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Abstract

After reviewing earlier contributions to the understanding of the physiology of circadian system in man, in particular his cognitive aspects, we report on own studies obtained using the fractional desynchronization technique to induce internal desynchronization in man. These results show that in temporal isolation studies, rhythms in some performance measures follow a period of about 21 hours, even when the subject's physiological rhythms are apparently synchronized to the 24 hour day. These data are discussed in relationship to current theoretical frameworks in chronobiology.

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... General cognitive- and memory performances have also been shown to vary over the circadian cycle (for review see Carrier and Monk, 2000). In line with this, disruption of circadian rhythms due to age, shift work, and shifts of the LD cycle (jet lag) have been associated with impairments of cognitive function (Fekete et al., 1985; Folkard et al., 1985a,b; Antoniadis et al., 2000; Devan et al., 2001; Biemans et al., 2003; Cain et al., 2004b; Craig and McDonald, 2008). ...
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Time-Place learning (TPL) refers to the ability of animals to remember important events that vary in both time and place. This ability is thought to be functional to optimize resource localization and predator avoidance in a circadian changing environment. Various studies have indicated that animals use their circadian system for TPL. However, not much is known about this specific role of the circadian system in cognition. This review aims to put TPL in a broader context and to provide an overview of historical background, functional aspects, and future perspectives of TPL. Recent advances have increased our knowledge on establishing TPL in a laboratory setting, leading to the development of a behavioral paradigm demonstrating the circadian nature of TPL in mice. This has enabled the investigation of circadian clock components on a functional behavioral level. Circadian TPL (cTPL) was found to be Cry clock gene dependent, confirming the essential role of Cry genes in circadian rhythms. In contrast, preliminary results have shown that cTPL is independent of Per genes. Circadian system decline with aging predicts that cTPL is age sensitive, potentially qualifying TPL as a functional model for episodic memory and aging. The underlying neurobiological mechanism of TPL awaits further examination. Here we discuss some putative mechanisms.
... This variation is partly governed by heritable factors (Hur et al., 1998) (Klei et al., 2005). It is correlated with circadian phase and reflects important physiological and psychological variables (Carrier and Monk, 2000;Folkard et al., 1985;Kerkhof, 1985;Webb, 1982). The morningness-eveningness (M/E) continuum can be conveniently evaluated using pen and paper, as well as web based questionnaires (Greenwood, 1994;Horne and Ostberg, 1976;Natale et al., 2003;Zavada et al., 2005). ...
Article
Objectives: To develop Arabic versions of English language questionnaires to estimate morningness/eveningness and sleep variables. Methods: We translated the Composite scale of morningness (CSM) and the sleep timing questionnaire (STQ) [with added siesta questions] into Arabic; the Arabic versions were then back translated. The revised Arabic and the original English versions were next administered to bi-lingual Egyptians using a crossover design (n=25). The Arabic versions of both scales were subsequently administered to an independent Egyptian sample (n=79) and the siesta variables examined in relation to the CSM. Results: Satisfactory correlations were present between the English and Arabic versions for total CSM scores (Spearman's ρ=0.90, p<0.001). All but one of the STQ variables were significantly correlated (Spearman's ρ=0.45-0.88, p≤0.05). In the Arabic version, the frequency of siesta naps per week was significantly correlated with the total CSM score, with evening types taking more naps (Spearman's ρ=-0.23, p≤0.05). Conclusions: Arabic versions of the STQ and CSM have been developed in Egypt, and are freely available. They can be used for behavioral research related to sleep and circadian function and can be adapted for use in other Arab speaking populations.
... Human performance shows circadian rhythmicity with some differences depending on the aspect studied (Andrade & Menna-Barreto, 1996; Folkard et al., 1985; Gauthier et al., 1997; Gillooly et al., 1990; Miller et al., 1992; Winget et al., 1985). Whereas some variations in performance may parallel the arousal, this may not be so for others (Owens et al., 1998), suggesting that different tasks may be under the control of different circadian oscillators (Monk et al., 1983; Folkard et al., 1983). ...
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Before a rehabilitation therapy, a variety of tests are used to investigate the sensory-motor system condition of the patient. Since some parameters evaluated by those tests exhibit temporal variations, this work was conducted to investigate the performance of healthy subjects at different times during the day in a visual-motor coordination test, consisting in perfectly drawing a diagonal in as many 1 × 1 cm squares as possible during a 1 min interval. The test was applied to 14 diurnally active subjects (7 men and 7 women; 18–25 years old) in sessions at 3 h intervals from 06:00 to 00:00 h during four days divided in two blocks of two days each. Oral temperature was digitally measured before each test session in order to check the synchronization of the subjects. The results showed a significant difference (Anova, p < 0.001) between sexes with women (122.4 ± 16.4 sq/min; x ± SD) being faster than men (110.1 ± 22.8 sq/min), although daily profiles for both sexes were quite similar with better performances occurring between 09:00 and 15:00 h. Single Cosinor analysis detected significant circadian rhythmicity for 5 individuals (1 men and 4 women) with acrophases distributed between 09:15 and 13:03 h. The profiles for oral temperature and test performance were very similar with significant correlation (R = 0.26, p = 0.0002) only for men. The variation coefficient shows lower values at 15:00 h for both sexes, suggesting this time as the appropriate moment to apply the test.
... In contrast, processing speed, and vocabulary were not modulate by time of the day (Borella et al., 2011). Using the fractional desynchronization technique to induce internal desynchronization in humans, was observed a period of 21 hours in some performance even when the participant's physiological rhythms are apparently synchronized to the 24-hour day (Folkard et al., 1985) Memory is link with mood disorders. The normal function of the circadian clock is disrupted in jetlag. ...
... In the context of the hypothesis that circadian organization may be related to mood disturbances it is unfortunate that behavioral/physiological indicators of the underlying organization are scarce, in contrast to biochemical or endocrinological indicators. On the behavioral level self-ratings of mood and arousal, measures reflecting cognitive processes (such as finger tapping, time estimation), and sleep-wake timing are usually measured as possible indicators of the internal biological clock (Wever, 1979;Monk, 1987), Voice parameters may be a valuable addition to this fist. Considering the levels of measurement mentioned above, voice parameters may fill the gap between on the one hand the biochemical and physiological levels, reflecting unconscious processes, and on the other hand the behavioral level, reflecting conscious processes. ...
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The mechanism underlying improvement after total sleep deprivation (TSD) was studied in 14 major depressed patients. The suggestions that (1) circadian processes and/or (2) dimensions of arousal may play a role in the response to TSD were investigated. Diurnal variation of depressed mood and of mood- and arousal-related vocal parameters was studied in relation to the effect of TSD on depressed mood and vocal parameters. During 3 baseline days, during TSD and 2 days after TSD vocal parameters and depressed mood were assessed 6 and 3 times daily respectively. The mean fundamental frequency (frequency of vocal fold vibration, F0) (presumably reflecting aspects of arousal) as well as the range of the F0 (proposed to reflect sadness) showed a clear circadian pattern with a peak at about 4.00 p.m. TSD affected the circadian organization of the mean F0 and advanced the peak of the curve. After one night of subsequent sleep this effect disappeared. In addition, improvement after TSD coincided with an increase of the mean F0. The diurnal variation of mood before TSD predicted the mood response to TSD, whereas diurnal variation of vocal parameters did not. Moreover, circadian changes in vocal parameters were not related to changes in depressed mood. These findings suggest that the diurnal variations in mood and vocal parameters are regulated by different mechanisms. Data support the presumption that circadian as well as arousal processes are involved in the mood response to TSD. Circadian changes in vocal parameters due to TSD are not likely to reflect changes in the biological clock.
... In addition to the indirect effects of sleep loss on subsequent waking function, displacement of the circadian system can have a direct influence on performance. The circadian variation in numerous performance measures is well documented (2,(20)(21)(22)(23)(24). With few exceptions, the variation in performance efficiency across the 24-hour day parallels the circadian course of body-core temperature with poorest performance occurring around the temperature minimum. ...
Article
Shift workers suffer from a constellation of symptoms that can severely compromise their ability to perform optimally on-shift. The largest single factor contributing to shift-worker problems is sleep disturbance, and there is little question that the primary cause of such sleep disturbance is circadian disruption. Recently, a number of studies have demonstrated that timed exposure to bright light can help facilitate adaptation to simulated shift-work schedules, at least in younger subjects. The aim of the current study was to assess the effects of bright-light interventions in middle-aged individuals undergoing a simulated shift-work regimen. Results indicate that although light was effective in resetting the circadian clocks of these subjects by more than 6 hours, there was little effect on measures of on-duty alertness and performance or on off-duty sleep. These findings suggest that middle-aged subjects may be less phase-tolerant than young subjects, and they raise questions concerning the utility of bright-light interventions in some shift-work populations.
Article
Background: A number of school systems worldwide have proposed and implemented later school start times as a means of avoiding the potentially negative impacts that early morning schedules can have on adolescent students. Even mild sleep deprivation has been associated with significant health and educational concerns: increased risk for accidents and injuries, impaired learning, aggression, memory loss, poor self-esteem, and changes in metabolism. Although researchers have begun to explore the effects of delayed school start time, no one has conducted a rigorous review of evidence to determine whether later school start times support adolescent health, education, and well-being. Objectives: We aimed to assess the effects of a later school start time for supporting health, education, and well-being in high school students.Secondary objectives were to explore possible differential effects of later school start times in student subgroups and in different types of schools; to identify implementation practices, contextual factors, and delivery modes associated with positive and negative effects of later start times; and to assess the effects of later school start times on the broader community (high school faculty and staff, neighborhood, and families). Search methods: We conducted the main search for this review on 28 October 2014 and updated it on 8 February 2016. We searched CENTRAL as well as 17 key electronic databases (including MEDLINE, Embase, ERIC, PsycINFO, and Sociological Abstracts), current editions of relevant journals and organizational websites, trial registries, and Google Scholar. Selection criteria: We included any randomized controlled trials, controlled before-and-after studies, and interrupted time series studies with sufficient data points that pertained to students aged 13 to 19 years and that compared different school start times. Studies that reported either primary outcomes of interest (academic outcomes, amount or quality of sleep, mental health indicators, attendance, or alertness) or secondary outcomes (health behaviors, health and safety indicators, social outcomes, family outcomes, school outcomes, or community outcomes) were eligible. Data collection and analysis: At least two review authors independently determined inclusion and exclusion decisions through screening titles, abstracts, and full-text reports. Two review authors independently extracted data for all eligible studies. We presented findings through a narrative synthesis across all studies. When two or more study samples provided sufficient information to permit effect size calculations, we conducted random-effects meta-analyses to synthesize effects across studies. Main results: Our search located 17 eligible records reporting on 11 unique studies with 297,994 participants; the studies examined academic outcomes, amount and quality of sleep, mental health indicators, attendance, and student alertness. Overall, the quality of the body of evidence was very low, as we rated most studies as being at high or unclear risk of bias with respect to allocation, attrition, absence of randomization, and the collection of baseline data. Therefore, we cannot be confident about the effects of later school start times.Preliminary evidence from the included studies indicated a potential association between later school start times and academic and psychosocial outcomes, but quality and comparability of these data were low and often precluded quantitative synthesis. Four studies examined the association between later school start times and academic outcomes, reporting mixed results. Six studies examined effects on total amount of sleep and reported significant, positive relationships between later school start times and amount of sleep. One study provided information concerning mental health outcomes, reporting an association between decreased depressive symptoms and later school start times. There were mixed results for the association between later school start times and absenteeism. Three studies reported mixed results concerning the association between later school start times and student alertness. There was limited indication of potential adverse effects on logistics, as the qualitative portions of one study reported less interaction between parents and children, and another reported staffing and scheduling difficulties. Because of the insufficient evidence, we cannot draw firm conclusions concerning adverse effects at this time.It is important to note the limitations of this evidence, especially as randomized controlled trials and high-quality primary studies are difficult to conduct; school systems are often unwilling or unable to allow researchers the necessary control over scheduling and data collection. Moreover, this evidence does not speak to the process of implementing later school starts, as the included studies focused on reporting the effects rather than exploring the process. Authors' conclusions: This systematic review on later school start times suggests several potential benefits for this intervention and points to the need for higher quality primary studies. However, as a result of the limited evidence base, we could not determine the effects of later school start times with any confidence.
Chapter
All natural environments have an inherent spatial and temporal organization. Spatial experience can be mapped onto a Cartesian coordinate system. Furthermore, there is a natural temporal order to all physical events and human experience. Though these tenets are intuitively evident and seem obvious today, the basis for people’s experience of space and time has been one of the enduring problems for philosophers and scientists throughout the ages.
Chapter
The selection of stimuli and responses for cognitive processing is an essential element of attention. As we have discussed in the preceding chapters, the processes underlying selective attention has been a primary emphasis. Yet, as the cognitive science of attention evolved, it became evident that it was necessary to account for other important aspects of attentional phenomena. Kahneman’s capacity theory of attention was an early effort to address constraints on the amount of information that can be processed at any given point in time and the type of attentional limitations that emerge on concurrent task conditions [1]. Studies that demonstrated a distinction between controlled and automatic attentional processes [2–6] laid the groundwork for moving the cognitive science beyond its focus on attentional selection. The distinction between automatic and controlled attention provided an entrée into consideration of the neurophysiological underpinning of attention as measured by arousal and activation and their relationship to effort [7]. The fact that controlled attentional processes were fundamentally different from automatic processes with respect to capacity limitation constraints, performance characteristics over time, as well as demands for attentional focus, led to more directed study of focused attention and the notion that besides being tuned to certain information over others (selectivity), attention typically has an intensity. Furthermore, tasks with high demands for focused attention are often effortful and difficult to sustain for long periods of time, provided a foundation for expanding the concept of sustained attention beyond the simple vigilance paradigms of the information-processing approaches of the 1950s and 1960s.
Book
It has been 15 years since the original publication of Neuropsychology of Attention. At the time of its publication, attention was a construct that had long been of theoretical interest in the field of psychology and was receiving increased research by cognitive scientists. Yet, attention was typically viewed as a nuisance variable; a factor that needed to be accounted for when assessing brain function, but of limited importance in its own right. There is a need for a new edition of this book within Neuropsychology to present an updated and integrated review of what is know about attention, the disorders that affect it, and approaches to its clinical assessment and treatment. Such a book will provide perspectives for experimental neuropsychological study of attention and also provide clinicians with insights on how to approach this neuropsychological domain. © Springer Science+Business Media New York 2014. All rights reserved.
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CNS stimulants are the most widely used drugs to treat narcolepsy which is characterized by the excessive daytime sleepiness and typically associated with cataplexy. However, a number of side effects may often arise with this therapeutic approach. Thus, investigating new drugs which are efficient but well tolerated is of utmost importance in the treatment of narcolepsy. Although modafinil, an alpha-1 adrenoreceptor agonist, has been reported to bring substantial awakening properties in animals, the studies performed in man, particularly in narcoleptic subjects, are few. In the present study, we evaluated the effects of a 300 mg daily dose of modafinil on sleepiness and psychomotor performance of 16 narcoleptic subjects. The major effect of modafinil in narcoleptic subjects was a decrease of daytime sleepiness and corresponding improvement of performances involving attentive functions. However, the learning effect in psychomotor tests may mask the drug effect.
Conference Paper
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El Seminario Internacional “Ritmos Psicológicos y Jornada Escolar” responde a la necesidad de abordar, desde el conocimiento y la objetividad de los especialistas, una temática que ha tenido y sigue teniendo repercusiones prácticas en la organización temporal de la jornada escolar. Se pretende ofrecer conclusiones científicas sobre las fluctuaciones de los procesos psicológicos del niño durante el día y la semana. Dichas conclusiones deberían tenerse en cuenta, por ejemplo, en el debate sobre la jornada escolar, que en los últimos años aparece y reaparece en el contexto escolar, ya que afectan al rendimiento de los alumnos/as, a su adaptación y satisfacción en el contexto escolar.
Article
Previous studies have led to the beliefs: (1) that short-term memory is best during the night when the body temperature is at its nadir, and (2) that the circadian rhythms of short-term memory and subjective alertness are driven by oscillators independent from each other and from the body temperature cycle. Unfortunately, these conclusions, which would have major implications for understanding the organization of the human circadian timing system, are largely based on field and laboratory studies, which in many cases sampled data infrequently and/or limited data collection to normal waking hours. In order to investigate these points further, we have monitored behavioural variables in two different protocols under controlled laboratory conditions: (1) during a period of 36-60 h of sustained wakefulness; and (2) during forced desynchrony between the body temperature and sleep/wake cycles, allowing testing of non-sleep-deprived subjects at all circadian phases. Contrary to earlier findings, we report here that the circadian rhythm of short-term memory varies in parallel with the circadian rhythms of subjective alertness, calculation performance, and core body temperature under both these experimental conditions. These results challenge the notion that short-term memory is inversely linked to the body temperature cycle and suggest that the human circadian pacemaker, which drives the body temperature cycle, is the primary determinant of endogenous circadian variations in subjective alertness and calculation performance as well as in the immediate recall of meaningful material.
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The current project examined how time of day of neuropsychological testing influenced the performance of schizophrenic patients and healthy controls. All subjects were tested twice, once in the morning (AM) and once in the afternoon (PM), on a battery of neuropsychological tests. Testings were separated by 1week, and order of first testing (AM versus PM) was counterbalanced. Consistent with recent research, the current study found that time of day (TOD) influenced performance on most measures. However, the TOD effect differentially influenced the performance of each group. The controls showed better performance during PM (compared with AM) testings on measures of verbal memory and attention; whereas the patients showed better performance during PM (compared with AM) testings on measures of visual memory and motor speed. These results were not due to practice effects. Finally, there were trends for patient medication dosage to be associated with performance on some measures.
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