Circadian Rest-activity Rhythm Research Articles

The impact of long-haul travel and 13h time change on sleep and rest activity circadian rhythm in speed skaters during World Cup competitions.

Athletes frequently compete only a few days after long-haul travel. Longitudinal real-world data on athletes' sleep and sleep-wake cycle in competitive settings remain scarce. This study assessed the impact of a long-haul travel across ∼13 time zones on sleep patterns, rest-activity circadian rhythms (RAR), and their subsequent effects on neuromuscular function and race performance in the Canadian Short-Track Speed Skating Team. Nineteen athletes (24±4years, 11 women) travelled from Montréal (UTC-5) to Asia (UTC+8, UTC+9) for World Cup races between 2017 and 2019. Actigraphy data were collected before (Baseline) and during travel, during the stay in Asia (SIA), and during competition days. RAR were computed using cosinor analyses on accelerometry data with 24h phase periods. Countermovement jump height (CMJ) was measured in a subsample (n=10). Compared to baseline (7:08±0:53), athletes obtained less sleep during travel (6:16±1:27) and competition days (6:35±1:10), and more during SIA (7:32±0:46; time effect P<0.0001). Sleep efficiency and CMJ were greater in SIA than baseline (P=0.007 and P=0.0004, respectively). During SIA, sleep time increased by 9 min per night until the fifth day (P<0.0001), with a slight decrease in sleep efficiency (P=0.005) and an increase in CMJ (P<0.0001). For RAR, mean activity peaked on day 2, shifting from late evening to ∼15:00. Race performance was not different from other races of the same season (P>0.254). Our results demonstrated that, despite the possible sleep debt from the long-haul travel, athletes recovered within 5 days, highlighting their adaptability to manage sleep debt and jetlag without impacting competitive outcomes.

Disrupted rest-activity circadian rhythms are associated with all-cause mortality in patients with chronic kidney diseases

ABSTRACT Circadian rhythms are important biological contributors to health. Rest activity rhythms (RAR) are emerging as biomarkers of circadian behavior that are associated with chronic disease when abnormal. RAR have not yet been characterized in chronic kidney diseases (CKD). Leveraging the National Health and Nutrition Examination Survey (2011–2014), patients with CKD (n = 1114; Mean [95% CI]: Age, 50 [58–61] y; 52% female) were compared with non-CKD individuals (n = 5885; Age, 47 [46–48] y; 52% female). Actigraphy data were processed for RAR parameters including rhythmic strength (amplitude), the rhythm adjusted mean (mesor), the timing of peak activity (acrophase), activity regularity (inter-daily stability), and activity fragmentation (intra-daily variability). Cox regression was performed to assess RAR parameters for the prediction of all-cause mortality. Compared to non-CKD adults, patients with CKD had a lower rhythmic amplitude and mesor, and exhibited greater fragmentation and less day-to-day stability in RAR (ps < 0.001). Among CKD patients, a lower rhythmic amplitude (HR [95% CI]: 0.88 [0.82–0.96]; p < 0.001), a lower rhythm adjusted mean (0.87 [0.81–0.95]; p = 0.002), and a higher daily activity fragmentation (1.87 [1.10–3.18]; p = 0.023) were associated with an increased risk of all-cause mortality. Patients with CKD showed dampened rhythmic amplitudes and greater fragmentation of activity that were associated with a higher risk of all-cause mortality. These findings demonstrate a relationship between circadian disruption and prognosis in patients with CKD.

Rest-activity Circadian Rhythms Are Disrupted In Patients With Chronic Kidney Diseases

Rest-activity Circadian Rhythms Are Disrupted In Patients With Chronic Kidney Diseases

Biobehavioral mechanisms underlying symptoms in cancer patients with chronic graft-versus-host disease

Chronic graft-versus-host disease (cGVHD) is a complication of allogeneic hematopoietic cell transplant (HCT) and is associated with morbidity and high symptom burden. This study evaluated two biobehavioral mechanisms, inflammation and circadian rest-activity rhythms, that may underly commonly reported psychological and physical symptoms in cGVHD patients. Adults with cGVHD (N=57) wore a wrist actigraph for 7 days, provided a blood sample, and completed patient-reported outcome (PRO) measures. 24-hour rest-activity indices were derived from actigraphy. Cytokines and chemokines relevant to cGVHD were measured in peripheral blood plasma using multi-analyte immunoassays. Multiple regression evaluated the extent to which rest-activity indices and inflammatory biomarkers predicted PROs. Higher levels of circulating IL-8 and MIP-1α were associated with worse depression (β = 0.35, p = 0.01; β = 0.33, p = 0.02) and sexual function (β = -0.41, p = 0.01; β = -0.32, p = 0.03). MIP-1α was associated with more severe insomnia (β = 0.36, p = 0.01). Higher circulating MIF was associated with more severe anxiety (β = 0.28, p = 0.048) and fatigue (β = 0.35, p = 0.02). Il-6, TNFα, and MCP-1 showed few associations with PROs. There were few associations between actigraphy indices and PROs; however, participants with a later daily activity peak (acrophase) reported poorer sexual function (β = -0.31, p = 0.04). Models covarying for age, cGVHD severity, and time since HCT yielded a similar pattern of results. Results suggest that pro-inflammatory cytokines and chemokines associated with cGVHD may contribute to PROs, identifying a biobehavioral mechanism that may be a useful target for future interventions.

Violet Light Effects on the Circadian Rest-Activity Rhythm and the Visual System.

Rooms illuminated by "black light" (<400 nm wavelength) has become popular, but there is not enough scientific evidence to support its implementation. This study aims to assess the effects of violet light (392 nm) on the circadian rest-activity rhythm and the visual system through animal experimentation. Five groups of four mice were exposed to different white light, violet light, and dark periods, and their circadian rhythm was analyzed by measuring the circadian period using rest-activity cycles. Electroretinographic recordings and structural analysis of the retina were also performed on experimental animals. Our study demonstrates that mice present normal circadian activity during exposure to violet light, taking rest not only under white light but under violet lighting periods. However, mice suffered a decrease in electrical retinal response after exposure to violet light as measured by electroretinography. Nevertheless, no structural changes were observed in the retinas of the animals under different lighting conditions. Violet light elicits circadian rest-activity rhythm in mice but alters their visual function, although no structural changes are observed after short periods of violet light exposure.

Five-year changes in 24-hour sleep-wake activity and dementia risk in oldest old women.

Sleep disruptions are associated with cognitive aging in older adults. However, it is unclear whether longitudinal changes in 24-hour multidimensional sleep-wake activity are linked to cognitive impairment in the oldest old. We studied 733 cognitively unimpaired women (mean age=82.5±2.9 years) who completed two actigraphy assessments over five years. We performed hierarchical clustering on principal components in nine sleep, napping, and circadian rest-activity rhythm parameters to identify multidimensional sleep-wake change profiles and multinomial logistic regression to evaluate the associations between sleep-wake changes and risk of cognitive impairment at follow-up. We identified three sleep-wake change profiles: Stable Sleep (43.8%), Declining Nighttime Sleep (34.9%), and Increasing Sleepiness (21.3%). After adjustment for demographics and comorbidities, women with Increasing Sleepiness had approximately doubled (odds ratio=2.21, p=0.018) risk of dementia compared to those with Stable Sleep. Increasing sleepiness may be an independent marker or risk factor for dementia in oldest old women.

Exploring actigraphy as a digital phenotyping measure: A study on differentiating psychomotor agitation and retardation in depression.

Psychomotor activity stands out as a crucial symptom in characterizing behaviors associated with depression. This study aims to explore the potential of actigraphy as a tool for digital phenotyping in characterizing symptoms of psychomotor agitation and retardation, which are clinically challenging dimensions to capture, in patients diagnosed with major depressive episode (MDE) according to DSM-5 criteria. We compared rest-activity circadian rhythm biomarkers measured by the Motion Watch 8 actigraphy between 58 (78.4%) patients with MDE and psychomotor retardation (PMR), and 16 (21.6%) patients with MDE and psychomotor agitation (PMA), according to DSM-5 criteria. Actigraphy allowed to objectively report PMA through heightened activity over a 24-h period, while PMR manifests as reduced activity during the most active 10 h. Lower rest-activity rhythm (RAR) amplitude in PMR was accompanied by increased irregularities in intra- and inter-day rhythms. Interestingly, actigraphy emerges as an objective tool to measure the characteristics of the active and rest periods, free from the confounding effects of sleep disturbances. Indeed, no differences in sleep disturbances were identified between patients exhibiting psychomotor agitation and those displaying PMR. Digital phenotyping through actigraphy may aid in distinguishing psychomotor retardation and psychomotor agitation allowing for a more precise characterization of the depression phenotype. When integrated with clinical assessment, measurements from actigraphy could offer additional insights into activity rhythms alongside subjective assessments and hold the potential to augment existing clinical decision-making processes in psychiatry.

Associations between accelerometer-measured circadian rest-activity rhythm, brain structural and genetic mechanisms, and dementia.

Knowledge of how circadian rhythm influences brain health remains limited. We aimed to investigate the associations of accelerometer-measured circadian rest-activity rhythm (CRAR) with incident dementia, cognitive dysfunction, and structural brain abnormalities in the general population and underlying biological mechanisms. Fifty-seven thousand five hundred and two participants aged over 60 years with accelerometer data were included to investigate the association of CRAR with incidental dementia. Non-parametric CRAR parameters were utilized, including activity level during active periods of the day (M10), activity level during rest periods of the day (L5), and the relative difference between the M10 and L5 (relative amplitude, RA). Associations of CRAR with cognitive dysfunction and brain structure were studied in a subset of participants. Neuroimaging-transcriptomics analysis was utilized to identify the underlying molecular mechanisms. Over 6.86 (4.94-8.78) years of follow-up, 494 participants developed dementia. The risk of incident dementia was associated with decreasing M10 (hazard ratio [HR] 1.45; 95% conference interval [CI], 1.28-1.64) and RA (HR 1.37; 95% CI, 1.28-1.64), increasing L5 (HR 1.14, 95% CI 1.07-1.21) and advanced L5 onset time (HR 1.12; 95% CI, 1.02-1.23). The detrimental associations were exacerbated by APOE ε4 status and age (>65 years). Decreased RA was associated with lower processing speed (Beta -0.04; SE 0.011), predominantly mediated by abnormalities in subcortical regions and white matter microstructure. The genes underlying CRAR-related brain regional structure variation were enriched for synaptic function. Our study underscores the potential of intervention targeting at maintaining a healthy CRAR pattern to prevent dementia risk.

0001 Circadian Rest-Activity Rhythm Patterns and Physical Performance in Community-Dwelling Older Men

0001 Circadian Rest-Activity Rhythm Patterns and Physical Performance in Community-Dwelling Older Men

Sleep and Circadian Health of Critical Survivors: A 12-Month Follow-Up Study.

To investigate the sleep and circadian health of critical survivors 12 months after hospital discharge and to evaluate a possible effect of the severity of the disease within this context. Observational, prospective study. Single-center study. Two hundred sixty patients admitted to the ICU due to severe acute respiratory syndrome coronavirus 2 infection. None. The cohort was composed of 260 patients (69.2% males), with a median (quartile 1-quartile 3) age of 61.5 years (52.0-67.0 yr). The median length of ICU stay was 11.0 days (6.00-21.8 d), where 56.2% of the patients required invasive mechanical ventilation (IMV). The Pittsburgh Sleep Quality Index (PSQI) revealed that 43.1% of the cohort presented poor sleep quality 12 months after hospital discharge. Actigraphy data indicated an influence of the disease severity on the fragmentation of the circadian rest-activity rhythm at the 3- and 6-month follow-ups, which was no longer significant in the long term. Still, the length of the ICU stay and the duration of IMV predicted a higher fragmentation of the rhythm at the 12-month follow-up with effect sizes (95% CI) of 0.248 (0.078-0.418) and 0.182 (0.005-0.359), respectively. Relevant associations between the PSQI and the Hospital Anxiety and Depression Scale (rho = 0.55, anxiety; rho = 0.5, depression) as well as between the fragmentation of the rhythm and the diffusing lung capacity for carbon monoxide (rho = -0.35) were observed at this time point. Our findings reveal a great prevalence of critical survivors presenting poor sleep quality 12 months after hospital discharge. Actigraphy data indicated the persistence of circadian alterations and a possible impact of the disease severity on the fragmentation of the circadian rest-activity rhythm, which was attenuated at the 12-month follow-up. This altogether highlights the relevance of considering the sleep and circadian health of critical survivors in the long term.

Real-world Digital Biomarkers Index Circadian Rest-activity Rhythms in Persons Taking Dopaminergic Medications for Parkinson’s Disease (P11-3.007)

Real-world Digital Biomarkers Index Circadian Rest-activity Rhythms in Persons Taking Dopaminergic Medications for Parkinson’s Disease (P11-3.007)

Circadian rest-activity rhythms associated with affect and cognition in stroke survivors: An ambulatory assessment study

Circadian rest-activity rhythms associated with affect and cognition in stroke survivors: An ambulatory assessment study

Associations of Circadian Rest-Activity Rhythms With Affect and Cognition in Community-Dwelling Stroke Survivors: An Ambulatory Assessment Study

Background Rest-activity rhythm (RAR) is a modifiable behavioral factor associated with affect and cognition. Identifying RAR characteristics associated with affect and cognition among stroke survivors provides insight into preventing poststroke affective and cognitive impairment. Objective To examine the associations of RAR characteristics with affect and cognition among community-dwelling stroke survivors. Methods Forty participants with mild stroke (mean age = 52.8; 42.5% female; 55% White) reported their affect and cognitive complaints using ecological momentary assessment and wore an accelerometer for 7 consecutive days and completed the National Institutes of Health Toolbox Cognition Battery. RAR characteristics were extracted using parametric and non-parametric approaches. Multivariable linear regressions were used to identify RAR characteristics associated with affect and cognition. Results Later onset of rest (B = 0.45; P = .008) and activity (B = 0.36; P = .041) were positively associated with depressed affect. These associations were reversed for cheerful effect (rest onset: B = −0.42; P = .017; activity onset: B = −0.39; P = .033). Cheerful affect was also positively associated with relative amplitude (ie, distinctions in activity levels between rest and activity; B = .39; P = .030). Intra-daily variability (ie, RAR fragmentation; B = 0.35; P = .042) and later onset of activity (B = .36; P = .048) were positively associated with cognitive complaints. Less erratic RAR was positively associated with fluid cognition (B = 0.29; P = .036); RAR fragmentation was positively associated with crystallized cognition (B = 0.39; P = .015). Conclusions We identified RAR correlates of affect and cognition among stroke survivors, highlighting the value of managing RAR and sleep in stroke rehabilitation. Future studies should test whether advancing the onset of rest and activity, promoting a regular active lifestyle, and improving rest and sleep in the nighttime protect stroke survivors from affective and cognitive impairment.

Individual-specific change points in circadian rest-activity rhythm and sleep in individuals tapering their antidepressant medication: an actigraphy study

Group-level studies showed associations between depressive symptoms and circadian rhythm elements, though whether these associations replicate at the within-person level remains unclear. We investigated whether changes in circadian rhythm elements (namely, rest-activity rhythm, physical activity, and sleep) occur close to depressive symptom transitions and whether there are differences in the amount and direction of circadian rhythm changes in individuals with and without transitions. We used 4 months of actigraphy data from 34 remitted individuals tapering antidepressants (20 with and 14 without depressive symptom transitions) to assess circadian rhythm variables. Within-person kernel change point analyses were used to detect change points (CPs) and their timing in circadian rhythm variables. In 69% of individuals experiencing transitions, CPs were detected near the time of the transition. No-transition participants had an average of 0.64 CPs per individual, which could not be attributed to other known events, compared to those with transitions, who averaged 1 CP per individual. The direction of change varied between individuals, although some variables showed clear patterns in one direction. Results supported the hypothesis that CPs in circadian rhythm occurred more frequently close to transitions in depression. However, a larger sample is needed to understand which circadian rhythm variables change for whom, and more single-subject research to untangle the meaning of the large individual differences.

Sleep, Mental Health, and Cognition Across Diverse Adult Populations

Abstract Sleep is often impaired in late life, raising concerns about the effect of poor sleep on mental and cognitive health in aging individuals. This symposium brings together five rigorous studies that show how poor sleep may be an under-recognized risk factor for mental health and cognitive outcomes in the second half of life. Specifically, this symposium showcases data from a variety of study cohorts (including Midlife in the United Study, Einstein Aging Study, and Study of Muscle, Mobility, and Aging), using diverse indicators of subjective and objective sleep. Paper 1 focuses on healthcare workers (HCWs), a group critical for the delivery of quality patient care, and examines both individual and joint associations of poor sleep and pain with mental health in HCWs vs. non-HCWs. Paper 2 investigates the association between EEG-measured sleep and depressive symptoms in older adults. Paper 3 explores the relationship between intra-individual variability of sleep and mild cognitive impairment (MCI) and identifies gender differences in these associations. Paper 4 establishes the associations of actigraphy-measured sleep and circadian rest-activity rhythms with multiple domains of cognition in older adults. Paper 5 examines the effect of latent dose/duration patterns of common sleep medications on development of Alzheimer’s disease and related dementias. The discussant, Dr. Adam Spira, will integrate key findings from these studies, discuss their contributions to the literature, and consider opportunities for future research. This is a Sleep, Circadian Rhythms and Aging Interest Group Sponsored Symposium. This is a collaborative symposium between the Alzheimer’s Disease and Related Dementias, Geroscience, and Health Behavior Change Interest Groups.

OBJECTIVE SLEEP AND CIRCADIAN REST–ACTIVITY RHYTHMS AND MULTIPLE DOMAINS OF COGNITIVE FUNCTION IN OLDER ADULTS

Abstract Evidence suggests that sleep and circadian rest-activity rhythms (RAR) play a key role in dementia and Alzheimer Disease (AD) pathology. Studies with objective measures of sleep and RAR and multiple domains of cognition remain limited. We studied 820 older adults enrolled in the Study of Muscle, Mobility and Aging (SOMMA). Actigraphs were worn for one week, and processed for sleep-wake measures including total sleep time (TST) and sleep efficiency (SE); and parametric (acrophase, pseudo-F) and non-parametric (interdaily stability [IS], intradaily variability [IV], and relative amplitude [RA]) 24-hour RAR variables. Cognitive assessments included global cognition (the Montreal Cognitive Assessment), executive function (Trails B test), memory (California Verbal Learning Test-short form; and psychomotor performance (Digit-Symbol Coding Test). Adjusting for age, sex, clinic site and education, we examined adjusted mean cognitive test scores by categories of sleep and RAR exposures. Mean age was 76 years, 58% were female, and 15% were non-white. Higher RA, reflecting a more robust 24-hour RAR, was associated with better cognition on all tests (p for trend &amp;lt;0.05). Reduced SE was related to lower cognitive function (psychomotor performance, global cognition, memory; p&amp;lt;.05). There were no associations with TST and any cognitive measures examined. SE and RAR were variably associated with both global and specific domains of cognition in older men and women. The RA in particular was strongly related to multiple domains of cognition related to AD, and may be useful in identifying individuals at risk. Additional analyses will explore sex differences and longitudinal associations.

SOCIAL PARTICIPATION, LONELINESS, AND CIRCADIAN RHYTHMS OF MIDDLE-AGED AND OLDER ADULTS IN TAIWAN

Abstract Loneliness among middle-aged and older adults is a growing public health concern in the aging society. While social participation is known as a protective factor against loneliness, not all older adults enjoy social participation. The purpose of this study is to investigate the social participation and loneliness characteristics in communities and their association with the demographic data, health-related variables, objective sleep parameters and rest-activity circadian rhythms with a sample of 242 Taiwan community-dwelling middle-aged and older adults aged 45 to 89 years. Loneliness and social participation levels were grouped in different clusters via Two-Step Cluster Analysis. Subsequently, Chi-square test and ANOVA were performed to identify the differences between clusters with relevant variables. Results showed that five social participation-loneliness clusters were grouped: Average(40.1%), Active-Lonely(3.8%), Not Active-Lonely(13.1%),Active -Not Lonely(5.9%),Not Active -Not Lonely(37.1%). Age, employment status, property management, self-perceived health, depression, life satisfaction and relative amplitude were related to clusters. The Active-Not Lonely cluster was older, had a higher retirement percentage, and higher life satisfaction. Compared with the Not Active-Lonely cluster, the Not Active -Not Lonely cluster had more power to manage their property, felt healthier and less depressive. The Active-Lonely cluster had a high percentage of unemployment and felt unhealthier. The Not Active-Lonely cluster had the lowest relative amplitude, which meant they had weaker rest-activity circadian rhythms. Objective sleep parameters were no difference between each cluster. These findings provide the potential benefits of developing appropriate social care programs to reduce loneliness for middle-aged and older adults via objective data.

A biological age biomarker based on circadian rest‐activity rhythms and risk of dementia

AbstractBackgroundCircadian function is altered with aging, leading to changes in the ∼24‐h rhythms of behavior and physiology. Based on circadian rest‐activity rhythms (CRAR), we previously constructed a biological age biomarker to characterize the aging profile of circadian function—circadian age (CircAge)—in older adults (&gt;65 years) and showed its association with risk of Alzheimer’s dementia. Here, we constructed CircAge in middle‐to‐older‐aged adults and tested whether it predicts all‐cause dementia.MethodParticipants from the UK Biobank with valid actigraphy data were studied (n = ∼97,000; 42‐78 years old). We developed a machine‐learning‐based regression model with 23 CRAR features derived from actigraphy (using cosinor, nonparametric, uniform‐phase‐empirical‐mode‐decomposition, and detrended‐fluctuation analyses). The fitting target was chronological age (ChrAge), and the prediction output was defined as CircAge. Model parameters were optimized using cross validation on 47,234 participants not performing shift work and without mental/behavioral or nervous system diseases. The optimized model was applied to all dementia‐free participants with valid CRAR (n = 80,805) to obtain their CircAge.ResultCircAge was 1.03±0.01 years older per one‐year older in ChrAge that explained ∼25% of the variance of CircAge (p&lt;0.0001). Male sex, European ethnicity, or having mental/behavioral/nervous system diseases were associated with a greater CircAge (all p&lt;0.0001). We compared CircAge of current shift workers (n = 6,389) with that of matched non‐shift workers to examine whether CircAge captures CRAR perturbations and found that CircAge of current shift workers was 1.1±0.2 years greater (p&lt;0.0001) than non‐shift workers. We then associated the difference between CircAge and ChrAge (DCC, = CircAge‐ChrAge) to incident all‐cause dementia using a Cox proportional hazards model adjusting for ChrAge, sex, ethnic groups, mental/behavioral diseases, and nervous system diseases. Results showed that greater DCC predicted higher adjusted risk of all‐cause dementia (n = 451): each decade higher DCC corresponding to a 1.10‐fold higher risk (95% CI: 1.02‐1.18; p = 0.009).ConclusionCRAR patterns can be translated into a biological aging biomarker for circadian function (CircAge), and greater CircAge than ChrAge is independently associated with risk of dementia in middle‐to‐older‐aged adults. Future studies are warranted to examine the use of CircAge (and/or in combination with other risk markers) for identifying at‐risk individuals in a clinical setting.

Rest-activity circadian rhythm in hospitalized older adults with mild cognitive impairment in Korea and its relationship with salivary alpha amylase: an exploratory study

Purpose: This study aimed to evaluate the rest-activity circadian rhythm (RAR) using data obtained from wearable actigraph devices in hospitalized older adults with mild cognitive impairment (MCI), and to investigate its relationship with salivary alpha amylase (sAA).Methods: This secondary data analysis used data from the Hospitalized Older Adults’ Cognition and Physical Activity Study. Actigraph data for 3-4 days were analyzed for RAR. RAR indices such as interdaily stability (IS), intradaily variability (IV), activity level during the most active 10-hour period and during the most least active 5-hour period, and relative amplitude (RA) were calculated. Data on sAA collected in the morning and general characteristics, including body mass index (BMI), were analyzed. Results: Data from 92 hospitalized older adults with MCI were analyzed. The IS, IV, RA were 0.23, 0.73, 0.88, respectively. The average level of sAA was 77.02 U/mL, and a higher level of sAA was significantly associated with better IS and RA in the regression analysis, while age, BMI, and cognitive level were not. BMI showed positive correlations with IS and RA. Conclusion: RAR in the hospitalized older adults with MCI was attenuated, showing especially low IS, which implies they failed to maintain regular and repetitive 24-hour RAR. Increased sAA and BMI were associated with robust RAR. Nurses need to pay attention to maintain robust RAR in hospitalized older adults with MCI, and strategies should be developed to improve their RAR.

Mediation and Dose-Response Relationship Among Physical Activity, Daylight Exposure, and Rest-Activity Circadian Rhythm in Patients With Esophageal and Gastric Cancer.

Physical activity and daylight exposure predict rest-activity circadian rhythm (RACR) in patients with cancer. However, whether daylight exposure mediates the relationship between physical activity and RACR and the optimal amounts of physical activity and daylight that benefit RACR remain unclear. This study investigated the mediating role of daylight exposure and determined the dose-response relationship among daylight exposure, physical activity, and RACR in patients with cancer. This cross-sectional exploratory study recruited 319 patients with esophageal and gastric cancer from 2 surgery outpatient departments in Taiwan. Daylight exposure (>500 lux), physical activity (up activity mean), and RACR (midline estimating statistic of rhythm) were measured through actigraphy. Regression was performed, and the receiver operating characteristic curve was plotted. Daylight exposure (>500 lux) partially mediated the relationship between physical activity (up activity mean) and RACR (midline estimating statistic of rhythm). The optimal cutoffs for discriminating between satisfactory and poor RACR were 187.43 counts/min for physical activity (sensitivity, 90.3%; specificity, 84.4%) and 35.71 min/d for daylight exposure (sensitivity, 55.9%; specificity, 78.2%). Participants who engaged in physical activity were more likely to receive daylight exposure and experience improved RACR. The optimal level of daylight exposure and frequency of physical activity that can improve RACR in patients with esophageal and gastric cancer are 36 min/d and 187 counts/min, respectively. Healthcare professionals should encourage patients to engage in exercise or physical activity during the daytime to improve their circadian rhythm.