The association between circadian rest-activity patterns and the behavioral and psychological symptoms depending on the cognitive status in Japanese nursing-home residents

ABSTRACT

Background: 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. Method: 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. Results: 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. Conclusion: 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.     

Rest-activity rhythm in breast cancer survivors: an update based on non-parametric indices

ABSTRACT

Recently we evaluated by actigraphy the rest-activity circadian rhythm (RAR) in breast cancer (BC) survivors at 5 years from primary diagnosis, as well as in a control group with similar age and body mass index (BMI). RAR, analyzed by Cosinor method, resulted significantly different in BC survivors compared to healthy subjects: BC survivors showed lower values of MESOR and Amplitude (A), while acrophase (φ) was similar in the two groups.

Now, using non-parametric methods we have detected Interdaily Stability (IS), Intradaily Variability (IV), nocturnal activity (L5), and daily activity (M10) on the same sample of previous study: 15 BC survivors at 5 years from the primary diagnosis (mean age = 56.7 ± 6.6 yrs; mean BMI = 24.5 ± 3.8 Kg/m²) and 13 healthy controls (mean age = 54.4 ± 7.2 yrs; mean BMI = 25.2 ± 2.8 Kg/m²).

The non-parametric indices showed that in BC-group IV was significantly higher than in Ctrl-group (0.86 vs. 0.65 a.u. in BC and Ctrl, respectively; p <.01), while L5 (11.27 vs. 34.41 a.c. in BC and Ctrl, respectively; p <.0001) and M10 (326.82 vs. 428.07 a.c. in BC and Ctrl, respectively; p <.01) were significantly lower compared to Ctrl-group.

The data suggest that BC patients need constant clinical assessment of RAR characteristics along the years following the primary diagnosis. The analysis of RAR in all its components, parametric and non-parametric, is important to detect alterations in the sleep-wake cycle and can be useful for developing new strategies for health protection, such as structured and tailored physical activity programs, to improve circadian activity level in order to raise the quality of life in BC survivors.     

Circadian rest-activity rhythm in chronic obstructive pulmonary disease

To characterize circadian rest-activity rhythm in COPD, 26 cases (66.9 ± 8.5y) and 15 controls (63.0 ± 10.7y) were assessed by actimetry. Rhythm fragmentation was measured by intradaily variability (IV), while synchronization to the 24-h light-dark cycle was measured by interdaily stability (IS). The average activity during the least active 5-h period (L5) and the average activity during the most active 10-h period (M10) were used to calculate the relative amplitude mean [RAm = (M10-L5)/(M10+L5)]. COPD patients presented higher IVm (0.242 ± 0.097 vs 0.182 ± 0.063) and L5 (36.849 ± 18.239 vs 19.888 ± 12.268) and lower RAm (0.696 ± 0.134 vs 0.833 ± 0.093) than controls. Future studies on the effects of chronotherapy measures in COPD are warranted.     

Progressive retinal ganglion cell loss in primary open-angle glaucoma is associated with temperature circadian rhythm phase delay and compromised sleep

Advanced primary open-angle glaucoma (POAG) is characterized by progressive retinal ganglion cell complex (RGCC) damage that may cause subsequent disruption of the circadian rhythms. Therefore, we evaluated circadian body temperature (BT) rhythm and sleep characteristics of 115 individuals (38 men and 77 women) diagnosed with POAG. GLV (global loss volume; %), a measure of RGCC damage, was estimated by high-definition optical coherence tomography, and RGC functional ability was assessed by pattern electroretinogram amplitude (PERGA). Depending on dynamics of POAG progression criteria, two groups were formed that were distinctively different in GLV: Stable POAG group (S-POAG; GLV = 5.95 ± 1.84, n = 65) and Progressive POAG group (P-POAG; GLV = 24.27 ± 5.09, n = 50). S-POAG and P-POAG groups were not different in mean age (67.61 ± 7.56 versus 69.98 ± 8.15) or body mass index (24.66 ± 3.03 versus 24.77 ± 2.90). All subjects performed 21 around-the-clock BT self-measurements during a 72-h period and kept activity/sleep diaries. Results showed pronounced disruption of circadian physiology in POAG and its progression with increasing severity of the disease. The daily mean of BT was unusually low, compared to age-matched controls. Moreover, our results revealed distinctive features of BT circadian rhythm alterations in POAG development and POAG progression. S-POAG is associated with lowered BT circadian rhythm robustness and inter-daily phase stability compared to controls. In the P-POAG group, the mean phase of the circadian BT rhythm was delayed by about 5 h and phases were highly scattered among individual patients, which led to reduced group mean amplitude. Circadian amplitudes of individuals were not different between the groups. Altogether, these results suggest that the body clock still works in POAG patients, but its entrainment to the 24-h environment is compromised. Probably because of the internal desynchronization, bedtime is delayed, and sleep duration is accordingly shortened by about 55 min in P-POAG compared to S-POAG patients. In the entire POAG cohort (both groups), later sleep phase and shorter mean sleep duration correlate with the delayed BT phase (r = 0.215; p = 0.021 and r = 0.322; p = 0.0004, respectively). An RGCC GLV of 15% apparently constitutes a threshold above which a delay of the circadian BT rhythm and a shortening of sleep duration occur.     

Rest-activity rhythms characteristics and seasonal changes in seasonal affective disorder

ABSTRACT

Identifying objectively measurable seasonal changes in 24-h 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 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 min earlier in the winter compared with the summer (1-h 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.     

基于Logistic回归模型分析维持性血液透析患者肌少症的危险因素及其对患者生活质量、负性情绪及生存状况的影响

摘要 目的：基于Logistic回归模型分析维持性血液透析（MHD）患者肌少症的危险因素及其对患者生活质量、负性情绪及生存状况的影响。方法：选取江苏省人民医院肾内科肾脏病重症病房于2019年2月-2021年2月期间收治的MHD患者289例,收集所有患者的一般资料,根据是否患有肌少症将患者分为肌少症组（n=71）及非肌少症组（n=218）。采用单因素和多因素Logistic回归模型分析MHD患者肌少症的危险因素,并观察两组生活质量、负性情绪及生存状况。结果：肌少症组、非肌少症组在年龄、透析时间、规律运动、体质量指数（BMI）、人体蛋白质含量（PM）、去脂体质量（FFM）、改良定量主观评估表（MQSGA）评分、血磷、超敏C反应蛋白（hs-CRP）、血肌酐、前白蛋白、白蛋白组间对比差异有统计学意义（P<0.05）。多因素Logistic回归分析,结果显示年龄偏大、透析时间偏长、BMI下降、MQSGA评分偏高、hs-CRP偏高、血肌酐偏高是MHD患者发生肌少症的危险因素,高血磷、规律运动则是其保护因素（P<0.05）。肌少症组患者的精神健康、生理职能、总体健康、生理功能、社会功能、活力、躯体疼痛、情感职能评分均低于非肌少症组（P<0.05）。肌少症组患者的抑郁自评量表（SDS）、焦虑自评量表（SAS）评分高于非肌少症组（P<0.05）。随访1年后,肌少症组的死亡率明显高于非肌少症组（P<0.05）。结论：MHD患者并发肌少症受到年龄、透析时间、BMI、MQSGA评分、hs-CRP、血肌酐、血磷、规律运动等因素的影响,且并发肌少症的患者其抑郁焦虑程度更重,生活质量更差,生存期缩短。     

Variation in actigraphy-estimated rest-activity patterns by demographic factors

Rest-activity patterns provide an indication of circadian rhythmicity in the free-living setting. We aimed to describe the distributions of rest-activity patterns in a sample of adults and children across demographic variables. A sample of adults (N = 590) and children (N = 58) wore an actigraph on their nondominant wrist for 7 days and nights. We generated rest-activity patterns from cosinor analysis (MESOR, acrophase and magnitude) and nonparametric circadian rhythm analysis (IS: interdaily stability; IV: intradaily variability; L5: least active 5-hour period; M10: most active 10-hour period; and RA: relative amplitude). Demographic variables included age, sex, race, education, marital status, and income. Linear mixed-effects models were used to test for demographic differences in rest-activity patterns. Adolescents, compared to younger children, had (1) later M10 midpoints (β = 1.12 hours [95% CI: 0.43, 1.18] and lower M10 activity levels; (2) later L5 midpoints (β = 1.6 hours [95% CI: 0.9, 2.3]) and lower L5 activity levels; (3) less regular rest-activity patterns (lower IS and higher IV); and 4) lower magnitudes (β = ?0.95 [95% CI: ?1.28, ?0.63]) and relative amplitudes (β = ?0.1 [95% CI: ?0.14, ?0.06]). Mid-to-older adults, compared to younger adults (aged 18–29 years), had (1) earlier M10 midpoints (β = ?1.0 hours [95% CI: ?1.6, ?0.4]; (2) earlier L5 midpoints (β = ?0.7 hours [95% CI: ?1.2, ?0.2]); and (3) more regular rest-activity patterns (higher IS and lower IV). The magnitudes and relative amplitudes were similar across the adult age categories. Sex, race and education level rest-activity differences were also observed. Rest-activity patterns vary across the lifespan, and differ by race, sex and education. Understanding population variation in these patterns provides a foundation for further elucidating the health implications of rest-activity patterns across the lifespan.     

Entraining effects of variations in light spectral composition on the rest-activity rhythm of a nocturnal rodent

The ability to predict and adjust physiology and behavior to recurring environmental events has been necessary for survival on Earth. Recent discoveries revealed that not only changes in irradiance but also light spectral composition can stimulate the suprachiasmatic nucleus (SCN), ensuring the body’s synchronization to the environment. Therefore, using a lighting system that modulates spectral composition during the day using combined red-green-blue (RGB) lights, we evaluated the effect of variations in light spectral composition on the rest-activity rhythm of rodents. Male Wistar rats (n = 17) were gestated and raised under different lighting conditions and exposed to a long photoperiod (16 h light: 8 h dark). The difference between groups was the presence of variations in light spectral composition during the day (RGB-v) to simulate daily changes in natural light, or not (RGB-f). After weaning, spontaneous motor activity was recorded continuously for rhythm evaluation. Our results indicated that animals under RGB-v did not present a reactive peak of activity after the beginning of the light phase, suggesting that this group successfully detected the variations aimed at mimicking daily alterations of natural light. Furthermore, RGB-v animals exhibited an earlier activity acrophase in comparison to animals under RGB-f (RGB-v = 12:16 – “hh:mm”, RGB-f = 13:02; p < 0.001), which might have been due to the capability to predict the beginning of the dark phase when exposed to variations in light spectrum. However, this earlier activity acrophase can be also explained by the blue-light peak that occurred in RGB-v. The spectral and waveform analysis of daily patterns of motor activity revealed that rats in the RGB-v group were better entrained to a circadian rhythm throughout the experiment. RGB-v showed higher interdaily stability (IS) values (29.75 ± 6.5, n = 9) than did RGB-f (t₍₁₅₎ = 2.74, p = 0.015). Besides, the highest power content (PC) on the first harmonic (circadian) was reached earlier in the RGB-v group. The circadianity index (CI) of the whole period was higher in the RGB-v group (t₍₁₅₎ = 3.47, p = 0.003). Thus, we could consider that locomotor activity rhythm was entrained to the light-dark cycle in the RGB-v rats earlier compared to the RGB-f rats. Our results provide additional evidence for the effect of variations in light spectral composition on the rest-activity pattern of nocturnal rodents. This suggests that these animals might predict the arrival of the activity phase by its advanced acrophase when exposed to RGB-v, demonstrating a better synchronization to a 24-h rhythm.     

Rest-activity circadian rhythm in breast cancer survivors at 5 years after the primary diagnosis

ABSTRACT

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 (p < .001). The group analysis revealed a significant RAR both in BC- and Ctrl-group (p < .001). The acrophase was not different between the BC- and Ctrl-group (15:09 vs. 15:01 hr:min in BC- and Ctrl-group, respectively). In contrast, the MESOR (Midline Estimating Statistic of Rhythm) and the amplitude were lower in the BC-group with respect to the Ctrl-group. Indeed, the MESOR was 192.0 vs. 276.4 activity counts in BC- and Ctrl-group, respectively (p < .001), while the amplitude was 167.0 vs. 222.6 activity counts in BC- and Ctrl-group, respectively (p < .001). These results provide the first experimental evidence of alterations in RAR parameters in BC survivors at 5 years after the primary diagnosis. Larger studies with a prospective design are needed to assess the role of RAR in the quality of life and prognosis in BC survivors.     

Variations in rest-activity rhythm are associated with clinically measured disease severity in Parkinson’s disease

ABSTRACT

The continuous, longitudinal nature of accelerometry monitoring is well-suited to capturing the regular 24-hour oscillations in human activity across the day, the cumulative effect of our circadian rhythm and behavior. Disruption of the circadian rhythm in turn disrupts rest-activity rhythms. Although circadian disruption is a major feature of Parkinson’s disease (PD), rest-activity rhythms and their relationship with disease severity have not been well characterized in PD. 13 PD participants (Hoehn & Yahr Stage [H&Y] 1–3) wore a Philips Actiwatch Spectrum PRO continuously for two separate weeks. Rest-activity rhythms were quantified by fitting an oscillating 24-hour cosinor model to each participant-day of activity data. One-way ANOVAs adjusted for demographics revealed significant variation in the amount (MESOR, F = 12.76, p < .01), range (Amplitude, F = 9.62, p < .01), and timing (Acrophase, F = 2.7, p = .05) of activity across H&Y Stages. Those with higher H&Y Stages were significantly more likely to be active later in the day, where-as those who shifted between H&Y Stages during the study were significantly more active than those who did not change H&Y Stage. Being active later in the day was also significantly associated with higher scores on the Movement Disorder Society’s Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) Section III (motor symptom severity, p = .02), Section II (self-reported impact of motor symptoms on daily living, p = .01), and Total Score (p = .01) in an adjusted linear regression model; significant associations between MDS-UPDRS scores and activity levels were observed only in the unadjusted model. These findings demonstrate that continuous actigraphy is capable of detecting rest-activity disruption in PD, and provides preliminary evidence that rest-activity rhythms are associated with motor symptom severity and H&Y Stage.     

Association of rest–activity and light exposure rhythms with sleep quality in insomnia patients

ABSTRACT

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, p < 0.01), indicating a negative relationship of the IS with SOL in ID unlike its positive relationship in NC. There were no significant main effects of IV on the SOL, SE, and WASO, but significant main effects of RA on the SE and WASO (β = 63.65 and β = ?221.43, respectively, p < 0.01). GLMs for LER revealed no significant main effects of IS, IV or RA on the SOL, SE, and WASO, but significant interactions between group and RA on the SE and WASO (β = 56.17 and β = ?171.93, respectively, p < 0.05), indicating a stronger positive relationship of the RA with SE in ID compared to NC, and a negative relationship of the RA with WASO in ID, unlike its positive relationship in NC. Although our study did not reveal group differences in circadian variables of RAR and LER, it suggested that the regularity of RAR could be positively associated with sleep initiation, while the robustness of LER could be positively associated with sleep maintenance in insomnia patients.     

Alterations of the characteristics of the circadian rest-activity rhythm of cancer in-patients

The aim of the present study was to evaluate the characteristics of the circadian rest-activity rhythm of cancer patients. Thirty-one in-patients, consisting of 19 males and 12 females, were randomly selected from the Regional Cancer Center, Pandit Jawaharlal Nehru Medical College, Raipur, India. The rest-activity rhythm was studied non-invasively by wrist actigraphy, and compared with 35 age-matched apparently healthy subjects (22 males and 13 females). All subjects wore an Actiwatch (AW64, Mini Mitter Co. Inc., USA) for at least 4-7 consecutive days. Fifteen-second epoch length was selected for gathering actigraphy data. In addition, several sleep parameters, such as time in bed, assumed sleep, actual sleep time, actual wake time, sleep efficiency, sleep latency, sleep bouts, wake bouts, and fragmentation index, were also recorded. Data were analyzed using several statistical techniques, such as cosinor rhythmometry, spectral analysis, ANOVA, Duncan's multiple-range test, and t-test. Dichotomy index (I相似文献   

Preoperative circadian physical activity rhythm and postoperative delirium in cardiovascular surgery patients

ABSTRACT

Postoperative delirium, a common perioperative complication, is frequently observed in elderly surgical patients. Few studies have investigated the life rhythm of preoperative patients, and whether or not the preoperative life rhythm is associated with the development of postoperative delirium. The purpose of this study was to investigate the relationship between the preoperative circadian physical activity rhythm and postoperative delirium in cardiovascular surgery patients. A total of 43 patients who underwent cardiovascular surgery were included in this prospective study between July 2016 and September 2017 at Kobe University Hospital. All subjects used a “Life Microscope” wristband (a wristwatch-type terminal incorporating a 3-axis accelerometer monitoring) for 3–7 days at home before the planned surgery. Hourly mean values were calculated for the metabolic equivalents from the obtained activity amounts, and subsequently evaluated using cosine periodic regression analysis. The circadian rhythm parameters of mesor (24 h time series mean), amplitude (half the peak-trough variation), and acrophase (peak time) for the metabolic equivalents were obtained. The intensive care delirium screening checklist was used to assess for postoperative delirium. The acrophase significantly advanced in the postoperative delirium group (median, 11:55 h [interquartile range, 11:06–12:27 h]) compared to the group without postoperative delirium (median, 13:25 h [interquartile range, 12:52–14:13 h]) (p < .001). Furthermore, binary logistic regression analysis showed that advances in the physical activity phase remained independently associated with postoperative delirium (odds ratio, 0.003 [95% confidence interval, 0–0.63]). These results suggest that misalignment between advanced life rhythm before hospitalization and life rhythm after hospitalization might be associated with risk for developing postoperative delirium. Our results led us to speculate that adequate consideration of the patient’s life rhythm before hospitalization is needed to prevent postoperative delirium.     

Differences in workday sleep fragmentation,rest-activity cycle,sleep quality,and activity level among nurses working different shifts

ABSTRACT

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 (r24), and daytime activity mean was collected in order to investigate workday sleep fragmentation, rest-activity cycle, and daytime activity level. We obtained complete questionnaires and data from 191 nurses. Day- and evening-shift nurses had more regular workday rest-activity cycles than did night-shift nurses (F = 51.26, p < .001). After controlling for r24 coefficients, we determined that nurses who experienced greater workday sleep fragmentation had higher PSQI scores (β = .18, p = .008). After controlling for WASO times, we determined that nurses who had more regular rest-activity cycles on workdays had lower PSQI scores (β = – .16, p = .036). After controlling for shift type and WASO times, we determined that nurses with higher PSQI scores displayed lower activity levels (β = – .21, p = .015) and those with higher r24 coefficients displayed higher activity levels (β = .18, p = .040) on workdays. We then examined the causal path relationships. Among the shifts, only the day-shift nurses had a higher r24 (β = ?.59, p < .001) than did the night-shift nurses; WASO exerted a significant impact on PSQI scores (β = .20, p = .002); r24 had a significant and negative influence on PSQI scores (β = ?.38, p < .001), and PSQI scores significantly and negatively influenced workday activity levels (β = ?.20, p = .006). This study determined that day- and evening-shift nurses enjoyed more regular and consistent rest-activity cycles than did night-shift nurses; nurses with greater workday sleep fragmentation and/or more irregular rest-activity cycles experienced poorer sleep quality; and nurses suffering from poorer sleep quality displayed lower daytime activity levels on workdays.     

Relationship Between Infant and Mother Circadian Rest-Activity Rhythm Pre- and Postpartum,in Comparison to an Infant With Free-Running Rhythm

Some infants show a free-running rhythm in their rest-activity. We do not know why, nor do we know exactly what the entrainment factors are for the development of the normal 24-h rest-activity rhythm. Actigraphic recordings on 10 primiparae during late pregnancy and these mothers and their infants during the 2nd, 6th, and 12th wks after birth were made over 3–5 continuous days to investigate maternal and infant entrainment. One infant showed a free-running rest-activity circadian rhythm. In late pregnancy, the period in the autocorrelogram of the mother with the free-running infant was longer than the significant period of the mean autocorrelogram of the mothers with non-free-running infants. The finding of this study indicates the free-running rhythm of infant is not reset by maternal entrainment factors. (Author correspondence: nishihara-kk@igakuken.or.jp)     

Environmental stress of mobile phone EM radiation on locomotor activity and melatonin circadian rhythms of rats

Biological clocks are innate timing mechanisms that regulate many behavioral and physiological parameters in most organisms. In our modern life, heavy use of mobile phones (MPs) exerts a massive stress on organisms because their electromagnetic radiation usually results in varying degrees of damage to their biological systems including the biological rhythms. In the present study, the possible effects of exposure to radiofrequency–electromagnetic radiation (RF–EMR) from MPs on two characteristic circadian rhythms, locomotor activity and melatonin hormone rhythms, were investigated. Rats were exposed to RF–EMR from MPs at 900 MHz frequency (2-h/day for 2 weeks) during nighttime (20:00–22:00 h) followed by another two weeks without exposure for recovery. Locomotor activity rhythms of the control and treated groups (n = 5/group) were daily recorded using running wheels along the experimental period. For evaluating melatonin hormone rhythm, blood samples of control and treated groups (n = 12/group), were collected at the end of exposure and recovery periods, at 6-h time intervals per day (at 4:00, 10:00, 16:00, and 22:00 h). Rats exposed to RF–EMR exhibited phase shifting as well as a significant increased acrophase level in locomotor activity. Meanwhile, a significant decrease in serum melatonin levels with retaining lower amplitude rhythmicity was observed. Ceasing exposure for two weeks did not restore melatonin levels and circadian locomotor activity rhythms. It could be concluded that, under the current conditions, exposure to RF–EMR revealed disturbances in locomotor activity and melatonin level, although they maintained rhythmicity.     

Thermoregulatory plasticity in free-ranging vervet monkeys,Chlorocebus pygerythrus

We used implanted miniature data loggers to obtain the first measurements of body temperature from a free-ranging anthropoid primate. Vervet monkeys (Chlorocebus pygerythrus) living in a highly seasonal, semi-arid environment maintained a lower mean 24-h body temperature in winter (34.6 ± 0.5 °C) than in summer (36.2 ± 0.1 °C), and demonstrated increased heterothermy (as indexed by the 24-h amplitude of their body temperature rhythm) in response to proximal environmental stressors. The mean 24-h amplitude of the body temperature rhythm in summer (2.5 ± 0.1 °C) was lower than that in winter (3.2 ± 0.4 °C), with the highest amplitude for an individual monkey (5.6 °C) recorded in winter. The higher amplitude of the body temperature rhythm in winter was a consequence primarily of lower 24-h minimum body temperatures during the nocturnal phase, when monkeys were inactive. These low minimum body temperatures were associated with low black globe temperature (GLMM, β = 0.046, P < 0.001), short photoperiod (β = 0.010, P < 0.001) and low rainfall over the previous 2 months, which we used as a proxy for food availability (β = 0.001, P < 0.001). Despite the lower average winter minimum body temperatures, there was no change in the lower modal body temperature between winter and summer. Therefore, unlike the regulated physiological adjustments proposed for torpor or hibernation, these minimum winter body temperatures did not appear to reflect a regulated reduction in body temperature. The thermoregulatory plasticity nevertheless may have fitness benefits for vervet monkeys.     

Sarcopenia as a Determinant of Blood Pressure in Older Koreans: Findings from the Korea National Health and Nutrition Examination Surveys (KNHANES) 2008–2010

Background

Blood pressure (BP) is directly and causally associated with body size in the general population. Whether muscle mass is an important factor that determines BP remains unclear.

Objective

To investigate whether sarcopenia is associated with hypertension in older Koreans.

Participants

We surveyed 2,099 males and 2,747 females aged 60 years or older.

Measurements

Sarcopenia was defined as an appendicular skeletal muscle mass divided by body weight (ASM/Wt) that was <1 SD below the gender-specific mean for young adults. Obesity was defined as a body mass index (BMI) ≥25 kg/m². Subjects were divided into four groups based on presence or absence of obesity or sarcopenia. Hypertension was defined as a systolic BP (SBP) ≥140 mmHg, a diastolic BP (DBP) ≥90 mmHg, or a self-reported current use of antihypertensive medications.

Results

The overall prevalence of hypertension in the four groups was as follows 49.7% for non-obese non-sarcopenia, 60.9% for non-obese sarcopenia, 66.2% for obese non-sarcopenia and 74.7% for obese sarcopenia. After adjustment for age, gender, regular activity, current smoking and alcohol use, the odds ratio (OR) for having hypertension was 1.5 (95% confidence interval (CI) = 1.23–1.84) in subjects in the non-obese sarcopenia group, 2.08 (95% CI = 1.68–2.57) in the obese non-sarcopenia group and 3.0 (95% CI = 2.48–3.63) in the obese sarcopenia group, compared with the non-obese non-sarcopenia group (p for trend <0.001). Controlling further for body weight and waist circumference did not change the association between hypertension and sarcopenia. The association between sarcopenia and hypertension was more robust in the subjects with diabetes mellitus.

Conclusion

Body composition beyond BMI has a considerable impact on hypertension in elderly Koreans. Subjects with sarcopenic obesity appear to have a greater risk of hypertension than simply obese or sarcopenia subjects.