Owls,larks, swifts,woodcocks and they are not alone: A historical review of methodology for multidimensional self-assessment of individual differences in sleep-wake pattern

Differences between the so-called larks and owls representing the opposite poles of morningness-eveningness dimension are widely known. However, scientific consensus has not yet been reached on the methodology for ranking and typing people along other dimensions of individual variation in their sleep-wake pattern. This review focused on the history and state-of-the-art of the methodology for self-assessment of individual differences in more than one trait or adaptability of the human sleep-wake cycle. The differences between this and other methodologies for the self-assessment of trait- and state-like variation in the perceived characteristics of daily rhythms were discussed and the critical issues that remained to be addressed in future studies were highlighted. These issues include a) a failure to develop a unidimensional scale for scoring chronotypological differences, b) the inconclusive results of the long-lasting search for objective markers of chronotype, c) a disagreement on both number and content of scales required for multidimensional self-assessment of chronobiological differences, d) a lack of evidence for the reliability and/or external validity of most of the proposed scales and e) an insufficient development of conceptualizations, models and model-based quantitative simulations linking the differences between people in their sleep-wake pattern with the differences in the basic parameters of underlying chronoregulatory processes. It seems that, in the nearest future, the wide implementation of portable actigraphic and somnographic devices might lead to the development of objective methodologies for multidimensional assessment and classification of sleep-wake traits and adaptabilities.     

Empirical evaluation of a model-driven approach to enlargement of multi-dimensional questionnaires for assessing adaptability of the sleep–wake cycle

The spherical cube model was earlier proposed for explaining interrelationships between scales of multidimensional questionnaires designed for assessing adaptability of the human sleep–wake cycle. The purpose of this report was to use the model’s predictions for identification of new items associated with yet unassessed sub-traits of the sleep–wake adaptability. The 72-item Sleep–Wake Pattern Assessment Questionnaire (SWPAQ) and an initial 320-item list created for a new inventory were administered to 139 respondents. Results of correlating the responses to these items with scores on six SWPAQ’ scales were used for classification of items in accord with the nomenclature proposed by the model and for selection of 120 items for the new inventory that allowed the assessment of the majority (more than 24) of the sleep–wake adaptability sub-traits predicted by the model. Some of these newly assessed sub-traits reflect individual variation in the success of biological adaptation to night and shift work.     

A self-assessment survey of the Institutional Animal Care and Use Committee, Part 1: animal welfare and protocol compliance

Nearly half of all external grants from the US National Institutes of Health require approval by the recipient organization's Institutional Animal Care and Use Committee (IACUC) before the funds can be used for research with animals. Given that large sums of money are spent annually on research involving animals, studies evaluating the strengths, weaknesses and overall effectiveness of IACUCs and similar animal welfare committees are needed. The authors designed and carried out a self-assessment survey on IACUC function and effectiveness. They found that 98% of all respondents believed that their IACUCs advanced animal welfare, but in many instances, veterinarians' responses to individual survey items were significantly different from those of other IACUC members. Protocol compliance, protocol review training and better understanding among non-committee members of the need for regulatory oversight are some areas where improvements could be made. Less than 50% of respondents stated that literature searches to find alternatives to animal use or painful or distressful procedures were helpful.     

Big six of the individual adaptive ability of the sleep-wake cycle: Explanation and measurement

Research is directed at understanding the nature of differences between individuals in the adaptive abilities of their sleep-wake cycles. We proposed a three-dimensional model that reduces the subjectively assessed variation of the sleep-wake patterns to three underlying physiological variables. This model explains the results of factor analysis of chronotypological questionnaires and predicts the hierarchical structure of the sleep-wake adaptability with three most general abilities at the top level, six basic abilities at the middle level, and 18 primary (most specific) abilities at the bottom level. Any such subjectively assessed trait of any of these three hierarchical levels might be located in the space of three physiological parameters (namely, these are amplitude of circadian modulation of sleep-wake states, rate of accumulation of sleep debt and intensity of circadian arousal). The present study is aimed at generation and testing a particular prediction of the model. It points to the features of one basic and five primary abilities that are not accounted by the 52-item Sleep-Wake Pattern Assessment Questionnaire. Twenty new questionnaire items relevant to these predicted abilities were produced and corrected through a series of three questionnaire surveys of the residents of Novosibirsk (n = 150, 180 and 200). The results of factor analysis of the intermediate and final versions of the questionnaire provided evidence of applicability of the model for identification of the abilities that have not yet been measured by means of the questionnaire and for improvement of measurement of already identified abilities.     

The Relationships between Sleep-Wake Cycle and Academic Performance in Medical Students

Survey and laboratory studies suggest that several factors, such as social and academic demands, part-time jobs and irregular school schedules, affect the sleep-wake cycle of college students. In this study, we examined the sleep-wake pattern and the role played by academic schedules and individual characteristics on the sleep-wake cycle and academic performance. The subjects were 36 medical students (male = 21 and female = 15), mean age = 20.7 years, SD = 2.2. All students attended the same school schedule, from Monday to Friday. The volunteers answered a morningness-eveningness questionnaire, the Pittsburgh Sleep Quality Index (PSQI) and kept a sleep-wake diary for two weeks. The relationships between sleep-wake cycle, PSQI, chronotypes and academic performance were analyzed by a multiple regression technique. The results showed that 38.9% of the students had a poor sleep quality according to the PSQI. When the medical students were evening type or moderate evening type the PSQI showed a tendency of poor sleep. The multiple regression analysis showed a correlation between sleep onset, sleep irregularity and sleep length with academic performance. These results suggest that chronotypes influence the quality of the sleep-wake cycle and that irregularity of the sleep-wake cycle, as well as sleep deprivation (average length was 6:52), influence the learning of college students.     

The Relationships between Sleep-Wake Cycle and Academic Performance in Medical Students

Survey and laboratory studies suggest that several factors, such as social and academic demands, part-time jobs and irregular school schedules, affect the sleep-wake cycle of college students. In this study, we examined the sleep-wake pattern and the role played by academic schedules and individual characteristics on the sleep-wake cycle and academic performance. The subjects were 36 medical students (male = 21 and female = 15), mean age = 20.7 years, SD = 2.2. All students attended the same school schedule, from Monday to Friday. The volunteers answered a morningness-eveningness questionnaire, the Pittsburgh Sleep Quality Index (PSQI) and kept a sleep-wake diary for two weeks. The relationships between sleep-wake cycle, PSQI, chronotypes and academic performance were analyzed by a multiple regression technique. The results showed that 38.9% of the students had a poor sleep quality according to the PSQI. When the medical students were evening type or moderate evening type the PSQI showed a tendency of poor sleep. The multiple regression analysis showed a correlation between sleep onset, sleep irregularity and sleep length with academic performance. These results suggest that chronotypes influence the quality of the sleep-wake cycle and that irregularity of the sleep-wake cycle, as well as sleep deprivation (average length was 6:52), influence the learning of college students.     

月经周期对女性睡眠-觉醒和静息-活动的影响

目前有关月经周期对睡眠影响的研究结果并不一致,而对月经周期中昼夜睡眠-觉醒及静息-活动节律尚缺乏系统性的研究.本研究旨在观察正常育龄期女性月经周期中睡眠-觉醒及静息-活动昼夜节律的变化.我们采用静息-活动监测仪(actigraphy)和睡眠日志,调查了12个自然生活状态下健康育龄期妇女在月经周期不同阶段,即行经期、围排卵期、黄体早期及黄体晚期中睡眠与活动节律的变化.结果显示,睡眠-觉醒节律参数在四期之间无统计学显著差异;而静息-活动节律方面,所有受试女性静息-活动节律的平均日周期长度为(24.01±0.29)h,并且四期之间无显著性差异.行经期日间稳定系数(interdaily stability,IS)比黄体早期显著增加(P＜0.05).黄体早期日间活动开始时间明显较黄体晚期提前(P＜0.05);黄体早期的活动峰值时相比围排卵期显著提前(P＜0.05).月经周期可以影响静息-活动昼夜节律时相.而总体静息-活动数量与质量未发生显著变化;健康育龄期妇女在月经周期的各阶段中睡眠-觉醒节律亦无明显变异.     

Daily rhythms of the sleep-wake cycle

ABSTRACT: The amount and timing of sleep and sleep architecture (sleep stages) are determined by several factors, important among which are the environment, circadian rhythms and time awake. Separating the roles played by these factors requires specific protocols, including the constant routine and altered sleep-wake schedules. Results from such protocols have led to the discovery of the factors that determine the amounts and distribution of slow wave and rapid eye movement sleep as well as to the development of models to determine the amount and timing of sleep. One successful model postulates two processes. The first is process S, which is due to sleep pressure (and increases with time awake) and is attributed to a 'sleep homeostat'. Process S reverses during slow wave sleep (when it is called process S'). The second is process C, which shows a daily rhythm that is parallel to the rhythm of core temperature. Processes S and C combine approximately additively to determine the times of sleep onset and waking. The model has proved useful in describing normal sleep in adults. Current work aims to identify the detailed nature of processes S and C. The model can also be applied to circumstances when the sleep-wake cycle is different from the norm in some way. These circumstances include: those who are poor sleepers or short sleepers; the role an individual's chronotype (a measure of how the timing of the individual's preferred sleep-wake cycle compares with the average for a population); and changes in the sleep-wake cycle with age, particularly in adolescence and aging, since individuals tend to prefer to go to sleep later during adolescence and earlier in old age. In all circumstances, the evidence that sleep times and architecture are altered and the possible causes of these changes (including altered S, S' and C processes) are examined.     

The triple-120 meter shuttle test: a sport-specific test for assessing anaerobic endurance fitness in rugby league players

The aim of this study was to design a simple field test to measure the anaerobic endurance fitness of rugby league players, which is an important fitness quality in the game of rugby league. Twelve amateur football players with a mean (+/-SD) age of 21.5 years (+/-2.2) volunteered to participate in the study. The subjects completed 1 trial of the Wingate 60-second (W60) cycle test and 2 trials of the new Triple-120 meter shuttle (T120S) test. All trials were completed 4 days apart. The validity of the T120S was determined by comparing physiological responses (heart rate and blood lactate) and rating of perceived exertion to the all-out W60 cycle test. The results indicate there is a significant relationship between maximum heart rate (r = 0.63 and 0.71) for the 2 trials of the T120S and the W60 cycle test. There was no significant relationship between the 2 trials and the W60 cycle test for post 3 minute lactate (r = 0.112 and 0.101) and rating of perceived exertion (r = 0.94 and 0.161). However, the T120S test elicited greater mean values for these measures than the W60 cycle test. The results indicate that the T120S is a valid test of anaerobic endurance and represents a sports specific test of this quality that may provide useful information for players and coaches involved in the sport of rugby league.     

Addition of a non-photic component to a light-based mathematical model of the human circadian pacemaker

Mathematical models have become vital to the study of many biological processes in humans due to the complexity of the physiological mechanisms underlying these processes and systems. While our current mathematical representation of the human circadian pacemaker has proven useful in many experimental situations, it uses as input only a direct effect of light on the circadian pacemaker. Although light (a photic stimulus) has been shown to be the primary synchronizer of the circadian pacemaker across a number of species, studies in both animals and humans have confirmed the existence of non-photic effects that also contribute to phase shifting and entrainment. We modified our light-based circadian mathematical model to reflect evidence from these studies that the sleep-wake cycle and/or associated behaviors have a non-photic effect on the circadian pacemaker. In our representation, the sleep-wake cycle and its associated behaviors provides a non-photic drive on the circadian pacemaker that acts both independently and concomitantly with light stimuli. Further experiments are required to validate fully our model and to understand the exact effect of the sleep-wake cycle as a non-photic stimulus for the human circadian pacemaker.     

Neuronal activity in the amygdaloid structure during the sleep-wake cycle of the rat

The pattern of neuronal spike activity in the amygdaloid structure was studied in the sleep-wake cycle during experiments on unrestrained rats. It was shown that most neurons of the dorsomedial portion of the amygdala display greater spike activity during active wakefulness (80%) and paradoxical sleep (66.7%) than during slow-wave sleep. Most neurons of the basolateral amygdaloid region discharged at high frequency during active wakefulness (84.6%) and during paradoxial sleep (38.4%) compared with the frequency of firing during slow-wave sleep. Some neurons were found whose rate of discharge rose during slow-wave sleep in comparison with a similar period of paradoxical sleep (38.4%) and of active wakefulness (7.7%). Our findings show how the pattern of neuronal activity in the dosromedial and basolateral regions of the amygdaloid structure differs at various stages of the sleep-wake cycle. It is postulated that this structure serves mainly to regulate emotionally motivated processes rather than helping to govern the basic mechanisms of the sleep-wake cycle.Beritashvili Institute of Physiology, Academy of Sciences of the Georgian SSR, Tbilisi. Translated from Neirofiziologiya, Vol. 17, No. 6, pp. 747–756, November–December, 1985.     

Effects of dietary resveratrol on the sleep-wake cycle in the non-human primate gray mouse lemur (Microcebus murinus)

Converging evidence shows that the non-human primate gray mouse lemur (Microcebus murinus) is ideal for the study of the aging process and for testing the effects of new therapies and dietary interventions on age-associated pathologies. One such dietary supplement is resveratrol (RSV), a dietary polyphenolic compound with several positive effects on metabolic functions and longevity. However, little is known about the effect of RSV on the lemur sleep-wake cycle, which reflects mammalian brain function and health. In the present study, the authors investigated this effect by comparing sleep-wake cycles in adult lemurs based on electroencephalographic (EEG) rhythms. The effect of short-term RSV supplementation on the sleep-wake cycle of mouse lemurs was evaluated in entrained conditions (long-day photoperiods, light:dark 14:10). After 3 wks of RSV supplementation, the animals exhibited a significantly increased proportion of active-wake time, occurring mainly during the resting phase of the sleep-wake cycle (+163%). The increase in active-wake time with RSV supplementation was accompanied by a significant reduction of both paradoxical sleep (-95%) and slow-wave sleep (-38%). These changes mainly occurred during the resting phase of the sleep-wake cycle (RSV supplementation induced negligible changes in active-wake time during the active phase of the sleep-wake cycle). The present data suggest that RSV may be a potent regulator of sleep-wake rhythms and could be of major interest in the study of sleep perturbations associated with aging and neuropathology.     

Intra-individual variability in the sleep of senior and junior rugby league athletes during the competitive season

This study examined the sleep intra-individual variability (IIV) of rugby league athletes across senior and junior levels during one week of the competitive season. Forty-five rugby league athletes across elite senior, sub-elite senior and elite junior levels each wore actigraphy monitors for seven days during the competitive season, and completed a subjective sleep diary each morning upon waking. Linear mixed models were used to assess differences in sleep measures between playing levels. Intra-individual standard deviations for each sleep measure were calculated for each athlete to determine their respective IIV, allowing differences in IIV between groups to be assessed. Elite junior athletes went to bed later (ES = 0.94 ± 0.50, p < 0.05) and woke later than elite senior athletes (ES = 0.94 ± 0.40, p < 0.05), while also displaying greater IIV when considering time in bed (ES = 1.14 ± 0.60, p < 0.05) and sleep duration (ES = 1.53 ± 0.64, p < 0.05) compared with elite senior athletes. Similarly, IIV was more pronounced in elite junior players for time in bed (ES = 0.88 ± 0.60, p < 0.05) and sleep duration (ES = 1.03 ± 0.64, p < 0.05) compared with sub-elite senior athletes. Despite this, elite junior athletes still obtained sufficient sleep duration, efficiency and quality. The outcomes of this investigation show a distinct difference in the habitual sleep-wake patterns of senior and junior rugby league athletes, and show how sleep IIV differs between playing levels in rugby league.     

Circadian rhythm disruption: health consequences

Circadian rhythms control many facets of biology and their disruption can be associated with severe pathological conditions. In healthy individuals, disturbances to the sleep-wake cycle can be the root cause of many problems. In the present review, we explore the major factors contributing to circadian rhythm disruption, including sleep disorders, jet lag, and shift work. The consequences of these disruptions on central and peripheral clocks and the important areas of the body controlled by them involve immune function and metabolism, as well as alterations in cognitive abilities, thereby impairing social and occupational behavior. Further work exploring clock genes, light exposure, and cellular changes will be critical for identifying how these factors interact to affect health and behavior.     

中华越北蝗食性的初步观察

本文报道了中华越北蝗取食37科74种植物。对该蝗的生物学特性也作了简要的描述。中华越北蝗是园林植物的重要害虫之一,应引起我们注意。     

The Effects of Timing of Grazing on Plant and Arthropod Communities in High-Elevation Grasslands

Livestock grazing can be used as a key management tool for maintaining healthy ecosystems. However, the effectiveness of using grazing to modify habitat for species of conservation concern depends on how the grazing regime is implemented. Timing of grazing is one grazing regime component that is less understood than grazing intensity and grazer identity, but is predicted to have important implications for plant and higher trophic level responses. We experimentally assessed how timing of cattle grazing affected plant and arthropod communities in high-elevation grasslands of southwest Montana to better evaluate its use as a tool for multi-trophic level management. We manipulated timing of grazing, with one grazing treatment beginning in mid-June and the other in mid-July, in two experiments conducted in different grassland habitat types (i.e., wet meadow and upland) in 2011 and 2012. In the upland grassland experiment, we found that both early and late grazing treatments reduced forb biomass, whereas graminoid biomass was only reduced with late grazing. Grazing earlier in the growing season versus later did not result in greater recovery of graminoid or forb biomass as expected. In addition, the density of the most ubiquitous grassland arthropod order (Hemiptera) was reduced by both grazing treatments in upland grasslands. A comparison of end-of-season plant responses to grazing in upland versus wet meadow grasslands revealed that grazing reduced graminoid biomass in the wet meadow and forb biomass in the upland, irrespective of timing of grazing. Both grazing treatments also reduced end-of-season total arthropod and Hemiptera densities and Hemiptera biomass in both grassland habitat types. Our results indicate that both early and late season herbivory affect many plant and arthropod characteristics in a similar manner, but grazing earlier may negatively impact species of conservation concern requiring forage earlier in the growing season.     

Mathematical Models for Sleep-Wake Dynamics: Comparison of the Two-Process Model and a Mutual Inhibition Neuronal Model

Sleep is essential for the maintenance of the brain and the body, yet many features of sleep are poorly understood and mathematical models are an important tool for probing proposed biological mechanisms. The most well-known mathematical model of sleep regulation, the two-process model, models the sleep-wake cycle by two oscillators: a circadian oscillator and a homeostatic oscillator. An alternative, more recent, model considers the mutual inhibition of sleep promoting neurons and the ascending arousal system regulated by homeostatic and circadian processes. Here we show there are fundamental similarities between these two models. The implications are illustrated with two important sleep-wake phenomena. Firstly, we show that in the two-process model, transitions between different numbers of daily sleep episodes can be classified as grazing bifurcations. This provides the theoretical underpinning for numerical results showing that the sleep patterns of many mammals can be explained by the mutual inhibition model. Secondly, we show that when sleep deprivation disrupts the sleep-wake cycle, ostensibly different measures of sleepiness in the two models are closely related. The demonstration of the mathematical similarities of the two models is valuable because not only does it allow some features of the two-process model to be interpreted physiologically but it also means that knowledge gained from study of the two-process model can be used to inform understanding of the behaviour of the mutual inhibition model. This is important because the mutual inhibition model and its extensions are increasingly being used as a tool to understand a diverse range of sleep-wake phenomena such as the design of optimal shift-patterns, yet the values it uses for parameters associated with the circadian and homeostatic processes are very different from those that have been experimentally measured in the context of the two-process model.     

Truck Drivers Sleep-Wake Time Arrangements

Irregular working hours, including night work, change sleep-wake time arrangements which in turn might affect the ability to drive safely. This study aims to compare the effects of an irregular and a fixed day shift system on the sleep-wake cycle of truck drivers. The investigation of sleep-wake cycle was carried-out with 37 truck drivers working on two transportation plants: 24 working on irregular working hours and 13 on fixed day shift. The truck drivers filled out sleep logs and wore actigraphs for 10 consecutive days to identify activity and rest episodes. The group working in irregular hours showed more sleep episodes per 24 h and they were shorter compared to the fixed shift group (p &lt; 0.05). No differences were found between the two transportation plants. These results suggest an the influence of working hours on specific sleep-wake patterns. The polyphasic sleep pattern shown by irregular shift group could be a strategy to cope with sleep deprivation, which may account for their difficulty to resist falling asleep behind the wheel.     

Asian medaka fishes offer new models for studying mechanisms of seawater adaptation

Japanese medaka (Oryzias latipes) is a freshwater (FW) teleost that is popular throughout the world for laboratory use. In this paper, we discuss the utility of Japanese medaka and related species for studying mechanisms of seawater (SW) adaptation. In addition to general advantages as an experimental animal such as their daily spawning activity, transparency of embryos, short generation time and established transgenic techniques, Japanese medaka have some adaptability to SW unlike the strictly stenohaline zebrafish (Danio rerio). Since other species in the genus Oryzias exhibit different degrees of adaptability to SW, comparative studies between Japanese medaka, where molecular-biological and genetic information is abundant, and other Oryzias species are expected to present varying approaches to solving the problems of SW adaptation. We introduce some examples of interspecies comparison for SW adaptabilities both in adult fish and in embryos. Oryzias species are good models for evolutionary, ecological and zoogeographical studies and a relationship between SW adaptability and geographic distribution has been suggested. Medaka fishes may thus deliver new insights into our understanding of how fish have expanded their distribution to a wide variety of osmotic environments.