Highlights

• Bedroom nighttime light exposure was associated with increased allostatic load.

• Significant associations between LAN exposure and separate AL biomarkers were observed.

• Keeping bedroom dark at night may be a viable option to reduce the wear of body systems.

https://www.sciencedirect.com/science/article/abs/pii/S0269749122008855

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In several regions of the world, the recent Coronavirus Disease-2019 (COVID-19) pandemic outbreak increased morbidity and mortality. The pandemic situation disrupted many workers’ previously established lifestyles. The main aim of the present review was to describe the circadian disruption and occupational toxicant exposure affecting the immunity of shift workers during the SARS CoV-2 pandemic. We retrieved pertinent published literature from the Google Scholar, PubMed, and Scopus databases. In the present review, we discuss the circadian rhythm involving the hypothalamic-pituitary-adrenal (HPA) axis at the molecular level, its disruption, occupational toxicant exposure causing immunomodulatory effects, and the role of immunity during the SARS CoV-2 pandemic. The severity of the progression of the viral infection depends on multiple factors affecting immunity. Hence, shift workers may need to be aware of those factors such as circadian rhythm disruption as well as occupational toxicant exposure. The timing of shift workers’ energy intake is also important concerning the shift of the workers. The information in the present review may be important for all workers who are at risk during the pandemic. In the absence of any published literature related to association of circadian rhythm disruption with occupational toxicant exposure, the present review may have greater importance.

https://www.frontiersin.org/articles/10.3389/fpubh.2022.829013/full

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http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1009994

The findings provide a mechanism that links Alzheimer’s disease with circadian rhythm disruptions

Peer-Reviewed Publication

PLOS

Researchers report that the immune cells responsible for clearing away a key protein that builds up in the brains of patients with Alzheimer’s disease operate according to daily circadian rhythms. The discovery, reported by Jennifer Hurley of Rensselaer Polytechnic Institute and colleagues in a new study publishing February 10^th in the journal PLOS Genetics, provides a potential explanation for the link between Alzheimer’s disease and disruptions to a person’s sleep cycle. 

Alzheimer’s disease is known to be associated with disruptions in circadian rhythms, the 24-hour cycle that controls many aspects of human behavior and physiology. For example, sleep disruptions begin years before symptoms of Alzheimer’s disease appear and are linked to more severe symptoms and a higher risk of developing the disease.

Read more at: https://www.eurekalert.org/news-releases/942364

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Abstract

Sleep is vital to human bodily function. Growing evidence indicates that sleep deprivation, disruption, dysrhythmia, and disorders are associated with impaired reproductive function and poor clinical outcomes in women. These associations are largely mediated by molecular-genetic and hormonal pathways, which are crucial for the complex and time sensitive processes of hormone synthesis/secretion, folliculogenesis, ovulation, fertilization, implantation, and menstruation. Pathologic sleep patterns are closely linked to menstrual irregularity, polycystic ovarian syndrome, premature ovarian insufficiency, sub/infertility, and early pregnancy loss. Measures of success with assisted reproductive technology are also lower among women who engage in shift work, or experience sleep disruption or short sleep duration. Extremes of sleep duration, poor sleep quality, sleep disordered breathing, and shift work are also associated with several harmful conditions in pregnancy, including gestational diabetes and hypertensive disorders. While accumulating evidence implicates pathologic sleep patterns in impaired reproductive function and poor reproductive outcomes, additional research is needed to determine causality and propose therapeutic interventions.

https://pubmed.ncbi.nlm.nih.gov/35042515/

© 2022. The Author(s).

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Abstract

Study Objectives

Individual circadian type is a ubiquitous trait defining sleep, with eveningness often associated with poorer sleep and mental health than morningness. However, it is unknown whether COVID-19 pandemic has differentially affected sleep and mental health depending on the circadian type. Here, the differences in sleep and mental health between circadian types are examined globally before and during the COVID-19 pandemic.

Methods

The sample collected between May and August 2020 across 12 countries/regions consisted of 19,267 adults with information on their circadian type. Statistical analyses were performed by using Complex Sample procedures, stratified by country and weighted by the number of inhabitants in the country/area of interest and by the relative number of responders in that country/area.

Evening-types had poorer mental health, well-being, and quality of life or health than other circadian types during the pandemic. Sleep-wake schedules were delayed especially on working days, and evening-types reported an increase in sleep duration. Sleep problems increased in all circadian types, but especially among evening-types, moderated by financial suffering and confinement. Intermediate-types were less vulnerable to sleep changes, although morningness protected from most sleep problems. These findings were confirmed after adjusting for age, sex, duration of the confinement or socio-economic status during the pandemic.

Conclusions

These findings indicate an alarming increase in sleep and mental health problems, especially among evening-types as compared to other circadian types during the pandemic.

https://academic.oup.com/sleep/advance-article/doi/10.1093/sleep/zsab216/6357297

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Highlights

• Greater time in outdoor light was associated with lowered odds of lifetime major depressive disorder•

• More daylight predicted better outcomes across a range of mood and sleep measures•

• These relationships held in both cross-sectional and longitudinal analyses

Abstract

Background

: Light has powerful effects on mood, sleep, and the circadian system. Humans evolved in an environment with a clear distinction between day and night, but our modern environments have blurred this distinction. Negative effects of light exposure at night have been well characterized. The importance of daytime light exposure has been less well characterized. Here we examine the cross-sectional and longitudinal associations of time spent in daytime outdoor light with mood-, sleep-, and circadian-related outcomes.

Methods

: Participants were drawn from the UK Biobank cohort, a large study of UK adults (n = 502,000; 37-73 years old; 54% women).

Results

: UK Biobank participants reported spending a median of 2.5 daylight hours (IQR = 1.5 – 3.5 hours) outdoors per day. Each additional hour spent outdoors during the day was associated with lower odds of lifetime major depressive disorder (95% CI OR:0.92-0.98), antidepressant usage (OR:0.92-0.98), less frequent anhedonia (OR:0.93-0.96) and low mood (OR:0.87-0.90), greater happiness (OR:1.41-1.48) and lower neuroticism (incident rate ratio, IRR:0.95-0.96). In addition, each hour of daytime light was associated with greater ease of getting up (OR:1.46-1.49), less frequent tiredness (OR:0.80-0.82), fewer insomnia symptoms (OR:0.94-0.97), and earlier chronotype (adjusted odds ratio; OR:0.75-0.77). Auto-Regressive Cross-Lagged (ARCL) models were used to examine the longitudinal association of time spent in outdoor light at baseline with later mood-, sleep- and circadian-related outcomes reported at time point 2. Overall, longitudinal associations support cross-sectional findings, though generally with smaller effect sizes.

Limitations

: Future studies that examine the intensity of daytime light exposure at the ocular level are needed.

Conclusions

: Our findings suggest that daytime light exposure is a relevant environmental risk factor for mood-, sleep-, and circadian-related outcomes. These findings support the increased daytime light exposure as beneficial for both mood and sleep disorders.

https://www.sciencedirect.com/science/article/abs/pii/S0165032721008612

© 2021 Elsevier B.V. All rights reserved.

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Abstract

Sleep homeostasis and circadian function are important maintaining factors for optimal health and well-being. Conversely, sleep and circadian disruptions are implicated in a variety of adverse health outcomes, including substance use disorders. These risks are particularly salient during adolescence. Adolescents require 8 to 10 hours of sleep per night, although few consistently achieve these durations. A mismatch between developmental changes and social/environmental demands contributes to inadequate sleep. Homeostatic sleep drive takes longer to build, circadian rhythms naturally become delayed, and sensitivity to the phase-shifting effects of light increases, all of which lead to an evening preference (i.e., chronotype) during adolescence. In addition, school start times are often earlier in adolescence and the use of electronic devices at night increases, leading to disrupted sleep and circadian misalignment (i.e., social jet lag). Social factors (e.g., peer influence) and school demands further impact sleep and circadian rhythms. To cope with sleepiness, many teens regularly consume highly caffeinated energy drinks and other stimulants, creating further disruptions in sleep. Chronic sleep loss and circadian misalignment enhance developmental tendencies toward increased reward sensitivity and impulsivity, increasing the likelihood of engaging in risky behaviors and exacerbating the vulnerability to substance use and substance use disorders. We review the neurobiology of brain reward systems and the impact of sleep and circadian rhythms changes on addiction vulnerability in adolescence and suggest areas that warrant additional research.

https://www.sciencedirect.com/science/article/abs/pii/S0006322317322850

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Abstract

Declining female fertility has become a global health concern. It results partially from an abnormal circadian clock caused by unhealthy diet and sleep habits in modern life. The circadian clock system is a hierarchical network consisting of central and peripheral clocks. It not only controls the sleep–wake and feeding–fasting cycles but also coordinates and maintains the required reproductive activities in the body. Physiologically, the reproductive processes are governed by the hypothalamic–pituitary–gonadal (HPG) axis in a time-dependent manner. The HPG axis releases hormones, generates female characteristics, and achieves fertility. Conversely, an abnormal daily rhythm caused by aberrant clock genes or abnormal environmental stimuli contributes to disorders of the female reproductive system, such as polycystic ovarian syndrome and premature ovarian insufficiency. Therefore, breaking the “time code” of the female reproductive system is crucial. In this paper, we review the interplay between circadian clocks and the female reproductive system and present its regulatory principles, moving from normal physiology regulation to disease etiology.

Extract only, for the full study https://academic.oup.com/endo/article/162/8/bqab117/6298422

Remaining Questions and Future Direction

The normal routine of working at sunrise and resting at sunset has been gradually eroded in the social development process. Instead, high-intensity working patterns along with consequent eating and sleeping disorders and other “modern diseases” are becoming the main theme of daily life. Therefore, larger population studies are needed to characterize this remolding of the circadian rhythm. On this basis, chronobiology can help reverse poor physical conditions and improve existing treatment methods.

As early as 1994, the United Nations highlighted the importance of reproductive health in human development. The decline in female fertility resulting from abnormal circadian rhythms caused by unhealthy diet and sleep habits in modern life has become a global health concern (124, 125). Therefore, breaking the “time code” of the female reproductive system is an urgent task. Despite a large number of studies at present, most studies confine the role of a certain clock gene to a specific cell. As the female reproductive system is by no means a simple superposition of cells and tissues, future chronobiology studies are encouraged from a holistic perspective. Furthermore, constructing and improving the circadian clock network of the female reproductive system is needed to help determine biomarkers that could detect and diagnose circadian rhythm disturbances.

https://academic.oup.com/endo/article/162/8/bqab117/6298422

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Abstract

Particular working conditions and/or organization of working time may cause important sleep disturbances that have been proposed to be predictive of cognitive decline. In this regard, circadian rhythm misalignment induced by exposure to night work or long working hours would be responsible for cognitive impairment. Nevertheless, evidence supporting this correlation is limited and several issues still need to be elucidated. In this regard, we conducted a systematic review to evaluate the association between shift/night work and cognitive impairment and address its main determinants. Information provided by the reviewed studies suggested that night work might have serious immediate negative effects especially on cognitive domains related to attention, memory and response inhibition. Furthermore, cognitive performance would progressively worsen over consecutive night shifts or following exposure to very long work shifts. Otherwise, conflicting results emerged regarding the possible etiological role that night work chronic exposure would have on cognitive impairment. Therefore, circadian rhythm desynchronization, lack of sleep and fatigue resulting from night work may negatively impact worker’s cognitive efficiency. However, in light of the considerable methodological variability of the reviewed studies, we proposed to develop a standardized research and evaluation strategy in order to obtain a better and comprehensive understanding of this topic.

https://www.mdpi.com/1660-4601/18/12/6540

The post Impact of Shift Work and Long Working Hours on Worker Cognitive Functions: Current Evidence and Future Research Needs appeared first on EMFSA.

Abstract

Several endogenous and exogenous factors interact to influence stroke occurrence, in turn contributing to discernable daily distribution patterns in the frequency and severity of cerebrovascular events. Specifically, strokes that occur during the morning tend to be more severe and are associated with elevated diastolic blood pressure, increased hospital stay, and worse outcomes, including mortality, compared to strokes that occur later in the day. Furthermore, disrupted circadian rhythms are linked to higher risk for stroke and play a role in stroke outcome. In this review, we discuss the interrelation among core clock genes and several factors contributing to ischemic outcomes, sources of disrupted circadian rhythms, the implications of disrupted circadian rhythms in foundational stroke scientific literature, followed by a review of clinical implications. In addition to highlighting the distinct daily pattern of onset, several aspects of physiology including immune response, endothelial/vascular and blood brain barrier function, and fibrinolysis are under circadian clock regulation; disrupted core clock gene expression patterns can adversely affect these physiological processes, leading to a prothrombotic state. Lastly, we discuss how the timing of ischemic onset increases morning resistance to thrombolytic therapy and the risk of hemorrhagic transformation.

https://www.frontiersin.org/articles/10.3389/fnins.2021.675732/full

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