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BACKGROUND: There is little knowledge about rest-activity cycles (RAC) in patients with severe-acquired brain injury (sABI) during early in-hospital rehabilitation. This study aimed to investigate if patients with sABI displayed unconsolidated RACs at the beginning of in-hospital rehabilitation, and how these changed over time.METHODS: This study was a prospective observational study. All patients consecutively admitted to one ward were screened for eligibility. We recorded accelerometric activity for 20 days. The Daytime Activity Ratio (DAR) of activity between daytime (7-22) and the total activity during the entire day was calculated and used to estimate consolidation.RESULTS: Fifty-five patients were screened and 20 patients were included. Complete day 1 & 2 data was obtained on 18 patients. Fifty-six percentage of these had a consolidated RAC at the beginning of rehabilitation. On day 19 & 20, complete data could be obtained from 15 patients, 80% of these had consolidation of RAC. When comparing these a significant mean increase of 5.8% 95%CI(0.52; 11.01) in DAR was found p < .05, and the model of all data also showed a significant increase in median DAR over time p < .01.CONCLUSION: RAC consolidation improves over time in patients admitted for in-hospital early neurorehabilitation.

We evaluated the effects of the exposure to radio-frequency radiation emanating from the base transceiver station (BTS) on the characteristics of circadian rest-activity rhythm and behavioral sleep...

Cancer-related fatigue can continue long after curative cancer treatment. The aim of this study was to investigate sleep and rest–activity cycles in fatigued and non-fatigued cancer survivors. We hypothesized that sleep and rest–activity cycles would be more disturbed in people experiencing clinically-relevant fatigue, and that objective measures of sleep would be associated with the severity of fatigue in cancer survivors. Cancer survivors (n = 87) completed a 14-day wrist actigraphy measurement to estimate their sleep and rest–activity cycles. Fatigue was measured using the Functional Assessment of Chronic Illness Therapy Fatigue Scale (FACIT-F). Participants were dichotomised into two groups using a previously validated score (fatigued n = 51 and non-fatigued n = 36). The participant’s perception of sleep was measured using the Insomnia Severity Index (ISI). FACIT-F score was correlated with wake after sleep onset (r = −0.28, p = 0.010), sleep efficiency (r = 0.26, p = 0.016), sleep onset latency (r = −0.31, p = 0.044) and Insomnia Severity Index (ISI) score (r = −0.56, p &lt, 0.001). The relative amplitude of the rest–activity cycles was lower in the fatigued vs. the non-fatigued group (p = 0.017, d = 0.58). After treatment for cancer, the severity of cancer-related fatigue is correlated with specific objective measures of sleep, and there is evidence of rest–activity cycle disruption in people experiencing clinically-relevant fatigue.

Sleep disturbance and decreased daytime activity are well-described among people with chronic heart failure (HF) who suffer from disabling daytime symptoms and poor function. Alterations in the circadian rhythmicity of rest-activity may also be associated with these outcomes. However, little is known about the associations between rest-activity rhythms (RARS), symptoms, and functional performance or the extent to which they are explained by sleep characteristics among people with HF. The purpose of this study is to evaluate parametric and non-parametric circadian characteristics of RARs and the associations between these variables, daytime symptoms, and functional performance among patients with stable heart failure (HF). We recruited adults with stable HF from HF disease management programs. Participants wore wrist actigraphs for 3 d, completed one night of unattended polysomnography and the Six Minute Walk Test, and reported daytime symptoms and physical function. We performed cosinor, non-parametric, and spectral analyses to evaluate the rest-activity rhythms and computed bivariate correlations between the rest-activity rhythm, demographics, daytime symptoms, and functional performance. We conducted multiple regression analysis to examine how RARs contribute to daytime symptoms and functional performance after controlling for insomnia and covariates. The sample included 135 participants [Mean age = 60.6 (16.1) y, n = 88 (65.2%) male]. Older age, greater comorbidity, and poorer New York Heart Association (NYHA) Class, and more EEG arousals were associated with greater intra-daily variability of the RAR. More robust rhythmicity represented by the circadian quotient was associated with better NYHA class and less sleep fragmentation. A higher circadian quotient was significantly associated with lower fatigue, depression, and sleepiness, and better functional performance after controlling for insomnia and clinical and demographic characteristics. Circadian parameters of rest-activity are associated with symptoms and functional performance among people with HF independent of insomnia or sleep disordered breathing. Interventions targeted at improving the stability and strength of rest-activity rhythms may improve symptom and functional outcomes for these patients.

Increasing evidence suggests an association between typical age-related changes in sleep and brain structure. Here we review studies exploring the association between human histo-pathological and in vivo neuroimaging markers of brain structure and sleep-wake parameters in healthy older adults. Evidence from both large-scale epidemiological studies and in-lab quantification of specific sleep signatures are reviewed and advantages and pitfalls highlighted. Overall, the results point to an association between sleep-wake disruption and both local and diffuse changes in brain structure. The associative strength largely varies between studies and seems to partially depend on the sleep trait under investigation. The role of specific sleep-wake regulating mechanisms on human cognitive and brain fitness and more particularly their causal relationship remains to be disentangled.

Study objectives Heart failure has previously been linked to sleep disorders that are often associated with frequent disturbances to human rest/activity patterns. We tested whether fragmentation of sustained rest/activity patterns derived from actigraphic recordings at baseline predicts incident heart failure in community-based elderly individuals. Methods We studied 1099 community-based elderly adults participating in the Rush Memory and Aging Project who had baseline motor activity monitoring up to 11 days and were followed annually for up to 14 years. Fragmentation was assessed using previously validated indexes, derived from the probability of transitions once sustained rest or activity has been established. Heart failure was recorded via a clinical interview during the annual follow-up. Cox proportional hazards models were constructed to examine the relationship between rest fragmentation index and incident heart failure. Covariates grouped in terms of demographics, lifestyle factors and co-morbidities and cardiovascular risk factors/diseases were included. Results Increased rest fragmentation (but not activity fragmentation) was associated with higher risk for incident heart failure. Specifically, a subject with a rest fragmentation at the 90th percentile showed a 57% increased risk of developing incident heart failure compared to a subject at the 10th percentile in this cohort. This effect was equivalent to that of being over a decade older. These observations were consistent after adjusting for all covariates. Conclusion Increased rest fragmentation, a potential surrogate for sleep fragmentation, is independently associated with a higher risk of developing heart failure in community-based elderly adults during up to 14 years of follow-up. Further work is required to examine the specific contributions from daytime napping versus nighttime sleep periods in the elderly, as well as the underlying autonomic and cardio-dynamic pathways that may explain the effects on heart function.

The relevance of altered rest-activity rhythm (RAR) and light exposure rhythm (LER) in insomnia patients under natural conditions remains unclear. The aim of this study was to compare the parametric and nonparametric circadian variables of RAR and those of LER under natural conditions between insomnia patients and normal controls (NC) in a community-dwelling setting. The relationship of the nonparametric variables with sleep quality was also explored in both groups. Participants above 18 years old were recruited from three Public Health Centers in a rural area of Korea. Actigraphy (Actiwatch 2; Philips Respironics, Murrysville PA, USA) recording was conducted for 7 days. Subjects were eligible for our study if they had an insomnia disorder (ID) for at least 1 month. Actigraphy data of 78 normal control (NC) subjects (Age, 55.95 ± 13.22 years) and 104 patients with insomnia disorder (ID) (Age, 62.14 ± 12.34 years) were included for the analysis. Acrophases and amplitudes of RAR and LER were estimated using cosinor analysis. Interdaily stability (IS), intradaily variability (IV), and relative amplitude (RA) of these rhythms were determined using nonparametric methods. Parametric cosinor and nonparametric variables of RAR and LER were compared between the NC and ID groups. Generalized linear models (GLMs) were applied to evaluate the main effects of group and each nonparametric variable as well as a group by each variable interaction on the sleep onset latency (SOL), sleep efficiency (SE), and wake after sleep onset (WASO) reflecting sleep quality. Among sleep parameters, the ID group showed significantly lower SE and greater WASO than the NC group. There were no significant differences in the acrophase and amplitude of RAR and LER between the two groups. There were no significant differences in IV, IS, and RA of RAR and LER between the two groups either. GLMs for RAR revealed a significant interaction between the group and IS on the SOL (β = -46.39

Fatigue is defined as an unpleasant symptom surrounded by sensations that vary from tiredness to exhaustion. There are several careers that demand much effort from their workers, inducing fatigue and affecting their health and performance. The goal of this paper is to establish a series of alerts to anticipate the level of fatigue an individual exposed to emergency situations may experience. In order to do this, it is intended to make use of non-invasive analysis techniques to monitor physiological parameters (heart rate and internal body temperature). The data used for this work were collected in a laboratory environment from 6 individuals with an average age of 22.67 years. Their physiological responses were analysed and classified using a set of programs created with Visual Basic for Applications software. The obtained data were compared to a fatigue alert system, and results evidenced the internal body temperature as the most consistent parameter. Heart rate and internal body temperature are compatible variables for creating systems capable of indicating and anticipating the conditions resulting from intense physical efforts, which could later lead to fatigue states. The analysis of additional non-invasive parameters is an alternative for refining the system contributing to fatigue prevention and management.

Background: Regulator of calcineurin 1 (RCAN1) is overexpressed in Down syndrome (DS), but RCAN1 levels are also increased in Alzheimer's disease (AD) and normal aging. AD is highly comorbid among individuals with DS and is characterized in part by progressive neurodegeneration that resembles accelerated aging. Importantly, abnormal RCAN1 levels have been demonstrated to promote memory deficits and pathophysiology symptomatic of DS, AD, and aging. Anomalous diurnal rest-activity patterns and circadian rhythm disruptions are also common in DS, AD, and aging and have been implicated in facilitating age-related cognitive decline and AD progression. However, no prior studies have assessed whether RCAN1 dysregulation may also promote the age-associated alteration of rest-activity profiles and circadian rhythms, which could in turn contribute to neurodegeneration in DS, AD, and aging. Methods: The present study examined the impacts of RCAN1 deficiency and overexpression on the photic entrainment, circadian periodicity, intensity and distribution, diurnal patterning, and circadian rhythmicity of wheel running in young (3-6 months old) and aged (9-14 months old) mice. All data were initially analyzed by multifactorial ANOVA with variables of genotype, age, treatment, and sex considered as dependent variables.Results: We found that daily RCAN1 levels in the hippocampi of light-entrained young mice are generally constant and that balanced RCAN1 expression is necessary for normal circadian locomotor activity rhythms. While the light-entrained diurnal period was unaltered, RCAN1-null and -overexpressing mice displayed lengthened endogenous (free-running) circadian periods like mouse models of AD and aging. In light-entrained young mice, RCAN1 knockout and overexpression also recapitulated the general hypoactivity, diurnal rest-wake pattern fragmentation, and attenuated amplitudes of circadian activity rhythms reported in DS, preclinical and clinical AD, healthily aging individuals, and rodent models thereof. Under constant darkness, RCAN1-null and -overexpressing mice displayed altered locomotor behavior indicating circadian clock dysfunction. Using the Dp(16)1Yey/+ (Dp16) mouse model for DS, which expresses three copies of Rcan1, we found reduced wheel running activity and rhythmicity in both light-entrained and free-running young Dp16 mice like young RCAN1-overexpressing mice. Critically, these diurnal and circadian deficits were rescued in part or entirely by restoring Rcan1 to two copies in Dp16 mice. Conclusions: Collectively, this study's findings suggest that both loss and aberrant gain of RCAN1 precipitate anomalous light-entrained diurnal and circadian activity patterns emblematic of DS, AD, and aging.

Introduction Misalignment between lifestyle behaviors and endogenous circadian rhythms is associated with elevated nocturnal blood pressure (BP) in experimental studies; however, less is known about free-living (i.e. nonlaboratory) circadian disruption and nocturnal BP. Additionally, sex-specific cardiovascular implications of circadian disruption are unclear. Objective To examine the associations between rest--activity rhythms (RAR), a field-based estimate of circadian disruption, and nocturnal BP characteristics in male and female young adults. Methods Fifty participants (20 ± 1 years; 20 men/30 women) underwent 24-h ambulatory BP monitoring following 14 days of wrist actigraphy. RAR variables of interdaily stability (day-to-day consistency in RAR), intradaily variability (within-day fragmentation of RAR), and relative amplitude (difference between peak vs. trough activity) were derived from actigraphy. Multivariable regression models of mean nocturnal SBP, DBP, and SBP dipping were generated to test main associations with RAR variables, and sex × RAR interactions. Daytime BP, race, BMI, physical activity, sleep duration, alcohol, caffeine, and sodium intake were considered as covariates. Results In the full sample, no main associations between RAR and nocturnal BP characteristics were found. Sex interacted with RAR such that in women, higher interdaily stability (β = -5.39, 95% CI = -10.04 to -0.73, P = 0.024) and relative amplitude (β = -4.78, 95% CI = -9.22 to -0.34, P = 0.036) were both associated with lower nocturnal SBP. Sex-stratified multivariable models of nocturnal BP also revealed associations between interdaily stability and relative amplitude with SBP dipping in women (all P ≤ 0.01). No associations were apparent in men. Conclusion Consistent and high-amplitude RAR are favorably associated with nocturnal BP characteristics in young female adults.

Since the circadian system seems to modulate stress responses, this study aimed to evaluate if the combination of circadian strain and stress amplifies changes expected from each factor alone. Control Balb/c mice (12:12-NS) kept in standard 12:12 light:dark cycles (LD) and submitted to no stress procedures (NS) were compared to groups submitted to shortened LD (10:10-NS), chronic mild stress (CMS) but no circadian strain (12:12-CMS), or shortened LD followed by CMS (10:10-CMS). Rest-activity/temperature rhythms and body weight were assessed throughout the experiments. In Experiment 1 mice were submitted to 3 weeks of CMS; in Experiment 2 sucrose preference and light-dark tests were performed. Also, blood samples were collected at the end of Experiment 2 to assess metabolic parameters. Relative amplitude of temperature after CMS was increased only in the 10:10-CMS group, while body weight change was reduced during CMS regardless of LD intervention. During the CMS, the relative amplitude of temperature was negatively correlated with body weight gain. No differences in behavior and metabolic parameters were seen among groups. Identifying suitable research designs to investigate our hypothesis that circadian disturbances may increase vulnerability to stress-induced depression and anxiety is warranted.

Chronic increases in pro-inflammatory cytokines in older adults, known as inflammaging, are an important risk factor for morbidity and mortality in the aging population. It has been suggested that circadian disruption may play a role in chronic inflammation, but there has been limited study that investigated the overall profile of 24-hour rest–activity rhythms in relation to inflammation using longitudinal data. In the Outcomes of Sleep Disorders in Older Men Study, we applied the extended cosine model to derive multiple rest–activity rhythm characteristics using multiday actigraphy, and examined their associations with 6 inflammatory markers (ie, C-reactive protein [CRP], interleukin 6 [IL-6], tumor necrosis factor alpha [TNF-α], tumor necrosis factor alpha soluble receptor II [TNF-α-sRII], interleukin-1β [IL-1β], interferon gamma [IFN-γ]) measured from fasting blood. We assessed both the cross-sectional association between rest–activity rhythms and inflammatory markers measured at baseline, and the prospective association between baseline rest–activity rhythms and changes in inflammatory markers over 3.5 years of follow-up. We found that multiple rest–activity characteristics, including lower amplitude and relative amplitude, and decreased overall rhythmicity, were associated with higher levels of CRP, IL-6, TNF-α, and TNF-α-sRII, but not IL-1β and IFN-γ at baseline. Moreover, the lowest quartile of these 3 rest–activity characteristics was associated with an approximately 2-fold increase in the odds of having elevated inflammation (ie, having 3 or more markers in the highest quartile) at baseline. However, we found little evidence supporting a relationship between rest–activity rhythm characteristics and changes in inflammatory markers. Future studies should clarify the dynamic relationship between rest–activity rhythms and inflammation in different populations, and evaluate the effects of improving rest–activity profiles on inflammation and related disease outcomes.

Emerging adulthood (18–25 years) represents a window of opportunity to modify the trajectory of cardiometabolic disease risk into older adulthood. Not known is the extent to which rest-activity rhythms (RAR) may be related to biomarkers of cardiometabolic health in this population. In this cross-sectional, observational study, 52 healthy emerging adults wore wrist accelerometers (14 consecutive days; 24h/day) for assessment of nonparametric RAR metrics, including interdaily stability (IS; day-to-day RAR consistency), intradaily variability (IV; within-day RAR fragmentation), and relative amplitude (RA; robustness of RAR), as well as autocorrelation (correlation of rest/activity levels at 24-hour lag-times). Cardiometabolic biomarkers, including body mass index (BMI), body fat percentage, blood pressure (BP), fasting lipids, glucose, and C-reactive protein (CRP) were assessed. Additional measures including physical activity, sleep duration, and habitual caffeine and alcohol consumption were also evaluated. A series of multivariable regression models of cardiometabolic biomarkers were used to quantify associations with RAR metrics. On average, participants were 20±1 years of age (21 male, 31 female), non-obese, and non-hypertensive. All were non-smokers and free of major diseases or conditions. In separate models, which adjusted for sex, BMI, moderate-vigorous physical activity, sleep duration, caffeine, and alcohol consumption, IS was inversely associated with total cholesterol (p≤0.01) and non-HDL cholesterol (p

By collecting data continuously over 24 hours, accelerometers and other wearable devices can provide novel insights into circadian rhythms and their relationship to human health. Existing approaches for analyzing diurnal patterns using these data, including the cosinor model and functional principal components analysis, have revealed and quantified population-level diurnal patterns, but considerable subject-level variability remained uncaptured in features such as wake/sleep times and activity intensity. This remaining informative variability could provide a better understanding of chronotypes, or behavioral manifestations of one's underlying 24-hour rhythm. Curve registration, or alignment, is a technique in functional data analysis that separates "vertical" variability in activity intensity from "horizontal" variability in time-dependent markers like wake and sleep times; this data-driven approach is well-suited to studying chronotypes using accelerometer data. We develop a parametric registration framework for 24-hour accelerometric rest-activity profiles represented as dichotomized into epoch-level states of activity or rest. Specifically, we estimate subject-specific piecewise linear time-warping functions parametrized with a small set of parameters. We apply this method to data from the Baltimore Longitudinal Study of Aging and illustrate how estimated parameters give a more flexible quantification of chronotypes compared to traditional approaches.

Objectives: to compare the parameters of the activity/rest cycle of early postpartum breastfeeding women under a controlled and uncontrolled long wavelength ray light regimen. Methods: quasi-experimental study with breastfeeding women and their babies during postnatal rooming-in, São Paulo, Brazil. Participants were allocated to either an experimental (intervention) or a comparison group. The intervention involved exposure of the woman in a controlled room with artificial long wavelength ray light at night. Each woman’s level of 6-sulfatoxymelatonin at 24 hours and activity/rest times was analyzed. Results: the mean activity/rest times of women in the experimental and comparison groups were similar. The mean percentages of total load of 6-sulfatoxymelatonin during the day and night were similar (p=0.09). At 24 hours, the experimental group presented a significantly lower mean percentage of total load compared to the comparison group (p=0.04). Conclusions: women who stayed in the room with long-wavelength artificial light showed no difference in activity/rest and 6-sulfatoxymelatonin levels in the early postpartum period. RESUMO Objetivos: comparar os parâmetros do ciclo de atividade/descanso de puérperas lactantes no início do pós-parto sob regime de iluminação com raios de comprimento de onda longo controlado e descontrolado. Métodos: estudo quase-experimental com lactantes e seus bebês em alojamento conjunto, São Paulo, Brasil. Os participantes foram alocados para grupos experimental (intervenção) ou de comparação. A intervenção consistia na exposição em uma sala controlada com iluminação artificial de raios de comprimento de onda longo à noite. Foram analisados os horários de atividade/repouso (horas) e nível de 6-sulfatoximelatonina em 24 horas. Resultados: a atividade média e os tempos de repouso das mulheres nos grupos experimental e comparação foram semelhantes. Os percentuais médios de volume total de 6-sulfatoximelatonina durante o dia e a noite foram semelhantes (p=0,09). Em 24 horas, o grupo experimental apresentou percentual médio significantemente menor de volume total em relação ao grupo comparação (p=0,04). Conclusões: as mulheres que permaneceram no quarto com luz artificial de comprimento de onda longa não apresentaram diferenças nos níveis de atividade/repouso e 6-sulfatoximelatonina no início do período pós-parto. RESUMEN Objetivos: comparar parámetros del ciclo actividad/descanso en madres lactantes en posparto temprano bajo régimen lumínico de rayos de longitud de onda larga controlado y no controlado. Métodos: estudio cuasiexperimental con madres lactantes y sus bebés, São Paulo, Brasil. Las participantes fueron asignadas a grupos experimental (intervención) y comparación, consistente en exposición en habitación controlada con luz artificial de rayos de longitud de onda larga durante la noche. Se analizaron tiempos de actividad/descanso (horas) y nivel de 6-sulfatoximelatonina a las 24 horas. Resultados: actividad media y tiempos de descanso fueron similares en grupos comparación e intervención. Porcentajes promedio de volumen total de 6-sulfatoximelatonina durante día y noche resultaron similares (p=0,09). A las 24 horas, el grupo intervención presentó porcentaje promedio de volumen total significantemente menor comparado con grupo comparación (p=0,04). Conclusiones: las mujeres expuestas a luz artificial de longitud de onda larga no mostraron diferencias en niveles actividad/descanso y 6-sulfatoximelatonina durante el posparto temprano.

Study Objectives Disturbances of rest–activity rhythms are associated with higher body mass index (BMI) in adults. Whether such relationship exists in children is unclear. We aimed to examine cross-sectional associations of rest–activity rhythm characteristics with BMI z-score and obesity-related inflammatory markers in school-age children. Methods Participants included 411 healthy children (mean ± SD age 10.1 ± 1.3 years, 50.8% girls) from a Mediterranean area of Spain who wore wrist accelerometers for 7 consecutive days. Metrics of rest–activity rhythm were derived using both parametric and nonparametric approaches. Obesity-related inflammatory markers were measured in saliva (n = 121). Results In a multivariable-adjusted model, higher BMI z-score is associated with less robust 24-h rest–activity rhythms as represented by lower relative amplitude (–0.16 [95% CI –0.29, –0.02] per SD, p = 0.02). The association between BMI z-score and relative amplitude persisted with additional adjustment for sleep duration, and attenuated after adjustment for daytime activity level. Less robust rest–activity rhythms were related to increased levels of several salivary pro-inflammatory markers, including C-reactive protein, which is inversely associated with relative amplitude (–32.6% [–47.8%, –12.9%] per SD), independently of BMI z-score, sleep duration, and daytime activity level. Conclusion Blunted rest–activity rhythms are associated with higher BMI z-score and salivary pro-inflammatory markers already at an early age. The association with BMI z-score seem to be independent of sleep duration, and those with pro-inflammatory markers further independent of BMI z-score and daytime activity. Novel intervention targets at an early age based on improving the strength of rest–activity rhythms may help to prevent childhood obesity and related inflammation. Clinical Trials Registration NCT02895282

The possible mechanisms for the synchronization of rest–activity rhythms of individual animals living in groups is a relatively understudied question; synchronized rhythms could occur by entrainment of individuals to a common external force and/or by social synchronization between individuals. To gain insight into this question, we explored the synchronization dynamics of populations of globally coupled Kuramoto oscillators and analyzed the effects of a finite oscillator number ( N) and the variable strengths of their periodic forcing ( F) and mutual coupling ( K). We found that increasing N promotes entrainment to a decreasing value of F, but that F could not be reduced below a certain level determined by the number of oscillators and the distribution width of their intrinsic frequencies. Our analysis prompts some simple predictions of ecologically optimal animal group sizes under differing natural conditions.

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 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

Introduction Misalignment between endogenous circadian rhythms and environmental signals – an emerging risk factor for cardiovascular disease (CVD) – can disrupt diurnal blood pressure (BP) rhythms, resulting in higher nocturnal BP and less-pronounced BP dipping (i.e., % decline in nighttime systolic BP [SBP] relative to daytime values). Daily patterns of rest and activity (‘rest-activity rhythms’ [RAR]) are a proxy for estimating circadian disruption in free-living settings and have been independently associated with elevated CVD risk. However, the relation between RAR and nocturnal BP is unclear. Thus, we aimed to quantify the associations between RAR and nocturnal BP characteristics in male and female emerging adults (18-25y). Methods Fifty healthy emerging adults (20±1y; 20M/30F) underwent 24-h ambulatory BP monitoring following 14 consecutive days of continuous wrist actigraphy. RAR variables of interdaily stability (IS; day-to-day consistency in RAR), intradaily variability (IV; within-day fragmentation of RAR), and relative amplitude (RA; difference between trough vs. peak activity) were computed. Bivariate correlations were used to quantify associations between RAR variables and nocturnal BP characteristics for all participants, and separately for males and females. Linear regression models of mean nocturnal SBP, nocturnal diastolic BP (DBP), and SBP dipping were also generated to test main and interactive effects of sex and RAR. Potential confounders (variables associated with outcomes at p Results Overall, IS and RA positively correlated with % SBP dipping (IS: r=0.33, p=0.02; RA: r=0.35, p=0.01). Among females only, correlations strengthened (IS: r=0.50, p Conclusion Findings suggest that consistent and high-amplitude RAR associate with more favorable nocturnal BP characteristics, particularly in emerging female adults. Support (if any) Supported in part by NIH P20-GM113125.

By collecting data continuously over 24 hours, accelerometers and other wearable devices can provide novel insights into circadian rhythms and their relationship to human health. Existing approaches for analyzing diurnal patterns using these data, including the cosinor model and functional principal components analysis, have revealed and quantified population-level diurnal patterns, but considerable subject-level variability remained uncaptured in features such as wake/sleep times and activity intensity. This remaining informative variability could provide a better understanding of chronotypes, or behavioral manifestations of one’s underlying 24-hour rhythm. Curve registration, or alignment, is a technique in functional data analysis that separates “vertical” variability in activity intensity from “horizontal” variability in time-dependent markers like wake and sleep times; this data-driven approach is well-suited to studying chronotypes using accelerometer data. We develop a parametric registration framework for 24-hour accelerometric rest-activity profiles represented as dichotomized into epoch-level states of activity or rest. Specifically, we estimate subject-specific piecewise linear time-warping functions parametrized with a small set of parameters. We apply this method to data from the Baltimore Longitudinal Study of Aging and illustrate how estimated parameters give a more flexible quantification of chronotypes compared to traditional approaches.

This study aimed to identify differences between physiological age-related and Alzheimer's disease (AD)-related alterations in sleep and rest-activity rhythm. All participants (n = 280; 20–90 years) underwent clinical assessments, [11C] Pittsburgh compound B–positron emission tomography, and actigraphic monitoring. In cognitively normal adults without cerebral amyloid-β, older age was associated with earlier timing of circadian phase and robust rest-activity rhythm, but sleep quantity and quality were mostly unaffected by age. While preclinical AD was associated with earlier circadian timing, clinical AD exhibited later timing of daily rhythm and increased sleep duration. In conclusion, our findings suggest that older age itself leads to a more regular daily activity rhythm, but does not affect sleep duration. While preclinical AD made the effects of age-related phase advance more prominent, clinical AD was related to later circadian timing and increased sleep duration.

In modern societies, human rest-activity rhythms and sleep result from the tensions and dynamics between the conflicting poles of external social time (e.g., work hours and leisure activities) and an individual's internal biological time. A mismatch between the two has been suggested to induce 'social jetlag' [1] and 'social sleep restriction', that is, shifts in sleep timing and differences in sleep duration between work days and free days. Social jetlag [2,3] and sleep restrictions [4] have repeatedly been associated with negative consequences on health, mental wellbeing, and performance. In a large-scale quasi-experimental design, we investigated the effects of the phase with the most rigorous COVID-19 restrictions on the relationship between social and biological rhythms as well as sleep during a six-week period (mid-March until end of April 2020) in three European societies (Austria, Germany, Switzerland). We found that, on one hand, the restrictions reduced the mismatch between external (social) and internal (biological) sleep-wake timing, as indexed by significant reductions in social jetlag and social sleep restriction, with a concomitant increase in sleep duration. Sleep quality on the other hand was slightly reduced. The improved individual sleep-wake timing can presumably be attributed to an increased flexibility of social schedules, for instance due to more work being accomplished from home. However, this unprecedented situation also led to a significant increase in self-perceived burden, which was attendant to the decrease in sleep quality. These adverse effects may be alleviated by exposure to natural daylight as well as physical exercise.

OBJECTIVE The purpose of this study was to investigate the differences in actigraphy-measured rest-activity patterns (eg, sleep-wake cycle, circadian rest-activity rhythm, and physical activity) across different stages of α-synucleinopathy. METHODS We compared alterations in 7-day actigraphy-measured rest-activity patterns among patients with clinically diagnosed α-synucleinopathies (n = 44), and their age-, sex-, and body mass index (BMI)-matched patients with idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD, n = 88), and non-rapid eye movement (REM) sleep behavior disorder (RBD) controls (n = 44) in a case-control study (study 1) and between convertors (n = 22) and their age-, sex-, BMI-, iRBD-duration, and follow-up duration-matched non-convertors (n = 66) in a prospective nested case-control study (study 2). RESULTS In study 1, there were significant increases (all p values were adjusted by false discovery rate

Limited information is available on the relationship between sleep disturbances during nighttime and the behavioral and psychological symptoms of dementia in older nursing-home residents. However, a few reports on the association between the circadian rest-activity rhythm and the behavioral and psychological symptoms of dementia in older residents have been published. The main objective of the present study was to examine the association among the circadian rest-activity rhythm, behavioral and psychological symptoms, and the cognitive function status among older individuals living in facilities.The investigation was conducted from September 2017 to February 2018, and participants were recruited from five nursing homes in Akita prefecture, Japan, after obtaining patient agreement to participate in the study. To measure nonparametric circadian rest-activity parameters such as interdaily stability, intradaily variability, relative amplitude, mean of the least active 5-h period, and mean of the most active 10-h period, Actigraph devices were worn on the participants' nondominant wrists continuously for seven days. The score or classification of the cognitive status and the severity of the behavioral and psychological symptoms of dementia (BPSD) were assessed using the clinical dementia rating (CDR) and the dementia behavior disturbance scale (DBD), respectively. The binomial logistic regression model was applied to clarify which kinds of circadian rest-activity parameters predicted the cognitive status in nursing home residents as well as the BPSD outcome. A multi-level model was also used to examine the association between the nonparametric rest-activity parameters and the BPSD outcome explained by the cognitive status among older individuals in facilities.Seventy-seven participants (49 residents with dementia, and 28 residents without dementia) were included in this study. According to the binomial logistic regression analysis after adjusting for covariates, the classification of the cognitive status for older residents was associated with the DBD score (odds ratio, 1.22; 95% confidence interval [CI], 1.08, 1.38; p 0.001), the IS (odds ratio, 0.01; 95% CI, 0.00, 1.00; p = 0.05) and the L5 (odds ratio, 0.99; 95% CI, 0.99, 1.00; p = 0.05). The results of a multi-level model also indicated that the IV at individual-level was significantly associated with the DBD score for nursing home residents, with the CDR score at cluster-level as an explanatory variable. As well, a significant association between the RA at individual level and the DBD score was observed in a multi-level model explained by the CDR score at cluster-level.Of these models, the multi-level model provided grounds for our proposal that the fragmentation or the amplitude of rest-activity parameters might be associated with the outcome of BPSD, considering the cognitive status of older individuals in different facilities. The findings offer practical insight into the prevention of BPSD and the improvement of rest-activity rhythms in rehabilitative care in nursing homes.

Identifying objectively measurable seasonal changes in 24-hour activity patterns (rest-activity rhythms or RARs) that occur in seasonal affective disorder (SAD) could help guide research and practice towards new monitoring tools or prevention targets. We quantified rest-activity rhythms (RARs) from actigraphy data using non-parametric and extended cosine based approaches, then compared RARs between people with SAD and healthy controls in the summer (n=70) and winter seasons (n=84). We also characterized the within-person seasonal RAR changes that occurred in the SAD (n=19) and control (n=26) participants who contributed repeated measures. Only controls had significant winter increases in RAR fragmentation (intra-daily variability; in controls mean winter-summer changes (log scale) = 0.05, 0.21 standard deviation, p = 0.03). In SAD participants only, estimated evening settling times (down-mesor) were an average of 30 minutes earlier in the winter compared with the summer (1-hour standard deviation, p=0.045). These RAR characteristics correlated with greater fatigue (Spearman |r|=0.36) but not depression symptom severity. Additional research is needed to ascertain why healthy controls, but not people with SAD, appear to have increased RAR fragmentation in the winter. People with SAD lacked this increase in RAR fragmentation, and instead had earlier evening setting in the winter. Prospective and intervention studies with greater temporal resolution are warranted to ascertain how these seasonal behavioral differences relate to fatigue pathophysiology in SAD. Future research is needed to determine whether extending the winter active period, even in relatively fragmented bouts, could help reduce the fatigue symptoms common in SAD.

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 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 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)

Introduction Rest-activity patterns are important aspects of healthy sleep and may be disturbed in conditions like circadian rhythm disorders, insomnia, insufficient sleep syndrome, and neurological disorders. Long-term monitoring of rest-activity patterns is typically performed with diaries or actigraphy. Here, we propose a fully unobtrusive method to obtain rest-activity patterns using smartphone keyboard activity. This study investigated whether keyboard activities from habitual smartphone use are reliable estimates of rest and activity timing compared to daily self-reports within healthy participants. Methods First-year students (n = 51) used a custom smartphone keyboard to passively and objectively measure smartphone use behaviours, and filled out the Consensus Sleep Diary for one week. The time of the last keyboard activity before a nightly absence of keystrokes, and the time of the first keyboard activity following this period were used as markers. Results Results revealed high correlations between these markers and user-reported onset and offset of resting period (r ranged 0.74 - 0.80). Linear mixed models could estimate onset and offset of resting periods with reasonable accuracy (R2 ranged 0.60 - 0.66). This indicates that smartphone keyboard activity can be used to estimate rest-activity patterns. In addition, effects of chronotype and type of day were investigated. Conclusion Implementing this monitoring method in longitudinal studies would allow for long-term monitoring of (disturbances to) rest-activity patterns, without user burden or additional costly devices. It could be particularly useful in studies amongst clinical populations with sleep-related problems, or in populations for whom disturbances in rest-activity patterns are secondary complaints, such as neurological disorders. Support (if any)

Background An enriched environment for residents with dementia may have a positive effect on the rest-activity rhythm. A small scaled homelike special care unit might be such an enriched environment. The present study shows whether the rest-activity rhythm of residents with moderate to severe dementia responds positively to a transfer from a regular Special Care Unit (SCU) to a small scaled homelike SCU. Methods Initially, a group of 145 residents living in a regular SCU participated. Out of this group, 77 residents moved to a small scaled homelike SCU. This group was compared to the group of 68 residents that remained at the regular SCU. Rest-activity rhythm was assessed by means of actigraphy and observation scales before and after relocation. Results No significant main effects nor significant interaction effects in intradaily and interdaily activity were found for the data of 38 residents in the small scaled homelike SCU and 20 residents of the regular SCU. The effect sizes, however, ranged from small to large. Conclusions Considering the effect sizes, a new study with a larger number of participants is necessary before firm conclusions can be drawn. Trial registration Current Controlled Trials ISRCTN11151241 . registration date: 21–06-2017. Retrospectively registered.

Introduction Resting-state functional connectivity is coherent brain activity in a task-free state that strongly correlates to task-evoked sensory, motor, and higher-order cognitive systems. Certain networks show decreased functional connectivity with aging. Aging is associated with changes in circadian rhythms and sleep-wake cycles. Limited research has been conducted on how circadian activity and sleep are related to markers of functional brain aging. The purpose of this study was to explore whether rest-activity patterns and shorter sleep duration are related to functional connectivity of specific resting-state networks in older adults. Methods A total of 124 cognitively normal participants (mean age (SD) = 67.2 (5.7), 42% men) underwent 3.0 T MRI and week-long wrist actigraphy protocols. Rest-activity pattern was analyzed using an extended cosine model calculating acrophase (time of peak activity) and pseudo-F statistics of goodness-of-fit (a measure of overall rhythmicity). We used resting-state fMRI scans to measure functional connectivity in association and sensory networks as defined by the Schaefer 17 network functional atlas. Multiple linear regression analysis was used to investigate how rest-activity pattern parameters and sleep duration are associated with resting-state functional connectivity, adjusting for age, sex, and sleep apnea. Results We found that the average acrophase was 2:30 PM (SD = 54 min), and delayed acrophase (average vs. delayed [+1SD]) was associated with lower functional connectivity of the right-lateralized default mode network A (p=0.02), and higher pseudo-F statistics was associated with higher functional connectivity in networks including left dorsal attention B (p=0.001), right somatomotor A (p = 0.05), and somatomotor B (both p=0.02). Longer sleep duration was associated with higher right executive control B (p=0.03). Conclusion The overall rhythmicity of diurnal rest-activity patterns and longer sleep duration are associated with some resting-state functional networks. Further investigation is needed to understand the mechanisms between circadian rhythm and brain function. Support National Institute of Health, U of Iowa Aging Mind Brain Initiative, Center on Aging

Schedule changes associated with rotating shifts can interfere with the circadian rhythms of nurses and thereby affect their sleep duration, sleep quality, work efficiency, and work performance. The objectives of this study was to investigate differences in workday sleep fragmentation, rest-activity cycle, sleep quality, and activity level among nurses working different shifts. After filling out a basic information questionnaire and completing the Pittsburgh Sleep Quality Index (PSQI) questionnaire, participants were asked to wear an actigraph and keep sleep records for seven consecutive days. Data pertaining to wake after sleep onset (WASO), 24-hour autocorrelation coefficient (

Rest-activity circadian rhythm (RAR) is a marker of the circadian timing system. Particular attention has been given to RAR characteristics in cancer diseases. Specifically, alterations of RAR parameters have been found, at different stages of clinical pathway, in breast cancer (BC) patients. No studies to date have analyzed RAR alterations in breast cancer survivors several years after the diagnosis. The aim of this study was to determine RAR by actigraphy in a population of BC survivors at 5 years after the primary diagnosis, and to compare their RAR characteristics with healthy controls. The study sample was 28 women: 15 BC survivors at 5 years from the primary diagnosis (BC-group) and 13 healthy controls (Ctrl-group), matched for age and body mass index. All participants have been monitored for 7 days by actigraphy to evaluate RAR. A statistically significant circadian rhythm (T = 24) was found in all 28 subjects (

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.

International audience; The success of chemotherapy treatment is achieved based on “Chronotherapy”: the concept of administering the correct drug at a precise time based on the circadian rhythm study. This paper aims to detect the rest/activity cycle and automatically calculate the dichotomy index (I

The correct expression of circadian rhythmicity is crucial for the body homeostasis. The rest-activity circadian rhythms (RARs) are involved in the control of the sleep-wake cycle and altered RARs could lead to a compromised health status. Many studies focused on examining sleep behavior and circadian rhythms in physically active subjects or athletes but, unexpectedly, no data on RARs are available. Therefore, we studied the existence of the RAR in athletes and the possible difference in RAR’s characteristics among sport disciplines. The study had a prospective observational design and RARs were recorded for five consecutive training days through actigraphy (Actiwatch 2 actigraph; Philips Respironics, OR, USA) in 43 athletes (mean age: 25.6 ± 3.2 years). Athletes competed in three different disciplines and had different training schedules and competition levels: professional triathletes (N = 10; 6 females and 4 males) had 2 morning (08:30–12:00) and 1 afternoon (15:00–17:00) training sessions, professional volleyball players (N = 19; 12 females and 7 males) used to train once in the morning (09:00–11:30) and once in the afternoon (15:00–18:00), and non-professional soccer players (N = 14; all males) trained always late in the evening (20:30–22:30). To determine the existence of RARs, the activity counts (A.C.) data were analyzed using the single and the population mean cosinor method; a one-way analysis of variance (ANOVA) followed by the Tukey–Kramer post-hoc test was used for the comparison of RAR characteristics among soccer, volleyball and triathlon athletes. Partial eta squared (ή p2 ) was used to determine the magnitude of the effect for significant outcomes (α = 0.05) in ANOVA. The presence of a significant RAR both for each of the 43 athletes (p

Introduction Sleep is an important element of health that can impact daytime performance in brain injury rehabilitation. Actigraphy in a pediatric inpatient setting can pose challenges when there are increased amounts of time spent in a hospital bed. A rest-activity ratio (Duclos et al., 2013) has demonstrated utility in adult brain injury populations, showing sensitivity to improved regulation of the sleep-wake cycle as individuals recover during their hospitalization. The present study sought to examine the utility of this ratio in differentiating children with and without acquired brain injury (ABI). Methods Sixteen individuals, ages 8-16 (M=12.6, SD=2.4) admitted to an inpatient pediatric rehabilitation hospital wore an actigraph over a 7-day period. Eight inpatients were being treated for ABI whereas another 8 inpatients treated for other, non-neurological conditions served as a control. Raw activity counts across the 24-hour period were analyzed to derive a rest-activity ratio. Results Those with ABI had lower average ratios (0.73) compared with patients without ABI (0.84), F(1,14)=4.3, p=0.058. Individuals with ratios of 0.85 or higher were rated by their physical therapists as being more alert during therapy using a 5-point Likert scale, F(1,14)=4.1, p=0.061. While these results were marginally significant, this pilot sample was small, and the effect sizes were large (eta squared = 0.234 and 0.229 respectively). Conclusion The rest-activity ratio successfully distinguished those with ABI from a non-ABI sample. This preliminary evidence in a pediatric sample suggests that this ratio, shown to be sensitive to the effects of brain injury on sleep-wake regulation, may be a useful metric in the inpatient pediatric rehabilitation setting when sleep diaries may be difficult to obtain and patients may be spending more time in bed while awake. Future studies with larger sample sizes are needed to explore the correlates of this ratio with other aspects of rehabilitation after pediatric brain injury. Support This study was funded in part through a generous grant from the Church & Dwight Employee Giving Fund

Zeitgebers such as light, eating and physical activity provide input to the circadian clock. Chronic circadian misalignment is associated with significant adverse health effects. An improved understanding of the impact of the timing of zeitgebers on the stability of 24-hour rest-activity rhythm in free-living settings may identify behavioural and environmental intervention targets. A total of 133 healthy adults, aged 21-60 years, wore a wrist actigraph for 7 consecutive days. We applied a non-parametric analysis to activity counts to derive rest-activity patterns. We administered a questionnaire through a smartphone app to collect self-reported timing of light exposure, eating episodes and physical activity. To assess the relationship between timing exposures (first and last exposure to outdoor light, first exposure to indoor light, last eating episode, first eating episode, morning physical activity proportion, evening physical activity proportion) and rest-activity or sleep outcomes (bedtimes, total sleep time, inter-daily stability, intra-daily variability, L5 and M10 midpoint), we first calculated Spearman correlations, using the false discovery rate method to control for multiple comparisons. From those significant associations, we then fit regression models adjusting for age, sex, race, household income, education level, study site, body mass index, as well as physical activity. Finally, we tested for interaction between chronotype and each timing-related exposure and stratified the analysis by morning type. All zeitgebers, except for evening physical activity proportion, were correlated with at least four of the seven sleep and rest-activity outcomes. In adjusted analysis, later timing of first (after 6:30 to 7:45 AM versus earlier) and last exposure to indoor light (after 11:00 PM versus earlier) and first (after 7:45-9:45 AM versus earlier) and last eating episode (after 8:00-09:00 PM versus earlier) were associated with a shift of 0.60-1.39 hours to later bedtimes, M10 and L5 midpoints (i.e. timing of peak activities or inactivities). Later timing of first exposure to outdoor light (after 09:30 AM versus earlier) was also associated with 0.51 (95% CI: 0.19 to 0.83) hours longer total sleep time. Higher morning physical activity proportion ( 33%) was associated with 0.95 (95% CI: -1.38 to -0.53) hours earlier in-bed time and 0.69 (95% CI: -1.14 to -0.24) hours earlier out-of-bed time, 0.92 (95% CI: -1.41 to -0.42) hours earlier M10 and 0.96 (95% CI: -1.42 to -0.49) min earlier L5 midpoint. The results did not change substantially with further adjustment for total activity. There was a significant interaction between morning chronotype and first eating episode with rest-activity patterns (p 0.05), with first eating episode associating with timing of activities only in non-morning type adults. Timing of zeitgebers was associated with sleep and rest-activity patterns, including bedtimes, L5 and M10 midpoint. Future research should evaluate the impact of manipulating zeitgebers on both circadian rhythms and health outcomes.