Circadian disruption: New clinical perspective of disease pathology and basis for chronotherapeutic intervention

Aging and circadian dysfunction increase alcohol sensitivity and exacerbate mortality in Drosophila melanogaster

Alcohol abuse is a rising problem in middle-aged and older individuals resulting in serious health, family and economic consequences. Effective treatment necessitates the identification of factors influencing alcohol toxicity with aging. We investigated the interaction between aging, alcohol toxicity and circadian function using Drosophila as a model system. We found as wild type flies age, sensitivity to alcohol increases and circadian regulation of alcohol-induced behaviors weakens. Decreased circadian modulation is correlated with significantly greater alcohol sensitivity during the subjective day. The circadian clock modulates alcohol-induced mortality in younger flies with increased mortality following alcohol exposure at night. Older flies exhibit significantly longer recovery times following alcohol-induced sedation and increased mortality following binge-like or chronic alcohol exposure. Flies rendered arrhythmic either genetically or environmentally exhibit significantly increased alcohol sensitivity, longer recovery times and increased mortality. We hypothesize that the circadian clock phase specifically buffers behavioral and cellular alcohol sensitivity with this protection diminishing as the circadian clock weakens with age.

Night Shift Work and Risk of Depression: Meta-analysis of Observational Studies

This study aimed to assess whether night shift work is associated with the risk of depression by using a meta-analysis of observational studies. We searched PubMed and EMBASE in August, 2016 to locate eligible studies and investigated the association between night shift work and the risk of depression, reporting outcome measures with adjusted odds ratios (ORs) or relative risks (RRs) and 95% confidence intervals (CIs). In the meta-analysis of a total of 11 observational studies with 9 cross-sectional study, 1 longitudinal study, and 1 cohort study, night shift work was significantly associated with an increased risk of depression (OR/RR, 1.43; 95% CI, 1.24-1.64; I² = 78.0%). Also, subgroup meta-analyses by gender, night shift work duration, type of occupation, continent, and type of publication showed that night shift work was consistently associated with the increased risk of depression. The current meta-analysis suggests that night shift work is associated with the increased risk of depression. However, further large prospective cohort studies are needed to confirm this association.

What keeps children with cystic fibrosis awake at night?

BACKGROUND

Sleep disturbance is common in children with cystic fibrosis (CF) however there are limited studies investigating the causes for poor sleep quality. In a cross sectional observational study we aimed to evaluate the clinical correlates of sleep disturbance in this population.

METHODS

Children with CF (7-18years) free from pulmonary exacerbation completed medical review, overnight oximetry, the OSA-18 and 14days of actigraphy recordings with a sleep diary.

RESULTS

In addition to FEV₁ <80% and low baseline SpO₂, CF-related diabetes, PEG feeding and co-morbid behaviour disorder were associated with lower objective sleep quantity. Paternal smoking and a family member with a mood disorder were also associated with sleep disturbance. The use of electronic devices before bedtime was associated with lower sleep quantity and quality. FEV₁, nocturnal cough, age and a behaviour disorder predicted sleep duration. FEV₁, nocturnal cough, SpO₂ nadir and asthma predicted sleep efficiency. Conversely, sleep efficiency independently predicted FEV₁.

CONCLUSIONS

Reduced sleep quality in children with CF is related to lung health and co-morbidities. However, family characteristics and poor sleep hygiene in the child were also associated with sleep disturbance. Optimal management of CF would seem to be the primary intervention to alleviate children's sleep disturbance, however our data raises additional targets for attempts to improve sleep.

The impact of daytime light exposures on sleep and mood in office workers

BACKGROUND

By affecting the internal timing mechanisms of the brain, light regulates human physiology and behavior, perhaps most notably the sleep-wake cycle. Humans spend over 90% of their waking hours indoors, yet light in the built environment is not designed to affect circadian rhythms.

OBJECTIVE

Using a device calibrated to measure light that is effective for the circadian system (circadian-effective light), collect personal light exposures in office workers and relate them to their sleep and mood.

SETTING

The research was conducted in 5 buildings managed by the US General Services Administration.

PARTICIPANTS

This study recruited 109 participants (69 females), of whom 81 (54 females) participated in both winter and summer.

MEASUREMENTS

Self-reported measures of mood and sleep, and objective measures of circadian-effective light and activity rhythms were collected for 7 consecutive days.

RESULTS

Compared to office workers receiving low levels of circadian-effective light in the morning, receiving high levels in the morning is associated with reduced sleep onset latency (especially in winter), increased phasor magnitudes (a measure of circadian entrainment), and increased sleep quality. High levels of circadian-effective light during the entire day are also associated with increased phasor magnitudes, reduced depression, and increased sleep quality.

CONCLUSIONS

The present study is the first to measure personal light exposures in office workers using a calibrated device that measures circadian-effective light and relate those light measures to mood, stress, and sleep. The study's results underscore the importance of daytime light exposures for sleep health.

Plasma Vitamin D Deficiency Is Associated With Poor Sleep Quality and Night-Time Eating at Mid-Pregnancy in Singapore

Plasma 25-hydroxyvitamin D (25OHD) deficiency, poor sleep quality, and night-time eating, have been independently associated with adverse pregnancy outcomes, but their inter-relationships are yet to be evaluated. We aimed to investigate the associations between maternal plasma 25OHD status and sleep quality and circadian eating patterns during pregnancy. Data on pregnant women (n = 890) from a prospective cohort (Growing Up in Singapore Towards healthy Outcomes) were analyzed. Plasma 25OHD concentration was measured, while the Pittsburgh sleep quality index (PSQI) and 24-h dietary recall were administered to women at 26-28 weeks' gestation. Plasma 25OHD status was defined as sufficient (>75 nmol/L), insufficient (50-75 nmol/L), or deficient (<50 nmol/L). Poor sleep quality was defined by a total global PSQI score >5. Predominantly day-time (pDT) and predominantly night-time (pNT) were defined according to consumption of greater proportion of calories (i.e., >50%) from 07:00-18:59 and from 19:00-06:59, respectively. After adjustment for confounders, women with plasma 25OHD deficiency had higher odds of poor sleep quality (odds ratio (OR) 3.49; 95% confidence interval (CI) 1.84-6.63) and pNT eating (OR: 1.85; 95% CI 1.00-3.41) than those who were 25OHD sufficient. Our findings show the association of maternal plasma 25OHD deficiency with poor sleep quality and pNT eating at mid-pregnancy.

Short communication: Early modification of the circadian organization of cow activity in relation to disease or estrus

Biological rhythms are an essential regulator of life. There is evidence that circadian rhythm of activity is disrupted under chronic stress in animals and humans, and it may also be less marked during diseases. Here we investigated whether a detectable circadian rhythm of activity exists in dairy cows in commercial settings using a real-time positioning system. We used CowView (GEA Farm Technologies) to regularly record the individual positions of 350 cows in a Danish dairy farm over 5 mo and to infer the cows' activity (resting, feeding, in alley). We ran a factorial correspondence analysis on the cows' activities and used the first component of this analysis to express the variations in activity. On this axis, the activities obtained the following weights: resting = -0.15; in alleys = +0.12; feeding = +0.34. By applying these weights to the proportions of time each cow spent on each of the 3 activities, we were able to chart a circadian rhythm of activity. We found that average level of activity of a cow on a given day and its variations during that day varied with specific states (i.e., estrus, lameness, mastitis). More specifically, circadian variations in activity appeared to be particularly sensitive and to vary 1 to 2 d before the farmer detected a disorder. These findings offer promising avenues for further research to design models to predict physiological or pathological states of cows from real-time positioning data.

Circadian behavior of adult mice exposed to stress and fluoxetine during development

INTRODUCTION

Women of child-bearing age are the population at greatest risk for depression. The stress experienced during pregnancy and the associated antidepressant treatments can both affect fetal development. Fluoxetine (FLX) is among the most common antidepressants used by pregnant women. We have previously demonstrated that perinatal exposure to FLX can alter expression of circadian rhythms in adulthood. Here, we examine the combined effects of maternal stress during pregnancy and perinatal exposure to the antidepressant FLX on the circadian behavior of mice as adults.

METHODS

Mouse dams were exposed to chronic unpredictable stress (embryonic (E) day 7 to E18), FLX (E15 to postnatal day 12), a combination of both stress and FLX, or were left untreated. At 2 months of age, male offspring were placed in recording chambers and circadian organization of wheel running rhythms and phase shifts to photic and non-photic stimuli were assessed.

RESULTS

Mice exposed to prenatal stress (PS) had smaller light-induced phase delays. Mice exposed to perinatal FLX required more days to re-entrainment to an 8-h phase advance of their light-dark cycle. Mice subjected to either perinatal FLX or to PS had larger light-induced phase advances and smaller phase advances to 8-OH-DPAT. FLX treatment partially reversed the effect of PS on phase shifts to late-night light exposure and to 8-OH-DPAT.

CONCLUSIONS

Our results suggest that, in mice, perinatal exposure to either FLX, or PS, or their combination, leads to discernible, persistent changes in their circadian systems as adults.

Mixed States in Bipolar Disorder: Etiology, Pathogenesis and Treatment

Many bipolar disorder patients exhibit mixed affective states, which portend a generally more severe illness course and treatment resistance. In the previous renditions of Diagnostic and Statistical Manual mixed states were narrowly defined in the context of bipolar I disorder, but with the advent of DSM-5 the term “mixed episode” was dropped and replaced by “mixed features” specifier which could be broadly applied to manic, hypomanic and depressive episodes in both the bipolar spectrum and major depressive disorders. This paradigm shift reflected their significance in the prognosis and overall management of mood disorders, so that the clinicians should thoroughly familiarize themselves with the contemporary notions surrounding these conditions. The purpose of this manuscript is to bring to light the current conceptualizations regarding the etiology, pathogenesis and treatment of mixed states. To achieve this goal, in June 2016 an extensive literature search was undertaken using the PubMed database. Some exploratory terms utilized included “mixed states”, “mixed episodes”, “switching”, “rapid cycling” cross referenced with “bipolar disorder”. Focusing on the most relevant and up to date studies, it was revealed that mixed states result from genetic susceptibility in the circadian and dopamine neurotransmission apparatuses and disturbance in the intricate catecholamine-acetylcholine neurotransmission balance which leads to mood fluctuations. The management of mixed states is challenging with atypical antipsychotics, newer anticonvulsants and electroconvulsive therapy emerging as the foremost treatment options. In conclusion, while progress has been made in the neurobiological understanding of mixed states, the currently available therapeutic modalities have only shown limited effectiveness.

Does selection for short sleep duration explain human vulnerability to Alzheimer's disease?

Compared with other primates, humans sleep less and have a much higher prevalence of Alzheimer 's disease (AD) pathology. This article reviews evidence relevant to the hypothesis that natural selection for shorter sleep time in humans has compromised the efficacy of physiological mechanisms that protect against AD during sleep. In particular, the glymphatic system drains interstitial fluid from the brain, removing extra-cellular amyloid beta (eAβ) twice as fast during sleep. In addition, melatonin - a peptide hormone that increases markedly during sleep - is an effective antioxidant that inhibits the polymerization of soluble eAβ into insoluble amyloid fibrils that are associated with AD. Sleep deprivation increases plaque formation and AD, which itself disrupts sleep, potentially creating a positive feedback cycle. These and other physiological benefits of sleep may be compromised by short sleep durations. Our hypothesis highlights possible long-term side effects of medications that reduce sleep, and may lead to potential new strategies for preventing and treating AD.

Effects of exercise and stress management training on nighttime blood pressure dipping in patients with coronary heart disease: A randomized, controlled trial

INTRODUCTION

Blunted nighttime blood pressure (BP) dipping is prognostic of cardiovascular morbidity and mortality. Patients with coronary heart disease (CHD) are often characterized by a blunted nighttime BP dipping pattern. The present study compared the effects of 2 behavioral intervention programs, aerobic exercise (EX) and stress management (SM) training, with a usual care (UC) control group on BP dipping in a sample of CHD patients.

METHODS

This was a secondary analysis of a randomized, controlled trial with allocation concealment and blinded outcome assessment in 134 patients with stable CHD and exercise-induced myocardial ischemia. Nighttime BP dipping was assessed by 24-hour ambulatory BP monitoring, at prerandomization baseline and after 16 weeks of one of the following treatments: usual medical care; UC plus supervised aerobic EX for 35 minutes, 3 times per week; UC plus weekly 1.5-hour sessions of SM training.

RESULTS

The EX and SM groups exhibited greater improvements in systolic BP dipping (P=.052) and diastolic BP dipping (P=.031) compared with UC. Postintervention systolic BP percent-dipping means were 12.9% (SE=1.5) for SM, 11.1% (SE=1.4) for EX, and 8.6% (SE=1.4) for UC. Postintervention diastolic BP percent-dipping means were 13.3% (SE=1.9) for SM, 14.1% (SE=1.8) for EX, and 8.8% (1.8) for UC.

CONCLUSIONS

For patients with stable CHD, EX or SM training resulted in improved nighttime BP dipping compared with usual medical care. These favorable effects of healthy lifestyle modifications may help reduce the risk of adverse clinical events.

Report and Research Agenda of the American Geriatrics Society and National Institute on Aging Bedside-to-Bench Conference on Sleep, Circadian Rhythms, and Aging: New Avenues for Improving Brain Health, Physical Health, and Functioning

The American Geriatrics Society, with support from the National Institute on Aging and other funders, held its eighth Bedside-to-Bench research conference, entitled "Sleep, Circadian Rhythms, and Aging: New Avenues for Improving Brain Health, Physical Health and Functioning," October 4 to 6, 2015, in Bethesda, Maryland. Part of a conference series addressing three common geriatric syndromes-delirium, sleep and circadian rhythm (SCR) disturbance, and voiding dysfunction-the series highlighted relationships and pertinent clinical and pathophysiological commonalities between these three geriatric syndromes. The conference provided a forum for discussing current sleep, circadian rhythm, and aging research; identifying gaps in knowledge; and developing a research agenda to inform future investigative efforts. The conference also promoted networking among developing researchers, leaders in the field of SCR and aging, and National Institutes of Health program personnel.