit experiment lasting 1 week, conducted with 25 female participants (mean age 23.4 ± 1.9 years). Factor analysis showed 71.7% of total variance explained by four components: impaired thermoregulation (C for cold), disrupted appetite (H for hunger), affective problems (I for irritability) and lowered level of cognitive functioning (Ca for cognitive attenuation). A Polish version of the CHICa scale showed satisfactory psychometric properties. Cronbach's alpha of the subscales were between 0.90 and 0.95. All four subscales exhibited a significant increase with an experimental 3‐h daily sleep restriction over a period of 1 week; cognitive attenuation was the most symptomatic. Cognitive problems (reduced concentration, comprehension and accuracy) and a lack of energy seem to be the most specific subjective manifestations of the chronic sleep deficit state. CHICa may be helpful in research on inter‐and intra‐individual differences and on the efficacy of various counteractive treatments for the consequences of sleep deprivation.     

Investigating the interaction between the homeostatic and circadian processes of sleep-wake regulation for the prediction of waking neurobehavioural performance

The two-process model of sleep regulation has been applied successfully to describe, predict, and understand sleep-wake regulation in a variety of experimental protocols such as sleep deprivation and forced desynchrony. A non-linear interaction between the homeostatic and circadian processes was reported when the model was applied to describe alertness and performance data obtained during forced desynchrony. This non-linear interaction could also be due to intrinsic non-linearity in the metrics used to measure alertness and performance, however. Distinguishing these possibilities would be of theoretical interest, but could also have important implications for the design and interpretation of experiments placing sleep at different circadian phases or varying the duration of sleep and/or wakefulness. Although to date no resolution to this controversy has been found, here we show that the issue can be addressed with existing data sets. The interaction between the homeostatic and circadian processes of sleep-wake regulation was investigated using neurobehavioural performance data from a laboratory experiment involving total sleep deprivation. The results provided evidence of an actual non-linear interaction between the homeostatic and circadian processes of sleep-wake regulation for the prediction of waking neurobehavioural performance.     

Relationship between autonomic and behavioral thermoregulation in the mouse

Preferred ambient temperature (Ta) was measured in nine mice of the BALB/c strain using a temperature gradient. When tested over four consecutive days the mean preferred Ta was 30.9 degrees C. In another study using the same animals, metabolic rate, evaporative water loss, whole-body thermal conductance, and colonic temperature were measured at specific Ta's over a range of 18 to 34 degrees C. The preferred Ta of 30.9 degrees C was associated with the lower critical Ta (i.e., Ta below which metabolic rate increased) a 57% elevation in evaporative water loss when expressed in units of mg water evaporated per ml consumed oxygen, a thermal conductance that was 92% above baseline levels, and a normothermic colonic temperature of between 37.0 to 37.5 degrees C. The data indicate that mice will select an environmental temperature associated with a minimal energy expenditure but a higher than minimal rate of evaporation and higher thermal conductance.     

Circasemidian sleep propensity and the phase-amplitude maintenance model of human sleep/wake regulation

SUMMARY  Evidence for circasemidian sleep/wake regulation is briefly reviewed with respect to protocols used to quantify sleep propensity. Existing models of sleep/wake regulation are examined in view of their ability to accommodate data which demonstrate an afternoon sleep period. Finally, a modelling approach is briefly outlined which emphasizes the maintenance of the phase and amplitude characteristics of the circadian rhythm of body (and brain) temperature and predicts the circasemidian phenomena.     

Time of day effects in, and the relationship between, sleep quality and movement

The study aimed to measure the effects of a 27-h 'day' sleep-wake regime on actigraphic and subjective sleep variables, and to examine the relationships between these variables. Nine subjects spent 30 days and nights in the laboratory. After sleeping 8 h for each of 8 nights, the subjects had an imposed 27-h 'day', for 18 'days', remaining in bed for 9 h on each sleep period. Sleep periods therefore started 3 h later each day, although subjects' circadian rhythms stayed entrained to 24 h, because subjects were not isolated from the natural light-dark cycle. Time asleep, subjective sleep efficiency and subjective sleep quality, but not movement during sleep, were found to be significantly affected by time of going to bed. There were significant decreases in movement during recovery sleeps following each of two episodes of 26 h sleep deprivation. Over the study there were significant within-subject correlations between subjective sleep quality and subjective sleep efficiency (r_av=0.65), movement during sleep and subjective sleep efficiency (r_av=−0.48), and movement during sleep and subjective sleep quality (r_av=–0.26). We conclude that sleep movement, despite its low within-and between-subjects variability, is nevertheless a statistically reliable, but weak, indicator of subjective sleep efficiency and quality.     

Reaction of sleepiness indicators to partial sleep deprivation,time of day and time on task in a driving simulator – the DROWSI project

Studies of driving and sleepiness indicators have mainly focused on prior sleep reduction. The present study sought to identify sleepiness indicators responsive to several potential regulators of sleepiness: sleep loss, time of day (TOD) and time on task (TOT) during simulator driving. Thirteen subjects drove a high‐fidelity moving base simulator in six 1‐h sessions across a 24‐h period, after normal sleep duration (8 h) and after partial sleep deprivation (PSD; 4 h). The results showed clear main effects of TOD (night) and TOT but not for PSD, although the latter strongly interacted with TOD. The most sensitive variable was subjective sleepiness, the standard deviation of lateral position (SDLAT) and measures of eye closure [duration, speed (slow), amplitude (low)]. Measures of electroencephalography and line crossings (LCs) showed only modest responses. For most variables individual differences vastly exceeded those of the fixed effects, except for subjective sleepiness and SDLAT. In a multiple regression analysis, SDLAT, amplitude/peak eye‐lid closing velocity and blink duration predicted subjective sleepiness bouts with a sensitivity and specificity of about 70%, but were mutually redundant. The prediction of LCs gave considerably weaker, but similar results. In summary, SDLAT and eye closure variables could be candidates for use in sleepiness‐monitoring devices. However, individual differences are considerable and there is need for research on how to identify and predict individual differences in susceptibility to sleepiness.     

A review of the tripartite model for understanding the link between anxiety and depression in youth

Although research from numerous investigations indicates that there is substantial overlap in anxiety and depressive symptoms and comorbid diagnoses in youth, these constructs can be adequately differentiated. Clark and Watson [Clark, L. A. & Watson, D., (1991). Tripartite model of anxiety and depression: Psychometric evidence and taxonomic implications. Journal of Abnormal Psychology, 100, 316-336] proposed a tripartite model to account for the symptom overlap and diagnostic comorbidity between anxiety and depression. This tripartite model posits that anxiety and depression share a common component of negative affect, but can be differentiated by low positive affect associated with depression and high physiological hyperarousal associated with anxiety. The present article reviews initial research which has supported the utility of the tripartite model for explaining the association between anxiety and depression in adult and youth samples. Following that review, more recent investigations which have called into question the applicability of the tripartite constructs for youth are presented. Finally, the paper reviews evidence suggesting that the tripartite factors may not function similarly across all anxiety and depressive disorders. This article concludes by suggesting that more research is necessary with children and adolescents in order to determine the functioning of tripartite constructs across anxiety disorders in youth.     

The impact of break duration,time of break onset,and prior shift duration on the amount of sleep between shifts in heavy vehicle drivers

This study aimed to examine the impact of break duration between consecutive shifts, time of break onset, and prior shift duration on total sleep time (TST) between shifts in heavy vehicle drivers (HVDs), and to assess the interaction between break duration and time of break onset. The sleep (actigraphy and sleep diaries) and work shifts (work diaries) of 27 HVDs were monitored during their usual work schedule for up to 9 weeks. Differences in TST between consecutive shifts and days off were assessed. Linear mixed models (followed by pairwise comparisons) assessed whether break duration, prior shift duration, time of break onset, and the interaction between break duration and break onset were related to TST between shifts. Investigators found TST between consecutive shifts (mean [SD] 6.38 [1.38] h) was significantly less than on days off (mean [SD] 7.63 [1.93] h; p < 0.001). Breaks starting between 12:01 and 8:00 a.m. led to shorter sleep (p < 0.05) compared to breaks starting between 4:01 and 8:00 p.m. Break durations up to 7, 9, and 11 h (Australian and European minimum break durations) resulted in a mean (SD) of 4.76 (1.06), 5.66 (0.77), and 6.41 (1.06) h of sleep, respectively. The impact of shift duration prior to the break and the interaction between break duration and time of break were not significant. HVDs’ sleep between workdays is influenced independently by break duration and time of break onset. This naturalistic study provides evidence that current break regulations prevent sufficient sleep duration in this industry. Work regulations should evaluate appropriate break durations and break onset times to allow longer sleep opportunities for HVDs.     

An animal model of the relationship between systemic hypertension and repetitive episodic hypoxia as seen in sleep apnoea

SUMMARY  Multiple factors may be responsible for acute and chronic blood pressure changes during obstructive sleep apnoea. A popular hypothesis is that recurrent episodic hypoxia stimulates chemoreceptors which, in turn, cause sympathetically mediated vasoconstriction and perhaps long-term vascular remodelling. Disruption of sleep architecture secondary to frequent arousals may also cause chronic stress which may contribute to diurnal hypertension. A less likely factor elevating blood pressure is the effect of abrupt intra-thoracic pressure changes on venous return and cardiac output. The rat responds to chronic, recurrent episodic hypocapnic hypoxia (12-s bursts of nitrogen followed by air into Plexiglas chambers, every 30 s, 7h d^-1, 2–4% nadir ambient oxygen) with sustained increase in diurnal blood pressure (10–14 mmHg). Subsequent studies reveal that carotid sinus nerve section (chemodener-vation) and chemically induced peripheral sympathetic denervation with the neurotoxin 6-OH dopamine both eliminate this blood pressure-elevating effect of chronic episodic hypoxaemia. Using this model, Sprague-Dawley rats have been challenged with both eucapnic hypoxia and asphyxia and failed to show an additional blood pressure elevation above that caused by hypoxia (hypocapnic) alone. It appears that hypocapnic hypoxia creates a maximal stimulus to the sympathetic nervous system to which the addition of hypercarbia does not increase the blood pressure response. An alternative explanation is that the rat has protective mechanisms that limit the diurnal blood pressure response from further increase.     

Age differences in the association of obstructive sleep apnea risk with cognition and quality of life

Using a sample of 2925 stroke‐free participants drawn from a national population‐based study, we examined cross‐sectional associations of obstructive sleep apnea (OSA) risk with cognition and quality of life and whether these vary with age, while controlling for demographics and comorbidities. Included participants from the REasons for Geographic And Racial Differences in Stroke (REGARDS) study were aged 47–93 years. OSA risk was categorized as high or low based on responses to the Berlin Sleep Questionnaire. Cognitive function was assessed with standardized fluency and recall measures. Depressive symptoms were assessed with the four‐item Center for Epidemiologic Studies Depression Scale. Health‐related quality of life (HRQoL) was assessed with the Medical Outcomes Study Short Form‐12 (SF‐12). Multivariate analyses of covariance (mancova ) statistics were applied separately to the cognitive and quality of life dependent variables while accounting for potential confounders (demographics, comorbidities). In fully adjusted models, those at high risk for OSA had significantly lower cognitive scores (Wilks’ lambda = 0.996, F_3,2786 = 3.31, P < 0.05) and lower quality of life [depressive symptoms and HRQoL] (Wilks’ lambda = 0.989, F_3,2786 = 10.02, P < 0.0001). However, some of the associations were age‐dependent. Differences in cognition and quality of life between those at high and low obstructive sleep apnea risk were most pronounced during middle age, with attenuated effects after age 70 years.     

Looking for the social and cultural dimension of the human brain

The theories of brain function generally stem from elementary units and mechanisms to explain behavioral and psychological processes. The concept of the reflex arc is still today the paradigm of this trend. Other views have pointed out that molar and dynamic principles of brain functioning are more suitable for the explanation of complex processes. Social and cultural factors, whilst considered fundamental in the development of psychological functions, are neglected in brain research. The relevance of these factors is illustrated for what concerns some topics of growing interest in neuropsychological research, from the hemisphere specialization in people of different cultures to the individual organization of brain functioning.     

Modulation of TASK-1/3 channels at the hypoglossal motoneuron pool and effects on tongue motor output and responses to excitatory inputs in vivo: implications for strategies for obstructive sleep apnea pharmacotherapy

Obstructive sleep apnea (OSA) occurs exclusively during sleep due to reduced tongue motor activity. Withdrawal of excitatory inputs to the hypoglossal motor nucleus (HMN) from wake to sleep contributes to this reduced activity. Several awake–active neurotransmitters with inputs to the HMN (e.g. serotonin [5-HT]) inhibit K⁺ leak mediated by TASK-1/3 channels on hypoglossal motoneurons, leading to increased neuronal activity in vitro. We hypothesize that TASK channel inhibition at the HMN will increase tongue muscle activity in vivo and modulate responses to 5-HT. We first microperfused the HMN of anesthetized rats with TASK channel inhibitors: doxapram (75 μM, n = 9), A1899 (25 μM, n = 9), ML365 (25 μM, n = 9), acidified artificial cerebrospinal fluid (ACSF, pH = 6.25, n = 9); and a TASK channel activator terbinafine (50 μM, n = 9); all with and without co-applied 5-HT (10 mM). 5-HT alone at the HMN increased tongue motor activity (202.8% ± 45.9%, p < 0.001). However, neither the TASK channel inhibitors, nor activator, at the HMN changed baseline tongue activity (p > 0.716) or responses to 5-HT (p > 0.127). Tonic tongue motor responses to 5-HT at the HMN were also not different (p > 0.05) between ChAT-Cre:TASK^f/f mice (n = 8) lacking TASK-1/3 channels on cholinergic neurons versus controls (n = 10). In freely behaving rats (n = 9), microperfusion of A1899 into the HMN increased within-breath phasic tongue motor activity in wakefulness only (p = 0.005) but not sleep, with no effects on tonic activity across all sleep–wake states. Together, the findings suggest robust maintenance of tongue motor activity despite various strategies for TASK channel manipulation targeting the HMN in vivo, and thus currently do not support this target and direction for potential OSA pharmacotherapy.     

Systematic review of the associations between prenatal sleep behaviours and components of energy balance for regulating weight gain

This systematic review aimed to examine the magnitude and direction of the associations between prenatal sleep behaviours (i.e. nighttime sleep duration, sleep quality, night awakenings and daytime nap duration) and eating behaviours, physical activity and gestational weight gain. A systematic search was conducted using Medline/PubMed, PsychINFO, CINAHL Complete, ProQuest Dissertations and Thesis A&I, and Web of Science to identify studies with at least one sleep measure, and either eating behaviours, physical activity and/or gestational weight gain. In summary, 11 studies met the review criteria and generated 11 total effect size across 10,900 participants. The majority of the studies were conducted after 2010, which highlights the infancy of this research. Overall, the strengths of the effect size were small: sleep-gestational weight gain (effect size = 0.29), sleep-eating behaviours (effect size = 0.13) and sleep-physical activity (effect size = 0.13). The only effect size that emerged as significant was for the pooled sleep behaviours-physical activity association; good sleep behaviours were positively associated with higher levels of physical activity. These findings summarize and provide insight on how sleep behaviours are related to prenatal gestational weight gain, eating behaviours and physical activity by identifying the strength and direction of the associations that have been previously unknown. Results support the rationale for future longitudinal and randomized control trials to examine the effects of sleep behaviours on gestational weight gain, eating behaviours and physical activity over the course of pregnancy.     

The relation between common sleep problems and emotional and behavioral problems among 2- and 3-year-olds in the context of known risk factors for psychopathology

The contribution of sleep problems to emotional and behavioral problems among young children within the context of known risk factors for psychopathology was examined. Data on 2- and 3-year-olds, representative of Canadian children without a chronic illness, from three cross-sectional cohorts of the Canadian National Longitudinal Study of Child and Youth were analysed ( n  = 2996, 2822, and 3050). The person most knowledgeable (PMK), usually the mother, provided information about her child, herself, and her family. Predictors included: child health status and temperament; parenting and PMK depressive symptomatology; family demographics (e.g., marital status, income) and functioning. Child sleep problems included night waking and bedtime resistance. Both internalizing/emotional (i.e., anxiety) and externalizing/behavioral problems (i.e., hyperactivity, aggression) were examined. Adjusting for other known risk factors, child sleep problems accounted for a small, but significant, independent proportion of the variance in internalizing and externalizing problems. Structural equation models examining the pathways linking risk factors to sleep problems and emotional and behavioral problems were a good fit of the data. Results were replicated on two additional cross-sectional samples. The relation between sleep problems and emotional and behavioral problems is independent of other commonly identified risk factors. Among young children, sleep problems are as strong a correlate of child emotional and behavioral problems as PMK depressive symptomatology, a well-established risk factor for child psychopathology. Adverse parenting and PMK symptomatology, along with difficult temperament all contribute to both sleep problems and emotional and behavioral problems. Children's sleep problems appear to exacerbate emotional and behavioral problems.     

The key role of insomnia and sleep loss in the dysregulation of multiple systems involved in mood disorders: A proposed model

Mood disorders are amongst the most prevalent and severe disorders worldwide, with a tendency to be recurrent and disabling. Although multiple mechanisms have been hypothesized to be involved in their pathogenesis, just a few integrative theoretical frameworks have been proposed and have yet to integrate comprehensively all available findings. As such, a comprehensive framework would be quite useful from a clinical and therapeutic point of view in order to identify elements to evaluate and target in the clinical practice. Because conditions of sleep loss, which include reduced sleep duration and insomnia, are constant alterations in mood disorders, the aim of this paper was to review the literature on their potential role in the pathogenesis of mood disorders and to propose a novel theoretical model. According to this hypothesis, sleep should be considered the main regulator of several systems and processes whose dysregulation is involved in the pathogenesis of mood disorders. The model may help explain why sleep disturbances are so strikingly linked to mood disorders, and underscores the need to evaluate, assess and target sleep disturbances in clinical practice, as a priority, in order to prevent and treat mood disorders.     

利用结构方程模型研究老年糖尿病患者健康相关生命质量与临床表现之间的关系

目的以Wilson-Cleary模型为向导构建结构方程模型（SEM）,了解老年糖尿病患者的健康相关生命质量（HRQOL）与临床表现之间的相互关系。方法自行设计调查问卷,选择来本院诊断治疗的450例老年糖尿病患者作为研究人群,运用SF-36生活质量调查表、老年人多功能评估问卷（OMFAQ）、医疗社会支持量表（MOS-SSS）、兰特心理健康量表（RMHI）和临床结果（与糖尿病有关的特征和生理数据）进行评估,构建机构方程模型。采用拟合优度的指标来评估路径模型的整体,配合卡方检验处理数据。结果心理困扰、收入和充足社会保障等四个因素,可通过一般健康感知对HRQOL产生直接影响（66%变异量）;而症状、身体功能状态和心理状态等三个因素,则通过一般健康感知对HRQOL产生间接的影响（64%的变异量）。另外,症状、年龄、性别和体力活动等四个因素通过身体功能状态间接影响HRQOL（72%的变异量）。结论提高社会和财政支持或提供其他干预措施,可有效地提高老年糖尿病患者身体素质和心理抗压能力,并提高他们的HRQOL。     

Zygomatic bone shape in intentional cranial deformations: a model for the study of the interactions between skull growth and facial morphology

Intentional cranial deformations (ICD) were obtained by exerting external mechanical constraints on the skull vault during the first years of life to permanently modify head shape. The repercussions of ICD on the face are not well described in the midfacial region. Here we assessed the shape of the zygomatic bone in different types of ICDs. We considered 14 non‐deformed skulls, 19 skulls with antero‐posterior deformation, nine skulls with circumferential deformation and seven skulls with Toulouse deformation. The shape of the zygomatic bone was assessed using a statistical shape model after mesh registration. Euclidian distances between mean models and Mahalanobis distances after canonical variate analysis were computed. Classification accuracy was computed using a cross‐validation approach. Different ICDs cause specific zygomatic shape modifications corresponding to different degrees of retrusion but the shape of the zygomatic bone alone is not a sufficient parameter for classifying populations into ICD groups defined by deformation types. We illustrate the fact that external mechanical constraints on the skull vault influence midfacial growth. ICDs are a model for the study of the influence of epigenetic factors on craniofacial growth and can help to understand the facial effects of congenital skull malformations such as single or multi‐suture synostoses, or of external orthopedic devices such as helmets used to correct deformational plagiocephaly.     

The basic reproduction ratio for a model of directly transmitted infections considering the virus charge and the immunological response

Correspondent author email: hyunyang{at}ime.unicamp.br In order to describe mathematically the transmission of microparasites,especially directly transmitted infections, it is usual to setup differential equations assuming the mass action law and ahomogeneously mixed population. In this paper we analyze sucha model taking into account heterogeneity with respect to theinfectivity, that is, the variability in the evolution of theinteraction between parasite and the human host during the infectiousperiod. The well established biological phenomenon of initialincrease in parasite abundance followed by its decrease, dueto the interaction between the host's immunological responseand the parasite, has thus been taken into account The variableamount of microparasites eliminated by an infectious individual,and the different (heterogeneous) immunological response buildup by the host when in interaction with parasite are presentin the model. The analytical expression for the basic reproductionratio is derived through stability analysis.     

“The developmental and functional logic of neuronal circuits”: commentary on the Kavli Prize in Neuroscience

The first Kavli Prize in Neuroscience recognizes a confluence of career achievements that together provide a fundamental understanding of how brain and spinal cord circuits are assembled during development and function in the adult. The members of the Kavli Neuroscience Prize Committee have decided to reward three scientists (Sten Grillner, Thomas Jessell, and Pasko Rakic) jointly “for discoveries on the developmental and functional logic of neuronal circuits”.