Sleep duration varies as a function of glutamate and GABA in rat pontine reticular formation

The oral part of the pontine reticular formation (PnO) is a component of the ascending reticular activating system and plays a role in the regulation of sleep and wakefulness. The PnO receives glutamatergic and GABAergic projections from many brain regions that regulate behavioral state. Indirect, pharmacological evidence has suggested that glutamatergic and GABAergic signaling within the PnO alters traits that characterize wakefulness and sleep. No previous studies have simultaneously measured endogenous glutamate and GABA from rat PnO in relation to sleep and wakefulness. The present study utilized in vivo microdialysis coupled on-line to capillary electrophoresis with laser-induced fluorescence to test the hypothesis that concentrations of glutamate and GABA in the PnO vary across the sleep/wake cycle. Concentrations of glutamate and GABA were significantly higher during wakefulness than during non-rapid eye movement sleep and rapid eye movement sleep. Regression analysis revealed that decreases in glutamate and GABA accounted for a significant portion of the variance in the duration of non-rapid eye movement sleep and rapid eye movement sleep episodes. These data provide novel support for the hypothesis that endogenous glutamate and GABA in the PnO contribute to the regulation of sleep duration.     

Iron-Deficiency Anemia is Associated with Altered Characteristics of Sleep Spindles in NREM Sleep in Infancy

Objective To determine the effects of iron-deficiency anemia on the development of non-rapid-eye-movement (NREM) sleep stages, as indexed by sleep spindles. Study design Patterns of sleep spindles during NREM sleep stages 2 and 3–4 (slow-wave-sleep, SWS) were compared in 26 otherwise healthy 6-month-old Chilean infants with iron-deficiency anemia and 18 non-anemic control infants. From polygraphic recordings, EEG activity was analyzed for sleep spindles to assess their number (density), duration, frequency, and inter-spindle interval. Results Iron-deficient anemic infants differed from the control group by having sleep spindles with reduced density, lower frequency, and longer inter-spindle intervals in NREM sleep stage 2 and SWS. Conclusions These results provide evidence of delayed sleep spindle patterns in iron-deficient anemic infants, suggesting that iron is an essential micronutrient for the normal progression of NREM sleep pattern development in the human. Special issue dedicated to Dr. Moussa Youdim.     

Sleeping Dreams, Waking Hallucinations, and the Central Nervous System

Consciousness is now considered a primary function and activity of the brain itself. If so, consciousness is simply the brain's interpretation and integration of all the information made available to it at any given time. On the assumption that the brain is active across all states of being (wakefulness, REM sleep, and NREM sleep), this article proposes that dreaming and hallucinations represent variations on the same theme. Under usual circumstances during wakefulness, the brain ignores internally generated activity and attends to environmental sensory stimulation. During sleep, dreaming occurs because the brain attends to endogenously generated activity. In unusual settings, such as sleep-deprivation, sensory deprivation, or medication or drug ingestion, the brain attends to exogenous and endogenous activities simultaneously, resulting in hallucinations, or wakeful dreaming. This concept is supported by numerous neurologic conditions and syndromes that are associated with hallucinations.     

Sleep in birds: lying on the continuum of activity and rest

Abstract

Sleep is highly organized activity which is associated with decreased muscular activity and reduced response to environmental stimuli. The sleep is regulated by both, circadian and homeostatic mechanisms. Sleep patterns can be studied by behavioral assays by observing different sleep behaviors or by neuronal activity such as EEG (electroencephalogram), EOG (electro-oculogram), and EMG (electromyogram). Sleep is organized into non-rapid eye movement (NREM) and rapid eye movement. The sleep pattern in birds are similar to that in mammals, however, few differences such as existence of unihemispheric sleep (UHS) in almost all birds compared to few marine mammals do exist. The UHS results in asymmetry of the brain function measured as slow wave activity (SWA). Several migrants exhibit sleeplessness and they compensate it by NREM. They employ UHS during their migratory flight to remain alert while sleeping and maintain the balance while flying which is advantageous for these birds. Thus, sleep is of fundamental significance for the animal as it lies on the continuum of activity and rest. The present review focuses on some of above mentioned facts about sleep in higher vertebrates particularly in birds.     

Representation of the self in REM and NREM dreams.

The authors hypothesized that representations of the Self (or the dreamer) in dreams would change systematically, from a prereflective form of Self to more complex forms, as a function of both age and sleep state (REM vs. non-REM). These hypotheses were partially confirmed. While the authors found that all the self-concept-related dream content indexes derived from the Hall/Van de Castle dream content scoring system did not differ significantly between the dreams of children and adults, adult Selves were more likely to engage in "successful" social interactions. The Self never acted as aggressor in NREM dream states and was almost always the befriender in friendly interactions in NREM dreams. Conversely, the REM-related dream Self preferred aggressive encounters. Our results suggests that while prereflective forms of Self are the norm in children's dreams, two highly complex forms of Self emerge in REM and NREM dreams. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Growth and development of children with a special focus on sleep

The first two decades of life are characterised complex biological processes involving growth and maturation as well as differentiation. The Central Nervous System (CNS) where among others internal and external stimuli are integrated and responses of the body are prepared starts to evolve quite early during ontogenesis. One of the complex behaviours, which are regulated by the brain, is the sleep-wake cycle.The discussion of age-related changes in sleep comprises changes at the physiological level (e.g. changes in the frequency and amplitude of EEG signal, as well as development and distribution of sleep stages), changes in the corresponding behaviour (e.g. changes in the absolute amount of sleep and its distribution in 24 h perspective), and finally the subjective perception of sleep and sleep as a measure of well-being.Studies on the impact of a specific factor on sleep during childhood and adolescence have to consider chronological and biological age as well as sex as relevant biological parameters. Even when these factors are controlled for large interindividual differences persist, that is why prospective instead of cross-sectional approaches should be used whenever possible. Furthermore, it has to be distinguished between sleep assessed at the level of brain functioning (i.e. by polysomnography), which gives information on effects at the physiological level and at the level of self-assessment, which focuses on behaviour. Both, sleep at the subjective as well as at the objective level, can to a considerable degree be affected by life style factors, which hence have to be considered as potential confounders.     

睡眠研究的科学前沿

关于睡眠机制的研究是一门历史悠久的学科.在过去的几十年中,运用细胞电生理学来研究睡眠取得了可喜的成果.由于种种技术上的困难,近年来该领域的研究多集中于临床和医学范围,例如嗜睡症、抑郁症等.虽说睡眠的节律性较易理解,但作为其本质———睡眠的基因和分子水平的自动平衡调节仍是一个谜.细胞因子(IL-1和TNFα)对睡眠的诱导作用已显示从分子水平上了解睡眠的可能性.到目前为止,关于睡眠的功能已有不少理论和假说,但人类对睡眠的生化机制的认识尚处于起步阶段.     

Early Onset and Accumulation of Rem Sleep in Depression: A Study of the Phase-Advance Hypothesis

–Twenty-two depressed subjects who met criteria for major depressive disorder were grouped according to their initial REM latency. Subjects with short (≥ 60 min) initial REM latency were separated from those with normal (< 60 min) initial REM latency. Subjects with short initial REM latency were found to have earlier onsets to at least two subsequent REM periods. The number of minutes of REM sleep accumulated were also plotted against elapsed time after sleep onset. The short-latency group accumulated REM sleep earlier than, but at about the same rate as, the normal latency group. These data support the phase-advance hypothesis of REM sleep in depression.     

环境光导致昼夜节律紊乱对睡眠的影响

目的:研究通过环境光扰乱正常昼夜节律对睡眠的影响。方法:使用小鼠昼夜节律模型(20小时一个循环,10小时见光,10小时避光),利用小鼠睡眠生物解析系统,记录脑电波和肌电波,分析睡眠觉醒量、不同时间睡眠觉醒波delta功率和睡眠时相转换等参数。结果:昼夜节律干扰后导致昼夜觉醒差异、非快速眼动睡眠差异(NREM),和快速眼动睡眠(REM)差异消失(P0.05),昼夜节律干扰后增加了觉醒和NREM睡眠之间的转换次数(P0.05),昼夜节律紊乱的光照时相在开始时没有delta功率减弱征象(P0.05)。结论:昼夜节律模型不会导致典型的睡眠剥夺,但是会对睡眠时间和质量会产生影响。本研究一步证实昼夜节律对睡眠调节有着重要的作用。     

Dim Light at Night Does Not Disrupt Timing or Quality of Sleep in Mice

Artificial nighttime illumination has recently become commonplace throughout the world; however, in common with other animals, humans have not evolved in the ecological context of chronic light at night. With prevailing evidence linking the circadian, endocrine, immune, and metabolic systems, understanding these relationships is important to understanding the etiology and progression of several diseases. To eliminate the covariate of sleep disruption in light at night studies, researchers often use nocturnal animals. However, the assumption that light at night does not affect sleep in nocturnal animals remains unspecified. To test the effects of light at night on sleep, we maintained Swiss-Webster mice in standard light/dark (LD) or dim light at night (DLAN) conditions for 8–10 wks and then measured electroencephalogram (EEG) and electromyogram (EMG) biopotentials via wireless telemetry over the course of two consecutive days to determine differences in sleep timing and homeostasis. Results show no statistical differences in total percent time, number of episodes, maximum or average episode durations in wake, slow-wave sleep (SWS), or rapid eye movement (REM) sleep. No differences were evident in SWS delta power, an index of sleep drive, between groups. Mice kept in DLAN conditions showed a relative increase in REM sleep during the first few hours after the dark/light transition. Both groups displayed normal 24-h circadian rhythms as measured by voluntary running wheel activity. Groups did not differ in body mass, but a marked negative correlation of body mass with percent time spent awake and a positive correlation of body mass with time spent in SWS was evident. Elevated body mass was also associated with shorter maximum wake episode durations, indicating heavier animals had more trouble remaining in the wake vigilance state for extended periods of time. Body mass did not correlate with activity levels, nor did activity levels correlate with time spent in different sleep states. These data indicate that heavier animals tend to sleep more, potentially contributing to further weight gain. We conclude that chronic DLAN exposure does not significantly affect sleep timing or homeostasis in mice, supporting the use of dim light with nocturnal rodents in chronobiology research to eliminate the possible covariate of sleep disruption.     

A Paradoxical Kind of Sleep in Drosophila melanogaster

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Development of physiological regulatory systems: altering the timing of crucial events

There is currently tremendous interest in how the physiology of individual animals changes and develops during ontogeny. One of the key areas is the extent to which the timing and/or rate of physiological development is fixed within an individual and to what extent can it be altered. We propose that plasticity in the timing of the onset of a particular physiological regulatory system during an individuals development be referred to as physiological heterokairy (to clearly distinguish this phenomenon from physiological heterochrony, which is an evolutionary pattern), and we marshal evidence for three different patterns of heterokairy: 1. altering relative position in the physiological itinerary; 2. altering overall rate of development per se and; 3. a combination of 1 and 2. Using these patterns as a starting point, we develop a framework for investigating physiological heterokairy which takes cognizance of the facts that multiple components of each regulatory system could appear at different times and multiple regulatory systems could come 'on-line' at different times. We finish by placing physiological heterokairy in the wider context of its ecological and evolutionary implications and its relationship to physiological genomics and heterochrony.     

快速眼动睡眠产生的神经机制:蓝斑核神经元停止发放是一个必要的条件

两种类型的神经元参与了快速眼动（rapid eye movement,REM）睡眠的调节：快速眼动一发放（REM-ON）神经元和快速眼动-沉寂神经元（REM-OFF）。快速眼动-沉寂神经元属去甲肾上腺素能神经元,正如名字表示的那样——在快速眼动睡眠期间停止发放。已有研究表明,这些神经元放电活动的停止是导致快速眼动睡眠的前提条件,γ-氨基丁酸（γ-aminobutyric acid,GABA）可使它们停止发放。如果这嗤神经元不停止发放,脑中的去甲肾上腺素水平将升高,不出现快速眼动睡眠。剥夺快速眼动睡眠所引起的去甲肾上腺素增加,至少是快速眼动睡眠丧失引起Na^＋-K^＋ATP酶活性增加的原因,而这可能是导致快速眼动睡眠剥夺所引发的各种效应的主要因素。     

Human Cytokinome: a new challenge for systems biology

Cytokines play an important role in the evolution of inflammatory processes. Therefore, they are also key components of the cancer evolution, a disease recognized to depend on chronic inflammation. On the whole, we define cytokinome as the totality of these proteins and their interactions in and around biological cells. Understanding the complex interaction network of cytokines in patients affected from cancers should be very useful both to follow the cancer evolution from its early steps and to define innovative therapeutic strategies by using systems biology approaches.     

Sleep quality and duration following evening intake of alpha-lactalbumin: a pilot study#

Tryptophan loading enhances sleep quality by increasing the ratio of plasma tryptophan to large neutral amino acids (TRP:LNAA) and consequently synthesis and availability of serotonin in the brain. Alpha-lactalbulmin (A-LAC) is rich in tryptophan and has the highest TRP:LNAA of all protein sources. This pilot study investigated the effect of an evening intake of A-LAC on objective and subjective sleep measures in male subjects without sleep complaints. Ten healthy male university students (aged: 26.9 ± 5.3 years; BMI: 21.7 ± 1.9 kg.m^?2) participated in a double-blind, randomized, and placebo-controlled crossover counter-balanced study. Objective (actigraphy) and subjective (sleep log) sleep measures were recorded for two nights after a standardized evening meal supplemented with either A-LAC (20 g) or a placebo of sodium caseinate (20 g) one hour before bedtime. Evening A-LAC intake resulted in increased objective and subjective total sleep time by 12.8% (p = 0.037) and 10.8% (p = 0.013), respectively, compared to placebo. Objective sleep efficiency increased by 7.0% (p = 0.028) following A-LAC with no significant effects for other sleep indices. This pilot study demonstrates the efficacy of evening A-LAC intake on sleep quality in young healthy adults, however further large-scale studies are warranted to confirm the benefit.