A vast network of cellular circadian clocks regulates 24‐hour rhythms of behavior and physiology in mammals. Complex environments are characterized by multiple, and often conflicting time signals demanding flexible mechanisms of adaptation of endogenous rhythms to external time. Traditionally this process of circadian entrainment has been conceptualized in a hierarchical scheme with a light‐reset master pacemaker residing in the hypothalamus that subsequently aligns subordinate peripheral clocks with each other and with external time. Here we review (...) new experiments using conditional mouse genetics suggesting that resetting of the circadian system occurs in a more “federated” and tissue‐specific fashion, which allows for increased noise resistance and plasticity of circadian timekeeping under natural conditions. (shrink)

The plant maintains a 24‐h circadian cycle that controls the sequential activation of many physiological and developmental functions. There is empirical evidence suggesting that two types of circadian rhythms exist. Some plant rhythms appear to be set by the light transition at dawn, and are calibrated to circadian (zeitgeber) time, which is measured from sunrise. Other rhythms are set by both dawn and dusk, and are calibrated to solar time that is measured from mid‐day. Rhythms (...) on circadian timing shift seasonally in tandem with the timing of dawn that occurs earlier in summer and later in winter. On the other hand, rhythms set to solar time are maintained independently of the season, the timing of noon being constant year‐round. Various rhythms that run in‐phase and out‐of‐phase with one another seasonally may provide a means to time and induce seasonal events such as flowering. (shrink)

Positing representations and operations on them as a way of explaining behavior was one of the major innovations of the cognitive revolution. Neuroscience and biology more generally also employ representations in explaining how organisms function and coordinate their behavior with the world around them. In discussions of the nature of representation, theorists commonly differentiate between the vehicles of representation and their content—what they denote. Many contentious debates in cognitive science, such as those pitting neural network models against symbol processing accounts, (...) have focused on the types of vehicles proposed for mental representation and whether they have the appropriate structure to succeed in bearing their contents. Philosophers, in contrast, have focused their debates on content and the particular way in which vehicles might bear content—that is, the process of representing rather than the format of representations. I will offer a novel answer to the question of how it is that a representation has content by focusing on the architecture of representation. My proposal is that representations occur in a particular type of mechanism—one in which a control system regulates a plant—and that we can gain traction on cognitive systems of representation by considering how this works in physical systems more generally. (shrink)

A paradigm shift in the human chronotoxicity of xenobiotics would study two‐sided desynchronized phenomena of interfacial interactions between cyclic or periodic environmental insults and the endogenous response and recovery profile. These systems‐based networks are under the influence of well‐synchronized biological clocks and their metabolic regulators. This perspective argues in favor of addressing the concept of synchronization in studies involving critical life windows of susceptibility, or circadian rhythms, or 24‐hour (periodic) diurnal rhythms and answering whether these disruptions in synchronization would (...) affect response and recovery or disease phenotypes associated with environmental insults, e.g., xenobiotics. Synchronization or synchrony is defined as the totality of elements that appear during the same time period within a system, including the network of interactions between the system's elements. Desynchronized interfaces during critical life windows or in time‐repeated exposure events would likely lead to initiating a cascade of adverse health effects associated with differentiated disease phenotypes. (shrink)

ObjectiveIndividuals with an evening chronotype prefer to sleep later at night, wake up later in the day and perform best later in the day as compared to individuals with morning chronotype. Thus, college students without ADHD symptoms with evening chronotypes show reduced cognitive performance in the morning relative to nighttime. In combination with symptoms presented in attention deficit hyperactivity disorder, we predicted that having evening chronotype renders impairment in attention during the morning, when students require optimal performance, amplifying desynchrony.MethodFour hundred (...) college students were surveyed for evening chronotype and symptoms of ADHD. Of those surveyed, 43 students with evening chronotype performed laboratory attention tasks and were queried about fatigue during morning and evening sessions.ResultsStudents with ADHD symptoms demonstrated a greater decrement in sustained attentional vigilance when abstaining from stimulants and asked to perform cognitive tests at times misaligned with natural circadian rhythms in arousal compared to their non-ADHD counterparts with the same chronotype. While individuals with ADHD symptoms had slower reaction-times during sustained attention tasks in the morning session compared to those without symptoms, there was no significant group difference in working memory performance, even though both groups made more errors in the morning session compared to the evening session.ConclusionThese findings suggest that evening chronotype students with ADHD symptoms are at a greater disadvantage when having to perform sustained attention tasks at times that are not aligned to their circadian rhythm compared to their neuro-typical peers. The implications of this finding may be useful for the provision of disability accommodations to college age students with ADHD when they are expected to perform tasks requiring sustained attention at times misaligned with their circadian rhythms. (shrink)

On receiver-based teleosemantic theories of representation, the chemical states of the circadian clocks in animal, plant and cyanobacterial cells constitute signals of future states of affairs, often the rising and setting of the sun. This signalling is much more rigid than sophisticated representational systems like human language, but it is not simple on all dimensions. In most organisms the clock regulates many different circadian rhythms. The process of entrainment ensures that the mapping between chemical states of the clock (...) and the daily light-dark cycle is adjusted to deal with seasonal changes. In regulating anticipatory behaviour, the states of the clock look forward both to the time the behaviour is supposed to happen and the later time when the anticipated circumstances are supposed to arise. The case of the circadian clock shows that purely indicative signals can arise in very basic biological systems and brings into sharp relief the trade-offs involved in characterizing representational systems. On receiver-based teleosemantic theories, future-directed signals are not restricted to complex multicellular organisms but are ubiquitous in the biological world. (shrink)

The circadian clock is a cell autonomous oscillator that controls many aspects of physiology through generating rhythmic gene expression in a time of day dependent manner. In addition, in endothermic mammals body temperature cycles contribute to rhythmic gene expression. These body temperature‐controlled rhythms are hard to distinguish from classic circadian rhythms if analyzed in vivo in endothermic organisms. However, they do not fulfill all criteria of being circadian if analyzed in cell culture or in conditions where (...) body temperature of an endothermic organism can be manipulated. Here we review and compare these characteristics, discuss the core clock independent mechanism of temperature‐controlled alternative splicing and highlight the requirement of double‐checking rhythms that appear circadian within an endothermic organism in a system that allows temperature manipulation. (shrink)

Coordinated daily rhythms are evident in most aspects of our physiology, driven by internal timing systems known as circadian clocks. Our understanding of how biological clocks are built and function has grown exponentially over the past 20 years. With this has come an appreciation that disruption of the clock contributes to the pathophysiology of numerous diseases, from metabolic disease to neurological disorders to cancer. However, it remains to be determined whether it is the disruption of our rhythmic physiology per (...) se (loss of timing itself), or altered functioning of individual clock components that drive pathology. Here, we review the importance of circadian rhythms in terms of how we (and other organisms) relate to the external environment, but also in relation to how internal physiological processes are coordinated and synchronized. These issues are of increasing importance as many aspects of modern life put us in conflict with our internal clockwork. (shrink)

Autoimmune diseases such as rheumatoid arthritis and gastrointestinal disorders such as stomach ulcers are often treated with drugs. NSAIDs, a common treatment in rheumatoid arthritis, may cause stomach ulcers which call for additional medications, notably antacids in the sense of drugs that suppress acid secretion by the stomach. Infection with Helicobacter pylori also plays a role in the ulcers. The infection is typically treated with antibiotics added to antacids. Considering NSAIDs and antacids, we suspect that overmedication is common to the (...) extent that particular diets are a better option. Current research and current treatments with these drugs are also problematic since circadian rhythms are mostly disregarded. All the processes involved in the disorders treated show marked variations in the course of the day. Hence experiments conforming to the guidelines of evidence-based medicine, and treatments in line with them, have outcomes strongly depending on the time factor. This calls for reforms in medicine with fresh inputs from biology. (shrink)

Autoimmune diseases such as rheumatoid arthritis and gastrointestinal disorders such as stomach ulcers are often treated with drugs. NSAIDs, a common treatment in rheumatoid arthritis, may cause stomach ulcers which call for additional medications, notably antacids in the sense of drugs that suppress acid secretion by the stomach. Infection with Helicobacter pylori also plays a role in the ulcers. The infection is typically treated with antibiotics added to antacids. Considering NSAIDs and antacids, we suspect that overmedication is common to the (...) extent that particular diets are a better option. Current research and current treatments with these drugs are also problematic since circadian rhythms are mostly disregarded. All the processes involved in the disorders treated show marked variations in the course of the day. Hence experiments conforming to the guidelines of evidence-based medicine, and treatments in line with them, have outcomes strongly depending on the time factor. This calls for reforms in medicine with fresh inputs from biology. (shrink)

The glowing light of cinema, which continues to claim supremacy as a collective site for evolving senses of time, has fundamentally changed since its inception, from exclusively projected light to primarily emitted light. Digital, rather than analog projectors, dominate in personal rather than public spheres. The physiological and behavioral effects of those technologies manipulate our biological clocks, creating an entanglement of time-sensing. Similarly, the art of cinema now relies far more upon energy-intensive materials and methods, from equipment to (...) image manufacturing and data flow. This essay takes the twelve-hour clock as a slanted optic to address those profound shifts, choosing a handful of moving-image artists to feature, including Deborah Stratman, Nikolaus Geyrhalter, and Mikael Kristersson, who are attempting to find alternative temporal modes of depicting the hyperobjectiveness of eternity, ecocrises, dystopias, and deep time on screen. (shrink)

In mammals, a network of cellular circadian clocks organizes physiology and behavior along the 24‐h day cycle. The traditional hierarchical model of circadian clock organization with a central pacemaker and peripheral slave oscillators has recently been challenged by studies combining tissue‐specific mouse mutants with transcriptome analyses. First, a surprisingly small number of tissue rhythms are lost when only local clocks are ablated and, second, transcriptional circadian rhythms appear to be regulated by a complex mix of local and (...) systemic factors. As reviewed here, these findings suggest a more integrated model of clock network interaction with the central pacemaker as the main source of behavioral and systemic–physiological rhythms and peripheral clocks controlling some local rhythms while at the same time acting as gatekeepers that temporally adjust cellular responses to external stimuli. (shrink)

In the middle of the twentieth century, physiologists interested in human biological rhythms undertook a series of field experiments in natural spaces that they believed could closely approximate conditions of biological timelessness. With the field of rhythms research was still largely on the fringes of the life sciences, natural spaces seemed to offer unique research opportunities beyond what was available to physiologists in laboratory spaces. In particular, subterranean caves and the High Arctic became archetypal ‘natural laboratories’ for the study of (...) human circadian (daily) rhythms. This paper is explores the field experiments which occurred in these ‘timeless spaces’. It considers how scientists understood these natural spaces as suitably ‘timeless’ for studying circadian rhythms and what their experimental practices can tell us about contemporary physiological notions of biological time, especially its relationship to ‘environmentality’ (Formosinho et al. in Stud History Philos Sci 91:148–158, 2022). In so doing, this paper adds to a growing literature on the interrelationship of field sites by demonstrating the ways that caves and the Arctic were connected by rhythms scientists. Finally, it will explore how the use of these particular spaces were not just scientific but also political – leveraging growing Cold War anxieties about nuclear fallout and the space race to bring greater prestige and funding to the study of circadian rhythms in its early years. (shrink)

Recent studies have shown that making accurate passage of time judgments (POTJs) for long-time intervals is an important cognitive ability. Different temporal domains, such as circadian typology (biological time) and time perspective (psychological time), could have an effect on subjective POTJs, but few studies have investigated the reciprocal influences among these temporal domains. The present study is the first systematic attempt to fill this gap. A sample of 222 participants (53.20% females; 19–60 years) filled (...) in the Zimbardo Time Perspective Inventory for the measurement of time perspective, the reduced version of the Morningness-Eveningness Questionnaire (rMEQ) for chronotypes, and an ad-hoc questionnaire assessing sleep habits during weekdays and the weekend (for social jetlag). The POTJ was measured using a modified version of a pictorial timeline presented at five different moments. Also, participants judged how different temporal expressions were related to the past, present, and future along a 7-point Likert scale. After confirming the association between eveningness and present-hedonism orientation and morningness and future-orientation, we found that evening-types produced higher scores for future expressions. The subjective POTJ expressed in minutes was predicted by Deviation from Balanced Time (DBTP), present-fatalism orientation, and social jetlag. Finally, the rMEQ score, past-positive orientation, and DBTP predicted the difference between subjective and objective POT. The results are discussed offering an explanation in terms of the interconnections between circadian typology, individual time perspective, and the sense of the POT, suggesting the multicomponent nature of the concept of time. (shrink)

What could be a unifying principle for the manifold of temporal experiences: the simultaneity or temporal order of events, the subjective present, the duration of experiences, or the impression of a continuity of time? Furthermore, we time travel to the past visiting in imagination previous experiences in episodic memory, and we also time travel to the future anticipating actions or plans. For such time traveling we divide time into three domains: past, present, and future. What (...) could be an escape out of this “jungle of time” characterized by many different perceptual and conceptual phenomena? The key concept we want to propose is “identity” which is derived from homeostasis as a fundamental biological principle. Within this conceptual frame two modes of identity are distinguished: individual or self-identity required because of homeostatic demands, and object-related identity necessary for the reliability and efficiency of neuro-cognitive processing. With this concept of self- and object-identity, the different temporal experiences can be conceptualized within a common frame. Thus, we propose a fundamental biological principle to conceptually unify temporal phenomena on the psychological level. (shrink)

Dysregulation of lipid metabolism is a commonly observed feature associated with metabolic syndrome and leads to the development of negative health outcomes such as obesity, diabetes mellitus, non‐alcoholic fatty liver disease, or atherosclerosis. Time‐restricted feeding/eating (TRF/TRE), an emerging dietary intervention, has been shown to promote pleiotropic health benefits including the alteration of diurnal expression of genes associated with lipid metabolism, as well as levels of lipid species. Although TRF likely induces a response in multiple organs leading to the modulation (...) of lipid metabolism, a majority of the studies related to TRF effects on lipids have focused only on individual tissues, and furthermore there is a lack of insight into potential underlying mechanisms. In this review, we summarize the current insights regarding TRF effects on lipid metabolism and the potential mechanisms in adipose tissue, liver, skeletal muscle, and heart, and conclude by outlining possible avenues for future exploration. (shrink)

Many plants are adapted to flower at particular times of year, to ensure optimal pollination and seed maturation. In these plants flowering is controlled by environmental signals that reflect the changing seasons, particularly daylength and temperature. The response to daylength varies, so that plants isolated at higher latitudes tend to flower in response to long daylengths of spring and summer, while plants from lower latitudes avoid the extreme heat of summer by responding to short days. Such responses require a mechanism (...) for measuring time, and the circadian clock that regulates daily rhythms in behaviour also acts as the timer in the measurement of daylength. Plants from high latitudes often also show an extreme response to temperature called vernalisation in which flowering is repressed until the plant is exposed to winter temperatures for an extended time. Genetic approaches in Arabidopsis have identified a number of genes that control vernalisation and daylength responses. These genes are described and models presented for how daylength might regulate flowering by controlling their expression by the circadian clock. BioEssays 22:38–47, 2000. ©2000 John Wiley & Sons, Inc. (shrink)

It’s often claimed in the philosophical and scientific literature on temporal representation that there is no such thing as a genuine sensory system for time. In this paper, I argue for the opposite—many animals, including all mammals, possess a genuine sensory system for time based in the circadian system. In arguing for this conclusion, I develop a semantics and meta-semantics for explaining how the endogenous rhythms of the circadian system provide organisms with a direct information link (...) to the temporal structure of their environment. In doing so, I highlight the role of sensory systems in an information processing architecture. (shrink)

This dissertation offers new proposals, based on a philosophical appraisal of scientific findings, to address old philosophical problems regarding our immediate acquaintance with time. It focuses on two topics: our capacity to determine the length of intervals and our acquaintance with the present moment. A review of the relevant scientific findings concerning these topics grounds the main contributions of this dissertation. Thus, this study introduces to the philosophical literature an empirically adequate way to talk about how the mind represents (...) time at the most fundamental level. In order to account for our immediate acquaintance with the duration of intervals, a theoretical framework for classifying clocks is used to explain why the representational outputs of the circadian clock and the stopwatch have metric structure. A philosophical analysis of these outputs is proposed to classify them and explain their properties. With respect to our immediate acquaintance with the present, a novel two-phase model of the present is proposed. This model shows that there are two forms of acquaintance with the present, which has consequences for contemporary debates in the philosophy of time. (shrink)

With aging, incidence of severe stress‐related diseases increases. However, mechanisms, underlying individual vulnerability to stress and age‐related diseases are not clear. The goal of this review is to analyze finding from the recent literature on age‐related characteristics of the hypothalamic‐pituitary‐adrenal (HPA) axis associated with stress reactivity in animals that show behavioral signs of anxiety and depression under mild stress, and in human patients with anxiety disorders and depression with emphasis on the impact of the circadian rhythm and the negative (...) feedback mechanisms involved in the stress response. One can conclude that HPA axis reaction to psycho‐emotional stress, at least acute stress, increases in the aged individuals with anxiety and depression behavior. Elevated stress reactivity is associated with disruption of the circadian rhythm and the mineralocorticoid receptor‐mediated glucocorticoid negative feedback. The disordered function of the HPA axis in individuals with anxiety and depression behavior can contribute to aging‐related pathology. (shrink)

This paper proposes an abstract mathematical frame for describing some features of biological time. The key point is that usual physical (linear) representation of time is insufficient, in our view, for the understanding key phenomena of life, such as rhythms, both physical (circadian, seasonal …) and properly biological (heart beating, respiration, metabolic …). In particular, the role of biological rhythms do not seem to have any counterpart in mathematical formalization of physical clocks, which are based on frequencies (...) along the usual (possibly thermodynamical, thus oriented) time. We then suggest a functional representation of biological time by a 2-dimensional manifold as a mathematical frame for accommodating autonomous biological rhythms. The “visual” representation of rhythms so obtained, in particular heart beatings, will provide, by a few examples, hints towards possible applications of our approach to the understanding of interspecific differences or intraspecific pathologies. The 3- dimensional embedding space, needed for purely mathematical reasons, allows to introduce a suitable extra-dimension for “representation time”, with a cognitive significance. (shrink)

Contemporary literature distinguishes two ways to defend the claim that cognition is a matter of representations: one, cognition involves representation-hungry tasks; two, cognition involves a complex form of informational covariation between subcomponents of a system with an adaptive function. Each of these conceptions involves a different notion of representation, and promotes a particular view of the architecture of cognition. But despite the differences, each of them aims to support the claim that cognition is a matter of representations on architectural constraints. (...) The objective of this article is twofold: one, it is argued that architectural constraints do not entail either of those two ways to defend the claim that cognition is a matter of representations; two, it is claimed that both notions of representation share an objectionable common element – namely, the idea of a model that grounds the representational reading– that must be abandoned, in favor of a more economical explanation in terms of causal relations, in order to get a clear view of cognition. (shrink)

Following on from the target article, which presented a new model of procedural skill memory development, in this response I will reflect on issues raised by invited commentators and further expound attributes of the model. Discussion will focus on: evidence against sleep-dependent memory processing, definitions of memory stages and memory systems, and relationships between memory enhancement, sleep-stages, dreaming, circadian time, and sleep-disorders.

Little is known about how to generate plausible new scientific ideas. So it is noteworthy that 12 years of self-experimentation led to the discovery of several surprising cause-effect relationships and suggested a new theory of weight control, an unusually high rate of new ideas. The cause-effect relationships were: (1) Seeing faces in the morning on television decreased mood in the evening (>10 hrs later) and improved mood the next day (>24 hrs later), yet had no detectable effect before that (0–10 (...) hrs later). The effect was strongest if the faces were life-sized and at a conversational distance. Travel across time zones reduced the effect for a few weeks. (2) Standing 8 hours per day reduced early awakening and made sleep more restorative, even though more standing was associated with less sleep. (3) Morning light (1 hr/day) reduced early awakening and made sleep more restorative. (4) Breakfast increased early awakening. (5) Standing and morning light together eliminated colds (upper respiratory tract infections) for more than 5 years. (6) Drinking lots of water, eating low-glycemic-index foods, and eating sushi each caused a modest weight loss. (7) Drinking unflavored fructose water caused a large weight loss that has lasted more than 1 year. While losing weight, hunger was much less than usual. Unflavored sucrose water had a similar effect. The new theory of weight control, which helped discover this effect, assumes that flavors associated with calories raise the body-fat set point: The stronger the association, the greater the increase. Between meals the set point declines. Self-experimentation lasting months or years seems to be a good way to generate plausible new ideas. Key Words: breakfast; circadian; colds; depression; discovery; fructose; innovation; insomnia; light; obesity; sitting; standing; sugar. (shrink)

Acidity, generated in hypoxia or hypermetabolic states, perturbs homeostasis and is a feature of solid tumors. That acid peripherally disperses lysosomes is a three‐decade‐old observation, yet one little understood or appreciated. However, recent work has recognized the inhibitory impact this spatial redistribution has on mechanistic target of rapamycin complex 1 (mTORC1), a key regulator of metabolism. This finding argues for a paradigm shift in localization of mTORC1 activator Ras homolog enriched in brain (RHEB), a conclusion several others have now independently (...) reached. Thus, mTORC1, known to sense amino acids, mitogens, and energy to restrict biosynthesis to times of adequate resources, also senses pH and, via dampened mTOR‐governed synthesis of clock proteins, regulates the circadian clock to achieve concerted responses to metabolic stress. While this may allow cancer to endure metabolic deprivation, immune cell mTOR signaling likewise exhibits pH sensitivity, suggesting that suppression of antitumor immune function by solid tumor acidity may additionally fuel cancers, an obstacle potentially reversible through therapeutic pH manipulation. (shrink)

Abstract Although noting the importance of organization in mechanisms, the new mechanistic philosophers of science have followed most biologists in focusing primarily on only the simplest mode of organization in which operations are envisaged as occurring sequentially. Increasingly, though, biologists are recognizing that the mechanisms they confront are non-sequential and the operations nonlinear. To understand how such mechanisms function through time, they are turning to computational models and tools of dynamical systems theory. Recent research on circadian rhythms addressing (...) both intracellular mechanisms and the intercellular networks in which these mechanisms are synchronized illuminates this point. This and other recent research in biology shows that the new mechanistic philosophers of science must expand their account of mechanistic explanation to incorporate computational modeling, yielding dynamical mechanistic explanations. Developing such explanations, however, is a challenge for both the scientists and the philosophers as there are serious tensions between mechanistic and dynamical approaches to science, and there are important opportunities for philosophers of science to contribute to surmounting these tensions. Content Type Journal Article Category Original paper in Philosophy of Science Pages 1-16 DOI 10.1007/s13194-012-0046-x Authors William Bechtel, Department of Philosophy, Center for Chronobiology, and Science Studies Program, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0119, USA Journal European Journal for Philosophy of Science Online ISSN 1879-4920 Print ISSN 1879-4912. (shrink)

The paper examines both the phenomenology of the manic self as well as critical aspects of manic neurobiology, focusing, with respect to both domains, on manic temporality. We argue that the distortions of lived time in mania exceed mere acceleration and are fundamental for manic affectivity. Mania involves radical acceleration and radical asynchronicity, which result in an instantaneous existence. People with mania rebel against the facticity of reality and suffer from an existential leap towards the future, in which the (...) self abandons normal temporal boundaries. Excerpts from the interviews with persons with mania who experienced psychosis illustrate this phenomenon. Commenting upon disrupted circadian rhythms in mania and the role of lithium in its treatment the paper posits manic temporality as the link through which manic phenomenology and manic neurobiology intertwine. (shrink)

Recent studies have highlighted the relevance of sleep for procrastination at work. Procrastination at work is defined as the irrational delay of the initiation or completion of work-related activities. In line with recent studies, we offer a self-regulation perspective on procrastination. We argue that procrastination is an outcome of depleted self-regulatory resources and that the restoration of self-regulatory resources during high-quality sleep at night would prevent procrastination.AimsIn an attempt to further develop this line of research, the current study aimed to (...) achieve a broader understanding of the relevance of sleep and circadian rhythm for procrastination. Therefore, we explored the effect of sleep quality on procrastination for different chronotypes. We also considered the shift to daylight saving time as a phenomenon that aggravates circadian misalignment and thereby later chronotypes' dependence on high-quality sleep. Specifically, we hypothesized that compared to employees with an earlier chronotype, employees with a later chronotype are more dependent on good sleep at night to prevent procrastination the next day. This effect would be especially pronounced after the shift to daylight saving time.MethodsFor this repeated-measures study, participants were 101 full-time employees. They completed a general questionnaire and day-specific questionnaires on the Monday before and the Monday following the shift to daylight saving time.ResultsThe multilevel analyses showed that employees procrastinated less on days following nights during which they slept better and that later chronotypes experienced more procrastination than earlier chronotypes. Our findings also supported the hypothesis that the relationship between sleep quality and procrastination is stronger for later chronotypes compared to earlier chronotypes on the Monday following the shift to daylight saving time. In other words, the lower the sleep quality of later chronotypes during the previous night, the more they procrastinated on the Monday following the shift to daylight saving time.DiscussionOur findings further corroborate the existing findings on the relevance of sleep and chronotype for well-being and performance at work. (shrink)

A long history of research has revealed many neurophysiological changes and concomitant behavioral impacts of sleep deprivation, sleep restriction, and circadian rhythms. Little research, however, has been conducted in the area of computational cognitive modeling to understand the information processing mechanisms through which neurobehavioral factors operate to produce degradations in human performance. Our approach to understanding this relationship is to link predictions of overall cognitive functioning, or alertness, from existing biomathematical models to information processing parameters in a cognitive architecture, (...) leveraging the strengths from each to develop a more comprehensive explanation. The integration of these methodologies is used to account for changes in human performance on a sustained attention task across 88 h of total sleep deprivation. The integrated model captures changes due to time awake and circadian rhythms, and it also provides an account for underlying changes in the cognitive processes that give rise to those effects. The results show the potential for developing mechanistic accounts of how fatigue impacts cognition, and they illustrate the increased explanatory power that is possible by combining theoretical insights from multiple methodologies. (shrink)

Mutations that disrupt biological rhythms have existed in microbial and metazoan eukaryotes for some time. They have recently begun to be studied with increasing intensity, both in terms of phenotypic effects of the relevant genetic variants, and with regard to molecular isolation and analysis of the genes defined by two of the ‘clock mutations’. These genetic loci, called period (per) in Drosophila and frequency (frq) in Neurospora, influence not only the basic characteristics of circadian rhythmicity, but also temperature (...) compensation of such daily cycle durations, ‘re‐setting’ of the rhythms' phases, and (for the per mutants) behavioral oscillations associated with much shorter than circadian periodicities. Molecular cloning of Drosophila's per gene, accompanied crucially by the locus's identification in germ‐line transformants, has led to information on its expression ‐ temporally, spatially, and in regard to heterogeneity of mRNA types. Nucleotide‐sequencing analyses of genomic DNA (and/or cDNA) from normal and mutated per alleles have (1) led to the suggestion that this clock gene encodes a family of proteoglycans (which was further indicated by application of antibody reagents obtained by manipulation of one of the gene's exons); and (2) shown that the three types of per mutations ‐ which shorten or lengthen rhythm periodicities or appear to eliminate them ‐ are associated with interesting amino‐acid substitutions or a stop codon, respectively. Analogous molecular findings are awaited from Neurospora, whose frq gene has very recently been cloned and definitively identified, in part via transformation experiments. (shrink)

This edited book addresses four themes of contemporary importance in the experimental and applied analysis of behaviour: chronobiology (relationships between time and behaviour), the emergence of rational thinking, language, and behavioural medicine. The current empirical and theoretical status of each theme is considered in individual chapters, the authors of which are distinguished research scientists drawn from a wide range of scholarship and with a distinctive European dimension. This cultural and theoretical diversity emerges from the fact that each chapter is (...) developed from a paper originally presented by invitation at the Second European Meeting on the Experimental Analysis of Behaviour, which was held in Liège, Belgium in 1988. Within the four themes, individual topics address issues such as circadian rhythms in behaviour, temporal regulation in children and in animals, the emergence of equivalence relations in children and animals, the development of thinking in mentally retarded children, reasoning and associative learning in animals, rule'governed behaviour, theoretical issues relating language to the theory of mind, the relationship between behavioural and visceral functions, the relevance of behavioural approaches to the prevention of AIDS, and the development of self'detection skills for breast cancer. The book makes an important contribution to the literature of contemporary behaviour analysis by reviewing issues of current interest and importance from a broad theoretical base. (shrink)

Ultradian rhythms are those that cycle many times in a day and are therefore measured in hours, minutes, seconds or even fractions of a second. In yeasts and protists, a temperature‐compensated clock with a period of about an hour (30–90 minutes) provides the time base upon which all central processes are synchronized. A 40‐minute clock in yeast times metabolic, respiratory and transcriptional processes, and controls cell division cycle progression. This system has at its core a redox cycle involving NAD(P)H (...) and dithiol–disulfide interconversions. It provides an archetype for biological time keeping on longer time scales (e.g. the daily cycles driven by circadian clocks) and underpins these rhythms, which cannot be understood in isolation. Ultradian rhythms are the foundation upon which the coherent functioning of the organism depends. BioEssays 29:465–473, 2007. © 2007 Wiley Periodicals, Inc. (shrink)

Western science claims to provide unique, objective information about the world. This is supported by the observation that peoples across cultures will agree upon a common description of the physical world. Further, the use of scientific instruments and mathematics is claimed to enable the objectification of science. In this work, carried out by reviewing the scientific literature, the above claims are disputed systematically by evaluating the definition of physical reality and the scientific method, showing that empiricism relies ultimately upon the (...) human senses for the evaluation of scientific theories and that measuring instruments cannot replace the human sensory system. Nativist and constructivist theories of human sensory development are reviewed, and it is shown that nativist claims of core conceptual knowledge cannot be supported by the findings in the literature, which shows that perception does not simply arise from a process of maturation. Instead, sensory function requires a long process of learning through interactions with the environment. To more rigorously define physical reality and systematically evaluate the stability of perception, and thus the basis of empiricism, the development of the method of dimension analysis is reviewed. It is shown that this methodology, relied upon for the mathematical analysis of physical quantities, is itself based upon empiricism, and that all of physical reality can be described in terms of the three fundamental dimensions of mass, length and time. Hereafter the sensory modalities that inform us about these three dimensions are systematically evaluated. The following careful analysis of neuronal plasticity in these modalities shows that all the relevant senses acquire from the environment the capacity to apprehend physical reality. It is concluded that physical reality is acquired rather than given innately, and leads to the position that science cannot provide unique results. Rather, those it can provide are sufficient for a particular environmental setting. (shrink)

Rotating shifts are common among nurses to ensure continuity of care. This scheduling system encompasses several adverse health and performance consequences. One of the most injurious effects of night-time shift work is the deterioration of sleep patterns due to both circadian rhythm disruption and increased sleep homeostatic pressure. Sleep problems lead to secondary effects on other aspects of wellbeing and cognitive functioning, increasing the risk of errors and workplace accidents. A wide range of interventions has been proposed to (...) improve the sleep quality of nurses and promote an increase in attention levels. In recent years, particular attention has been paid to individual and environmental factors mediating the subjective ability to cope with sleep deprivation during the night shift. Given the predictive role of these factors on the negative impact of a night shift, an individualized intervention could represent an effective countermeasure by ensuring suitable management of shift schedules. Therefore, the aims of this mini-review are to: provide an updated overview of the literature on sleep problems in night shift nurses and their adverse consequences; and critically analyze the psychosocial factors that mediate the negative impact of shift work with the ultimate goal of defining an effective countermeasure based on an individualized approach. (shrink)

What is the biological function of daily mood variations? What is the relationship between mood and such factors as exercise, time of day, nutrition, stress, and illness? Drawing on his own wide-ranging research concerning subjective assessments of mood and on extensive research by others, Dr. Thayer presents a comprehensive theory of normal mood states, viewing them as subjective components of two biological arousal systems, one which people find energizing, and the other which people describe as producing tension. The author (...) explains these two mood effects in relation to a complex relationship between energy and tension. Relevant research is systematically reviewed, and moods are analyzed in relation to circadian rhythms, exercise, nutrition, sleep, stress, and cognition. Perceptual and motivational effects of mood are also discussed, as are measurement and research design issues. Unique in its depth and comprehensiveness, this book will be of interest not only to researchers in psychology, biology, and medicine, but its clear style of presentation and the practical activities suggested for mood regulation will make it interesting to general readers as well. (shrink)

Various writers have attempted to use the sender-receiver formalism to account for the representational capacities of biological systems. This paper has two goals. First, I argue that the sender-receiver approach to representation cannot be complete. The mammalian circadian system represents the time of day, yet it does not control circadian behaviours by producing signals with time of day content. Informative signalling need not be the basis of our most basic representational capacities. Second, I argue that representational (...) capacities are primarily about control, and only when specific conditions obtain does this control require informative signalling. (shrink)

Healthcare workers who are on the front line of coronavirus disease 2019 and are also undergoing shift schedules face long work hours with few pauses, experience desynchronization of their circadian rhythm, and an imbalance between work hours effort and reward in saving lives, resulting in an impact on work capacity, aggravated by the lack of personal protective equipment, few resources and precarious infrastructure, and fear of contracting the virus and contaminating family members. Some consequences are sleep deprivation, chronic insomnia, (...) stress-related sleep disorders, and post-traumatic stress disorder. These sleep alterations critically affect mental health, precipitating or perpetuating anxiety, stress, and depression, resulting in the inability to regulate positive and negative emotions. Pre-existing sleep disorders are an important risk factor for the development and maintenance of PSTD when individuals are exposed to an important stressor such as a COVID-19 pandemic. At the same time, how an individual regulates the emotion associated with worries during daytime functioning impacts nighttime sleep, precipitating and perpetuating difficulties in sleeping. All of these changes in sleep and emotional regulation also alter the immune system. Sleep deprivation is commonly associated with chronic inflammatory diseases, due to the desynchronizations in circadian rhythms, causing possible psychophysiological disorders and impaired neuroimmune-endocrine homeostasis. From this perspective, we clarify in this article how sleep disorders affect the immune system and emotional regulation, explaining their phenomenological and neurobiological mechanisms, and discussing elements of cognitive and behavioral coping for health professionals to adopt and manage a healthier sleep pattern in the COVID-19 outbreak. (shrink)

Philosophers examining mechanistic explanations in biology have identified heuristic strategies scientists use in discovering mechanisms. This paper examines the heuristic strategy of investigating phylogenetically distant model organisms, using research on sleep in fruit flies as an example. At the time sleep was discovered in flies in 2000 next to nothing was known about mechanisms regulating sleep in flies and what they could reveal about those in us. One relatively straightforward line of research focused on homologous genes in flies and (...) humans, using those in flies to understand what roles their homologs played in controlling sleep in us. But other research focused on a higher level of organization—the neural networks involved in homeostatic and circadian control of sleep. This raises a puzzle—given that fly and vertebrate brains are organized very differently, how could sleep regulation in flies serve as an informative model of vertebrate sleep? I argue that the basic design of mechanisms such as those regulating sleep can be conserved even as the composition of the mechanism changes and that researchers can hope to use the designs deciphered in flies as heuristic models for understanding sleep in humans. (shrink)

Motivation: A Biosocial and Cognitive Integration of Motivation and Emotion shows how motivation relates to biological, social, and cognitive issues. A wide range of topics concerning motivation and emotion are considered, including hunger and thirst, circadian and other biological rhythms, fear and anxiety, anger and aggression, achievement, attachment, and love. Goals and incentives are discussed in their application to work, child rearing, and personality. This book reviews an unusual breadth of research and provides the reader with the scientific basis (...) for understanding motivation as a major variable in human and animal life. It also offers insights that can be applied to immediate and practical problems. Various areas are examined in depth, such as the relationships between reward, incentives, and motivation. The discussion of biological rhythms shows that humans and animals are more alert at certain times than others, and these rhythms also affect performance. The topics in the book span the ways in which motivation connects with many aspects of contemporary psychology. Basic issues of design and methodology, details of research procedures, and important aspects of definition and measurement, are discussed throughout the book.Motivation: A Biosocial and Cognitive Integration of Motivation and Emotion examines the way motivation functions and how it interacts with other important variables: physiological processes; learning, attention, and memory; rewards and stressors; the role of culture as well as species characteristics. The presentation makes clear in what important ways motivation, as a construct, contributes to the scientific understanding of behavior. The book offers advanced undergraduate and graduate students a broad overview of motivation. It also is of value for the professional psychologist who seeks an integrated overview of the classical and contemporary literature in the field of motivation. The book provides information on a broad range of issues and thus can be used also as supplementary reading for courses on cognition and biological as well as social psychology. (shrink)

Circalunar clocks, which allow organisms to time reproduction to lunar phase, have been experimentally proven but are still not understood at the molecular level. Currently, a new generation of researchers with new tools is setting out to fill this gap. Our essay provides an overview of classic experiments on circalunar clocks. From the unpublished work of the late D. Neumann we also present a novel phase response curve for a circalunar clock. These experiments highlight avenues for molecular work and (...) call for rigor in setting up and analyzing the logistically complex experiments on circalunar clocks. Re‐evaluating classic experiments, we propose that (1) circalunar clocks in different organisms will have divergent mechanisms and physiological bases, (2) they may have properties very different from the well‐studied circadian clocks and (3) they may have close mechanistic and molecular relations to seasonal rhythms and diapause. (shrink)

Many biological systems experience a periodic environment. Floquet theory is a mathematical tool to deal with such time periodic systems. It is not often applied in biology, because linkage between the mathematics and the biology is not available. To create this linkage, we derive the Floquet theory for natural systems. We construct a framework, where the rotation of the Earth is causing the periodicity. Within this framework the angular momentum operator is introduced to describe the Earth’s rotation. The Fourier (...) operators and the Fourier states are defined to link the rotation to the biological system. Using these operators, the biological system can be transformed into a rotating frame in which the environment becomes static. In this rotating frame the Floquet solution can be derived. Two examples demonstrate how to apply this natural framework. (shrink)

The papers in this volume reflect much of the current unease of a world that perceives itself once more at the edge of chaos. The authors present different vistas of that experience and their inherent dialectic, expressed in numerous and ceaseless conflicts between ordering and disordering processes. They can be read as comments on the ongoing processes that lead toward greater complexity.