大鼠慢波睡眠和睡眠过渡期脑电信号的小波变换分析

EEG信号经常包含许多快速的时变信息 ,将较长时间段的EEG信号近似看作平稳信号 ,进行FFT谱估计 ,存在其局限性。应用多分辨率小波变换方法 ,在频域和时域上可以同时定位分析大鼠慢波睡眠和睡眠过渡期脑电的动态变化特性。采用慢性埋植电极记录自由活动大鼠的皮层脑电 ,将信号用小波变换分解成δ、θ、α和 β四个分量 ,求各分量的功率和功率百分比的时间变化曲线 ,并与FFT功率谱分析结果进行比较。结果表明 :慢波睡眠期EEG中有 2 6 .2 %± 7.7%的时间段上δ分量功率小于总功率的 5 0 % ,且δ分量较大时 ,其他分量较小 ;δ分量较小时 ,其他分量较大 ,差别显著。此结果揭示了δ节律与θ和α节律之间的一种互补关系。而传统的FFT功率谱分析方法只能显示δ分量为主 (占总功率 70 .6 %± 6 .4 % )的功率谱 ,不能提供时变信息。对于睡眠过渡期的非稳态EEG信号 ,利用小波变换分解得到的θ和α分量可以鉴别出睡眠纺锤波 ,计算睡眠纺锤波的平均持续时间 ,并比较纺锤波和非纺锤波时期各个频谱分量的变化情况。由此可见 ,小波变换可用于计算新的EEG时频定量分析指标用于分析生理、病理和药理作用引起的睡眠EEG的变化过程 ,以弥补传统FFT功率谱分析的不足之处     

Indoor climate and air quality

 In industrialized countries about 90% of the time is spent indoors. The ambient parameters affecting indoor thermal comfort are air temperature and humidity, air velocity, and radiant heat exchange within an enclosure. In assessing the thermal environment, one needs to consider all ambient parameters, the insulating properties of the occupants’ clothing, and the activity level of the occupants by means of heat balance models of the human body. Apart from thermal parameters, air quality (measured and perceived) is also of importance for well-being and health in indoor environments. Pollutant levels are influenced by both outdoor concentrations and by indoor emissions. Indoor levels can thus be lower (e.g. in the case of ozone and SO₂) or higher (e.g. for CO₂ and formaldehyde) than outdoor levels. Emissions from cooking play an important role, especially in developing countries. The humidity of the ambient air has a wide range of effects on the energy and water balance of the body as well as on elasticity, air quality perception, build-up of electrostatic charge and the formation or mould. However, its effect on the indoor climate is often overestimated. While air-handling systems are commonly used for achieving comfortable indoor climates, their use has also been linked to a variety of problems, some of which have received attention within the context of ”sick building syndrome”. Received: 27 October 1997 / Accepted 26 November 1997     

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.     

昆虫的睡眠与生物钟

近年来 ,越来越多的证据表明昆虫也要睡眠。该文介绍这方面的研究发现 ,包括确定昆虫睡眠的标准以及昆虫与哺乳动物的睡眠在生理机制上的相似性 ,最后阐述了生物钟基因对昆虫睡眠的调节作用     

Sleep Paralysis and the Structure of Waking-Nightmare Hallucinations

Sleep paralysis (SP) entails a period of paralysis upon waking or falling asleep and is often accompanied by terrifying hallucinations. These hallucinations constitute a waking nightmare (w-nightmare) REM experience and are the original referents of the term nightmare. W-nightmare hallucinations are described by a three-factor structure involving experiences consistent with 1) threatening intruders, 2) physical assaults, and 3) vestibular-motor (V-M) bodily sensations. The present study assesses the reliability of this structure and some of the underlying measurement assumptions using several large samples of w-nightmare experients. Causal modeling further elucidated the potential causal relations among the three types of hallucinations. The first two factors appear to be strongly thematically and sequentially linked by an underlying theme of threat and assault. The third factor is relatively autonomous but appears to be sometimes recruited into the threat and assault themes. A theoretical model is proposed that combines REM mechanisms, a threat activated vigilance system (TAVS), and a bodily-self neuromatrix (BSN), as generators and organizers of w-nightmare hallucinatory experiences. More generally, it is argued that these mechanisms underwrite two fundamental domains of conscious experience: the experience of an agent-inhabited world and that of a spatial-kinetic bodily self.     

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.     

Dreams and Dreamless Sleep

Dreamless sleep, as subjective experience, is mentioned primarily within Hindu and Buddhist contexts. In the Upanishads, dreamless sleep is presented for the most part as objectless consciousness. Tibetan Buddhists speak of dreamless sleep in terms of a progression of visual experiences consisting of darkness and light. Contemporary discussions of dreaming, unless concerned with Eastern religion or philosophy, do not tend to mention dreamless sleep. For some writers today, dreaming includes all subjective experience during sleep, leaving no room for an experience of dreamless sleep. Some writers describe dreaming as a simulation of waking life. Since not all experience during sleep is simulation, this concept allows for experiences during sleep that may be understood to be other than dreaming. The writer finds it useful to consider simulation as the determining characteristic of dreaming and finds certain other sleep experiences then that are best considered to be dreamless.     

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.     

基于Flexible ICA的睡眠EEG及EOG中心电伪差的消除

提出了一种采用自适应非线性函数的ICA学习算法,Flexible ICA算法,并将其应用于睡眠EEG自动分期的前期预处理中,用于消除采集到的各通道信号中的心电伪差.实验结果证明,Flexible ICA算法能够快速有效的消除各通道的心电伪差,为后期的睡眠EEG自动分期打下了良好的基础.     

Measuring air temperature in field studies

In order to find a simple technique for reducing errors in measurements of air temperature, experiments were performed in a wind tunnel using different sizes of thermocouples and a variety of shields. Thermocouples with a coat of clean, white enamel paint on the tip were simple and inexpensive, and they resulted in only small eroors due to radiation.     

Effects of Filtering Visual Short Wavelengths During Nocturnal Shiftwork on Sleep and Performance

Circadian phase resetting is sensitive to visual short wavelengths (450–480?nm). Selectively filtering this range of wavelengths may reduce circadian misalignment and sleep impairment during irregular light-dark schedules associated with shiftwork. We examined the effects of filtering short wavelengths (<480?nm) during night shifts on sleep and performance in nine nurses (five females and four males; mean age?±?SD: 31.3?±?4.6 yrs). Participants were randomized to receive filtered light (intervention) or standard indoor light (baseline) on night shifts. Nighttime sleep after two night shifts and daytime sleep in between two night shifts was assessed by polysomnography (PSG). In addition, salivary melatonin levels and alertness were assessed every 2?h on the first night shift of each study period and on the middle night of a run of three night shifts in each study period. Sleep and performance under baseline and intervention conditions were compared with daytime performance on the seventh day shift, and nighttime sleep following the seventh daytime shift (comparator). On the baseline night PSG, total sleep time (TST) (p?<?0.01) and sleep efficiency (p?=?0.01) were significantly decreased and intervening wake times (wake after sleep onset [WASO]) (p?=?0.04) were significantly increased in relation to the comparator night sleep. In contrast, under intervention, TST was increased by a mean of 40?min compared with baseline, WASO was reduced and sleep efficiency was increased to levels similar to the comparator night. Daytime sleep was significantly impaired under both baseline and intervention conditions. Salivary melatonin levels were significantly higher on the first (p?<?0.05) and middle (p?<?0.01) night shifts under intervention compared with baseline. Subjective sleepiness increased throughout the night under both conditions (p?<?0.01). However, reaction time and throughput on vigilance tests were similar to daytime performance under intervention but impaired under baseline on the first night shift. By the middle night shift, the difference in performance was no longer significant between day shift and either of the two night shift conditions, suggesting some adaptation to the night shift had occurred under baseline conditions. These results suggest that both daytime and nighttime sleep are adversely affected in rotating-shift workers and that filtering short wavelengths may be an approach to reduce sleep disruption and improve performance in rotating-shift workers. (Author correspondence: casper@lunenfeld.ca)     

Brain-State-Dependent Modulation of Neuronal Firing and Membrane Potential Dynamics in the Somatosensory Thalamus during Natural Sleep

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Basic Scale on Insomnia complaints and Quality of Sleep (BaSIQS): Reliability,initial validity and normative scores in higher education students

Based on successive samples totaling more than 5000 higher education students, we scrutinized the reliability, structure, initial validity and normative scores of a brief self-report seven-item scale to screen for the continuum of nighttime insomnia complaints/perceived sleep quality, used by our team for more than a decade, henceforth labeled the Basic Scale on Insomnia complaints and Quality of Sleep (BaSIQS). In study/sample 1 (n?=?1654), the items were developed based on part of a larger survey on higher education sleep–wake patterns. The test–retest study was conducted in an independent small group (n?=?33) with a 2–8 week gap. In study/sample 2 (n?=?360), focused mainly on validity, the BaSIQS was completed together with the Pittsburgh Sleep Quality Index (PSQI). In study 3, a large recent sample of students from universities all over the country (n?=?2995) answered the BaSIQS items, based on which normative scores were determined, and an additional question on perceived sleep problems in order to further analyze the scale’s validity. Regarding reliability, Cronbach alpha coefficients were systematically higher than 0.7, and the test–retest correlation coefficient was greater than 0.8. Structure analyses revealed consistently satisfactory two-factor and single-factor solutions. Concerning validity analyses, BaSIQS scores were significantly correlated with PSQI component scores and overall score (r?=?0.652 corresponding to a large association); mean scores were significantly higher in those students classifying themselves as having sleep problems (p?<?0.0001, d?=?0.99 corresponding to a large effect size). In conclusion, the BaSIQS is very easy to administer, and appears to be a reliable and valid scale in higher education students. It might be a convenient short tool in research and applied settings to rapidly assess sleep quality or screen for insomnia complaints, and it may be easily used in other populations with minor adaptations.     

Thermal sensation and thermophysiological responses to metabolic step-changes

This study investigated the effect on thermal perception and thermophysiological variables of controlled metabolic excursions of various intensities and durations. Twenty-four subjects were alternately seated on a chair or exercised by walking on a treadmill at a temperature predicted to be neutral at sedentary activity. In a second experimental series, subjects alternated between rest and exercise as well as between exercise at different intensities at two temperature levels. Measurements comprised skin and oesophageal temperatures, heart rate and subjective responses. Thermal sensation started to rise or decline immediately (within 1 min) after a change of activity, which means that even moderate activity changes of short duration affect thermal perceptions of humans. After approximately 15–20 min under constant activity, subjective thermal responses approximated the steady-state response. The sensitivity of thermal sensation to changes in core temperature was higher for activity down-steps than for up-steps. A model was proposed that estimates transient thermal sensation after metabolic step-changes. Based on predictions by the model, weighting factors were suggested to estimate a representative average metabolic rate with varying activity levels, e.g. for the prediction of thermal sensation by steady-state comfort models. The activity during the most recent 5 min should be weighted 65%, during the prior 10–5 min 25% and during the prior 20–10 min 10%.     

Efficient and Regular Patterns of Nighttime Sleep are Related to Increased Vulnerability to Microsleeps Following a Single Night of Sleep Restriction

Sleep-deprived people, or those performing extended monotonous tasks, can exhibit brief episodes in which they suspend performance and appear to fall asleep momentarily—behavioral microsleeps (“microsleeps”). In this study, microsleeps were identified using eye video and tracking response during a 20-min continuous tracking task undertaken by 16 healthy volunteers (mean age 24.9?yrs; 8 females, 8 males) in the early afternoon following a normally rested night and a night of restricted sleep (time-in-bed restricted to 4?h). Sessions were 1 wk apart and counterbalanced. Wrist actigraphy, self-reported sleepiness, and sleep quality were also recorded. We hypothesized that high microsleep rates when normally rested or after a night of sleep restriction would be related to poor sleep quality, sleep disturbance, circadian type, irregular sleep patterns, low daily sleep duration, or poor sleep efficiency. We also hypothesized that prior performance on a 10-min psychomotor vigilance task (PVT) (mean reaction time or number of PVT lapses) would be related to the number of microsleeps during the tracking task and that PVT performance could, therefore, be used as a fitness-for-duty indicator. The number of microsleeps during the tracking task increased following sleep restriction (mean 11.4 versus 27.9; p?=?0.03). There were no correlations between the number of microsleeps in the normally rested session and any of the actigraphically measured or self-reported sleep measures. However, the number of microsleeps following sleep restriction was correlated with sleep efficiency (r?=?0.73, p?=?0.001), sleep onset latency (r?=??0.57, p?=?0.02), and sleep onset time-of-day standard deviation (r?=??0.54, p?=?0.03) over 11 normally rested nights. There was no correlation between PVT performance and the subsequent number of microsleeps during the tracking task in either session. Attributes usually associated with beneficial nighttime sleep patterns—going to sleep at a similar time each night, falling asleep quickly, and infrequent arousals—were related to greater vulnerability to microsleeps following sleep restriction. There were intercorrelations between all the sleep measures associated with microsleep rate following sleep restriction, indicating that the measures form a pattern of behaviors and are not independently related to microsleep rate. Perhaps some people maintain a regular sleep pattern because they experience sleepiness the following day when their pattern is disrupted. Conversely, people with more variation in their sleep pattern may do so because this does not substantially increase sleepiness the following day. We conclude that people with consistent sleep patterns and efficient sleep may be more prone to microsleeps than other people when their usual regular pattern is disrupted by sleep restriction.     

Sleep and dream patterns of political liberals and conservatives.

In this study the author examined the dreams of American liberals and conservatives to highlight patterns that might correlate with their opposing political views. A total of 234 participants (134 self-described liberals and 100 self-described conservatives) completed a lengthy sleep and dream survey, and their answers revealed several notable patterns. People of both political persuasions shared a common substrate of basic human sleep and dream experience. Conservatives slept somewhat more soundly, with fewer remembered dreams. Liberals were more restless in their sleep and had a more active and varied dream life. In contrast to a previous study, liberals reported a somewhat greater proportion of bad dreams and nightmares. Consistent with earlier research, the dreams of conservatives were more mundane, whereas the dreams of liberals were more bizarre. (PsycINFO Database Record (c) 2010 APA, all rights reserved)