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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Abstract

Type 2 diabetes mellitus (T2DM) increases cardiac inflammation which promotes the development of cardiac fibrosis. We sought to determine the impact of circadian disruption on the induction of hyperglycaemia, inflammation and cardiac fibrosis. Methods: Psammomys obesus (P. obesus) were exposed to neutral (12 h light:12 h dark) or short (5 h light:19 h dark) photoperiods and fed a low energy (LE) or high energy (HE) diet for 8 or 20 weeks. To determine daily rhythmicity, P. obesus were euthanised at 2, 8, 14, and 20 h after ‘lights on’. Results: P. obesus exposed to a short photoperiod for 8 and 20 weeks had impaired glucose tolerance following oral glucose tolerance testing, compared to a neutral photoperiod exposure. This occurred with both LE and HE diets but was more pronounced with the HE diet. Short photoperiod exposure also increased myocardial perivascular fibrosis after 20 weeks on LE (51%, P < 0.05) and HE (44%, P < 0.05) diets, when compared to groups with neutral photoperiod exposure. Short photoperiod exposure caused elevations in mRNA levels of hypertrophy gene Nppa (atrial natriuretic peptide) and hypertrophy transcription factors Gata4 and Mef2c in myocardial tissue after 8 weeks. Conclusion: Exposure to a short photoperiod causes impaired glucose tolerance in P. obesus that is exacerbated with HE diet and is accompanied by an induction in myocardial perivascular fibrosis.

https://www.nature.com/articles/s41598-021-89191-7

EMFSA:

In this study the authors used the Psammomys obesus model of T2DM to simulate circadian disruption, similar to a shift worker, combined with a HE diet to assess the onset of features of T2DM and myocardial pathophysiology. The finding of this study provide insights into the potential adverse effects on the heart that may be experienced by shift workers due to T2DM that is induced by circadian dysfunction and amplified by a HE diet.

According to the authors, their studies may provide guidance for the prevention of diabetes-related cardiac fibrosis in shift workers in which a healthy diet and reduced time periods of circadian disruption should be promoted as a strategy for preventing cardiac dysfunction.

The authors remind us that cardiovascular disease is the leading cause of death worldwide1. Type 2 Diabetes Mellitus (T2DM) is regarded as pan epidemic, with more than 640 million people predicted to have T2DM by 20402. It is well-established that there is a link between cardiovascular disease (CVD) and T2DM with them frequently occurring simultaneously along with an associated elevated risk of adverse outcomes1,3,4. Specifically, people with diabetes or pre-diabetes are more likely to develop cardiovascular disease than their non-diabetic counterparts1,3,4.

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Night shift work has been a common feature of industrial economies for decades, and it has long been known that working through the night can negatively impact upon health. In recent years, the evidence base about these health impacts has expanded considerably. Here, Professor David Ray introduces this evidence and highlights how employers and policymakers should be paying increased attention to this issue. 

• There is a growing body of evidence for the adverse mental and physical health impacts of night shift working
• Recent research has revealed a wider number of health conditions that are related to night shift work, including a number of cancers
• The implications of this new evidence for employers, policymakers, and workers, makes a wider conversation about managing and mitigating the impacts of night shift work essential

Excerpt:

Nightshift work increases the risk of mental health issues, including mood disorder, and sleep disorder. In addition, there is an increase in the risk of metabolic diseases including obesity, and diabetes, malignant diseases, including breast and prostate cancers, and inflammatory diseases, including asthma.

New information identifies that night shiftwork carries a clear, and significant risk to mental and physical health, even after other factors such as smoking, have been taken into account.  Importantly, we now understand why shiftwork carries the risk. This is misalignment of the biological clock in the worker with the external light-dark environment. This is a major advance, as it offers a rational target for intervention to protect the health of nightshift workers.

Link to the complete article:

http://blog.policy.manchester.ac.uk/posts/2020/07/addressing-the-health-impacts-of-nig

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Have you ever had your blood pressure checked at the doctor’s? Did you assume your blood pressure stayed the same all day? It does not! It is in concert in a circadian rhythm orchestra with low base notes during the night and high peak notes during the day guided by a conductor in the brain called the master circadian clock. This master clock coordinates peripheral clocks, located in every cell and organ throughout the body, with environmental cues such as day/night, exercise, temperature, fasting and feeding. This prepares the body for anticipatory rest or activity by producing changes to heart rate, blood pressure, blood clotting ability, blood vessel function and cardiac hormones – the functional parts to pull the heartstrings to a heartbeat.

Excerpt

When the circadian clock concert’s harmony is repeatedly misaligned with behaviours and/or environment not appropriately timed to it – as happens in shift work or to a smaller degree in social jetlag – it can be injurious to health. Indeed, shift work can be an independent risk factor for heart disease due to repeated misalignment between cardiovascular system behaviours and the circadian clock. For example, non-dipping night-time blood pressure occurs, which is in disharmony to the circadian night-time music sheet for dipping blood pressure. This increases the risk for adverse cardiovascular events and hypertension in chronic shift workers. Experimentally induced heart attacks in mice recovered slower when there was a circadian disruption in light/dark cycles. Experiments tweaking clock genes showed impact on tolerance of the heart to deficient blood supply with some mutations making it worse and some making it better. The suggestion from research advances is that both light/dark cycles and internal clock disruption affect cardiovascular health. Shift-work circadian effects can be helped in workers with bright light use during shift and exposure to low light when they sleep during the day.

For the complete article, please see: https://srbr.org/a-heart-clock-rhythm-orchestra/

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The post Disruption of central and peripheral circadian clocks in police officers working at night appeared first on EMFSA.

Meeting begins at 8:30 a.m. EDT and continues until adjournment.

• The draft monograph will be available Aug. 24, 2018 on the Upcoming Peer Review Panels page.
• Sept. 21, 2018 is the deadline for written public comment submissions.
• Sept. 21, 2018 is the deadline for oral comment registration.
• Oct. 5, 2018 is the deadline for meeting registration and to view the webcast.
• Registration is required to view the webcast.

Federal Register notice, agenda, registration, and other meeting information are available on the Upcoming Peer Review Panels page.

Draft Report on Carcinogens Monograph on Night Shift Work and Light at Night; Availability of Document; Request for Comments; Notice of Peer-Review Meeting

A Notice by the National Institutes of Health on 08/17/2018   

(Excerpt)

SUPPLEMENTARY INFORMATION:

Background: The invention of electric light transformed society, from one in which people’s activities and sleep patterns were limited by the natural light: Dark cycle to a culture in which people now work, sleep, eat, and receive goods or services throughout the 24-hour day. Through lifestyle choices, home location, and work schedule, people are exposed to different patterns and types of light, including electric light at night (LAN), which may lead to cancer and other adverse health effects. These health effects may arise from misalignment of daily physiological and behavioral cycles (i.e., circadian rhythms) with external stimuli or with each other (i.e., circadian disruption). Circadian rhythms can include processes and behaviors like sleep-wake cycles, eating, and body temperature, among others.

NTP has conducted a literature-based assessment and applied the Report on Carcinogens (RoC) listing criteria to this assessment to determine whether night shift work (e.g., working at least three hours between midnight and 6 a.m.) and light at night are cancer hazards. As circadian disruption is thought to be a key intermediate step, NTP has also reviewed the literature on this topic.

The monograph assesses the evidence from cancer studies in humans and experimental animals and mechanistic data and provides NTP’s preliminary recommendation regarding whether night shift work and or light at night should be listed in the Report on Carcinogens, and if so, how the two exposure scenarios should be defined. The listing categories include known or reasonably anticipated to be a human carcinogen. https://www.federalregister.gov/documents/2018/08/17/2018-17782/draft-report-on-carcinogens-monograph-on-night-shift-work-and-light-at-night-availability-of

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