Circadian misalignment and health

The impact of maintenance therapy on sleep-wake rhythms and cancer-related fatigue in pediatric acute lymphoblastic leukemia

Purpose

To assess the impact of maintenance therapy and the additional impact of dexamethasone treatment on cancer-related fatigue and sleep-wake rhythms in pediatric acute lymphoblastic leukemia (ALL) patients and to determine the association between these outcomes.

Methods

A national cohort of pediatric ALL patients (≥ 2 years) was included (± 1 year post-diagnosis). Patients receiving dexamethasone were assessed twice (assessment with and without dexamethasone). Actigraphy assessments were used to calculate sleep-wake outcomes with nonparametric methods. Cancer-related fatigue was assessed with the PedsQL Multidimensional Fatigue Scale. Sleep-wake rhythms and cancer-related fatigue were compared between patients participating in the assessment without dexamethasone and healthy children (linear regression) and between assessments with and without dexamethasone (mixed models). Using linear regression, associations between sleep-wake outcomes and cancer-related fatigue were determined during assessments with and without dexamethasone.

Results

Responses were collected for 125 patients (113 assessments with and 81 without dexamethasone). The sleep-wake rhythm was less stable (p = 0.03) and less robust (p = 0.01), with lower physical activity levels (p < 0.001) and higher cancer-related fatigue levels (p < 0.001) in ALL patients compared to healthy children. Physical activity was lower (p = 0.001) and cancer-related fatigue more severe (p ≤ 0.001) during assessments with dexamethasone compared to without dexamethasone. Sleep-wake outcomes were significantly associated with cancer-related fatigue during periods without dexamethasone, but not during periods with dexamethasone.

Conclusion

Sleep-wake rhythms are disturbed, physical activity levels lower, and cancer-related fatigue levels higher during maintenance therapy. Interventions aimed to enhance sleep-wake rhythms during maintenance therapy could improve cancer-related fatigue. Families should be supported in coping with the additional burden of dexamethasone treatment to improve well-being of ALL patients.

Electronic supplementary material

The online version of this article (10.1007/s00520-020-05444-7) contains supplementary material, which is available to authorized users.

High-throughput transcriptome and pathogenesis analysis of clinical psoriasis

BACKGROUND

Previous psoriasis studies have mostly focused on skin-related immunology, but the exact mechanisms remain elusive. Clinical evidence, such as higher morbidity among obese individuals and emotional factors, indicate that psoriasis is a complex systemic disease. High-throughput transcriptome analysis provides an effective method to comprehensively assess the disease.

OBJECTIVE

The present study is aiming to understand transcriptome changes of clinical psoriasis skins and comprehensively assess the diseases using pathways analysis.

METHODS

We performed transcriptome sequence of clinical psoriatic samples. Biological pathway analyses were conducted using differentially expressed RNAs, as well as identified competing endogenous RNAs (ceRNAs). qRT-PCR and histological immunofluorescence staining was conducted to verify the differentially expressed RNAs (DE_RNAs) and the three important enriched biological pathways.

RESULTS

Numerous DE_RNAs were identified between psoriasis patients and healthy people. Functional analysis indicated PPAR-fatty acids metabolism pathways, neural-hormone regulations, circadian entrainment were the three mostly appeared pathways. For PPAR-fatty acids metabolism pathways, the expression of seven randomly selected genes, including ACSBG1, ACOT2), CYP27A1, ELOVL3, FABP7, FADS2 and PPARG were all significantly decreased in psoriasis lesions. For neural-hormone regulation pathways, the expression of CFL1, EPHA2, HRAS were all significantly upregulated in psoriasis lesions. While the expression of four randomly selected genes from circadian entrainment pathways, including CRY2, PER3, NR1D1 and RORC were all significantly downregulated. Histological immunofluorescence staining of FADS2, EPHA2 and CRY2 were consistent with their genes' expressions.

CONCLUSION

Our results revealed transcriptome changes of psoriasis, and indicated three important pathways involved in psoriasis, including PPAR-fatty acids metabolism pathways, neural-hormone regulations, circadian entrainment.

Constant Light Exerted Detrimental Cardiovascular Effects Through Sympathetic Hyperactivity in Normal and Heart Failure Rats

It has been documented that constant light exposure exerts complicated cardiovascular effects. However, a mounting collection of conflicting results did not make it any easier for researchers and physicians to consider the role of light on cardiovascular function. This study was designed to investigate how constant light exposure (24 h light/day) influences the cardiac function in normal and heart-failure (HF) rats. In normal rats, two groups of SD rats were accustomed in 12 h light/12 h dark (LD) or 24 h light (constant light, CL) for 4 weeks. In HF rats which was induced by myocardial infarction (MI) was let recover in LD for 4 weeks. Interestingly, compared with rats in LD environment (ejection fraction, EF%: 93.64 ± 2.02 in LD, 14.62 ± 1.53 in HF-LD), constant light (2 weeks) weakened the cardiac function in normal and HF rats (EF%: 79.42 ± 2.91 in CL, 11.50 ± 1.08 in HF-CL). The levels of renal sympathetic nerve activity and c-fos expression in the rostral ventrolateral medulla (RVLM), a key region controlling sympathetic outflow, were significantly increased in normal and HF rats after constant light (RSNA, Max%: 8.64 ± 0.48 in LD, 20.02 ± 1.24 in CL, 20.10 ± 1.16 in HF-LD, 26.82 ± 1.69 in HF-CL). In conclusion, it is suggested that constant light exposure exerts detrimental cardiovascular effects, which may be associated with the RVLM-related sympathetic hyperactivity.

Are Owls and Larks Different When it Comes to Aggression? Genetics, Neurobiology, and Behavior

This review focuses on the contribution of circadian rhythms to aggression with a multifaceted approach incorporating genetics, neural networks, and behavior. We explore the hypothesis that chronic circadian misalignment is contributing to increased aggression. Genes involved in both circadian rhythms and aggression are discussed as a possible mechanism for increased aggression that might be elicited by circadian misalignment. We then discuss the neural networks underlying aggression and how dysregulation in the interaction of these networks evoked by circadian rhythm misalignment could contribute to aggression. The last section of this review will present recent human correlational data demonstrating the association between chronotype and/or circadian misalignment with aggression. With circadian rhythms and aggression being a burgeoning area of study, we hope that this review initiates more interest in this promising and topical area.

Actigraphic estimates of sleep and the sleep-wake rhythm, and 6-sulfatoxymelatonin levels in healthy Dutch children

Sleep and the sleep-wake rhythm are essential for children's health and well-being, yet reference values are lacking. This study therefore aimed to assess actigraphic estimates of sleep and the 24-h sleep-wake rhythm, as well as 6-sulfatoxymelatonin (aMT6s) levels in healthy children of different age groups. Additionally, relationships between the outcomes and sex, highest parental educational level (as an indication of socioeconomic status (SES)), and body-mass-index (BMI) were explored. In this cross-sectional study, healthy Dutch children (2-18 years) wore an actigraph (GT3x) for 7 consecutive days, collected first-morning void urine and completed a sleep log and sociodemographic questionnaire. Actigraphically estimated sleep variables were sleep onset latency (SOL), sleep efficiency (SE), total sleep time (TST), and wake after sleep onset (WASO). Non-parametric sleep-wake rhythm variables were intradaily variability (IV); interdaily stability (IS); the activity counts and timing of the least active 5-h period (L5counts and midpoint) and of the most active 10-h period (M10 counts and midpoint); and the relative amplitude (RA), i.e. the ratio of the difference and the sum of M10 and L5 counts. Finally, creatinine-corrected aMT6s levels were obtained by isotope dilution mass spectrometry. Effects of age group (preschool 2-5 years/school-aged 6-12 years/teenager 13-18 years), sex, highest parental educational level and BMI (Z-scores) were explored. Ninety-four children participated, equally divided across age groups (53% boys). Teenagers slept less, but more efficiently, than younger children, while their 24 h sleep-wake rhythm was the least stable and most fragmented (likely due to fragmentation of daytime activity). Additionally, aMT6s levels significantly declined over the age groups. Children from highly educated parents had lower sleep efficiency, but a more stable sleep-wake rhythm. Finally, sex or increase in BMI was not associated with any of the outcomes in this study. In conclusion, this study provides reference values of healthy children across different age groups and different sociodemographic factors. In the future, this information may help to better interpret outcomes in clinical populations.

Evening chronotype is associated with poor cardiovascular health and adverse health behaviors in a diverse population of women

Chronotype reflects time of day preferences for performing daily activities. Previous research within Asian and European cohorts indicates evening chronotype is associated with elevated cardiometabolic risk. However, evidence is limited from population-based US cohorts, particularly among women in whom evening chronotype prevalence may become higher after middle-age, coinciding with life stages associated with higher cardiovascular disease (CVD) risk. This cross-sectional study evaluated associations of chronotype with overall cardiovascular health (CVH), health behaviors, and cardiometabolic risk factors among 506 women (mean age = 37 ± 16y, 62% racial/ethnic minority) in the American Heart Association (AHA)'s Go Red for Women Strategically-Focused Research Network cohort at Columbia University (New York City, NY, USA). Chronotype was assessed using the validated Morningness-Eveningness Questionnaire (MEQ) and categorized as "evening", "intermediate", and "morning" chronotypes. Health behaviors (diet, physical activity, and sleep) were assessed using validated questionnaires. Anthropometrics, clinical blood pressure, and blood biomarkers were assessed at the clinic visit. CVH was evaluated using the AHA Life's Simple 7 (LS7) metrics; LS7 scores of 0-8 and 9-14 were considered indicative of poor and moderate-to-high CVH, respectively. Linear and logistic regression models adjusted for age, race/ethnicity, education, health insurance, and menopausal status were used to examine associations of MEQ scores and chronotype categories with overall CVH, clinical cardiometabolic risk factors, and health behaviors. Overall, 13% of women identified as evening chronotypes, while 55% and 32% reported being intermediate and morning types. In linear models, higher MEQ scores were associated with higher AHA LS7 scores (β(SE) = 0.02(0.01); p = .014), indicative of more favorable CVH, and with health behaviors not included in the LS7. Higher MEQ scores were also associated with lower Pittsburgh Sleep Quality Index, i.e. better sleep quality, (β(SE) = -0.07(0.02), p < .0001), lower insomnia severity (β(SE) = -0.14(0.01), p < .0001), shorter time to fall asleep (β(SE) = -0.28(0.14), p = .044), and less sedentary time (β(SE) = -0.11(0.03), p = .001). In logistic regression models, evening chronotype, compared to intermediate/morning type, was associated with higher odds of having poor CVH (OR(95%CI):2.41(1.20-4.85)), not meeting AHA diet (OR(95%CI):2.89(1.59-5.23)) and physical activity guidelines (OR(95%CI):1.78(1.03-3.07)), and having short sleep (OR(95%CI):2.15(1.24-3.73)) or insomnia (OR(95%CI):2.69(1.53-4.75)). The evening type compared to morning type was also associated with being a current smoker (OR(95%CI):2.14(1.02-4.52)) and having poor sleep quality (OR(95%CI:2.35(1.27-4.37)) and long sleep onset latency (OR(95%CI:1.89(1.00-3.56)). In our cohort of women, evening chronotype was related to poor CVH, likely driven by its influence on health behaviors. These findings, although warranting confirmation prospectively in other populations, suggest chronotype is an important factor to consider and possibly target when designing lifestyle interventions for CVD prevention.

Sleep and Circadian Rhythms in Survivors of Acute Respiratory Failure

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

Wearable technologies for developing sleep and circadian biomarkers: a summary of workshop discussions

The "International Biomarkers Workshop on Wearables in Sleep and Circadian Science" was held at the 2018 SLEEP Meeting of the Associated Professional Sleep Societies. The workshop brought together experts in consumer sleep technologies and medical devices, sleep and circadian physiology, clinical translational research, and clinical practice. The goals of the workshop were: (1) characterize the term "wearable" for use in sleep and circadian science and identify relevant sleep and circadian metrics for wearables to measure; (2) assess the current use of wearables in sleep and circadian science; (3) identify current barriers for applying wearables to sleep and circadian science; and (4) identify goals and opportunities for wearables to advance sleep and circadian science. For the purposes of biomarker development in the sleep and circadian fields, the workshop included the terms "wearables," "nearables," and "ingestibles." Given the state of the current science and technology, the limited validation of wearable devices against gold standard measurements is the primary factor limiting large-scale use of wearable technologies for sleep and circadian research. As such, the workshop committee proposed a set of best practices for validation studies and guidelines regarding how to choose a wearable device for research and clinical use. To complement validation studies, the workshop committee recommends the development of a public data repository for wearable data. Finally, sleep and circadian scientists must actively engage in the development and use of wearable devices to maintain the rigor of scientific findings and public health messages based on wearable technology.

Behavioral and social routines and biological rhythms in prevention and treatment of pediatric obesity

A growing body of research supports the potential importance of behavioral and social routines for children's health promotion and obesity risk reduction. Evidence in support of this comes from multiple lines of research, which suggest that specific behavioral routines, namely, eating and sleep routines, may be protective against excessive weight gain and development of pediatric obesity. Emerging work also supports the potential importance of the timing of these behavioral routines. From a circadian perspective, alignment of behavioral and social routines with underlying circadian rhythms may be particularly important for enhancing children's weight regulation. Specifically, engaging in appropriately timed behavioral routines may serve to entrain circadian rhythms that affect metabolism and weight regulation. Thus, in addition to promoting healthier eating, activity, and sleep behaviors for prevention and treatment of pediatric obesity, it may also be important to consider promotion of consistency in, and optimal timing of, these behaviors in an effort to enhance extant prevention and treatment approaches. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Circadian disruption: What do we actually mean?

The circadian system regulates physiology and behavior. Acute challenges to the system, such as those experienced when traveling across time zones, will eventually result in re-synchronization to local environmental time cues, but this re-synchronization is oftentimes accompanied by adverse short-term consequences. When such challenges are experienced chronically, adaptation may not be achieved, as for example in the case of rotating night shift workers. The transient and chronic disturbance of the circadian system is most frequently referred to as "circadian disruption", but many other terms have been proposed and used to refer to similar situations. It is now beyond doubt that the circadian system contributes to health and disease, emphasizing the need for clear terminology when describing challenges to the circadian system and their consequences. The goal of this review is to provide an overview of the terms used to describe disruption of the circadian system, discuss proposed quantifications of disruption in experimental and observational settings with a focus on human research, and highlight limitations and challenges of currently available tools. For circadian research to advance as a translational science, clear, operationalizable, and scalable quantifications of circadian disruption are key, as they will enable improved assessment and reproducibility of results, ideally ranging from mechanistic settings, including animal research, to large-scale randomized clinical trials.

Evaluating the Effects of Different Sleep Supplement Modes in Attenuating Metabolic Consequences of Night Shift Work Using Rat Model

PURPOSE

To study the effects of chronic-simulated night shift work using the rat model and examines if a particular sleep supplement mode could be better in alleviating the effects.

METHODS

The male Wistar rats were randomly divided into the control (CTL: 8 rats) and night shift work (NW: 24 rats) groups of rats. Based on the sleep supplement strategy, the NW group was further segregated into three subgroups (8 rats each); late sleep supplement group (LSS), early sleep supplement group (ESS), and intermittent sleep supplement group (ISS). Sleep deprivation was achieved using the standard small-platform-over water method. Parameters such as animal body weight and food intake were measured daily. The intraperitoneal glucose tolerance test, fasting plasma insulin concentration, insulin resistance index and insulin sensitivity were measured twice, in the 4th and 8th weeks of the study. Plasma corticosterone concentration and pathological changes in islets (insulitis) were measured at the end of the 8th week.

RESULTS

In NW group, night work resulted in a gain of body weight and albeit lower than that of the CTL group. NW rats also had higher food intake, showed impaired glucose metabolism and higher plasma corticosterone concentration. The sleep supplement experiments suggested that compared to the other modes, intermittent sleep supplement had significantly low changes in the body weight, glucose metabolism and the islet cells.

CONCLUSION

Similar to previous studies, we also found that night shift work adversely impacts the body weight and glucose metabolism in rats. However, upon evaluating different sleep supplement strategies, we found the intermittent sleep supplement strategy to be most effective.

Time of Day Matters: An Exploratory Assessment of Chronotype in a Forensic Psychiatric Hospital

A growing body of evidence links the late chronotype to mental illness, aggression, and aversive personality traits. However, much of what we know about these associations is based on healthy cohorts, and it is unclear how individuals with high levels of aggression, including forensic psychiatric populations, but not offenders, are affected. The present study aimed to measure chronotype in a forensic psychiatric inpatient population, evaluate the impact of diagnosis, and identify any interactive relationships between chronotype, diagnosis, aggression, and dark triad traits. Subjects completed the reduced Morningness-Eveningness Questionnaire (rMEQ), Munich ChronoType Questionnaire (MCTQ), Pittsburgh Sleep Quality Index (PSQI), Buss Perry Aggression Questionnaire-Short Form (BPAQ-SF), and Short Dark Triad Questionnaire (SD3). We sampled 55 forensic psychiatric patients (52 males) between the ages of 23 and 73 years (mean ± SD: 39.6 ± 14.3 years). Among the patients sampled, 25% were evening types and 36% were morning types. Eveningness was greater in patients with a personality disorder; however, no chronotype differences were found for psychosis patients. Patients without psychosis had a positive association between anger and eveningness, as well as between hostility and eveningness. For subjects with a substance use disorder, morningness was positively associated with narcissism. Conversely, an association between eveningness and greater narcissism was identified in patients who did not have a substance use disorder. These findings suggest that, compared to the general population, evening types are more prevalent in forensic psychiatric populations, with the strongest preference among patients diagnosed with a personality disorder. No differences in chronotype were identified for psychosis patients, which may be related to anti-psychotic medication dosing. Given the sex distribution of the sample, these findings may be more relevant to male populations.

Improving fatigue risk management in healthcare: A systematic scoping review of sleep-related/fatigue-management interventions for nurses and midwives

BACKGROUND

Nurses and midwives make up almost 50% of the global healthcare shift working workforce. Shift work interferes with sleep and causes fatigue with adverse effects for nurses' and midwives' health, as well as on patient safety and care. Where other safety-critical sectors have developed Fatigue Risk Management Systems, healthcare is behind the curve; with published literature only focussing on the evaluation of discreet sleep-related/fatigue-management interventions. Little is known, however, about which interventions have been evaluated for nurses and midwives. Our review is a critical first step to building the evidence-base for healthcare organisations seeking to address this important operational issue.

OBJECTIVES

We address two questions: (1) what sleep-related/fatigue-management interventions have been assessed in nurses and midwives and what is their evidence-base? and (2) what measures are used by researchers to assess intervention effectiveness?

DESIGN AND DATA SOURCES

The following databases were searched in November, 2018 with no limit on publication dates: MEDLINE, PsychINFO and CINAHL.

REVIEW METHODS

We included: (1) studies conducted in adult samples of nurses and/or midwives that had evaluated a sleep-related/fatigue-management intervention; and (2) studies that reported intervention effects on fatigue, sleep, or performance at work, and on measures of attention or cognitive performance (as they relate to the impact of shift working on patient safety/care).

RESULTS

The search identified 798 potentially relevant articles, out of which 32 met our inclusion criteria. There were 8619 participants across the included studies and all were nurses (88.6% female). We did not find any studies conducted in midwives nor any studies conducted in the UK, with most studies conducted in the US, Italy and Taiwan. There was heterogeneity both in terms of the interventions evaluated and the measures used to assess effectiveness. Napping could be beneficial but there was wide variation regarding nap duration and timing, and we need to understand more about barriers to implementation. Longer shifts, shift patterns including nights, and inadequate recovery time between shifts (quick returns) were associated with poorer sleep, increased sleepiness and increased levels of fatigue. Light exposure and/or light attenuation interventions showed promise but the literature was dominated by small, potentially unrepresentative samples.

CONCLUSIONS

The literature related to sleep-related/fatigue-management interventions for nurses and midwives is fragmented and lacks cohesion. Further empirical work is warranted with a view to developing comprehensive Fatigue Risk Management Systems to protect against fatigue in nurses, midwives, and other shift working healthcare staff.

Stronger Correlations between Neurophysiological and Peripheral Disease Biomarkers Predict Better Prognosis in Two Severe Diseases

‘Mind–body’ debates assume that better brain–body associations are healthy. This study examined whether degree of associations between a neurophysiological vagal nerve index and peripheral disease biomarkers predict prognosis in pancreatic cancer (PC) and multiple sclerosis (MS). Sample 1 included 272 patients with advanced PC. Sample 2 included 118 patients with MS. We measured the vagal nerve index heart rate variability (HRV) derived from electrocardiograms. We examined associations between HRV and patients’ peripheral disease biomarkers: CA19-9 in PC and neurofilament light chain (NFL) in MS. Associations between HRV and each biomarker were examined separately in patients who survived or died (PC), and in those with and without relapse during 12 months (MS). In PC, HRV was significantly inversely related to the tumor marker CA19-9 in patients who later survived (r = −0.44, p < 0.05) but not in those who died (r = 0.10, NS). In MS, HRV was significantly and inversely related to NFL only in those who did not relapse (r = −0.25, p < 0.05), but not in those who relapsed (r = −0.05, NS). The degree of association between a neurophysiological vagal marker and peripheral disease biomarkers has prognostic value in two distinct diseases.

Hypoxia induces a time- and tissue-specific response that elicits intertissue circadian clock misalignment

The occurrence and sequelae of disorders that lead to hypoxic spells such as asthma, chronic obstructive pulmonary disease, and obstructive sleep apnea (OSA) exhibit daily variance. This prompted us to examine the interaction between the hypoxic response and the circadian clock in vivo. We found that the global transcriptional response to acute hypoxia is tissue-specific and time-of-day-dependent. In particular, clock components differentially responded at the transcriptional and posttranscriptional level, and these responses depended on an intact circadian clock. Importantly, exposure to hypoxia phase-shifted clocks in a tissue-dependent manner led to intertissue circadian clock misalignment. This differential response relied on the intrinsic properties of each tissue and could be recapitulated ex vivo. Notably, circadian misalignment was also elicited by intermittent hypoxia, a widely used model for OSA. Given that phase coherence between circadian clocks is considered favorable, we propose that hypoxia leads to circadian misalignment, contributing to the pathophysiology of OSA and potentially other diseases that involve hypoxia.

GABA and l-theanine mixture decreases sleep latency and improves NREM sleep

CONTEXT

γ-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter and it is well established that activation of GABA_A receptors favours sleep. l-Theanine, a naturally occurring amino acid first discovered in green tea, is a well-known anti-anxiety supplement with proven relaxation benefits.

OBJECTIVE

This study investigated the potential synergistic sleep enhancement effect of GABA/l-theanine mixture.

MATERIALS AND METHODS

Pentobarbital-induced sleep test was applied to find proper concentration for sleep-promoting effect in ICR mice. Electroencephalogram (EEG) analysis was performed to investigate total sleeping time and sleep quality in normal SD rats and caffeine-induced awareness model. Real-time polymerase chain reaction (RT-PCR) was applied to investigate whether the sleep-promoting mechanism of GABA/l-theanine mixture involved transcriptional processes.

RESULTS

GABA/l-theanine mixture (100/20 mg/kg) showed a decrease in sleep latency (20.7 and 14.9%) and an increase in sleep duration (87.3 and 26.8%) compared to GABA or theanine alone. GABA/l-theanine mixture led to a significant increase in rapid eye movement (REM) (99.6%) and non-REM (NREM) (20.6%) compared to controls. The use of GABA/l-theanine mixture rather than GABA or l-theanine alone restored to normal levels sleep time and quality in the arousal animal model. The administration of GABA/l-theanine led to increased expression of GABA and the glutamate GluN1 receptor subunit.

CONCLUSIONS

GABA/l-theanine mixture has a positive synergistic effect on sleep quality and duration as compared to the GABA or l-theanine alone. The increase in GABA receptor and GluN1 expression is attributed to the potential neuromodulatory properties of GABA/l-theanine combination, which seems to affect sleep behaviour.

Early evening light mitigates sleep compromising physiological and alerting responses to subsequent late evening light

The widespread use of electric light and electronic devices has resulted in an excessive exposure to light during the late-evening and at night. This late light exposure acutely suppresses melatonin and sleepiness and delays the circadian clock. Here we investigate whether the acute effects of late-evening light exposure on our physiology and sleepiness are reduced when this light exposure is preceded by early evening bright light. Twelve healthy young females were included in a randomised crossover study. All participants underwent three evening (18:30-00:30) sessions during which melatonin, subjective sleepiness, body temperature and skin blood flow were measured under different light conditions: (A) dim light, (B) dim light with a late-evening (22:30-23:30) light exposure of 750 lx, 4000 K, and (C) the same late-evening light exposure, but now preceded by early-evening bright light exposure (18.30-21.00; 1200 lx, 4000 K). Late-evening light exposure reduced melatonin levels and subjective sleepiness and resulted in larger skin temperature gradients as compared to dim. Interestingly, these effects were reduced when the late-evening light was preceded by an early evening 2.5-hour bright light exposure. Thus daytime and early-evening exposure to bright light can mitigate some of the sleep-disruptive consequences of light exposure in the later evening.

Interaction between the progression of Alzheimer's disease and fractal degradation

Many outputs from healthy neurophysiological systems including motor activity display nonrandom fluctuations with fractal scaling behavior as characterized by similar temporal fluctuation patterns across a range of time scales. Degraded fractal regulation predicts adverse consequences including Alzheimer's dementia. We examined longitudinal changes in the scaling behavior of motor activity fluctuations during the progression of Alzheimer's disease (AD) in 1068 participants in the Rush Memory and Aging Project. Motor activity of up to 10 days was recorded annually for up to 13 years. Cognitive assessments and clinical diagnoses were administered annually in the same participants. We found that fractal regulation gradually degraded over time (p < 0.0001) even during the stage with no cognitive impairment. The degradation rate was more than doubled after the diagnosis of mild cognitive impairment and more than doubled further after the diagnosis of Alzheimer's dementia (p's ≤ 0.0005). Besides, the longitudinal degradation of fractal regulation significantly correlated with the decline in cognitive performance throughout the progression from no cognitive impairment to mild cognitive impairment, and to AD (p < 0.001). All effects remained the same in subsequent sensitivity analyses that included only 255 decedents with autopsy-confirmed Alzheimer's pathology. These results indicate that the progression of AD accelerates fractal degradation and that fractal degradation may be an integral part of the process of AD.

Compensating for Sensor Error in the Model Predictive Control of Circadian Clock Phase

The circadian oscillator regulates many critical biological functions; misalignment between the phase of this oscillator and the environment has been linked to adverse health outcomes. Thus, shifting the circadian phase of the oscillator to align with the environment using either light or small molecule pharmaceuticals as control inputs is desired. One challenge to controlling circadian phase is that the magnitude and direction of the phase shift caused by these inputs is dependent on the phase at which the input is delivered. Simulations show that model predictive control (MPC) can successfully shift the phase of the circadian clock using perfect knowledge of the current phase of the system. However, methods to assess circadian phase continuously in real time, as would be needed to implement MPC in vivo, are limited in their accuracy. Here, we explore the impact of imperfect sensing on our ability to control circadian phase. While some pathological patterns of sensor error can make control impossible, we show that by assuming errors in the phase sensor are bounded to be sufficiently small, we can bound the error of our MPC algorithm. We propose using the expected phase response curve to improve control when sensor error is present.

Chronotype, social jetlag and sleep loss in relation to sex steroids

Chronotype describes preferences for functioning at different times of the day. At the onset of puberty, a sharp shift towards eveningness starts, reaching its peak at the end of adolescence, followed by a steady shift towards morningness as the ageing process occurs. Puberty is also the time when sex differences appear, with men being more inclined to eveningness than women, which diminishes around menopause; the described pattern of changes in chronotype leads to the hypothesis that reproductive hormones may be the driving factor behind this conversion. In the present study, we aimed to verify this hypothesis by analysing participants' testosterone, progesterone and dehydroepiandrosterone (DHEA) levels in the three months, as indicated by assays in 3-cm hair strands from the scalp. Participants (n = 239) of both sexes also completed the Munich Chronotype Questionnaire. The results showed that in men higher testosterone levels were related to eveningness and less sleep loss, whereas greater sleep loss was associated with lower levels of DHEA. In women, no associations between chronotype and levels of the analysed hormones were found. The results support the hypothesis that testosterone levels play a role in shaping eveningness. We further hypothesised that a possible cause of the higher secretion level of testosterone in men with the evening chronotype is a mechanism to offset the negative consequences of sleep loss.

The molecular clock in the skin, its functionality, and how it is disrupted in cutaneous melanoma: a new pharmacological target?

The skin is the interface between the organism and the external environment, acting as its first barrier. Thus, this organ is constantly challenged by physical stimuli such as UV and infrared radiation, visible light, and temperature as well as chemicals and pathogens. To counteract the deleterious effects of the above-mentioned stimuli, the skin has complex defense mechanisms such as: immune and neuroendocrine systems; shedding of epidermal squamous layers and apoptosis of damaged cells; DNA repair; and pigmentary system. Here we have reviewed the current knowledge regarding which stimuli affect the molecular clock of the skin, the consequences to skin-related biological processes and, based on such knowledge, we suggest some therapeutic targets. We also explored the recent advances regarding the molecular clock disruption in melanoma, its impact on the carcinogenic process, and its therapeutic value in melanoma treatment.

Impact of shift work schedules on actigraphy-based measures of sleep in Hispanic workers: results from the Hispanic Community Health Study/Study of Latinos ancillary Sueño study

Study Objectives

To describe sleep characteristics of shift workers compared with day workers from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) Sueño ancillary study and test the hypothesis that shift work is associated with shorter sleep duration, worse sleep quality, greater sleep variability, and other sleep/health-related factors.

Methods

Employed adults (N = 1253, mean age 46.3 years, 36.3% male) from the Sueño study were included. Measures of sleep duration, timing, regularity, and continuity were calculated from 7 days of wrist-activity monitoring. Participants provided information on demographics, employment, work schedule (day, afternoon, night, split, irregular, and rotating), sleepiness, depressive symptoms, medications, caffeine, and alcohol use. Survey linear regression adjusting for age, sex, background, site, number of jobs, and work hours was used.

Results

In age and sex-adjusted models, all shift work schedules were associated with delayed sleep timing. Night and irregular schedules were associated with shorter sleep duration, greater napping, and greater variability of sleep. Afternoon and rotating shifts were associated with lower sleep regularity. In fully adjusted models, night and irregular schedules remained associated with shorter sleep duration, later sleep midpoint, and greater variability in sleep measures compared with day schedules. Split schedules were associated with, less time in bed, less sleep fragmentation, and less wake during the sleep period than day schedules.

Conclusions

Work schedule significantly affects sleep-wake with substantial differences between day work and other types of schedule. Detailed assessment of work schedule type not just night shift should be considered as an important covariate when examining the association between sleep and health outcomes.

The human stress response

The human stress response has evolved to maintain homeostasis under conditions of real or perceived stress. This objective is achieved through autoregulatory neural and hormonal systems in close association with central and peripheral clocks. The hypothalamic-pituitary-adrenal axis is a key regulatory pathway in the maintenance of these homeostatic processes. The end product of this pathway - cortisol - is secreted in a pulsatile pattern, with changes in pulse amplitude creating a circadian pattern. During acute stress, cortisol levels rise and pulsatility is maintained. Although the initial rise in cortisol follows a large surge in adrenocorticotropic hormone levels, if long-term inflammatory stress occurs, adrenocorticotropic hormone levels return to near basal levels while cortisol levels remain raised as a result of increased adrenal sensitivity. In chronic stress, hypothalamic activation of the pituitary changes from corticotropin-releasing hormone-dominant to arginine vasopressin-dominant, and cortisol levels remain raised due at least in part to decreased cortisol metabolism. Acute elevations in cortisol levels are beneficial to promoting survival of the fittest as part of the fight-or-flight response. However, chronic exposure to stress results in reversal of the beneficial effects, with long-term cortisol exposure becoming maladaptive, which can lead to a broad range of problems including the metabolic syndrome, obesity, cancer, mental health disorders, cardiovascular disease and increased susceptibility to infections. Neuroimmunoendocrine modulation in disease states and glucocorticoid-based therapeutics are also discussed.

Timing of Australian flight attendant food and beverage while crewing: a preliminary investigation

Flight attendants experience circadian misalignment and disrupted sleep and eating patterns. This survey study examined working time, sleep, and eating frequency in a sample (n=21, 4 males, 17 females) of Australian flight attendants (mean age=41.8 yr, SD=12.0 yr, mean BMI=23.8 kg/m², SD=4.1 kg/m²). Respondents indicated frequencies of snack, meal, and caffeine consumption during their last shift. Reported sleep duration on workdays (mean=4.6 h, SD=1.9 h) was significantly lower than on days off (M=7.2 h, SD=1.2 h, p<0.001), and significantly lower than perceived sleep need (M=8.1 h, SD=0.8 h, p<0.001). Food intake was distributed throughout shifts and across the 24 h period, with eating patterns incongruent with biological eating periods. Time available, food available, and work breaks were the most endorsed reasons for food consumption. Caffeine use and reports of gastrointestinal disturbance were common. Working time disrupts sleep and temporal eating patterns in flight attendants and further research into nutritional and dietary-related countermeasures may be beneficial to improving worker health and reducing circadian disruption.

Early Time-Restricted Feeding Reduces Appetite and Increases Fat Oxidation But Does Not Affect Energy Expenditure in Humans

OBJECTIVE

Eating earlier in the daytime to align with circadian rhythms in metabolism enhances weight loss. However, it is unknown whether these benefits are mediated through increased energy expenditure or decreased food intake. Therefore, this study performed the first randomized trial to determine how meal timing affects 24-hour energy metabolism when food intake and meal frequency are matched.

METHODS

Eleven adults with overweight practiced both early time-restricted feeding (eTRF) (eating from 8 am to 2 pm) and a control schedule (eating from 8 am to 8 pm) for 4 days each. On the fourth day, 24-hour energy expenditure and substrate oxidation were measured by whole-room indirect calorimetry, in conjunction with appetite and metabolic hormones.

RESULTS

eTRF did not affect 24-hour energy expenditure (Δ = 10 ± 16 kcal/d; P = 0.55). Despite the longer daily fast (intermittent fasting), eTRF decreased mean ghrelin levels by 32 ± 10 pg/mL (P = 0.006), made hunger more even-keeled (P = 0.006), and tended to increase fullness (P = 0.06-0.10) and decrease the desire to eat (P = 0.08). eTRF also increased metabolic flexibility (P = 0.0006) and decreased the 24-hour nonprotein respiratory quotient (Δ = -0.021 ± 0.010; P = 0.05).

CONCLUSIONS

Meal-timing interventions facilitate weight loss primarily by decreasing appetite rather than by increasing energy expenditure. eTRF may also increase fat loss by increasing fat oxidation.

A pragmatic effectiveness randomized controlled trial of the duration of psychiatric hospitalization in a trans-diagnostic sample of patients with acute mental illness admitted to a ward with either blue-depleted evening lighting or normal lighting conditions

Background

There is increasing recognition of the need to stabilize sleep-wake cycles in individuals with major mental disorders. As such, clinicians and researchers advocate the use of interventions targeted at sleep and circadian dysrhythmias as an adjunct to the standard treatments offered for acute illness episodes of a broad range of diagnoses. To determine the trans-diagnostic generalizability of chronotherapy, we explore the benefits of admitting individuals with an acute illness episode to a psychiatric inpatient unit where changes in light exposure are integrated into the therapeutic environment.

Methods/design

A two-arm, pragmatic effectiveness, randomized controlled treatment trial, where individuals admitted for acute inpatient psychiatric care will be allocated to a ward with blue-depleted evening light or to a ward with the same layout and facilities but lacking the new lighting technology. The trial will test whether the experimental lighting conditions offer any additional benefits beyond those associated with usual treatment in an acute psychiatric inpatient unit. The main objectives are to examine any differences between groups in the mean duration of hospitalization in days. Additional analyses will compare group differences in symptoms, functioning, medication usage, and side effects and whether length of stay is associated with stability of sleep-wake cycles and circadian rhythms. Ancillary investigations should determine any benefits according to diagnostic subgroups and potential drawbacks such as any adverse effects on the well-being of professionals working across both wards.

Discussion

This unit offers a unique opportunity to explore how exposure to different lighting conditions may modify sleep-wake cycles and how any changes in sleep-wake cycle may impact on the clinical and functional outcomes of individuals experiencing an acute episode of a severe mental disorder that requires inpatient care. The findings could influence the future design of hospital units offering care to patients with mental or physical disorders.

Trial registration

ClinicalTrials.gov, ID: NCT03788993. Retrospectively registered on 28 December 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3582-2) contains supplementary material, which is available to authorized users.

Behavioral Modification Enhances the Benefits from Structured Aerobic and Resistance Training

Behavioral modification (BM) is a strategy designed to sustain or restore well-being through effects such as enhanced relaxation, reduced stress, and improved sleep. Few studies have explored the role of BM delivered in the context of fitness programs for healthy adults. Thus, the purpose of this investigation was to examine whether BM combined with aerobic and resistance training programs would improve health and fitness measures more than the exercise training alone. Thirty-two healthy fitness club members (19 men) were randomized to receive a BM program (n=15) or an equal-attention (EA) control (n=17). BM consisted of twelve, 10-min education sessions between a trained fitness professional and the participant, coupled with weekly, individualized relaxation, stress reduction, and sleep improvement assignments. All participants engaged in 1 h of coached resistance training and remotely guided aerobic exercise thrice weekly for 12 weeks. Fitness measures (aerobic performance, body composition, muscle strength and endurance, lower-body power), sleep characteristics, and heart rate variability (HRV) were obtained at baseline and after the 12-week program. BM resulted in greater improvements in aerobic performance (increased maximum oxygen uptake, metabolic (lactate) threshold, and percent of maximum oxygen uptake at which metabolic threshold occurred), peak and average lower-body power, and body composition (decreased body fat percentage and fat mass) compared to EA. BM also positively influenced parasympathetic tone through increased High-frequency HRV. BM resulted in greater improvements in fitness measures, body composition, and heart rate variability compared with EA. These findings have intriguing implications regarding the role of BM in augmenting health and physical performance.

Intermittent restraint stress induces circadian misalignment in the mouse bladder, leading to nocturia

Intermittent stress disrupts the circadian rhythm in clock genes such as Per2 only in peripheral organs without any effect on the central circadian clock in the suprachiasmatic nucleus. Here, the effect of restraint stress (RS) on circadian bladder function was investigated based on urination behavior and gene expression rhythms. Furthermore, PF670462 (PF), a Per2 phosphorylation enzyme inhibitor, was administered to investigate the effects on circadian bladder re-alignment after RS. Two-hour RS during the light (sleep) phase was applied to mice (RS mice) for 5 days. The following parameters were then examined: urination behaviors; clock gene expression rhythms and urinary sensory-related molecules such as piezo type mechanosensitive ion channel component 1 (Piezo1), transient receptor potential cation channel subfamily V member 4 (TRPV4), and Connexin26 (Cx26) in the bladder mucosa; Per2 expression in the excised bladder of Per2^luciferase knock-in mice (Per2::luc); in vivo Per2 expression rhythms in the bladder of Per2::luc mice. Control mice did not show altered urination behavior in the light phase, whereas RS mice exhibited a higher voiding frequency and lower bladder capacity. In the bladder mucosa, RS mice also showed abrogated or misaligned Piezo1, TRPV4, Connexin26, and clock gene expression. The rhythmic expression of Per2 was also altered in RS mice both in excised- and in vivo bladder, compared with control mice. After PF administration, voiding frequency was reduced and bladder capacity was increased during the light phase in RS mice; the in vivo Per2 expression rhythm was also fully restored. Therefore, RS can alter circadian gene expression in the bladder during the light phase and might cause nocturia via changes in circadian bladder function due the dysregulation of clock genes. Amending the circadian rhythm therapeutically could be applied for nocturia.

Circadian Rhythms and Measures of CNS/Autonomic Interaction

The physiological role and relevance of the mechanisms sustaining circadian rhythms have been acknowledged. Abnormalities of the circadian and/or sleep-wakefulness cycles can result in major metabolic disorders or behavioral/professional inadequacies and stand as independent risk factors for metabolic, psychiatric, and cerebrovascular disorders and early markers of disease. Neuroimaging and clinical evidence have documented functional interactions between autonomic (ANS) and CNS structures that are described by a concept model (Central Autonomic Network) based on the brain-heart two-way interplay. The circadian rhythms of autonomic function, ANS-mediated processes, and ANS/CNS interaction appear to be sources of variability adding to a variety of environmental factors, and may become crucial when considering the ANS major role in internal environment constancy and adaptation that are fundamental to homeostasis. The CNS/ANS interaction has not yet obtained full attention and systematic investigation remains overdue.

Daily interpersonal stress, sleep duration, and gene regulation during late adolescence

BACKGROUND

Psychological stress and poor sleep are associated with a wide range of negative health outcomes, which are thought to be mediated in part by alterations in immune processes. However, the molecular bases of links among stress, sleep, and immune processes are not completely understood, particularly during adolescence when sensitivity to stress and problems with sleep tend to increase. In the current study, we investigated whether various stressors (daily stress, major life events, perceived stress), sleep indices (duration, efficiency), and their interactions (e.g., moderating effects) are associated with expression of genes bearing response elements for transcription factors that regulate inflammatory and anti-viral processes.

METHOD

Eighty-seven late adolescents completed daily checklists of their social experiences across a 15-day period and reported on their major life events during the previous year. They also completed actigraphy-based assessments of sleep quality and duration during 8 consecutive nights. An average of 5.5 months later, participants reported on their global perceptions of stress during the previous month and provided blood samples for genome-wide expression profiling of mRNA from peripheral blood mononuclear cells (PBMCs).

RESULTS

Higher levels of daily interpersonal stress and shorter sleep duration were associated with upregulation of inflammation-related genes bearing response elements for proinflammatory transcription factor nuclear factor kappa B (NF-κB). Shorter sleep duration was also linked to downregulation of antiviral-related genes bearing response elements for interferon response factors (IRFs). Lastly, there was a significant interaction between daily stress and shorter sleep duration, such that the association between daily stress and inflammation-related gene expression was exacerbated in the context of shorter sleep duration. Results were independent of sex, ethnicity, parent education, body mass index, and smoking and alcohol history.

CONCLUSION

Everyday interpersonal stress and shortened sleep can be consequential for upstream NF-κB signaling pathways relevant to inflammatory processes during late adolescence. Notably, the occurrence of both may lead to even greater activation of NF-κB signaling.

Circadian reinforcement therapy in combination with electronic self-monitoring to facilitate a safe post-discharge period of patients with depression by stabilizing sleep: protocol of a randomized controlled trial

BACKGROUND

The transition phase from inpatient to outpatient care for patients suffering from Major Depressive Disorder represents a vulnerable period associated with a risk of depression worsening and suicide. Our group has recently found that the sleep-wake cycle in discharged depressive patients became irregular and exhibited a drift towards later hours, associated with worsening of depression. In contrast, an advancement of sleep phase has earlier been shown to have an antidepressant effect. Thus, methods to prevent drift of the sleep-wake cycle may be promising interventions to prevent or reduce worsening of depression after discharge.

METHODS

In this trial, we apply a new treatment intervention, named Circadian Reinforcement Therapy (CRT), to patients discharged from inpatient psychiatric wards. CRT consists of a specialized psychoeducation on the use of regular time signals (zeitgebers): daylight exposure, exercise, meals, and social contact. The aim is to supply stronger and correctly timed zeitgebers to the circadian system to prevent sleep drift and worsening of depression. The CRT is used in combination with an electronic self-monitoring system, the Monsenso Daybuilder System (MDB). By use of the MDB system, all patients self-monitor their sleep, depression level, and activity (from a Fitbit bracelet) daily. Participants can inspect all their data graphically on the MDB interface and will have clinician contact. The aim is to motivate patients to keep a stable sleep-wake cycle. In all, 130 patients referred to an outpatient service will be included. Depression rating is blinded. Patients will be randomized 1:1 to a Standard group or a CRT group. The intervention period is 4 weeks covering the transition phase from inpatient to outpatient care. The primary outcome is score change in interviewer rated levels of depression on the Hamilton Depression Rating Scale. A subset of patients will be assessed with salivary Dim Light Melatonin Onset (DLMO) as a validator of circadian timing. The trial was initiated in 2016 and will end in 2020.

DISCUSSION

If the described intervention is beneficial it could be incorporated into usual care algorithms for depressed patients to facilitate a better and safer transition to outpatient treatment.

TRIAL REGISTRATION

Posted prospectively at ClinicalTrials.gov at February 10, 2016 with identifier NCT02679768 .

Identification of earlier predictors of pregnancy complications through wearable technologies in a Brazilian multicentre cohort: Maternal Actigraphy Exploratory Study I (MAES-I) study protocol

INTRODUCTION

Non-invasive tools capable of identifying predictors of maternal complications would be a step forward for improving maternal and perinatal health. There is an association between modification in physical activity (PA) and sleep-wake patterns and the occurrence of inflammatory, metabolic, pathological conditions related to chronic diseases. The actigraphy device is validated to estimate PA and sleep-wake patterns among pregnant women. In order to extend the window of opportunity to prevent, diagnose and treat specific maternal conditions, would it be possible to use actigraphy data to identify risk factors for the development of adverse maternal outcomes during pregnancy?

METHODS AND ANALYSIS

A cohort will be held in five centres from the Brazilian Network for Studies on Reproductive and Perinatal Health. Maternal Actigraphy Exploratory Study I (MAES-I) will enrol 400 low-risk nulliparous women who will wear the actigraphy device on their wrists day and night (24 hours/day) uninterruptedly from 19 to 21 weeks until childbirth. Changes in PA and sleep-wake patterns will be analysed throughout pregnancy, considering ranges in gestational age in women with and without maternal complications such as pre-eclampsia, preterm birth (spontaneous or provider-initiated), gestational diabetes, maternal haemorrhage during pregnancy, in addition to perinatal outcomes. The plan is to design a predictive model using actigraphy data for screening pregnant women at risk of developing specific adverse maternal and perinatal outcomes.

ETHICS AND DISSEMINATION

MAES-I has been reviewed and approved by each institutional review board and also by the National Council for Ethics in Research. Detailed information about the study is provided in the Brazilian Cohort website (www.medscinet.com/samba) and findings will be published in the scientific literature and institutional webpages.

Circadian misalignment and weekend alcohol use in late adolescent drinkers: preliminary evidence

Alcohol use accelerates during late adolescence, predicting the development of alcohol use disorders (AUDs) and other negative outcomes. Identifying modifiable risk factors for alcohol use during this time could lead to novel prevention approaches. Burgeoning evidence suggests that sleep and circadian factors are cross-sectionally and longitudinally linked to alcohol use and problems, but more proximal relationships have been understudied. Circadian misalignment, in particular, is hypothesized to increase the risk for AUDs, but almost no published studies have included a biological measure of misalignment. In the present study, we aimed to extend existing research by assessing the relationship between adolescent circadian misalignment and alcohol use on a proximal timeframe (over two weeks) and by including three complementary measures of circadian alignment. We studied 36 healthy late (18-22 years old, 22 females) alcohol drinkers (reporting ≥1, standard drink per week over the past 30 days) over 14 days. Throughout the study, participants reported prior day's alcohol use and prior night's sleep each morning via smartphone and a secure, browser-based interface. Circadian phase was assessed via the dim light melatonin onset (DLMO) in the laboratory on two occasions (Thursday and Sunday nights) in counterbalanced order. The three measures of circadian alignment included DLMO-midsleep interval, "classic" social jet lag (weekday-weekend difference in midsleep), and "objective" social jet lag (weekday-weekend difference in DLMO). Multivariate imputation by chained equations was used to impute missing data, and Poisson regression models were used to assess associations between circadian alignment variables and weekend alcohol use. Covariates included sex, age, Thursday alcohol use, and Thursday sleep characteristics. As predicted, greater misalignment was associated with greater weekend alcohol use for two of the three alignment measures (shorter DLMO-midsleep intervals and larger weekday-weekend differences in midsleep), while larger weekday-weekend differences in DLMO were associated with less alcohol use. Notably, in contrast to expectations, the distribution of weekday-weekend differences in DLMO was nearly equally distributed between individuals advancing over the weekend and those delaying over the weekend. This unexpected finding plausibly reflects the fact that college students are not subject to the same systematically earlier weekday schedules observed in high school students and working adults. These preliminary findings support the need for larger, more definitive studies investigating the proximal relationships between circadian alignment and alcohol use among late adolescents.

Working Time Society consensus statements: Evidence based interventions using light to improve circadian adaptation to working hours

Interventions and strategies to improve health through the management of circadian (re) adaptation have been explored in the field, and in both human and animal laboratory manipulations of shiftwork. As part of an initiative by the Working Time Society (WTS) and International Committee on Occupational Health (ICOH), this review summarises the literature on the management of circadian (re) adaption using bright light treatment. Recommendations to maximise circadian adaptation are summarised for practitioners based on a variety of shiftwork schedules. In slowly rotating night shift schedules bright light appears most suitable when used in connection with the first three night shifts. These interventions are improved when combined with orange glasses (to block blue-green light exposure) for the commute home. Non-shifting strategies involve a lower dosage of light at night and promoting natural daylight exposure during the day (also recommended for day shifts) in acordance with the phase and amplitude response curves to light in humans.

Potential circadian and circannual rhythm contributions to the obesity epidemic in elementary school age children

Children gain weight at an accelerated rate during summer, contributing to increases in the prevalence of overweight and obesity in elementary-school children (i.e., approximately 5 to 11 years old in the US). Int J Behav Nutr Phys Act 14:100, 2017 explained these changes with the "Structured Days Hypothesis" suggesting that environmental changes in structure between the school year and the summer months result in behavioral changes that ultimately lead to accelerated weight gain. The present article explores an alternative explanation, the circadian clock, including the effects of circannual changes and social demands (i.e., social timing resulting from societal demands such as school or work schedules), and implications for seasonal patterns of weight gain. We provide a model for understanding the role circadian and circannual rhythms may play in the development of child obesity, a framework for examining the intersection of behavioral and biological causes of obesity, and encouragement for future research into bio-behavioral causes of obesity in children.

The effects of amplitude and stability of circadian rhythm and occupational stress on burnout syndrome and job dissatisfaction among irregular shift working nurses

AIM

To investigate the relation between the circadian rhythm amplitude and stability, and occupational stress with burnout syndrome and job dissatisfaction among shift working nurses.

BACKGROUND

Irregular shift working nurses are prone to burnout syndrome (BS) and job dissatisfaction (JD). circadian rhythm difference and occupational stress might be effective in causing burnout syndrome and dissatisfaction.

DESIGN

In total, 684 nurses who worked in four teaching hospitals were selected by stratified random sampling in a cross-sectional design based on STROBE guidelines.

METHODS

The data were collected by the Circadian Type Inventory, Job Content Questionnaire, Minnesota Satisfaction Questionnaire and the Maslach Burnout Inventory. Multiple linear regression, one-way ANOVA and independent t test were used for statistical analysis by SPSS v24.

RESULTS

About 15% of the nurses suffered from high levels of burnout syndrome. Psychological demand (β = 0.022, CI 95% = 0.003-0.047 and β = 0.016, CI 95% = 0.001-0.032) and workplace support (β = -0.043, CI 95% = -0.097-0.003 and β = -0.025, CI 95% = -0.046-0.006) were significant predictors of BS and JD. Male nurses reported lower BS and higher JD compared to female nurses. Irregular shift working schedule was also related to a significantly higher odd of BS (p = 0.009) and JD (p = 0.011). Nurses classified as languid experienced significantly more BS and JD than vigorous nurses.

CONCLUSION

This study shows that BS and JD were strongly associated with psychological demand and workplace support; and vigorous nurses were less prone to BS and JD, and were more suitable for irregular shift work.

RELEVANCE TO CLINICAL PRACTICE

In order to reduce burnout syndrome and job dissatisfaction among irregular shift working nurses, we need to identify the effect of risk factors such as individual differences on the circadian rhythm and job demand which can affect nurses who work in irregular schedules.

Cardiac autonomic activity during simulated shift work

Shift work leads to adverse health outcomes including increased risk of cardiovascular disease. Heart rate (HR) and heart rate variability (HRV) are measures of cardiac autonomic activity and markers of cardiovascular disease and mortality. To investigate the effects of shift work on cardiac autonomic activity, we assessed the influence of simulated night work on HR and HRV, and dissociated the direct effects of circadian misalignment from those of sleep displacement and altered physical activity patterns. A total of 29 subjects each participated in one of two in-laboratory, simulated shift work studies. In both studies, EKG was continuously monitored via Holter monitors to measure HR and the high frequency (HF) component of HRV (HF-HRV). We found endogenous circadian rhythmicity in HR and HF-HRV. Sleep and waking physical activity, both displaced during simulated night work, had more substantial, and opposite, effects on HR and HF-HRV. Our findings show systematic but complex, interacting effects of time of day, sleep/wake state, and physical activity on cardiac autonomic activity. These effects need to be taken into account when evaluating HR and HRV in shift work settings and when interpreting these measures of cardiac autonomic activity as markers of cardiovascular disease.

Coupling the Circadian Clock to Homeostasis: The Role of Period in Timing Physiology

A plethora of physiological processes show stable and synchronized daily oscillations that are either driven or modulated by biological clocks. A circadian pacemaker located in the suprachiasmatic nucleus of the ventral hypothalamus coordinates 24-hour oscillations of central and peripheral physiology with the environment. The circadian clockwork involved in driving rhythmic physiology is composed of various clock genes that are interlocked via a complex feedback loop to generate precise yet plastic oscillations of ∼24 hours. This review focuses on the specific role of the core clockwork gene Period1 and its paralogs on intra-oscillator and extra-oscillator functions, including, but not limited to, hippocampus-dependent processes, cardiovascular function, appetite control, as well as glucose and lipid homeostasis. Alterations in Period gene function have been implicated in a wide range of physical and mental disorders. At the same time, a variety of conditions including metabolic disorders also impact clock gene expression, resulting in circadian disruptions, which in turn often exacerbates the disease state.

Interactive effects of sleep duration and morning/evening preference on cardiovascular risk factors

Background

Sleep duration and morningness/eveningness (circadian preference) have separately been associated with cardiovascular risk factors (i.e. tobacco use, physical inactivity). Interactive effects are plausible, resulting from combinations of sleep homeostatic and circadian influences. These have not been examined in a population sample.

Methods

Multivariable regression models were used to test the associations between combinations of sleep duration (short [≤6 h], adequate [7-8 h], long [≥9 h]) and morning/evening preference (morning, somewhat morning, somewhat evening, evening) with the cardiovascular risk factors of tobacco use, physical inactivity, high sedentary behaviour, obesity/overweight and eating fewer than 5 daily servings of fruit and vegetables, in a cross-sectional sample of 439 933 adults enrolled in the United Kingdom Biobank project.

Results

Participants were 56% female, 95% white and mean age was 56.5 (SD = 8.1) years. Compared with adequate sleep with morning preference (referent group), long sleep with evening preference had a relative odds of 3.23 for tobacco use, a 2.02-fold relative odds of not meeting physical activity recommendations, a 2.19-fold relative odds of high screen-based sedentary behaviour, a 1.47-fold relative odds of being obese/overweight and a 1.62-fold relative odds of <5 fruit and vegetable daily servings. Adequate sleep with either morning or somewhat morning preference was associated with a lower prevalence and odds for all cardiovascular risk behaviours except fruit and vegetable intake.

Conclusions

Long sleepers with evening preference may be a sleep phenotype at high cardiovascular risk. Further work is needed to examine these relationships longitudinally and to assess the effects of chronotherapeutic interventions on cardiovascular risk behaviours.

Misaligned core body temperature rhythms impact cognitive performance of hospital shift work nurses

Circadian rhythms greatly influence 24-h variation in cognition in nearly all organisms, including humans. Circadian clock impairment and sleep disruption are detrimental to hippocampus-dependent memory and negatively influence the acquisition and recall of learned behaviors. The circadian clock can become out of sync with the environment during circadian misalignment. Shift work represents a real-world model of circadian misalignment that can be studied for its physiological implications. The present study aimed to test the hypothesis that circadian misalignment disrupts vigilance and cognitive performance on occupationally relevant tasks using shift work as a model. As such, we sought to (1) explore the general effects of night- and day-shift worker schedules on sleep-wake parameters and core body temperature (CBT) phase, and (2) determine whether shift-type and CBT phase impact cognitive performance and vigilance at the end of a 12-h shift. We observed a sample of day-shift and night-shift hospital nurses over a 10-day period. At the end of three, consecutive, 12-h shifts (7 pm-7am or 7am-7 pm), participants completed a cognitive battery assessing vigilance, cognitive throughput, and medication calculation fluency (via an investigator developed and tested metric). Night-shift nurses exhibited significantly greater sleep fragmentation as well as a greater disparity between their wake-time and time of CBT minimum compared to day-shift nurses. Night-shift nurses exhibited significantly slower cognitive proficiency at the end of their shifts, even after adjustment for CBT phase. These results suggest that circadian disruption and reduced sleep quality both contribute to cognitive functioning and performance.

Chronotype: Implications for Epidemiologic Studies on Chrono-Nutrition and Cardiometabolic Health

Chrono-nutrition is an emerging research field in nutritional epidemiology that encompasses 3 dimensions of eating behavior: timing, frequency, and regularity. To date, few studies have investigated how an individual's circadian typology, i.e., one's chronotype, affects the association between chrono-nutrition and cardiometabolic health. This review sets the directions for future research by providing a narrative overview of recent epidemiologic research on chronotype, its determinants, and its association with dietary intake and cardiometabolic health. Limited research was found on the association between chronotype and dietary intake in infants, children, and older adults. Moreover, most of the evidence in adolescents and adults was restricted to cross-sectional surveys with few longitudinal cohorts simultaneously collecting data on chronotype and dietary intake. There was a gap in the research concerning the association between chronotype and the 3 dimensions of chrono-nutrition. Whether chronotype modifies the association between diet and cardiometabolic health outcomes remains to be elucidated. In conclusion, further research is required to understand the interplay between chronotype, chrono-nutrition, and cardiometabolic health outcomes.

TPH-2 Gene Polymorphism in Major Depressive Disorder Patients With Early-Wakening Symptom

Background: Sleep disturbances, such as early wakening, are frequently observed in patients with major depressive disorder (MDD). The suprachiasmatic nuclei (SCN), which controls circadian rhythm, is innervated by the raphe nucleus, a region where Tryptophan hydroxylase-2 (TPH-2) gene is primarily expressed. Although TPH-2 is often implicated in the pathophysiology of depression, few studies have applied a genetic and imaging technique to investigate the mechanism of early wakening symptom in MDD. We hypothesized that TPH-2 variants could influence the function of SCN in MDD patients with early wakening symptom. Methods: One hundred and eighty five MDD patients (62 patients without early wakening and 123 patients with early wakening) and 64 healthy controls participated in this study. Blood samples were collected and genotyping of rs4290270, rs4570625, rs11178998, rs7305115, rs41317118, and rs17110747 were performed by next-generation sequencing (NGS) technology. Logistic regression model was employed for genetic data analysis using the PLINK software. Based on the allele type, rs4290270, which was significant in the early wakening MDD group, participants were categorized into two groups (A allele and T carrier). All patients underwent whole brain resting-state functional magnetic resonance imaging (rs-fMRI) scanning and a voxel-wise functional connectivity comparison was performed between the groups. Results: rs4290270 was significantly linked to MDD patients who exhibited early wakening symptom. The functional connectivities of the right SCN with the right fusiform gyrus and right middle frontal gyrus were increased in the T carrier group compared to the A allele group. In addition, the functional connectivities of the left SCN with the right lingual gyrus and left calcarine sulcus were decreased in the T carrier group compared to the A allele group. Conclusion: These findings suggested that the TPH-2 gene variant, rs4290270, affected the circadian regulating function of SCN. The altered functional connectivities, observed between the SCN and right fusiform gyrus, right middle frontal gyrus, the right lingual gyrus and left calcarine sulcus, could highlight the neural mechanism by which SCN induces sleep-related circadian disruption in T carrier MDD patients. Hence, rs4290270 could potentially serve as a reliable biomarker to identify MDD patients with early wakening symptom.

The role of chronotype, circadian misalignment, and tiredness in the substance use behaviors of gay and bisexual men

Although the potential of alcohol and drugs to detrimentally affect sleep has been established, the potential of tiredness to in turn influence substance use has received less attention. We contend that tiredness increases risk for substance use because tiredness impairs self-regulation and heightens the utility of substances to combat tiredness, albeit temporarily-and that these links are especially important because decision-making regarding use often occurs late at night when people are tired. Accordingly, we investigated chronotype, circadian misalignment, and perceived tiredness as risk factors in substance use among gay and bisexual men (GBM). We analyzed two online survey datasets-one of 3,696 GBM and one of 1,113 GBM-asking participants about their time for most frequently using alcohol or club/party drugs, their chronotype, whether they use substances to stay awake, and use severity. Alcohol use and club/party drug use most often occurred from 9pm onwards (for 51.3% and 75.1% of men, respectively), especially among younger men and evening types. Further, many men with a morning chronotype reported most often using alcohol (33.2%) and drugs (64.7%) from 9pm onwards, implicating circadian misalignment. Additionally, feeling tired was a motivator of alcohol use and drug use (for 53.1% and 26.9% of men, respectively), especially among younger men. Finally, those endorsing this motivation had greater use severity. These findings highlight the importance of chronotype, circadian misalignment, and tiredness in substance use, especially among younger men. We therefore recommend including substance use among the behaviors adversely affected by tiredness from circadian misalignment and inadequate/overdue sleep.