Articles de revues : « Rest-activity circadian rhythms »

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Fujioka, Haruna, Masato S. Abe et Yasukazu Okada. « Individual Ants Do Not Show Activity-Rest Rhythms in Nest Conditions ». Journal of Biological Rhythms 36, n^o 3 (5 avril 2021) : 297–310. http://dx.doi.org/10.1177/07487304211002934.

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Circadian rhythms, which respond to the day-night cycle on the earth, arise from the endogenous timekeeping system within organisms, called the “biological clock.” For accurate circadian rhythms, daily fluctuations in light and temperature are considered one of the important time cues. In social insects, both abiotic and biotic factors (i.e., social interactions) play a significant role in activity-rest rhythm regulation. However, it is challenging to monitor individual activity-rest rhythms in a colony because of the large group size and small body size. Therefore, it is unclear whether individuals in a colony exhibit activity-rest rhythms and how social interactions regulate their activity-rest rhythms in the colony. This study developed an image-based tracking system using 2D barcodes for Diacamma cf. indicum from Japan (a monomorphic ant) and measured the locomotor activities of all colony members under laboratory colony conditions. We also investigated the effect of broods on activity-rest rhythms by removing all broods under colony conditions. Activity-rest rhythms appeared only in isolated ants, not under colony conditions. In addition, workers showed arrhythmic activities after brood removal. These results suggested that a mixture of social interactions, and not light and temperature, induces the loss of activity-rest rhythms. These results contribute to the knowledge of a diverse pattern of circadian activity rhythms in social insects.

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Arzola-Rodríguez, Jesús José. « Sueño y ritmos circadianos en supervivientes de falla respiratoria aguda ». Kompass Neumología 3, n^o 1 (2021) : 14–15. http://dx.doi.org/10.1159/000513799.

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Background: Little is known about sleep and circadian rhythms in survivors of acute respiratory failure (ARF) after hospital discharge. Objectives: To examine sleep and rest-activity circadian rhythms in ARF survivors 3 months after hospital discharge, and to compare them with a community-dwelling population. Methods: Sleep diary, actigraphy data, and insomnia symptoms were collected in a pilot study of 14 ARF survivors. Rest-activity circadian rhythms were assessed with wrist actigraphy and sleep diary for 9 days, and were analyzed by cosinor and non-parametric circadian rhythm analysis. Results: All participants had remarkable actigraphic sleep fragmentation, 71.5% had subclinical or clinical insomnia symptoms. Compared to community-dwelling adults, this cohort had less stable rest-activity circadian rhythms (p < 0.001), and weaker circadian strength (p < 0.001). Conclusion: Insomnia and circadian disruption were common in ARF survivors. Sleep improvement and circadian rhythm regularity may be a promising approach to improve quality of life and daytime function after ARF.

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Slyepchenko, Anastasiya, Olivia R. Allega, Xiamin Leng, Luciano Minuzzi, Maha M. Eltayebani, Matthew Skelly, Roberto B. Sassi, Claudio N. Soares, Sidney H. Kennedy et Benicio N. Frey. « Association of functioning and quality of life with objective and subjective measures of sleep and biological rhythms in major depressive and bipolar disorder ». Australian & ; New Zealand Journal of Psychiatry 53, n^o 7 (13 février 2019) : 683–96. http://dx.doi.org/10.1177/0004867419829228.

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Objective: Disruptions in biological rhythms and sleep are a core aspect of mood disorders, with sleep and rhythm changes frequently occurring prior to and during mood episodes. Wrist-worn actigraphs are increasingly utilized to measure ambulatory activity rhythm and sleep patterns. Methods: A comprehensive study using subjective and objective measures of sleep and biological rhythms was conducted in 111 participants (40 healthy volunteers [HC], 38 with major depressive disorder [MDD] and 33 with bipolar disorder [BD]). Participants completed 15-day actigraphy and first-morning urine samples to measure 6-sulfatoxymelatonin levels. Sleep and biological rhythm questionnaires were administered: Biological Rhythms Interview of Assessment in Neuropsychiatry (BRIAN), Munich Chronotype Questionnaire (MCTQ), Pittsburgh Sleep Quality Index (PSQI) and Epworth Sleepiness Scale (ESS). Actigraph data were analyzed for sleep and daily activity rhythms, light exposure and likelihood of transitioning between rest and activity states. Results: Mood groups had worse subjective sleep quality (PSQI) and biological rhythm disruption (BRIAN) and higher objective mean nighttime activity than controls. Participants with BD had longer total sleep time, higher circadian quotient and lower 6-sulfatoxymelatonin levels than HC group. The MDD group had longer sleep onset latency and higher daytime probability of transitioning from rest to activity than HCs. Mood groups displayed later mean timing of light exposure. Multiple linear regression analysis with BRIAN scores, circadian quotient, mean nighttime activity during rest and daytime probability of transitioning from activity to rest explained 43% of variance in quality-of-life scores. BRIAN scores, total sleep time and probability of transitioning from activity to rest explained 52% of variance in functioning (all p < 0.05). Conclusions: Disruption in biological rhythms is associated with poorer functioning and quality of life in bipolar and MDD. Investigating biological rhythms and sleep using actigraphy variables, urinary 6-sulfatoxymelatonin and subjective measures provide evidence of widespread sleep and circadian system disruptions in mood disorders.

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Dispersyn, Garance, Laure Pain et Yvan Touitou. « Circadian Disruption of Body Core Temperature and Rest–Activity Rhythms after General (Propofol) Anesthesia in Rats ». Anesthesiology 110, n^o 6 (1 juin 2009) : 1305–15. http://dx.doi.org/10.1097/aln.0b013e3181a10225.

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Background General anesthesia is commonly associated with sleep disorders, fatigue, drowsiness, and mood alterations in patients. The authors examined whether general (propofol) anesthesia can impact the circadian temporal structure by disturbing circadian rest-activity and body temperature rhythms under normal light-dark conditions (light-dark 12:12 h) in rats. Methods A group of rats was anesthetized with propofol, and another was injected with 10% Intralipid, which was used as a control lipidic solution. The authors examined six groups of rats according to the Zeitgeber time of intraperitoneal administration (ZT6, ZT10, ZT16) and the substance injected (propofol or Intralipid). Results On the day after anesthesia, propofol induced a significant 60- to 80-min phase advance of both rest-activity and body temperature rhythms. A significant 45- to 60-min phase advance of body temperature and a significant 20-min phase advance of rest-activity were still observed on the second day after anesthesia. The amplitudes of both rest-activity and body temperature rhythms were decreased on the first and second days after anesthesia. The 24-h mean rest-activity rhythm was decreased on the day after anesthesia, whereas the 24-h mean body temperature rhythm was not modified. Conclusion The results demonstrate the disturbing effects of propofol anesthesia on the circadian time structure in rats under normal light conditions.

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Giannetto, C., F. Fazio, A. Assenza, G. Caola, P. Pennisi et G. Piccione. « Circadian rhythms of redox states and total locomotor activity in dairy cattle ». Czech Journal of Animal Science 55, No. 5 (17 mai 2010) : 183–89. http://dx.doi.org/10.17221/306/2009-cjas.

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We want to study the circadian rhythm of dROMs and anti-oxidative power in dairy cattle during dry period and the possible involvement of the circadian organization of rest/activity cycles in the fluctuation of redox state. For this purpose we recorded TLA in five clinically healthy Bruna Italian dairy cattle by means of an actigraphy-based data logger, Actiwatch-Mini®. Blood samples were collected every 3 hours over a 48-hour period for the assessment of free radicals (dROMs) and the antioxidant power: antioxidant barrier (Oxy-ads) and thiol-antioxidant barrier (SHp). All animals were in the same productive period (dry) and they were housed in the same stable under natural photoperiod and ambient temperature. One-way repeated measure ANOVA was used to determine a statistical significant effect of time on the studied parameters. A trigonometric statistical model was applied to characterize the main rhythmic parameters according to the single cosinor procedure. A significant effect of time on all studied parameters was observed. They showed a diurnal acrophase and different degrees of robustness of rhythms. In conclusion, we can claim that there is a synergism between the dROM circadian rhythm and the circadian rhythm of anti-oxidative power. These rhythms do not have any implication for the issue of causation with the TLA circadian rhythms.

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Calogiuri, Giovanna, Andi Weydahl et Franca Carandente. « Methodological Issues for Studying the Rest–Activity Cycle and Sleep Disturbances ». Biological Research For Nursing 15, n^o 1 (5 août 2011) : 5–12. http://dx.doi.org/10.1177/1099800411416224.

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Shift work schedules, intensive physical exercise late in the day, psychological stress, or a busy lifestyle might induce disorders of the circadian structure, which can affect health on both the physiological and neurobehavioral levels. Rest–activity rhythm is strongly connected with an organism’s circadian structure, and irregular sleep–wake patterns can lead to a disruption of entrainment, resulting in physiological and neurobehavioral dysfunction. Shift nurses are often subject to disturbances in the quality and duration of their sleep, raising the possibility of negative impacts on their health and their patients' safety. Researchers have used actigraphy in a number of studies to assess sleep patterns. Because of the close connection between sleep and circadian structure, it may be useful to extend the evaluation of actigraphy data to the analysis of the rest–activity rhythm with rhythmometric procedures to provide a better understanding of possible sleep disorders in relation to entrainment. Actigraphy is an easy and reliable way to study these rhythms and identify possible circadian-rhythm disorders. In this article, the authors discuss methodological issues concerning the evaluation of the rest–activity rhythm, with a focus on actigraphy.

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Gander, P. H., R. Lydic, H. E. Albers et M. C. Moore-Ede. « Forced internal desynchronization between circadian temperature and activity rhythms in squirrel monkeys ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 248, n^o 5 (1 mai 1985) : R567—R572. http://dx.doi.org/10.1152/ajpregu.1985.248.5.r567.

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In an attempt to force internal desynchronization between the rest-activity rhythm and the body temperature rhythm of the squirrel monkey (Saimiri sciureus), five animals were studied in a 14:14 light-dark cycle. In four animals a 28-h spectral component was found to predominate in the rest-activity rhythm, whereas an unentrained circadian component (tau = 25.9 +/- 0.4 h) predominated in the body temperature rhythm. Plots of the cycle-by-cycle acrophases of the two rhythms confirm that they desynchronize, due to the failure of the temperature rhythm to entrain to the light-dark cycle. These data from intact animals provide further support for the hypothesis that the squirrel monkey circadian timing system has at least two pacemakers. A rhythm for which the supra-chiasmatic nuclei (SCN) have previously been shown to be essential (rest-activity) simultaneously exhibited a different period from a rhythm (body temperature) that has been shown to persist after destruction of the SCN.

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Kim, Minjee, Kathryn Reid, Matthew Maas, Thanh-Huyen Vu, Rosemary Braun, Martha Daviglus et Phyllis Zee. « 164 Greater Light Exposure Is Associated with More Robust Rest-Activity Rhythms in Community-Dwelling Older Adults ». Sleep 44, Supplement_2 (1 mai 2021) : A67. http://dx.doi.org/10.1093/sleep/zsab072.163.

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Abstract Introduction Disrupted circadian rest-activity rhythms in older adults have been associated with an increased risk of cognitive decline and mortality. While light is one of the most potent synchronizing agents for the human circadian system, little is known about how light may influence rest-activity rhythms in older adults. We aimed to investigate the relationship between the amount of light exposure and rest-activity rhythm parameters using actigraphy data from a large cohort study. Methods 553 community-dwelling older adults (aged 72±5, 142 (25.5%) female) from the Chicago Healthy Aging Study cohort underwent recording of activity and ambient light exposure for a minimum of five 24-hour periods, using Actiwatch-L (Phillips Respironics). The average recording duration was 6.7±0.5 days. An extension to the traditional cosine model was used to compute circadian rest-activity rhythm parameters, including the amplitude (a measure of strength), the goodness of fit (pseudo F statistic; a measure of robustness), and acrophase (timing of peak activity). Light exposure was measured by time spent above light thresholds of 100, 200, 500, and 1000 lux per day (TAT100, TAT200, TAT500, TAT1000, respectively). Bivariate associations between rhythm parameters and TAT values were examined with Spearman’s correlation coefficients. Variables that met a significant threshold (p<0.05) were entered into multivariable models to adjust for potential confounders including age, sex, race, and season. Results Robustness of the rest-activity rhythm, measured by extended cosine pseudo-F statistics, was associated with TAT100 (partial Spearman’s correlation coefficient 0.12, p=0.008), TAT200 (coefficient 0.13, p=0.03), TAT500 (coefficient 0.16, p<0.001), and TAT 1000 (coefficient 0.18, p<0.001). TAT100/200/500/1000 were also associated with the strength of the rest-activity rhythm, measured by amplitude of the extended cosine fit (partial Spearman’s correlation coefficient vs. TAT100: 0.12, p=0.006, TAT200: 0.14, p=0.002, TAT500: 0.16, p<0.001, TAT1000: 0.18, p<0.001), after adjusting for age, sex, race, and season. Conclusion Across the seasons, greater daily light exposure is associated with more robust circadian rest-activity rhythm in community-dwelling older adults. Whether the enhancement of light exposure can improve the strength and robustness of rest-activity rhythm needs to be tested with future intervention studies. Support (if any):

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Lee, Jung Hyun, Eunsoo Moon, Jeonghyun Park, Chi Eun Oh, Yoo Rha Hong et Min Yoon. « Optimization of Analysis of Circadian Rest-Activity Rhythm Using Cosinor Analysis in Mice ». Psychiatry Investigation 19, n^o 5 (25 mai 2022) : 380–85. http://dx.doi.org/10.30773/pi.2021.0395.

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Objective Data processing in analysis of circadian rhythm was performed in various ways. However, there was a lack of evidence for the optimal analysis of circadian rest-activity rhythm. Therefore, we aimed to perform mathematical simulations of data processing to investigate proper evidence for the optimal analysis of circadian rest-activity rhythm.Methods Locomotor activities of 20 ICR male mice were measured by infrared motion detectors. The data of locomotor activities was processed using data summation, data average, and data moving average methods for cosinor analysis. Circadian indices were estimated according to time block, respectively. Also, statistical F and p-values were calculated by zero-amplitude test.Results The data moving average result showed well-fitted cosine curves independent of data processing time. Meanwhile, the amplitude, MESOR, and acrophase were properly estimated within 800 seconds in data summation and data average methods.Conclusion These findings suggest that data moving average would be an optimal method for data processing in a cosinor analysis and data average within 800-second data processing time might be adaptable. The results of this study can be helpful to analyze circadian restactivity rhythms and integrate the results of the studies using different data processing methods.

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Brown, Laurence, Angus Fisk, Carina Pothecary et Stuart Peirson. « Telling the Time with a Broken Clock : Quantifying Circadian Disruption in Animal Models ». Biology 8, n^o 1 (21 mars 2019) : 18. http://dx.doi.org/10.3390/biology8010018.

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Circadian rhythms are approximately 24 h cycles in physiology and behaviour that enable organisms to anticipate predictable rhythmic changes in their environment. These rhythms are a hallmark of normal healthy physiology, and disruption of circadian rhythms has implications for cognitive, metabolic, cardiovascular and immune function. Circadian disruption is of increasing concern, and may occur as a result of the pressures of our modern 24/7 society—including artificial light exposure, shift-work and jet-lag. In addition, circadian disruption is a common comorbidity in many different conditions, ranging from aging to neurological disorders. A key feature of circadian disruption is the breakdown of robust, reproducible rhythms with increasing fragmentation between activity and rest. Circadian researchers have developed a range of methods for estimating the period of time series, typically based upon periodogram analysis. However, the methods used to quantify circadian disruption across the literature are not consistent. Here we describe a range of different measures that have been used to measure circadian disruption, with a particular focus on laboratory rodent data. These methods include periodogram power, variability in activity onset, light phase activity, activity bouts, interdaily stability, intradaily variability and relative amplitude. The strengths and limitations of these methods are described, as well as their normal ranges and interrelationships. Whilst there is an increasing appreciation of circadian disruption as both a risk to health and a potential therapeutic target, greater consistency in the quantification of disrupted rhythms is needed.

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Robinson, Edward L., et Charles A. Fuller. « Endogenous thermoregulatory rhythms of squirrel monkeys in thermoneutrality and cold ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 276, n^o 5 (1 mai 1999) : R1397—R1407. http://dx.doi.org/10.1152/ajpregu.1999.276.5.r1397.

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Whole body heat production (HP) and heat loss (HL) were examined to determine if the free-running circadian rhythm in body temperature (Tb) results from coordinated changes in HP and HL rhythms in thermoneutrality (27°C) as well as mild cold (17°C). Squirrel monkey metabolism ( n = 6) was monitored by both indirect and direct calorimetry, with telemetered measurement of Tb and activity. Feeding was also measured. Rhythms of HP, HL, and conductance were tightly coupled with the circadian Tb rhythm at both ambient temperatures (TA). At 17°C, increased HP compensated for higher HL at all phases of the Tb rhythm, resulting in only minor changes to Tb. Parallel compensatory changes of HP and HL were seen at all rhythm phases at both TA. Similar time courses of Tb, HP, and HL in their respective rhythms and the relative stability of Tb during both active and rest periods suggest action of the circadian timing system on Tb set point.

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Yang, Hui-Wen, Sarah Chellappa, Arlen Gaba, Christian Cajochen et Kun Hu. « 758 Circadian rest-activity signatures in women with major depressive disorder ». Sleep 44, Supplement_2 (1 mai 2021) : A295—A296. http://dx.doi.org/10.1093/sleep/zsab072.755.

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Abstract Introduction Patients with major depressive disorder (MDD) show disrupted circadian rhythms and sleep, including reduced daytime physical activity and poor sleep quality. However, previous findings are masked by psychotropic medication intake, co-morbid diseases and years of chronic mental illness. Here, we aim at identifying circadian motor activity patterns in unmedicated women at the onset of MDD. Methods Twelve young unmedicated women with MDD (Mean+-SD: 24.9+-5.2y; range: 18-33y) and eight age-matched healthy women (Mean+-SD: 24.5+-3.2y; range: 20-31y) participated in our study. Activity recordings were collected using wrist-worn wearable devices (actigraphs) for ~7 days in real-life settings. Cosinor analyses were performed to assess the amplitude and phase of the 24-h rest-activity activity rhythms. Non-parametric analyses were used to quantify interdaily stability and intradaily variability of the rest-activity rhythm. Furthermore, we calculated the mean activity level and scaling exponent alpha, which quantifies the temporal correlation in activity fluctuations, per 3-h bins across the 24-h sleep-wake cycle. Results Women with MDD showed a significantly higher amplitude of the 24-h rest-activity activity rhythm (Mean+-SD: 332.7+-120.8 arbitrary units) than the controls (179.7+-122.9; p=0.002), elicited by higher activity levels during the daytime (0-12h after habitual wake-up time; p<0.01). In contrast, women with MDD showed a trend for lower interdaily stability levels than controls (respectively, 0.41+-0.07 and 0.46+-0.08; p=0.05). Interestingly, a significant interaction effect of “group” and “time since habitual wake” was elicited for scaling exponent alpha (p<0.001). Accordingly, women with MDD had higher alpha values during habitual sleep (0–6 hours before habitual wake-up time) than controls (respectively, 1.18+-0.22 and 1.12+-0.22). Conclusion Unmedicated women at the onset of MDD had altered circadian motor activity patterns, as indexed by higher amplitude particularly during daytime while awake, less stable 24-h activity rhythms, and highly correlated activity patterns during sleep that closely resemble those typically occurring during wakefulness. These findings suggest that MDD per se may be associated with impaired rest-activity profiles. Ultimately, the use of wearable devices might hold important prospects for the early detection of individuals at risk for mood disorders. Support (if any) Swiss National Science Foundation Grants START #3100–055385.98, 3130-0544991.98 and 320000-108108; NIH RF1AG064312, RF1AG059867

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Filipski, Elisabeth, Verdun M. King, Marie-Christine Etienne, XiaoMei Li, Bruno Claustrat, Teresa G. Granda, Gérard Milano, Michael H. Hastings et Francis Lévi. « Persistent twenty-four hour changes in liver and bone marrow despite suprachiasmatic nuclei ablation in mice ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 287, n^o 4 (octobre 2004) : R844—R851. http://dx.doi.org/10.1152/ajpregu.00085.2004.

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Rest-activity or cortisol rhythms can be altered in cancer patients, a condition that may impair the benefits from a timed delivery of anticancer treatments. In rodents, the circadian pattern in rest-activity is suppressed by the destruction of the suprachiasmatic nuclei (SCN) in the hypothalamus. We sought whether such ablation would result in a similar alteration of cellular rhythms known to be relevant for anticancer drug chronopharmacology. The SCN of 77 B6D2F1 mice synchronized with 12 h of light and 12 h of darkness were destroyed by electrocoagulation [SCN(−)], while 34 animals were sham operated. Activity and body temperature were recorded by telemetry. Blood and organs were sampled at one of six circadian times for determinations of serum corticosterone concentration, blood leukocyte count, reduced glutathione (GSH), and dihydropyrimidine dehydrogenase (DPD) mRNA expression in liver and cell cycle phase distribution of bone marrow cells. Sham-operated mice displayed significant 24-h rhythms in rest-activity and body temperature, whereas such rhythms were found in none and in 15% of the SCN(−) mice, respectively. SCN lesions markedly altered the rhythmic patterns in serum corticosterone and liver GSH, which became nonsinusoidal. Liver DPD mRNA expression and bone marrow cell cycle phase distribution displayed similar 24-h sinusoidal patterns in sham-operated and SCN(−) mice. These results support the existence of another light-dark entrainable pacemaker that can coordinate cellular functions in peripheral organs. They suggest that the delivery of anticancer treatments at an optimal time of day may still be beneficial, despite suppressed rest-activity or cortisol rhythms.

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Li, Xiao, Ka Sin Caroline Shea, Ching Kwong Dino Wong, Waiyan Vivian Chiu, Lok Fan Lau, Wai Man Mandy Yu, Albert Martin Li, Y. K. Wing, Yee Ching Kelly Lai et Shirley Xin Li. « 624 The association of circadian rhythms with cognitive functioning in children with attention-deficit hyperactivity disorder ». Sleep 44, Supplement_2 (1 mai 2021) : A245. http://dx.doi.org/10.1093/sleep/zsab072.622.

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Abstract Introduction Disrupted circadian rhythms is associated with impaired cognitive function. Although circadian rhythm disturbances are commonly seen in individuals with attention-deficit hyperactivity disorder (ADHD), whether their cognitive functioning is thus affected remains unclear. This study aimed to examine the associations of circadian-related parameters with different cognitive abilities in children with ADHD. Methods Fifty-seven children with ADHD were recruited into this study (age range: 6–12 years, 66.7% male). They were assessed by parent-report questionnaires on sleep problems (Children’s Sleep Habits Questionnaire, CSHQ), and ADHD symptoms (Strengths and Weaknesses of ADHD Symptoms and Normal Behaviour Scale). Actigraphic data collected for seven consecutive days were analyzed using parametric and nonparametric methods. Cognitive functioning was assessed with Continuous Performance Test (CPT) for sustained attention, Letter-digit test for processing speed, Digit Span test and N-back task for working memory, Tower of London test for planning skills and Bergs Card Sorting Test for set-shifting ability. The relationship between circadian parameters and cognitive performance was analyzed using multiple regression while controlling for age, sex, ADHD medication, the day of cognitive assessment (school days vs non-school days), total sleep time, and CSHQ total score. Results Increased activity during the most active 10-h period of the day (St. β = 0.39, p = 0.012) was related to more omission errors on CPT, and later onset of the least active 5-h period of the day (St. β = 0.44, p = 0.004) was associated with longer correct reaction time on CPT. Lower relative amplitude was associated with poorer performance on Digit Span (St. β = 0.33, p = 0.042). No significant associations were found between the circadian-related parameters and the performance on other tasks measuring processing speed and executive functions. Conclusion Circadian rest-activity rhythms (blunted rest-activity rhythms, higher daytime activity, and later onset of nocturnal rest) were associated with cognitive functioning in ADHD children. Future longitudinal studies are needed to explore the long-term impact of circadian rhythm disturbances and the effects of circadian-focused intervention on cognitive functioning in ADHD children. Support (if any) This work was supported by the Health and Medical Research Fund (Project No.: 30160604).

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McKinnon, Leela, David R. Samson, Charles L. Nunn, Amanda Rowlands, Katrina G. Salvante et Pablo A. Nepomnaschy. « Technological infrastructure, sleep, and rest-activity patterns in a Kaqchikel Maya community ». PLOS ONE 17, n^o 11 (16 novembre 2022) : e0277416. http://dx.doi.org/10.1371/journal.pone.0277416.

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Sleep duration, quality, and rest-activity pattern—a measure for inferring circadian rhythm—are influenced by multiple factors including access to electricity. Recent findings suggest that the safety and comfort afforded by technology may improve sleep but negatively impact rest-activity stability. According to the circadian entrainment hypothesis, increased access to electric lighting should lead to weaker and less uniform circadian rhythms, measured by stability of rest-activity patterns. Here, we investigate sleep in a Maya community in Guatemala who are in a transitional stage of industrialization. We predicted that (i) sleep will be shorter and less efficient in this population than in industrial settings, and that (ii) rest-activity patterns will be weaker and less stable than in contexts with greater exposure to the natural environment and stronger and more stable than in settings more buffered by technologic infrastructure. Our results were mixed. Compared to more industrialized settings, in our study population sleep was 4.87% less efficient (78.39% vs 83.26%). We found no significant difference in sleep duration. Rest-activity patterns were more uniform and less variable than in industrial settings (interdaily stability = 0.58 vs 0.43; intradaily variability = 0.53 vs 0.60). Our results suggest that industrialization does not inherently reduce characteristics of sleep quality; instead, the safety and comfort afforded by technological development may improve sleep, and an intermediate degree of environmental exposure and technological buffering may support circadian rhythm strength and stability.

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Gehrman, Phil, Matthew Marler, Jennifer L. Martin, Tamar Shochat, Jody Corey-Bloom et Sonia Ancoli-Israel. « The relationship between dementia severity and rest/activity circadian rhythms ». Neuropsychiatric Disease and Treatment 1, n^o 2 (2005) : 155–63. http://dx.doi.org/10.2147/nedt.1.2.155.61043.

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Fujioka, Haruna, Masato S. Abe, Taro Fuchikawa, Kazuki Tsuji, Masakazu Shimada et Yasukazu Okada. « Ant circadian activity associated with brood care type ». Biology Letters 13, n^o 2 (février 2017) : 20160743. http://dx.doi.org/10.1098/rsbl.2016.0743.

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In group-living animals, social interactions influence various traits including circadian activity. Maternal care, in particular, can have a strong effect on the circadian activity of parents or nurses across taxa. In social insects, nest-mates are known to have diverse activity rhythms; however, what kind of social environment is crucial in shaping an individual's rhythm is largely unknown. Here, we show that the focal brood types being taken care of (i.e. egg, larva and pupa) have significant effects on individual activity/rest rhythm, using the monomorphic ant Diacamma (putative species indicum ). When isolated from a colony, nurses exhibited a clear circadian rhythm. However, when paired with eggs or larvae, they exhibited around-the-clock activity with no apparent rhythm. In contrast, a clear activity rhythm emerged when nurses were paired with a pupa, requiring little care. Such brood-type-specific changes in circadian activity are considered to arise from the difference in caretaking demands. Our finding may contribute to the understanding of the organization of a colony in the context of behavioural variability under different microenvironments.

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Sommer, Rosa, Lei Yu, Julie A. Schneider, David A. Bennett, Aron S. Buchman et Andrew S. P. Lim. « Disrupted Rest-Activity Rhythms and Cerebral Small Vessel Disease Pathology in Older Adults ». Stroke 52, n^o 7 (juillet 2021) : 2427–31. http://dx.doi.org/10.1161/strokeaha.120.030870.

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Background and Purpose: The pathogenesis of cerebral small vessel disease remains incompletely understood. The relationship between circadian rhythm disturbances and histopathologic measures of cerebral small vessel disease has not been studied. We hypothesized that disrupted circadian rest-activity rhythms would be associated with a higher burden of cerebral small vessel disease pathology. Methods: We studied 561 community-dwelling older adults (mean age at death, 91.2, 27.4% male) from the Rush Memory and Aging Project. We used actigraphy to quantify several measures of 24-hour rest-activity rhythmicity, including interdaily stability, intradaily variability, and amplitude, and used ordinal logistic regression models to relate these measures to the severity of cerebral arteriolosclerosis, atherosclerosis, macroinfarcts, and microinfarcts, assessed at autopsy. Results: Lower interdaily stability was associated with a higher burden of arteriolosclerosis, higher intradaily variability was associated with a higher burden of atherosclerosis and subcortical infarcts, and lower amplitude was associated with a higher burden of arteriosclerosis, atherosclerosis and subcortical macroinfarcts. Moreover, the associations between interdaily stability and arteriolosclerosis and intradaily variability and subcortical infarcts were independent of cardiovascular risk factors, sleep fragmentation, and medical comorbidities. Conclusions: Disrupted rest-activity rhythms are associated with a greater burden of cerebral small vessel disease in older adults.

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Stahl, Sarah. « DIGITAL MONITORING OF SLEEP, MEALS, AND EXERCISE AS A PREVENTIVE INTERVENTION FOR DEPRESSION IN BEREAVED SPOUSES ». Innovation in Aging 3, Supplement_1 (novembre 2019) : S604. http://dx.doi.org/10.1093/geroni/igz038.2249.

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Abstract The death of a spouse brings profound change to bereaved survivors’ lifestyle and daily routine. These changes disrupt circadian rhythms which, in turn, places individuals at high risk for depression. The purpose of this study is to examine the feasibility and acceptability of a 12-week behavioral intervention that targets the timing and regularity of sleep, meals, and physical activity via digital monitoring and motivational health coaching. Participants were 60+ years of age and assessed on intervention acceptability and adherence, depression symptoms (Hamilton Rating Scale for Depression) and the rest-activity rhythm, (a downstream indicator of the body’s circadian rhythm (via actigraphic technology). The intervention was rated highly by participants (n=55); 88% were compliant in digital monitoring and 95% were retained. Depression symptoms declined from pre-to post-intervention; and the regularity of circadian rhythms increased. An intervention that targets the regularity of day- and nighttime activities may reduce depression in older spousally-bereaved adults.

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Bliwise, Donald L. « Circadian Rhythms and Agitation ». International Psychogeriatrics 12, S1 (juillet 2000) : 143–46. http://dx.doi.org/10.1017/s1041610200006931.

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In mammals, many aspects of physiology vary over the 24-hour day in a predictable, periodic manner. Hormones, such as thyroid-stimulating hormone and melatonin, as well as cardiovascular and autonomic measures such as heart rate, blood pressure, and body temperature all have a predictable diurnal pattern. It is important to understand that such variation is generated internally; that is, such variation represents a fundamental, endogenous circadian variation. Circadian variability is typically distinguished from the numerous exogenous factors that can influence the physiologic parameters in question by its periodic pattern (Turek & Zee, 1999). For example, sleep lowers body temperature, and physical activity, upright posture, food intake, and the state of wakefulness increase body temperature. Such exogenous masking factors can affect body temperature at any point in the 24-hour day. Thus, the behavioral act of going to sleep lowers body temperature, but the fall in body temperature during wakefulness also heralds the onset of sleep and incipient sleepiness. Nonetheless, when all such factors are strictly controlled (by having volunteers confined to supine bed rest with restricted activity, sleep deprivation, hourly isocaloric food intake, and controlled lighting conditions), body temperature continues to oscillate in a highly predictable way, affected only by age, sex, and, perhaps, mental status.

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Sultan, Armiya, Vivek Choudhary et Arti Parganiha. « Characteristics of circadian rhythms in rest-activity and energy expendi-ture in cancer in-patients ». South Asian Journal of Experimental Biology 4, n^o 6 (4 février 2015) : 327–35. http://dx.doi.org/10.38150/sajeb.4(6).p327-335.

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The objective of the current study was to assess the rest-activity (RA) and energy expenditure (EE) rhythms in cancer in-patients. Twenty chemothera-py receiving cancer in-patients (10 males and 10 females) and ten apparently healthy human subjects (5 males and 5 females) wore a non-invasive elec-tronic device – the Actical on their non dominant wrist. Data were recorded at 1-minute epoch for at least 3-4 consecutive days. Significant differences in RA and EE patterns were observed between cancer in-patients and control subjects, irrespective of gender. Control subjects showed absolute rhythm detection ratio in RA and EE, whereas, ratio was of low magnitude in cancer patients, especially with reference to EE. Statistically significant decrement in circadian amplitudes and advancement in circadian peaks of RA and EE were observed in cancer in-patients as compared to control subjects. Significant independent effects of factors, namely ‘disease’ and ‘gender’ on total activity count (TAC), average activity count (AAC), total energy expenditure (TEE) and average energy expenditure (AEE) were observed. TEE and AEE were signifi-cantly lower in cancer in-patients as compared to control subjects. Further, factors, ‘disease’ and ‘gender’ also produced significant effects on activity energy expenditure (AcEE), metabolic energy expenditure (MET) and resting energy expenditure (REE). In conclusion, the findings indicate disruption of the circadian rhythms in rest-activity and energy expenditure in cancer in-patients. This disruption is gauged from alterations in rhythm characteristics of RA and EE. However, additional studies involving more patients are re-quired for further validation of the present findings.

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Leng, Y., T. Blackwell, P. M. Cawthon, S. Ancoli-Israel, K. Stone et K. Yaffe. « 1145 Longitudinal Association Between Circadian Activity Rhythms And Risk Of Incident Parkinson’s Disease In Older Men ». Sleep 43, Supplement_1 (avril 2020) : A436. http://dx.doi.org/10.1093/sleep/zsaa056.1139.

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Abstract Introduction Disruption in circadian activity rhythms are very common in older adults, particularly among those with neurodegenerative diseases. However, the longitudinal association between circadian disruption and subsequent risk of developing neurodegenerative diseases, including Parkinson’s disease (PD), is unclear. Methods We examined rest-activity rhythms in 2930 community-dwelling older men (mean age 76.3 ± 5.5 years) without PD and followed them for incident PD over the next 11 years. 24-h rest-activity rhythm parameters (amplitude, mesor, robustness, acrophase) were generated by wrist actigraphy-extended cosinor analysis. Incident PD cases were identified based on physician-diagnosed PD between 2005 and 2016. Logistic regression was used to determine the association between quartiles of rest-activity parameters and risk of incident PD. Results 78 (2.7%) men developed PD during 11 years of follow-up. The risk of PD increased with decreasing circadian amplitude (strength of the rhythm), mesor (mean level of activity) or robustness (how closely activity follows a cosine 24h pattern); p for trend across quartiles <0.05. After accounting for demographics, clinic site, education, depressive symptoms, body mass index, physical activity, benzodiazepine use, alcohol, caffeine, smoking, comorbidities and baseline cognition, those in the lowest quartile of amplitude, mesor or robustness had approximately three times the risk of developing PD compared to those in the highest quartile of amplitude [ORs (95% CI)= 3.11 (1.54-6.29)], mesor [3.04 (1.54-6.01)] and robustness [2.65 (1.24-5.66)]. The association remained after further adjustment for nighttime sleep disturbances and sleep duration. These associations were somewhat attenuated, but the pattern remained similar after excluding PD cases developed within 2 years after baseline. Acrophase was not significantly associated with risk of PD. Conclusion Older men with reduced circadian rhythmicity had an increased risk of incident PD over 11 years. Circadian disruption in the elderly may represent an important prodrome or risk factor for PD. Randomized trials should evaluate whether strategies to improve circadian function impact risk of PD. Support This work was supported by the NIA, NIAMS, NCATS, NIH Roadmap for Medical Research and the NHLBI under the grant numbers: U01AG027810, U01AG042124, U01AG042139, U01AG042140, U01AG042143, U01AG042145, U01AG042168, U01AR066160, UL1TR000128, R01HL071194, R01HL070848, R01HL070847, R01HL070842, R01HL070841, R01HL070837, R01HL070838, and R01HL070839.

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Bulthuis, Nicholas, Katrina R. Spontak, Benjamin Kleeman et Daniel J. Cavanaugh. « Neuronal Activity in Non-LNv Clock Cells Is Required to Produce Free-Running Rest:Activity Rhythms in Drosophila ». Journal of Biological Rhythms 34, n^o 3 (17 avril 2019) : 249–71. http://dx.doi.org/10.1177/0748730419841468.

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Circadian rhythms in behavior and physiology are produced by central brain clock neurons that can be divided into subpopulations based on molecular and functional characteristics. It has become clear that coherent behavioral rhythms result from the coordinated action of these clock neuron populations, but many questions remain regarding the organizational logic of the clock network. Here we used targeted genetic tools in Drosophila to eliminate either molecular clock function or neuronal activity in discrete clock neuron subsets. We find that neuronal firing is necessary across multiple clock cell populations to produce free-running rhythms of rest and activity. In contrast, such rhythms are much more subtly affected by molecular clock suppression in the same cells. These findings demonstrate that network connectivity can compensate for a lack of molecular oscillations within subsets of clock cells. We further show that small ventrolateral (sLNv) clock neurons, which have been characterized as master pacemakers under free-running conditions, cannot drive rhythms independent of communication between other cells of the clock network. In particular, we pinpoint an essential contribution of the dorsolateral (LNd) clock neurons, and show that manipulations that affect LNd function reduce circadian rhythm strength without affecting molecular cycling in sLNv cells. These results suggest a hierarchical organization in which circadian information is first consolidated among one or more clock cell populations before accessing output pathways that control locomotor activity.

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Li, Xiao, Ka Sin Caroline Shea, Lok Fan Lau, Ching Kwong Dino Wong, Waiyan Vivian Chiu, Wai Man Mandy Yu, Albert Martin Li, Y. K. Wing, Yee Ching Kelly Lai et Shirley Xin Li. « 625 The association between circadian rhythms and psychosocial functioning in children with attention deficit hyperactivity disorder ». Sleep 44, Supplement_2 (1 mai 2021) : A245. http://dx.doi.org/10.1093/sleep/zsab072.623.

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Abstract Introduction Circadian rhythm disturbances, including delayed circadian rhythm and increased motor activity, are commonly seen in attention-deficit hyperactivity disorder (ADHD). Previous research suggested a link between circadian rhythm disturbances and poor psychosocial functioning in children, but such a relationship has not been examined in children with ADHD. This study aimed at examining the association between circadian-related parameters and psychosocial functioning in children with ADHD. Methods Seventy-nine children with ADHD were recruited into this study (age range: 6–12 years, 75.9% male). They were assessed by parent-report questionnaires on sleep problems (Children’s Sleep Habits Questionnaire, CSHQ), ADHD symptoms (Strengths and Weaknesses of ADHD Symptoms and Normal Behaviour Scale, SWAN), and psychosocial functioning (Strengths and Difficulties Questionnaire, SDQ). Actigraphic data collected for seven consecutive days were analyzed using parametric and nonparametric methods. The relationship between circadian parameters and psychosocial functioning was analyzed using multiple regression while controlling for age, sex, ADHD medication, total sleep time, and CSHQ total score. Results Later acrophase was significantly associated with higher scores on SDQ emotional problems (St. β = 0.30, p = 0.03) and SWAN inattention subscale (St. β = 0.27, p = 0.043). Lower relative amplitude was associated with higher scores on SDQ hyperactivity symptoms (St. β = -0.29, p = 0.045) and SDQ total difficulties (St. β = -0.31, p = 0.036). Higher levels of mean activity level during the least active 5-h period (L5) were related to higher scores on SDQ peer problems (St. β = 0.38, p = 0.021), SDQ internalizing problems (St. β = 0.38, p = 0.020) and SDQ total difficulties (St. β = 0.33, p = 0.036). Later onset of L5 was associated with increased SDQ emotional problems (St. β = 0.26, p = 0.046). Conclusion Circadian rest-activity rhythm disturbances (delayed phase, blunted rest-activity rhythms, higher level of nocturnal activity, and later onset of nocturnal rest) were associated with poor psychosocial functioning in children with ADHD. Further longitudinal studies are needed to examine the effects of circadian disruption on psychosocial functioning in children with ADHD. Support (if any) This work was supported by the Health and Medical Research Fund (Project No.: 30160604).

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Minaeva, O., E. Schat, E. Ceulemans, Y. Kunkels, A. Smit, M. Wichers, S. Booij et H. Riese. « Individual-specific changes in circadian rest-activity rhythm and sleep in symptom-free patients tapering their antidepressant medication ». European Psychiatry 65, S1 (juin 2022) : S679. http://dx.doi.org/10.1192/j.eurpsy.2022.1747.

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Introduction Group-level studies showed cross-sectional and prospective between-person associations between circadian rest-activity rhythms (RAR), physical activity (PA), sleep, and depressive symptoms. However, whether these associations replicate at the within-person level remains unclear. Therefore, it is clinically relevant to investigate these associations within persons and study whether changes in depressive symptoms are related to changes in circadian rhythm and sleep variables. Objectives To identify changes in circadian rhythm elements in proximity to a transition in depressive symptoms, whether changes are less frequent in individuals without compared to those with transitions, and whether there are individual differences in the direction of change of circadian rhythm variables. Methods Data of remitted individuals tapering antidepressants were used: 12 with and 14 without a transition in depressive symptoms. RAR, PA, and sleep variables were calculated as predictors from four months of actigraphy data. Transitions in depressive symptoms were based on weekly SCL-90 scores and evaluation interviews. Kernel Change Point analyses were used to detect change points (CPs) and CP timing in circadian rhythm variables for each individual separately. Results In 67% of individuals with depressive symptoms transitions, CPs were identified in proximity to symptom transitions. CPs were detected less frequently in the no-transition group with 7 CPs in 14 individuals, compared to transition groups with 10 CPs in 12 individuals. For several RAR and sleep variables, consistent changes were detected in expected directions. Conclusions Circadian rhythm variables provide potentially clinically relevant information although their patterns around transitions are highly person-specific. Future research is needed to disentangle which variables are predictive for which patients. Disclosure No significant relationships.

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Brown, Laurence A., Sibah Hasan, Russell G. Foster et Stuart N. Peirson. « COMPASS : Continuous Open Mouse Phenotyping of Activity and Sleep Status ». Wellcome Open Research 1 (15 novembre 2016) : 2. http://dx.doi.org/10.12688/wellcomeopenres.9892.1.

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Background: Disruption of rhythms in activity and rest occur in many diseases, and provide an important indicator of healthy physiology and behaviour. However, outside the field of sleep and circadian rhythm research, these rhythmic processes are rarely measured due to the requirement for specialised resources and expertise. Until recently, the primary approach to measuring activity in laboratory rodents has been based on voluntary running wheel activity. By contrast, measuring sleep requires the use of electroencephalography (EEG), which involves invasive surgical procedures and time-consuming data analysis. Methods: Here we describe a simple, non-invasive system to measure home cage activity in mice based upon passive infrared (PIR) motion sensors. Careful calibration of this system will allow users to simultaneously assess sleep status in mice. The use of open-source tools and simple sensors keeps the cost and the size of data-files down, in order to increase ease of use and uptake. Results: In addition to providing accurate data on circadian activity parameters, here we show that extended immobility of >40 seconds provides a reliable indicator of sleep, correlating well with EEG-defined sleep (Pearson’s r >0.95, 4 mice). Conclusions: Whilst any detailed analysis of sleep patterns in mice will require EEG, behaviourally-defined sleep provides a valuable non-invasive means of simultaneously phenotyping both circadian rhythms and sleep. Whilst previous approaches have relied upon analysis of video data, here we show that simple motion sensors provide a cheap and effective alternative, enabling real-time analysis and longitudinal studies extending over weeks or even months. The data files produced are small, enabling easy deposition and sharing. We have named this system COMPASS - Continuous Open Mouse Phenotyping of Activity and Sleep Status. This simple approach is of particular value in phenotyping screens as well as providing an ideal tool to assess activity and rest cycles for non-specialists.

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Brown, Laurence A., Sibah Hasan, Russell G. Foster et Stuart N. Peirson. « COMPASS : Continuous Open Mouse Phenotyping of Activity and Sleep Status ». Wellcome Open Research 1 (24 avril 2017) : 2. http://dx.doi.org/10.12688/wellcomeopenres.9892.2.

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Background: Disruption of rhythms in activity and rest occur in many diseases, and provide an important indicator of healthy physiology and behaviour. However, outside the field of sleep and circadian rhythm research, these rhythmic processes are rarely measured due to the requirement for specialised resources and expertise. Until recently, the primary approach to measuring activity in laboratory rodents has been based on voluntary running wheel activity. By contrast, measuring sleep requires the use of electroencephalography (EEG), which involves invasive surgical procedures and time-consuming data analysis. Methods: Here we describe a simple, non-invasive system to measure home cage activity in mice based upon passive infrared (PIR) motion sensors. Careful calibration of this system will allow users to simultaneously assess sleep status in mice. The use of open-source tools and simple sensors keeps the cost and the size of data-files down, in order to increase ease of use and uptake. Results: In addition to providing accurate data on circadian activity parameters, here we show that extended immobility of >40 seconds provides a reliable indicator of sleep, correlating well with EEG-defined sleep (Pearson’s r >0.95, 4 mice). Conclusions: Whilst any detailed analysis of sleep patterns in mice will require EEG, behaviourally-defined sleep provides a valuable non-invasive means of simultaneously phenotyping both circadian rhythms and sleep. Whilst previous approaches have relied upon analysis of video data, here we show that simple motion sensors provide a cheap and effective alternative, enabling real-time analysis and longitudinal studies extending over weeks or even months. The data files produced are small, enabling easy deposition and sharing. We have named this system COMPASS - Continuous Open Mouse Phenotyping of Activity and Sleep Status. This simple approach is of particular value in phenotyping screens as well as providing an ideal tool to assess activity and rest cycles for non-specialists.

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Huang, Yong-Lu, Rong-Yu Liu, Qing-Song Wang, Eus J. W. Van Someren, Hao Xu et Jiang-Ning Zhou. « Age-associated difference in circadian sleep–wake and rest–activity rhythms ». Physiology & ; Behavior 76, n^o 4-5 (août 2002) : 597–603. http://dx.doi.org/10.1016/s0031-9384(02)00733-3.

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Pollak, C. P., P. E. Stokes et P. R. Mourilhe. « Circadian rest-activity rhythms in demented nondemented elders and their caregivers ». Biological Psychiatry 39, n^o 7 (avril 1996) : 661. http://dx.doi.org/10.1016/0006-3223(96)84486-6.

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Rogers, Tara S., Stephanie Harrison, Christine Swanson, Jane A. Cauley, Elizabeth Barrett-Connor, Eric Orwoll, Katie L. Stone et Nancy E. Lane. « Rest-activity circadian rhythms and bone mineral density in elderly men ». Bone Reports 7 (décembre 2017) : 156–63. http://dx.doi.org/10.1016/j.bonr.2017.11.001.

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Wu, JQ, K. Hu, K. Stavitsky Gilbert et A. Cronin-Golomb. « 1142 CIRCADIAN REST-ACTIVITY RHYTHMS AND COGNITIVE FUNCTION IN PARKINSON’S DISEASE ». Sleep 40, suppl_1 (28 avril 2017) : A426. http://dx.doi.org/10.1093/sleepj/zsx050.1141.

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Wang, Joshua L., Andrew S. Lim, Wei-Yin Chiang, Wan-Hsin Hsieh, Men-Tzung Lo, Julie A. Schneider, Aron S. Buchman, David A. Bennett, Kun Hu et Clifford B. Saper. « Suprachiasmatic neuron numbers and rest-activity circadian rhythms in older humans ». Annals of Neurology 78, n^o 2 (18 juin 2015) : 317–22. http://dx.doi.org/10.1002/ana.24432.

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Dudek, Michal, et Qing-Jun Meng. « Running on time : the role of circadian clocks in the musculoskeletal system ». Biochemical Journal 463, n^o 1 (8 septembre 2014) : 1–8. http://dx.doi.org/10.1042/bj20140700.

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The night and day cycle governs the circadian (24 hourly) rhythm of activity and rest in animals and humans. This is reflected in daily changes of the global gene expression pattern and metabolism, but also in the local physiology of various tissues. A central clock in the brain co-ordinates the rhythmic locomotion behaviour, as well as synchronizing various local oscillators, such as those found in the musculoskeletal system. It has become increasingly recognized that the internal molecular clocks in cells allow a tissue to anticipate the rhythmic changes in their local environment and the specific demands of that tissue. Consequently, the majority of the rhythmic clock controlled genes and pathways are tissue specific. The concept of the tissue-specific function of circadian clocks is further supported by the diverse musculoskeletal phenotypes in mice with deletions or mutations of various core clock components, ranging from increased bone mass, dwarfism, arthropathy, reduced muscle strength and tendon calcification. The present review summarizes the current understanding of the circadian clocks in muscle, bone, cartilage and tendon tissues, with particular focus on the evidence of circadian rhythms in tissue physiology, their entrainment mechanisms and disease links, and the tissue-specific clock target genes/pathways. Research in this area holds strong potential to advance our understanding of how circadian rhythms control the health and disease of the musculoskeletal tissues, which has major implications in diseases associated with advancing age. It could also have potential implications in sports performance and sports medicine.

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Hammad, Grégory, Mathilde Reyt, Nikita Beliy, Marion Baillet, Michele Deantoni, Alexia Lesoinne, Vincenzo Muto et Christina Schmidt. « pyActigraphy : Open-source python package for actigraphy data visualization and analysis ». PLOS Computational Biology 17, n^o 10 (19 octobre 2021) : e1009514. http://dx.doi.org/10.1371/journal.pcbi.1009514.

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Over the past 40 years, actigraphy has been used to study rest-activity patterns in circadian rhythm and sleep research. Furthermore, considering its simplicity of use, there is a growing interest in the analysis of large population-based samples, using actigraphy. Here, we introduce pyActigraphy, a comprehensive toolbox for data visualization and analysis including multiple sleep detection algorithms and rest-activity rhythm variables. This open-source python package implements methods to read multiple data formats, quantify various properties of rest-activity rhythms, visualize sleep agendas, automatically detect rest periods and perform more advanced signal processing analyses. The development of this package aims to pave the way towards the establishment of a comprehensive open-source software suite, supported by a community of both developers and researchers, that would provide all the necessary tools for in-depth and large scale actigraphy data analyses.

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Li, Xiao-Mei, Xu-Hui Liu, Elisabeth Filipski, Gérard Metzger, Philippe Delagrange, Jean-Philippe Jeanniot et Francis Lévi. « Relationship of atypical melatonin rhythm with two circadian clock outputs in B6D2F1 mice ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 278, n^o 4 (1 avril 2000) : R924—R930. http://dx.doi.org/10.1152/ajpregu.2000.278.4.r924.

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Circadian rhythms in body temperature, locomotor activity, and the circadian changes of plasma and pineal melatonin content were investigated in B6D2F1mice synchronized by 12 h of light and 12 h of darkness. During 8 wk continuous recording, activity and temperature displayed a marked stable and reproducible circadian rhythm, with both peaks occurring near the middle of darkness. Both 24- and 12-h rhythmic components were also significantly detected. Mean plasma melatonin concentration rose steadily during the light span and reached a maximum (30.6 ± 10.0 pg/ml) at 11 h after light onset (HALO), then gradually decreased after the onset of darkness to a nadir (4.7 ± 0.4 pg/ml) at 20 HALO. Mean pineal content followed a pattern parallel to that of plasma concentration (peak at 11 HALO: 17.7 ± 1.0 pg/gland; trough at 17 HALO: 4.7 ± 1.0 pg/gland). In addition, a second sharp peak was observed at 21 HALO (20.2 ± 3.5 pg/gland). Plasma and pineal contents displayed large and statistically significant circadian changes, with a composite rhythm of period (24 + 12 h). This mouse model has predominant production and secretion of melatonin during the day. This possibly contributes to a similar coupling between chronopharmacology mechanisms and the rest-activity cycle in these mice and in human subjects.

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Hoopes, Elissa, Michele D'Agata, Talia Brookstein-Burke, Shannon Robson, Melissa Witman, Susan Malone et Freda Patterson. « 0003 On the Same Wavelength ? Quantifying the Associations between Eating Timing and Rest-Activity Rhythms in Free-Living Adults ». Sleep 45, Supplement_1 (25 mai 2022) : A1—A2. http://dx.doi.org/10.1093/sleep/zsac079.002.

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Abstract Introduction Misalignment between the central circadian clock and daily behaviors increases cardiometabolic morbidity and mortality risk, likely due to internal misalignment between central and peripheral circadian rhythms. Experimental studies suggest food intake may act as a time cue (‘zeitgeber’) for resetting circadian rhythms, representing a potential behavioral target to ameliorate circadian misalignment and associated health consequences. However, the extent to which eating timing relates to circadian rhythms in free-living adults is unclear. Therefore, we tested the associations between eating timing with 24-h rest-activity-rhythms (RAR), a free-living proxy for endogenous circadian rhythms, in non-shift-working adults. Methods Adults without chronic health conditions or sleep disorders completed 14 days of 24/7 wrist accelerometry to evaluate RAR variables of interdaily stability (IS; day-to-day stability in RAR), intradaily variability (IV; within-day fragmentation of RAR), relative amplitude (RA; difference between peak vs. trough activity), L5 onset time (5-h period with lowest activity), and M10 onset time (10-h period with highest activity). Concurrently, time-stamped image-assisted diet records were obtained to generate average eating timing variables, including daily eating onset (time of first caloric intake after awakening), offset (last caloric intake time), duration (time elapsed between eating onset and offset), and caloric midpoint (time at which 50% of daily kcals were consumed), and variables illustrating irregularity in eating timing (standard deviation of eating timing variables). Pearson’s correlations quantified the associations between RAR and eating timing variables. Results Participants (N=30) were 28.0±6.6 years, 57% female, with a BMI of 23.8±2.5 kg/m2. Higher IS was correlated with lower irregularity in both eating onset (r=-0.55, p<0.01) and duration (r=-0.51, p<0.01). Higher RA correlated with earlier eating onset (r=-0.47, p<0.01), longer eating duration (r=0.53, p<0.01), and lower eating onset irregularity (r=-0.37, p<0.05). Later L5 correlated with later eating onset (r=0.67, p<0.001), offset (r=0.58, p<0.001), caloric midpoint (r=0.56, p<0.01), and greater eating offset irregularity (r=0.53, p<0.01). Later M10 correlated with later eating offset (r=0.40, p<0.05). Conclusion Preliminary findings indicate that eating timing and RAR are moderately correlated in free-living adults. Earlier eating timing, increased eating regularity, and longer daily eating duration may represent behavioral targets for improving circadian rhythms and subsequent cardiometabolic outcomes. Support (If Any): Support provided by the American Heart Association (#831488) and a University of Delaware Research Fund-Strategic Initiative Award.

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Chaix, Amandine, Emily N. C. Manoogian, Girish C. Melkani et Satchidananda Panda. « Time-Restricted Eating to Prevent and Manage Chronic Metabolic Diseases ». Annual Review of Nutrition 39, n^o 1 (21 août 2019) : 291–315. http://dx.doi.org/10.1146/annurev-nutr-082018-124320.

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Molecular clocks are present in almost every cell to anticipate daily recurring and predictable changes, such as rhythmic nutrient availability, and to adapt cellular functions accordingly. At the same time, nutrient-sensing pathways can respond to acute nutrient imbalance and modulate and orient metabolism so cells can adapt optimally to a declining or increasing availability of nutrients. Organismal circadian rhythms are coordinated by behavioral rhythms such as activity–rest and feeding–fasting cycles to temporally orchestrate a sequence of physiological processes to optimize metabolism. Basic research in circadian rhythms has largely focused on the functioning of the self-sustaining molecular circadian oscillator, while research in nutrition science has yielded insights into physiological responses to caloric deprivation or to specific macronutrients. Integration of these two fields into actionable new concepts in the timing of food intake has led to the emerging practice of time-restricted eating. In this paradigm, daily caloric intake is restricted to a consistent window of 8–12 h. This paradigm has pervasive benefits on multiple organ systems.

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Lucas-Sánchez, Alejandro, Pedro Francisco Almaida-Pagán, Antonio Martinez-Nicolas, Juan Antonio Madrid, Pilar Mendiola et Jorge de Costa. « Rest-activity circadian rhythms in aged Nothobranchius korthausae. The effects of melatonin ». Experimental Gerontology 48, n^o 5 (mai 2013) : 507–16. http://dx.doi.org/10.1016/j.exger.2013.02.026.

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Lazreg, T. Ben, I. Laatiri et M. Dogui. « Circadian activity–rest and sleep–wake rhythms in blind adolescents and adults ». Biological Rhythm Research 42, n^o 3 (juin 2011) : 219–29. http://dx.doi.org/10.1080/09291016.2010.500869.

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Alfini, Alfonso, Marilyn Albert, Andreia Faria, Anja Soldan, Corinne Pettigrew, Sarah Wanigatunga, Vadim Zipunnikov et Adam Spira. « 045 Associations of Actigraphic Sleep and Circadian Rest/Activity Rhythms with Cognition in the Early Phase of Alzheimer’s Disease ». Sleep 44, Supplement_2 (1 mai 2021) : A19—A20. http://dx.doi.org/10.1093/sleep/zsab072.044.

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Abstract Introduction Alterations in sleep and circadian rhythms are common in persons with Alzheimer’s disease (AD) dementia, but the nature of such changes in the early phases of AD remains unclear. This study compared sleep and circadian rest/activity rhythms (RARs), measured by standard and novel actigraphic indices, between participants with normal cognition or mild cognitive impairment (MCI), and examined cross-sectional associations between these measures and cognition. Methods Actigraphy data were collected in 179 individuals (mean age=72.6 years, gender=64.8% female) with normal cognition (n=153) or MCI (n=26) from the Biomarkers for Older Controls at Risk of Dementia (BIOCARD) study. Standard sleep parameters (i.e., total sleep time [TST], sleep efficiency [SE], wake after sleep onset [WASO], average wake bout length [WBL]), and standard non-parametric RAR metrics (i.e., relative amplitude [RA], intradaily variability [IV], interdaily stability [IS]) were generated. Functional principal component (fPC) methods were used to generate three novel RAR indices (fPC1, fPC2, fPC3) representing 69% of the total variance. Cognitive test scores were used to generate composite measures reflecting the domains of episodic memory and executive function using factor analysis. Regression models were used to compare sleep and circadian RAR parameters between the diagnostic groups and to evaluate their associations with cognitive performance. Results After adjustment for age, sex, education, and APOE-4 genotype, compared to normal controls, MCI subjects had significantly lower SE, lower RA, and lower scores on the novel RAR measure fPC3, which reflects a later rhythm phase, lower amplitude, and lower activity both at night and early in the day. In analyses combining data from participants with MCI and controls, several standard RAR parameters (e.g., higher RA and IS) and higher fPC3 scores were associated with both better episodic memory and executive function. Additionally, several standard measures (e.g., lower WASO and IV) and lower fPC1 scores (reflecting higher rhythm amplitude and greater activity throughout daytime hours) were linked with better executive function. Conclusion MCI participants have sleep and circadian alterations, which are significantly associated with cognitive performance. A novel RAR measure, fPC3, showed differences in rhythm patterns that extended from the night into the daytime. Support (if any) Funding-support NIA (U19-AG033655, T32-AG027668, R01-AG050507) and AASMF (#223-BS-19).

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Helfrich-Förster, Charlotte, Michael N. Nitabach et Todd C. Holmes. « Insect circadian clock outputs ». Essays in Biochemistry 49 (30 juin 2011) : 87–101. http://dx.doi.org/10.1042/bse0490087.

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Insects display an impressive variety of daily rhythms, which are most evident in their behaviour. Circadian timekeeping systems that generate these daily rhythms of physiology and behaviour all involve three interacting elements: the timekeeper itself (i.e. the clock), inputs to the clock through which it entrains and otherwise responds to environmental cues such as light and temperature, and outputs from the clock through which it imposes daily rhythms on various physiological and behavioural parameters. In insects, as in other animals, cellular clocks are embodied in clock neurons capable of sustained autonomous circadian rhythmicity, and those clock neurons are organized into clock circuits. Drosophila flies spend their entire lives in small areas near the ground, and use their circadian brain clock to regulate daily rhythms of rest and activity, so as to organize their behaviour appropriately to the daily rhythms of their local environment. Migratory locusts and butterflies, on the other hand, spend substantial portions of their lives high up in the air migrating long distances (sometimes thousands of miles) and use their circadian brain clocks to provide time-compensation to their sun-compass navigational systems. Interestingly, however, there appear to be substantial similarities in the cellular and network mechanisms that underlie circadian outputs in all insects.

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Mesquita, Maria Eugênia, Maria Eliza Finazzi, Bruno Gonçalves, Lee Fu-I, Leandro L. Duarte, José Ricardo Lopes, José Alberto Del-Porto et Luiz Menna-Barreto. « Activity/rest rhythm of depressed adolescents undergoing therapy : case studies ». Trends in Psychiatry and Psychotherapy 38, n^o 4 (décembre 2016) : 216–20. http://dx.doi.org/10.1590/2237-6089-2015-0053.

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Abstract Introduction: Disorders of circadian rhythms have been reported in studies of both depressed children and of depressed adolescents. The aim of this study was to evaluate whether there is a relationship between the 24-hour spectral power (24h SP) of the activity/rest rhythm and the clinical course of depression in adolescents. Methods: Six 14 to 17-year-old adolescents were recruited for the study. They were all suffering from major depressive disorder, according to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) criteria, as identified by the Schedule for Affective Disorders and Schizophrenia for School Aged Children: Present and Lifetime Version (K-SADS-PL). Depressive symptoms were assessed using the Children's Depression Rating Scale - Revised (CDRS-R) and clinical evaluations. Locomotor activity was monitored over a period of 13 consecutive weeks. Activity was measured for 10-minute periods using wrist-worn activity monitors. All patients were prescribed sertraline from after the first week up until the end of the study. Results: We found a relationship between high CDRS values and low 24-hour spectral power. Conclusions: The 24h SP of the activity/rest rhythm correlated significantly (negatively) with the clinical ratings of depression.

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Tsai, Shao-Yu, Kathryn E. Barnard, Martha J. Lentz et Karen A. Thomas. « Mother-Infant Activity Synchrony as a Correlate of the Emergence of Circadian Rhythm ». Biological Research For Nursing 13, n^o 1 (26 août 2010) : 80–88. http://dx.doi.org/10.1177/1099800410378889.

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Objective: Entrainment to the day—night cycle is critical for infant sleep and social development. Synchronization of infant circadian systems with the social 24-hr day may require maternal activity signals as an entraining cue. This descriptive and exploratory research examines the activity level and circadian pattern in mothers and infants. Method: Twenty-two healthy mothers and their infants (postnatal age 49.8 ± 17.1 days) wore actigraph monitors for seven days. Daytime (06:00—21:59) and nighttime (22:00—05:59) activity levels and circadian parameters of rest—activity patterns (i.e., mesor, amplitude, acrophase, and 24-hr cosinor fit) were calculated. Results: Mothers and infants were significantly more active during the day than at night. The goodness-of-fit index for the model (R2) indicates that circadian rhythm accounted for a mean of 29 ± 10% and 12 ± 8% of the variability in maternal and infant activity, respectively. Acrophase of activity occurred at 15:46 ± 1:07 for the mothers and 15:20 ± 1:21 for the infants. The mean within-dyad correlation of activity counts was r = .46 ± .11, and the within-dyad correlation was associated with the amplitude (r = .66, p < .01) and 24-hr cosinor fit of infant activity (r = .67, p < .01). Conclusions: Our findings suggest maternal rhythms as a possible exogenous influence on shaping an infant’s emerging rhythms and synchronizing them with the external light—dark cycle. Strong pattern synchrony between maternal and infant activity may support infant circadian entrainment and enhance a regular 24-hr sleep—wake schedule during the early postnatal weeks.

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Boughattas, NA, XM Li, J. Filipski, G. Lemaigre, E. Filipski, K. Bouzouita, O. Belhadj et F. Lévi. « Modulation of cisplatin chronotoxicity related to reduced glutathione in mice ». Human & ; Experimental Toxicology 15, n^o 7 (juillet 1996) : 563–72. http://dx.doi.org/10.1177/096032719601500703.

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Intracellular reduced glutathione (GSH) concentrations were measured according to the tissue sampling-time along the 24 h scale in male B6D2F1 mice. A significant circadian rhythm in GSH content was statistically validated in liver, jejunum, colon and bone-marrow (P≤0.02) but not in kidney. Tissue GSH concentration increased in the dark-activity span and decreased in the light-rest span of mice. The minimum and maximum of tissue GSH content corresponded respectively to the maximum and minimum of cisplatin (CDDP) toxicity. The role of GSH rhythms with regard to CDDP toxicity was investigated, using a specific inhibitor of GSH biosynth esis, buthionine sulfoximine (BSO). Its effects were assessed on both tissue GSH levels and CDDP toxicity at three circadian times. BSO resulted in a 10-fold decrease of the 24 h-mean GSH in kidney. However a moderate GSH decrease characterized liver (-23%) and jejunum (-30%). BSO pretreatment largely enhanced CDDP toxicity which varied according to a circadian rhythm. Although BSO partly and/or totally abolished the tissue GSH rhythms, it did not modify those in CDDP toxicity. We conclude that GSH have an important influence on CDDP toxicity but not in the circadian mechanism of such platinum chronotoxicity.

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Innominato, Pasquale F., Oxana Palesh, Georg A. Bjarnason, Ayhan Ulusakarya, David Spiegel et Francis Levi. « Symptoms associated with circadian rest-activity rhythm disruption in 237 patients with metastatic colorectal cancer. » Journal of Clinical Oncology 33, n^o 29_suppl (10 octobre 2015) : 1. http://dx.doi.org/10.1200/jco.2015.33.29_suppl.1.

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1 Background: The circadian timing system exerts temporal control over physiology, generating rhythms of about 24 hours. Its alteration in benign conditions has been associated with several systemic symptoms, including fatigue, appetite loss and poor sleep. However, the clinical impact of circadian disruption in cancer patients remains overlooked. We hypothesized that patients with circadian disruption would report more severe symptoms than those with robust circadian function. Methods: Data were available for 237 patients with metastatic colorectal cancer: M/F ratio: 1.66; median age: 60.4 years; range: 20.7-77.6; WHO Performance Status (PS) = 0/1: 59.7%/33.5%. We estimated the occurrence of circadian disruption using a validated parameter (the dichotomy index I < O), derived from wrist-actigraphy for at least 72 consecutive hours. Symptoms were self-reported by the patients using the EORTC QLQ-C30 questionnaire. Mann-Whitney U test was used to compare symptom severity according to the presence or absence of circadian disruption. Cohen’s d effect sizes were computed to evaluate the clinical meaningfulness of the observed differences. Subgroup analyses were performed according to gender, age, and WHO Performance Status (PS). Results: Circadian disruption (I < O lower than or equal to 97.5%) occurred in 130 (54.9%) patients. Fatigue (p < 0.0001), appetite loss (p < 0.0001), difficulty sleeping (p = 0.009), pain (p < 0.0001) and dyspnea (p = 0.001) were significantly more severe in patients with circadian disruption than in those with robust circadian function. Largest effect sizes were observed for fatigue (0.64), appetite loss (0.59) and pain (0.57). Subgroup analyses showed similar results, regardless of gender, age or PS. Conclusions: In this large international study, the presence of circadian disruption was associated with a clinically meaningfully higher severity of fatigue, appetite loss, pain, dyspnea and sleep problems. Correcting circadian dysfunction with the use of pharmacological and/or behavioural interventions could improve these often difficult-to-manage systemic symptoms.

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Brüning, Franziska, Sara B. Noya, Tanja Bange, Stella Koutsouli, Jan D. Rudolph, Shiva K. Tyagarajan, Jürgen Cox, Matthias Mann, Steven A. Brown et Maria S. Robles. « Sleep-wake cycles drive daily dynamics of synaptic phosphorylation ». Science 366, n^o 6462 (10 octobre 2019) : eaav3617. http://dx.doi.org/10.1126/science.aav3617.

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The circadian clock drives daily changes of physiology, including sleep-wake cycles, through regulation of transcription, protein abundance, and function. Circadian phosphorylation controls cellular processes in peripheral organs, but little is known about its role in brain function and synaptic activity. We applied advanced quantitative phosphoproteomics to mouse forebrain synaptoneurosomes isolated across 24 hours, accurately quantifying almost 8000 phosphopeptides. Half of the synaptic phosphoproteins, including numerous kinases, had large-amplitude rhythms peaking at rest-activity and activity-rest transitions. Bioinformatic analyses revealed global temporal control of synaptic function through phosphorylation, including synaptic transmission, cytoskeleton reorganization, and excitatory/inhibitory balance. Sleep deprivation abolished 98% of all phosphorylation cycles in synaptoneurosomes, indicating that sleep-wake cycles rather than circadian signals are main drivers of synaptic phosphorylation, responding to both sleep and wake pressures.

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Levi, Francis, Sandra Komarzynski, Qi Huang, Teresa Young, Yeng Ang, Claire Fuller, Julia Brettschneider et al. « Relevance of real-time teletransmission of physical activity, sleep, and circadian rhythms from gastrointestinal cancer (GIC) patients (pts) during daily routine (IDEAs, IRAS 233972). » Journal of Clinical Oncology 38, n^o 4_suppl (1 février 2020) : 801. http://dx.doi.org/10.1200/jco.2020.38.4_suppl.801.

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801 Background: The relative amount of activity and rest over the 24-hours, as measured by the dichotomy index I < O from actimetry records, is an independent predictor of overall survival and quality of life, and an early warning signal for emergency hospitalisation. The IDEAs study aimed to determine the sleep, physical and circadian pathologies in pts during their daily routine at home, which could lower I < O and be modifiable through personalised interventions. Methods: The rest-activity and surface temperature patterns were monitored in real time using a tele-transmitting chest sensor and a GPRS-platform for one week in 25 pts, with a WHO performance status of 0-1 and metastatic GIC (colorectal, 56%). Each pt completed questionnaires including Chronotype, HADS, and Pittsburgh Sleep Index, filled a precise diary of daily activities, meals and sleep times, and the MD Anderson Symptoms Inventory daily. I < O counts the In-bed activity bouts per min that are below the median activity Out-of-bed. Other pt-specific circadian parameters were estimated with spectral analyses and Hidden Markov models (HMM). I < O predictors were identified through correlation and regression analyses. Results: A poor I < O was found for 13 pts (52%). Self-reported scores for sleep quality or physical fitness showed no significant differences according to I < O. Yet HMM-modelled rest-activity revealed that pts with poor I < O had lower activity out-of-bed (median activity counts per minute, 110 vs 52, p = 0.001) and fractionated sleep (probability of remaining at rest when asleep, 94% vs 90%, p = 0.01). Poor I < O was significantly associated with an abnormal circadian rhythm in chest surface temperature, that was either wrongly timed or suppressed, for 83% of the pts as compared to 25% of those with a good I < O (p = 0.012). Conclusions: Nearly half of the pts displayed altered circadian rest-activity rhythm, with poor sleep and low daytime activity. In most of them, the circadian rhythm in body temperature, which critically regulates sleep, was abnormal. Exploration and specific treatment of sleep and circadian disorders are warranted for improving outcomes in cancer pts. Clinical trial information: 233972.

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Kolberg, Eirin, Ståle Pallesen, Gunnhild Johnsen Hjetland, Inger Hilde Nordhus et Elisabeth Flo-Groeneboom. « The Effect of Bright Light Treatment on Rest–Activity Rhythms in People with Dementia : A 24-Week Cluster Randomized Controlled Trial ». Clocks & ; Sleep 3, n^o 3 (13 septembre 2021) : 449–64. http://dx.doi.org/10.3390/clockssleep3030032.

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Bright light treatment is an effective way to influence circadian rhythms in healthy adults, but previous research with dementia patients has yielded mixed results. The present study presents a primary outcome of the DEM.LIGHT trial, a 24-week randomized controlled trial conducted at nursing homes in Bergen, Norway, investigating the effects of a bright light intervention. The intervention consisted of ceiling-mounted LED panels providing varying illuminance and correlated color temperature throughout the day, with a peak of 1000 lx, 6000 K between 10 a.m. and 3 p.m. Activity was recorded using actigraphs at baseline and after 8, 16, and 24 weeks. Non-parametric indicators and extended cosine models were used to investigate rest–activity rhythms, and outcomes were analyzed with multi-level regression models. Sixty-one patients with severe dementia (median MMSE = 4) were included. After 16 weeks, the acrophase was advanced from baseline in the intervention group compared to the control group (B = −1.02, 95%; CI = −2.00, −0.05). There was no significant difference between the groups on any other rest–activity measures. When comparing parametric and non-parametric indicators of rest–activity rhythms, 25 out of 35 comparisons were significantly correlated. The present results indicate that ambient bright light treatment did not improve rest–activity rhythms for people with dementia.

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Lévi, Francis, Sandra Komarzynski, Qi Huang, Teresa Young, Yeng Ang, Claire Fuller, Matei Bolborea et al. « Tele-Monitoring of Cancer Patients’ Rhythms during Daily Life Identifies Actionable Determinants of Circadian and Sleep Disruption ». Cancers 12, n^o 7 (17 juillet 2020) : 1938. http://dx.doi.org/10.3390/cancers12071938.

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The dichotomy index (I < O), a quantitative estimate of the circadian regulation of daytime activity and sleep, predicted overall cancer survival and emergency hospitalization, supporting its integration in a mHealth platform. Modifiable causes of I < O deterioration below 97.5%—(I < O)low—were sought in 25 gastrointestinal cancer patients and 33 age- and sex-stratified controls. Rest-activity and temperature were tele-monitored with a wireless chest sensor, while daily activities, meals, and sleep were self-reported for one week. Salivary cortisol rhythm and dim light melatonin onset (DLMO) were determined. Circadian parameters were estimated using Hidden Markov modelling, and spectral analysis. Actionable predictors of (I < O)low were identified through correlation and regression analyses. Median compliance with protocol exceeded 95%. Circadian disruption—(I < O)low—was identified in 13 (52%) patients and four (12%) controls (p = 0.002). Cancer patients with (I < O)low had lower median activity counts, worse fragmented sleep, and an abnormal or no circadian temperature rhythm compared to patients with I < O exceeding 97.5%—(I < O)high—(p < 0.012). Six (I < O)low patients had newly-diagnosed sleep conditions. Altered circadian coordination of rest-activity and chest surface temperature, physical inactivity, and irregular sleep were identified as modifiable determinants of (I < O)low. Circadian rhythm and sleep tele-monitoring results support the design of specific interventions to improve outcomes within a patient-centered systems approach to health care.

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Klerman, Elizabeth B., David W. Rimmer, Derk-Jan Dijk, Richard E. Kronauer, Joseph F. Rizzo et Charles A. Czeisler. « Nonphotic entrainment of the human circadian pacemaker ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 274, n^o 4 (1 avril 1998) : R991—R996. http://dx.doi.org/10.1152/ajpregu.1998.274.4.r991.

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In organisms as diverse as single-celled algae and humans, light is the primary stimulus mediating entrainment of the circadian biological clock. Reports that some totally blind individuals appear entrained to the 24-h day have suggested that nonphotic stimuli may also be effective circadian synchronizers in humans, although the nonphotic stimuli are probably comparatively weak synchronizers, because the circadian rhythms of many totally blind individuals “free run” even when they maintain a 24-h activity-rest schedule. To investigate entrainment by nonphotic synchronizers, we studied the endogenous circadian melatonin and core body temperature rhythms of 15 totally blind subjects who lacked conscious light perception and exhibited no suppression of plasma melatonin in response to ocular bright-light exposure. Nine of these fifteen blind individuals were able to maintain synchronization to the 24-h day, albeit often at an atypical phase angle of entrainment. Nonphotic stimuli also synchronized the endogenous circadian rhythms of a totally blind individual to a non-24-h schedule while living in constant near darkness. We conclude that nonphotic stimuli can entrain the human circadian pacemaker in some individuals lacking ocular circadian photoreception.

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