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Regulation of sleep-wake cycles by the light-dark cycle, social time, a circadian pacemaker, and the sleep homeostat. Please note that light input reached the SCN via the feedback loop between the sleep-wake cycle and the SCN. Light input to extra SCN areas that may be involved in sleep, wakefulness, and performance is not represented in this scheme. Modified from Dijk and Lockley (2002).
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Daily rhythms in sleep and waking performance are generated by the interplay of multiple external and internal oscillators. These include the light-dark and social cycles, a circadian hypothalamic oscillator oscillating virtually independently of behavior, and a homeostatic oscillator driven primarily by sleep-wake behavior. Both internal oscillato...
Citations
... In humans, sleep timing is governed by an interaction between the circadian and homeostatic oscillators, which determine spontaneous bedtime and wake time in synchronisation with the earth's light/dark cycle [1]. Similar to most other living forms, humans and other mammals possess an internal body clock known as the circadian clock, which has a self-sustaining, nearly 24-hour periodicity (derived from the Latin circa diem, which means approximately one day). ...
Aim: We conducted this study to investigate the impact of social restrictions on chronotype categories, social jetlag, and sleep parameters in the Indian population. Materials and Methods: A cross-sectional study was conducted in 2021 with 139 participants. We used an online questionnaire (Google Form) enclosing respondents' sociodemographic information Social jetlag and sleep parameters were measured with the µ-MCTQ and chronotype was assessed by the r-MEQ. Chi-square, paired t-tests, and One-way ANOVA were used to analyse the data. Pearson correlation was used to determine the strength of the relationship between the variables. Results: Our results highlighted that a total of 23.8% of volunteers reported social jetlag before social restriction and it significantly reduced to 13.7% (P = .001) in the social restricted condition. There is no significant difference in sleep duration during the workday and free days of socially 117 restriction (P = .11). We found a difference between midsleep free day (MSf) and midsleep free day corrected (MSfsc) (mean of 13 min before restrictions (P = .05) and 10 min during restrictions; P = .001). Conclusion: Our findings provide crucial insights into variations in sleep/wake schedule stability, as seen by changes in the decrease of social jetlag between restriction. It was established that the individuals had significantly equivalent total sleep at both time points, as well as a later sleep-wake time under the social restriction.
... The duration of deep sleep in the sleep cycles decreases during the night, while the duration of REM sleep increases [3,4]. The sleep-wake cycle is controlled by complex neuronal networks [9], driven by internal oscillators and modulated by external oscillators [10]. These oscillators control not only sleepiness at night and alertness during the day, but also the timing, duration and composition of sleep and therefore sleep quality [10,11]. ...
... The sleep-wake cycle is controlled by complex neuronal networks [9], driven by internal oscillators and modulated by external oscillators [10]. These oscillators control not only sleepiness at night and alertness during the day, but also the timing, duration and composition of sleep and therefore sleep quality [10,11]. The internal oscillators control the homeostatic and the circadian component of sleep timing so that both are able to work independently of each other [11]. ...
... This suggests a strong temporal relationship between REM sleep and bedtime. This is consistent with the concept of tight control of REM sleep timing by the circadian process of sleep regulation, which is mainly based on experiments under artificial conditions [10][11][12][28][29][30]. However, under artificial conditions, the distortion by stress hormones, which strongly influence the circadian system, cannot be ruled out [31]. ...
Sleep timing is controlled by intrinsic homeostatic and circadian components. The circadian component controls the chronotype, which is defined by the propensity to sleep at a particular clock time. However, sleep timing can be significantly affected by external factors such as the morning alarm clock. In this study, we analysed the timing of deep and REM sleep as well as the composition of REM sleep using Fitbit sleep staging in young healthy adults (n = 59) under real-life conditions. Sleep stage percentiles were correlated with the timing of total sleep in time after sleep onset for the homeostatic component and in clock time for the circadian component. Regarding the circadian component, the phase of total sleep is most strongly associated with the phases of early deep sleep and REM sleep. Furthermore, a stronger phase relationship between deep and REM sleep with total sleep is associated with greater consolidation of REM sleep. Chronotype-dependent sleep loss correlates negatively with the strength of the phase relationship between deep sleep and total sleep. In conclusion, the interaction of the circadian component of sleep timing with the timing of sleep stages is associated with REM sleep quality. In particular, the interaction of the circadian component of sleep timing with deep sleep seems to be more vulnerable to external factors.
... Sleep timing (e.g., bedtime and wake time) is driven by interactions of circadian and homeostatic oscillations and reflects individual preferences for sleep. (Dijk and von Schantz, 2005) In response to changes in modern educational patterns, children and adolescents usually adhere to a relatively fixed waking and sleeping routine based on school schedules. (Whiting et al., 2021) This standardized sleep pattern minimizes individual differences, which may not be enough to influence the occurrence and prevalence of myopia. ...
... Another open question concerns the impact of moderators on the synchrony effect, such as the sleep-wake history (see, e.g., Dijk & von Schantz, 2005). In the present study, we followed previous research and we did not explicitly control for prior sleep-wake history. ...
Using physiologically validated questionnaires in which the peak of circadian arousal is determined through morningness-eveningness preferences, individuals can be categorized into morning or evening chronotypes. Typically, individuals with such chronotypes are assumed to show better cognitive performance at their subjective peak of circadian arousal than at off peak. Although this so-called synchrony effect is accepted as common knowledge, empirical evidence is rather mixed. This may be explained by two methodical challenges. First, most studies are underpowered. Second, they include one task, but tasks differ across studies. Here, we tested the synchrony effect by focusing on two cognitive constructs that are assumed to underlie a wide variety of behaviors, that is: short-term maintenance and attentional control. Short-term maintenance refers to our ability to maintain information temporarily. Attentional control refers to our ability to avoid being distracted by irrelevant information. We addressed the methodical challenges by asking 446 young adults to perform eight tasks at on- and off-peak times. Four tasks were used to assess temporary maintenance of information (i.e., short-term memory). Four tasks were used to assess temporary maintenance and manipulation of information (i.e., working memory). Using structural equation modeling, we modeled attentional control as the goal-directed nature of the working-memory tasks without their maintenance aspects. At the individual-task level, there was some evidence for a synchrony effect. However, the evidence was weak and limited to two tasks. Moreover, at the latent-variable level, the results showed no evidence for a robust and general synchrony effect. These results were observed for the full sample (N = 446) and the subsample including participants with moderate to definite morning or evening chronotypes (N = 191). We conclude that the synchrony effect is most likely a methodical artefact and discuss the impact of our research on psychological science and scientific research more widely.
... The circadian system functions to temporally organize the physiological processes of the body through specialized neural structures such as input pathways, which transmit signals such as light to the circadian master clock, that is the suprachiasmatic nucleus (SCN) of hypothalamus 12 . This master clock regulates the circadian rhythms in glucose, corticosteroids, leptin, and cardiovascular systems through the autonomic nervous system and humoral signs to the pancreas, liver, adrenal glands, adipose tissues, and heart 13 . ...
The purpose of this study was to analyze the rest-activity rhythm of type 2 diabetics mellitus
(T2DM) and compare it to healthy controls using the nonparametric analytic approach. Twentyone
diabetics and 21 healthy subjects matched for gender and age were recruited to participate in
the study. Data were analyzed using the Independent t-test, Mann-Whitney U test, and Spearmans
correlation. T2DM subjects demonstrate lower interdaily stability (IS) (p=.03), higher intradaily
variability (p=.046) and lower rhythm amplitude (p=.02) when compared to healthy controls. Also,
there was a positive correlation between IS and most active 10 hr (M10) in the average of 24
hours pattern (r =.44; p=.046) in the diabetes group and a negative correlation between IV and
M10 in the healthy group (r =-.57; p=.007). These data together suggest that T2DM exhibits a
dysfunction in the rest-activity rhythm due to alterations in the circadian function as well as in the
homeostatic capacity to maintain sleep; mainly characterized by less consistency across days of the
daily circadian signal, higher rhythm fragmentation and lower rhythm amplitude. Future approaches
may be developed considering the influence of circadian glucose variations throughout the day on
the coupling of the rest-activity rhythm to zeitgeber and rhythm fragmentation.
... 83 The study started at 1.00 pm to minimize the putative impact of both circadian and homeostatic factors on individual performance levels and sleep characteristics. 77,78,87 The experimental procedure was composed of seven main phases: familiarization, pre-test, training, post-test, 90-minute nap, retention and transfer tests ( Figure 1). Before training, participants underwent a brief familiarization phase during which they were instructed to repeatedly and slowly perform the 5-element sequence until they accurately reproduced the sequence three consecutive times. ...
Sleep benefits the consolidation of motor skills learned by physical practice, mainly through periodic thalamocortical sleep spindle activity. However, motor skills can be learned without overt movement through motor imagery or action observation. Here, we investigated whether sleep spindle activity also supports the consolidation of non-physically learned movements. Forty-five electroencephalographic sleep recordings were collected during a daytime nap after motor sequence learning by physical practice, motor imagery, or action observation. Our findings reveal that a temporal cluster-based organization of sleep spindles underlies motor memory consolidation in all groups, albeit with distinct behavioral outcomes. A daytime nap offers an early sleep window promoting the retention of motor skills learned by physical practice and motor imagery, and its generalizability toward the inter-manual transfer of skill after action observation. Findings may further have practical impacts with the development of non-physical rehabilitation interventions for patients having to remaster skills following peripherical or brain injury.
... Although the relationship between sleep and mood-related factors is bidirectional, there is evidence that the effect of sleep quality on mood is greater than vice versa [19]. Importantly, daily rhythms in sleep and wake are controlled by a complex interplay of different oscillators, including exogenous oscillators, such as light-dark and social cycles, and endogenous oscillators, such as circadian and homeostatic oscillators [20,21]. According to the endogenous oscillators, individuals differ in their intrinsically determined preferred sleep timing, defining the chronotype [22]. ...
Psychosocial stress is widespread worldwide and particularly affects young adults. There is a close and bidirectional relationship between sleep quality and mental health. Sleep duration, which is an important feature of sleep quality, shows both intra-individual variations and inter-individual differences. Internal clocks control individual sleep timing, which, in turn, defines the chronotype. On workdays, however, the end and duration of sleep are largely limited by external factors, such as alarm clocks, especially in later chronotypes. The aim of this study is to investigate whether there is a relationship between sleep timing and duration on workdays and measures for psychosocial stress, such as anxiety and depression; subjective workload; and the subjective impact of a high workload on sleep. We used a combination of Fitbit wearable actigraphy data and a questionnaire survey of young, healthy medical students and calculated correlations between the respective variables. We found that a shorter sleep duration on workdays is associated with a higher subjective workload and a higher subjective impact of a high workload on sleep, which, in turn, are associated with higher measures of anxiety and depression. Our study contributes to understanding the importance of sleep timing/duration and their regularity on weekdays for subjectively perceived psychosocial stress.
... For example, sleep follows a circadian pattern controlled by the secretion of melatonin [67] and indirectly by other hormones [68]. Wakefulness is directly controlled by orexin [74], but also by dopamine [23]. In addition, the brain controls the periodicity of many physiological processes, such as the heart rate [31]. ...
Modelling the biology behind animal behaviour has attracted great interest in recent years. Nevertheless, neuroscience and artificial intelligence face the challenge of representing and emulating animal behaviour in robots. Consequently, this paper presents a biologically inspired motivational model to control the biological functions of autonomous robots that interact with and emulate human behaviour. The model is intended to produce fully autonomous, natural, and behaviour that can adapt to both familiar and unexpected situations in human–robot interactions. The primary contribution of this paper is to present novel methods for modelling the robot’s internal state to generate deliberative and reactive behaviour, how it perceives and evaluates the stimuli from the environment, and the role of emotional responses. Our architecture emulates essential animal biological functions such as neuroendocrine responses, circadian and ultradian rhythms, motivation, and affection, to generate biologically inspired behaviour in social robots. Neuroendocrinal substances control biological functions such as sleep, wakefulness, and emotion. Deficits in these processes regulate the robot’s motivational and affective states, significantly influencing the robot’s decision-making and, therefore, its behaviour. We evaluated the model by observing the long-term behaviour of the social robot Mini while interacting with people. The experiment assessed how the robot’s behaviour varied and evolved depending on its internal variables and external situations, adapting to different conditions. The outcomes show that an autonomous robot with appropriate decision-making can cope with its internal deficits and unexpected situations, controlling its sleep–wake cycle, social behaviour, affective states, and stress, when acting in human–robot interactions.
... Recently, researchers have found that lights with different wavelengths can adjust human's psychological and physiological activities: blue light inhibits melatonin secretion which can keep human away from falling asleep, meanwhile the blue light with the wavelength near 460 nm is harmful to eyes, causing diseases like maculopathy [11,12]; red light provides a relaxing environment for human beings to relieve the tension of the brain and further research has found that a proper exposure to red light contributes to vision health [13,14]. Based on these findings, different health light lamps have been developed, such as a lamp that can simulate the change of sunlight in a day [15] and a special lamp capable of treating myopia [16]. ...
A driver safety assisting system is essential to reduce the probability of traffic accidents. But most of the existing driver safety assisting systems are simple reminders that cannot improve the driver's driving status. This paper proposes a driver safety assisting system to reduce the driver's fatigue degree by the light with different wavelengths that affect people's moods. The system consists of a camera, an image processing chip, an algorithm processing chip, and an adjustment module based on quantum dot LEDs (QLEDs). Through this intelligent atmosphere lamp system, the experimental results show that blue light reduced the driver’s fatigue degree when just turned on; but as time went on, the driver’s fatigue degree rebounded rapidly. Meanwhile, red light prolonged the driver's awake time. Different from blue light alone, this effect can remain stable for a long time. Based on these observations, an algorith was designed to quantify the degree of fatigue and detect its rising trend. In the early stage, the red light is used to prolong the awake time and the blue light to suppress when the fatigue value increases, so as to maximize the awake driving time. The result showed that our device prolonged the awake driving time of the drivers by 1.95 times and reduced fatigue during driving: the quantitative value of fatigue degree generally decreased by about 0.2 times. In most experiments, the subjects were able to complete four hours of safe driving, which reached the maximum length of continuous driving at night allowed by China laws. In conclusion, our system changes the assisting system from a reminder to a helper, thus effectively reducing the driving risk.
... Sleep is part of a person's daily routine and is regulated by homeostasis and circadian rhythms (Dijk & Von Schantz 2005). As poor sleep quality has been associated with gastrointestinal problems (Slavish et al. 2019), type 2 diabetes mellitus (Anothaisintawee et al. 2016), cognitive impairment (Pistollato et al. 2016) and abuse of addictive substances (Angarita et al. 2016), it has become a public health concern. ...
Poor sleep quality has become a public health concern due to its association with several health risks. Recent studies had shown that university students had poor sleep quality during the COVID-19 pandemic. Thus, this study aimed to determine the factors associated with sleep quality among undergraduate students in Malaysia during the COVID-19 pandemic. This cross-sectional study involved 377 undergraduates from public and private universities in Malaysia. The study ws conducted between 16 June 2021 to 31 July 2021. Respondents completed an online survey reagarding to their sociodemographic background, sleep quality, chronotype pattern, night eating syndrome, food security, physical activity, internet addiction and self-reported body weight and height. There was poor sleep quality in 62.3% of the respondents. Respondents who were Malay (AOR = 3.84, 95% CI =2.07-7.11), in the arts stream (AOR = 2.55, 95% CI = 1.20-5.42) and internet-addicted (AOR = 2.14, 95% CI = 1.22-3.77) had higher risk of poor sleep quality. Respondents who lived in a rented house (AOR = 0.38, 95% CI = 0.16-0.88), were sophomores (AOR = 0.49, 95% CI = 0.25-0.99) and were the morning chronotype (AOR = 0.35, 95% CI = 0.17-0.72) had lower risk for developing poor sleep quality. This study underscored the high prevalence of poor sleep quality among undergraduate students during the COVID-19 pandemic. The findings suggested that by preventing internet addiction and the evening chronotype can improve sleep quality.
