Rotating night shift work and menopausal age

Association Between Menopausal Symptoms and Work-Related Factors Among Female Workers in Japan: A Cross-Sectional Study

OBJECTIVE

Although menopausal symptoms are an important issue for female workers, their association with work-related factors is not well studied. Here, we explored the association between work-related factors and menopausal symptoms in Japan.

METHODS

A cross-sectional study was conducted in 2023 among all 1465 female employees of a large Japanese company. Associations between occupational factors and moderate or severe menopausal symptoms, as measured by the Menopause Rating Scale (MRS), were examined using logistic regression analysis.

RESULTS

Several workplace-related factors were significantly associated with moderate or severe menopausal symptoms, including company support and the number of night shifts. A marginally significant association was also seen for commuting time.

CONCLUSIONS

Workplace menopause interventions for the factors identified in this study may satisfy unmet needs.

Menopause and the workplace: consensus recommendations from The Menopause Society

ABSTRACT

Menopause is a natural life transition experienced by half the world's population. Women aged 50 years and older are the fastest growing demographic group in many countries, making essential contributions to the workforce. Although menopause is a universal and natural life transition, the symptom experience is highly variable among women. Some women may experience few or no symptoms, whereas others may be bothered by moderate to severe symptoms for a decade or longer, which can adversely affect quality of life, relationships, job satisfaction, and career advancement. Indeed, menopause symptoms, including vasomotor and genitourinary symptoms, as well as sleep and mood disturbances are associated with multiple adverse work outcomes. Studies to date have demonstrated that these adverse work outcomes related to menopause symptoms include a compromised ability to work, reduced work productivity, absenteeism, and even loss of employment or an early exit from the workforce. Further, the relationship between menopause symptoms and work may be bidirectional, with certain aspects of the work environment being linked with a greater menopause symptom burden, such as insufficient restroom facilities, unpredictable or long work hours, the inability to take breaks, and confined or crowded workspaces. Thus, workplace solutions may need to be tailored based on women's individual needs, the work environment, and the type of work.The Menopause Society, in conjunction with an expert panel of medical and legal experts and women's health advocates, has developed a set of consensus recommendations that challenges employers to create a menopause-supportive workplace for their employees. These recommendations include, among other things, suggestions for employers to review policies and healthcare plans and benefits and to consider flexibility and accommodations that may be needed for some women with menopause symptoms. Guidance for women with menopause symptoms that affect them at work in terms of understanding their resources and empowering them to be self-advocates are also provided, as well as recommendations for what occupational health professionals should know and do for women with bothersome menopause symptoms in the workplace.

Altered coordination between sleep timing and cortisol profiles in night working female hospital employees

BACKGROUND

Cortisol typically peaks in the morning after waking up and declines throughout the day, reaching its lowest levels during nighttime sleep. Shift work can cause misalignment between cortisol levels and sleep-wake timing. We analyzed this misalignment in female shift workers focusing on the timing and extent of these changes.

METHODS

We conducted a cross-sectional study involving 68 shift workers (aged 37 ± 10 years) and 21 non-shift workers (aged 45 ± 10 years) from a hospital. Shift workers were monitored through two day shifts and three night shifts, whereas non-shift workers were monitored during two day shifts. Each participant collected six to eight saliva samples (depending on their shift type) and provided sleep timing information, which was recorded via polysomnography and sleep diaries. Generalized additive mixed models were used to estimate shift-specific differences in cortisol smooth curves. Summary measures calculated for the cortisol smooth curves included cortisol awakening response, peak-to-bed slope, and total output.

RESULTS

Between shift workers and non-shift workers, we observed similar diurnal cortisol profiles with a steep negative diurnal slope during day shifts. In shift workers on night shifts, a flattened U-shaped cortisol profile after the post-awakening maximum was observed, with a peak-to-bed slope close to zero. When comparing night to day shifts in the group of shift workers, mean cortisol levels were lower between 42 and 56 minutes and 1.8-11.9 hours after waking up, and higher between 14.9 and 22 hours after waking up.

CONCLUSION

Our findings indicate altered cortisol profiles in female hospital employees on night shifts. Specifically, cortisol levels were lower at night when higher levels would typically be necessary for work activities, and higher at bedtime after a night shift, when levels should normally be low.

Significance of Melatonin in the Regulation of Circadian Rhythms and Disease Management

Melatonin, the 'hormone of darkness' is a neuronal hormone secreted by the pineal gland and other extra pineal sites. Responsible for the circadian rhythm and seasonal behaviour of vertebrates and mammals, melatonin is responsible for regulating various physiological conditions and the maintenance of sleep, body weight and the neuronal activities of the ocular sites. With its unique amphiphilic structure, melatonin can cross the cellular barriers and elucidate its activities in the subcellular components, including mitochondria. Melatonin is a potential scavenger of oxygen and nitrogen-reactive species and can directly obliterate the ROS and RNS by a receptor-independent mechanism. It can also regulate the pro- and anti-inflammatory cytokines in various pathological conditions and exhibit therapeutic activities against neurodegenerative, psychiatric disorders and cancer. Melatonin is also found to show its effects on major organs, particularly the brain, liver and heart, and also imparts a role in the modulation of the immune system. Thus, melatonin is a multifaceted candidate with immense therapeutic potential and is still considered an effective supplement on various therapies. This is primarily due to rectification of aberrant circadian rhythm by improvement of sleep quality associated with risk development of neurodegenerative, cognitive, cardiovascular and other metabolic disorders, thereby enhancing the quality of life.

Menopause in the workplace: Challenges, impact, and next steps

INTRODUCTION

Menopause is a natural part of a woman's life that coincides with a time when many women play significant roles in the workforce. Menopause symptoms, such as hot flashes, fatigue, and difficulty with concentration and memory, can have a negative effect on work productivity and efficiency.

OBJECTIVES

This paper summarizes the impact of menopause in the workplace, with an emphasis on the impact of symptoms on employed women and how the workplace influences their experiences. It highlights economic implications, promotes awareness, and suggests potential next steps.

METHODS

A search for papers was conducted between August and November 2023 in the PubMed and Medline databases. Papers were selected based on personal experience and interpretation of the findings. Recommendations for managing menopause symptoms in the workplace and guidance on an optimal workplace intervention strategy were provided.

RESULTS

Women experiencing severe menopause symptoms are more likely to report adverse work outcomes, including absenteeism and job-related decisions such as quitting, retiring early, or declining promotions than women experiencing few symptoms. Factors such as a lack of awareness about menopause, inflexible work conditions, and high-stress jobs can exacerbate the severity of these symptoms. Additionally, unaddressed menopause symptoms contribute to both direct and indirect economic costs, including medical resource utilization and lost work productivity, resulting in a substantial economic burden.

CONCLUSION

Menopause symptoms impair women's work experiences and productivity. In addition to dismantling the stigma associated with menopause, it is critical to create and implement menopause workplace policies and interventions aimed at supporting women in this universal life stage.

Nightshift work and irregular menstrual cycle: 8-year follow-up cohort study

BACKGROUND

Irregular menstruation is a major health problem among women, although its association with nightshift work remains controversial.

AIMS

To study the association between nightshift work and irregular menstrual cycle among female workers and investigate any differences according to sleep quality, working hours or obesity.

METHODS

This study included female workers who underwent health examinations from 2012 to 2019. Nightshift work, working hours, sleep quality and menstrual cycles were assessed using self-administered questionnaires. Irregular menstrual cycle was defined as self-reported irregular or ≥36 days. Adjusted odds ratios and 95% confidence intervals (CIs) were calculated by multivariable logistic regression; adjusted hazard ratios (95% CIs) for incident irregular menstrual cycle were calculated by Cox proportional hazard models with time-dependent analysis.

RESULTS

The study participants were 87 147 in the cross-sectional study and 41 516 in the longitudinal study. After adjusting for all covariates in the cross-sectional analyses, the odds ratio for prevalent irregular menstrual cycle among female nightshift workers versus the reference was 1.26 (95% CI 1.2-1.33). In the cohort study, the adjusted hazard ratio for incident irregular menstrual cycle among nightshift workers was 1.95 (95% CI 1.61-2.35) in the period after 6 years. No significant differences were observed among subgroups stratified by sleep quality, working hours or obesity.

CONCLUSIONS

Nightshift work is associated with an increased risk of both prevalent and incident irregular menstrual cycle in female workers without significant interactions by sleep quality, working hours or obesity.

Vasoactive intestinal peptide excites GnRH neurons via KCa3.1, a potential player in the slow afterhyperpolarization current

Vasoactive intestinal peptide (VIP) is an important component of the suprachiasmatic nucleus (SCN) which relays circadian information to neuronal populations, including GnRH neurons. Human and animal studies have shown an impact of disrupted daily rhythms (chronic shift work, temporal food restriction, clock gene disruption) on both male and female reproduction and fertility. To date, how VIP modulates GnRH neurons remains unknown. Calcium imaging and electrophysiology on primary GnRH neurons in explants and adult mouse brain slice, respectively, were used to address this question. We found VIP excites GnRH neurons via the VIP receptor, VPAC2. The downstream signaling pathway uses both Gs protein/adenylyl cyclase/protein kinase A (PKA) and phospholipase C/phosphatidylinositol 4,5-bisphosphate (PIP2) depletion. Furthermore, we identified a UCL2077-sensitive target, likely contributing to the slow afterhyperpolarization current (IAHP), as the PKA and PIP2 depletion target, and the KCa3.1 channel as a specific target. Thus, VIP/VPAC2 provides an example of Gs protein-coupled receptor-triggered excitation in GnRH neurons, modulating GnRH neurons likely via the slow IAHP. The possible identification of KCa3.1 in the GnRH neuron slow IAHP may provide a new therapeutical target for fertility treatments.

Shift work and menstruation: A meta-analysis study

Background

Shift work is a potential risk factor for women's reproductive health. Evidence suggests that shift work is associated with menstrual disorders, reproductive disturbances, and adverse pregnancy outcomes. However, previous studies did not systematically examine the results of menstrual irregularities, dysmenorrhea, and early menopause at the same time.

Objective

To determine the relationship between shift work and women's menstrual characteristics (e.g., irregular menstruation, dysmenorrhea, and early menopause).

Methods

Four databases (PubMed, Embase, Cochrane, and Web of Science) were searched up to December 2022. The study characteristics and risk assessment values of the literature were extracted from 21 studies that met the criteria. Odds ratios (ORs), relative risks (RRs), hazard ratios (HRs), and 95% confidence intervals (CIs) were calculated to assess the relationship between shift work exposure and menstruation. The included studies were evaluated for heterogeneity, publication bias, sensitivity analysis, and subgroup analysis.

Results

A total of 21 studies with 195,538 female participants, including 16 cross-sectional studies and 5 cohort studies, were included in this meta-analysis. According to the quality evaluation, the included research had high methodological quality. The overall ORs of shift work for the likelihood of irregular menstruation and dysmenorrhea were 1.30 (95% CI, 1.23-1.36) (I2 = 41.9%, P < 0.05) and 1.35 (95% CI, 1.04-1.75) (I2 = 73.0%, P < 0.05), respectively. There was a significant positive association between shift work and the risk of early menopause (HR = 1.09, 95% CI, 1.04-1.14), without significant heterogeneity (I2 = 0.0%, P > 0.05).

Conclusions

This meta-analysis indicated that shift workers have significantly higher odds of menstrual disorders, dysmenorrhea, and early menopause. This study focuses on female reproductive health and has broad implications for adjusting optimal working hours and shift schedules for female workers.

Gut microbiota-bile acid-vitamin D axis plays an important role in determining oocyte quality and embryonic development

OBJECTIVE

To reveal whether gut microbiota and their metabolites are correlated with oocyte quality decline caused by circadian rhythm disruption, and to search possible approaches for improving oocyte quality.

DESIGN

A mouse model exposed to continuous light was established. The oocyte quality, embryonic development, microbial metabolites and gut microbiota were analyzed. Intragastric administration of microbial metabolites was conducted to confirm the relationship between gut microbiota and oocyte quality and embryonic development.

RESULTS

Firstly, we found that oocyte quality and embryonic development decreased in mice exposed to continuous light. Through metabolomics profiling and 16S rDNA-seq, we found that the intestinal absorption capacity of vitamin D was decreased due to significant decrease of bile acids such as lithocholic acid (LCA), which was significantly associated with increased abundance of Turicibacter. Subsequently, the concentrations of anti-Mullerian hormone (AMH) hormone in blood and melatonin in follicular fluid were reduced, which is the main reason for the decline of oocyte quality and early embryonic development, and this was rescued by injection of vitamin D3 (VD3). Secondly, melatonin rescued oocyte quality and embryonic development by increasing the concentration of lithocholic acid and reducing the concentration of oxidative stress metabolites in the intestine. Thirdly, we found six metabolites that could rescue oocyte quality and early embryonic development, among which LCA of 30 mg/kg and NorDCA of 15 mg/kg had the best rescue effect.

CONCLUSION

These findings confirm the link between ovarian function and gut microbiota regulation by microbial metabolites and have potential value for improving ovary function.

Impact of Simulated Rotating Shift Work on Mammary Tumor Development in the p53R270H©/+WAPCre Mouse Model for Breast Cancer

Epidemiological studies associate night shift work with increased breast cancer risk. However, the underlying mechanisms are not clearly understood. To better understand these mechanisms, animal models that mimic the human situation of different aspects of shift work are needed. In this study, we used "timed sleep restriction" (TSR) cages to simulate clockwise and counterclockwise rotating shift work schedules and investigated predicted sleep patterns and mammary tumor development in breast tumor-prone female p53R270H©/+WAPCre mice. We show that TSR cages are effective in disturbing normal activity and estimated sleep patterns. Although circadian rhythms were not shifted, we observed effects of the rotating schedules on sleep timing and sleep duration. Sleep loss during a simulated shift was partly compensated after the shift and also partly during the free days. No effects were observed on body weight gain and latency time of breast cancer development. In summary, our study shows that the TSR cages can be used to model shift work in mice and affect patterns of activity and sleep. The effect of disturbing sleep patterns on carcinogenesis needs to be further investigated.

Concurrent trajectories of part-time work and sickness absence: a longitudinal cohort study over 11 years among shift working hospital employees

OBJECTIVES

To investigate the concurrent changes in part-time work and sickness absence (SA) in healthcare. Another aim was to investigate the role of age and sex on different concurrent trajectory groups.

DESIGN

Prospective cohort study.

SETTING

Public hospital districts (n=10) and cities (n=11) in Finland.

PARTICIPANTS

Payroll-based objective working hour data of the healthcare sector in Finland for 28 969 employees in 2008-2019 were used. The final sample included those working shifts with 3 consecutive years of data and without baseline (≥14 days) SA.

PRIMARY OUTCOMES

Part-time work (yes or no) and months of SA.

MEASURES

Group-based trajectory modelling to identify concurrent changes in part-time work, and months of SA while controlling the time-variant amount of night work and multinomial regression models for relative risk (RR) with 95% CIs were used.

RESULTS

Four-group trajectory model was the best solution: group 1 (61.2%) with full-time work and no SA, group 2 (16.9%) with slowly increasing probability of part-time work and low but mildly increasing SA, group 3 (17.6%) with increasing part-time work and no SA, and group 4 (4.3%) with fluctuating, increasing part-time work and highest and increasing levels of SA. Men had a lower (RR 0.49-0.75) and older age groups had a higher likelihood (RRs 1.32-3.79) of belonging to trajectory groups 2-4.

CONCLUSIONS

Most of the sample were in the trajectory group with full-time work and no SA. The probability of part-time work increased over time, linked with concurrent low increase or no SA. A minor group of employees had both an increased probability of part-time work and SA. Part-time work and other solutions might merit attention to promote sustainable working life among healthcare employees.

A narrative review of occupational scheduling that impacts fatigue and recovery relevant to veterinarian well-being

Background

Sleep insufficiency is a worldwide affliction with serious implications for mental and physical health. Occupational factors play a large role in determining sleep habits. Healthcare workers are particularly susceptible to job-mediated sleep insufficiency and inadequate rest in general. Little is published on sleep practices among veterinarians, and overall recognition of the impacts of inadequate rest within the veterinary profession is poor.

Objectives and procedures

This review describes occupational factors affecting sufficiency of rest and recovery, reviews veterinary-specific and relevant adjacent literature pertaining to sleep patterns, and discusses potential solutions for addressing occupational schedules contributing to sleep insufficiency and inadequate rest. Online databases were searched to extract contemporary literature pertaining to sleep, insufficient rest, and occupational factors, with a focus on veterinary medicine and other healthcare sectors.

Results

Occupational factors leading to inadequate rest among healthcare workers include excessive workloads, extended workdays, cumulative days of heavy work hours, and after-hours on-call duty. These factors are prevalent within the veterinary profession and may contribute to widespread insufficient rest and the resulting negative impacts on health and well-being among veterinarians.

Conclusion and clinical relevance

Sufficient sleep quantity and quality are critical to physical and mental health and are negatively affected by many aspects of the veterinary profession. Critical review of current strategies employed in clinical practice is essential to promote professional fulfillment, health, and well-being among veterinarians.

Consequences of Shift Work and Night Work: A Literature Review

Nonstandard work schedules such as shift work and night work tend to trigger problems for workers in different areas. To illustrate the diversity of areas affected and the relative interest of the scientific community, we conducted a literature review of the effects of shift work and night work on workers. In particular, we intended to identify the main variables addressed in the field of health, the family sphere, and the organizational context. The literature review was carried out using the Web of Science with the following terms: "shift work", "rotating shifts", and "night work". Inclusion criteria incorporated empirical studies and articles written in Portuguese or English published in 2019. We selected 129 of the 619 articles identified. Regarding the impacts of shift work and night work, there existed a high discrepancy of focus between the three defined areas: health, family life, and organizational context. Specifically, health-related variables were the most studied (83.4%), followed by organizational variables (9.2%), and, lastly, family variables (7.4%). Based on these results, it is essential to extend the study of the two underrepresented impacts to other crucial areas, not only for the worker but also for organizations.

Sleep disturbances and depressive symptoms of shift workers: Effects of shift schedules

This study explored sleep disturbances and depression among various types of shift workers (SWs) and non-SWs, focusing on work schedule diversity. We enrolled 6,654 adults (4,561 SWs, 2,093 non-SWs). Based on self-report questionnaires on work schedules, the participants were classified according to shift work type: non-shift work; and fixed evening, fixed night, regularly rotating, irregularly rotating, casual, and flexible shift work. All completed the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Insomnia Severity Index (ISI), and short-term Center for Epidemiologic Studies-Depression scale (CES-D). SWs reported higher PSQI, ESS, ISI, and CES-D than non-SWs. Fixed SWs (fixed evenings and fixed nights) and true SWs (regularly and irregularly rotating SWs) scored higher on the PSQI, ISI, and CES-D than non-SWs. True SWs scored higher on the ESS than fixed SWs and non-SWs. Among fixed SWs, fixed night SWs scored higher on the PSQI and ISI than fixed evening SWs. Among true SWs, irregular SWs (irregularly rotating and casual SWs) scored higher on the PSQI, ISI, and CES-D compared to regularly rotating SWs. The PSQI, ESS, and ISI independently were associated with the CES-D of all SWs. We found an interaction between the ESS and the work schedule on the one hand, and the CES-D on the other, which was stronger in SWs than non-SWs. Fixed night and irregular shifts were linked with sleep disturbances. The depressive symptoms of SWs are associated with sleep problems. The effects of sleepiness on depression were more prominent in SWs than non-SWs.

Scheduling practices for pregnant emergency medicine residents

Background

Night shift work is associated with adverse pathophysiologic effects on maternal and fetal well-being. Although emergency medicine (EM) residents work frequent night shifts, there is no existing guidance for residency program directors (PDs) regarding scheduling pregnant residents. Our study assessed scheduling practices for pregnant EM residents, differences based on program and PD characteristics, barriers and attitudes toward implementing a formal scheduling policy, and PDs' awareness of literature describing adverse effects of night shifts on maternal-fetal outcomes.

Methods

We conducted an anonymous, web-based survey of U.S. EM residencies (N = 276). Quantitative data were summarized; chi-square analysis and logistic regression were used to assess relationships between program and PD characteristics and schedule accommodations. Qualitative description was used to analyze an open-ended question, organizing findings into major and minor themes.

Results

Of the 167 completed surveys (response rate 61%), 67% of programs reported no formal policy for scheduling pregnant residents but made adjustments on an individual basis including block changes (85%), decreased (46%) or no night shifts (34%), and working shifts earlier in pregnancy to cover later shifts (20%). Barriers to adjustments included staffing constraints (60%), equity concerns (45%), or impact on wellness (41%) among all residents and privacy (28%). PDs endorsed scheduling adjustments as important (mean 8.1, 0-10 scale) and reported guidance from graduate medical education governance would be useful (60%). Larger program size, but not PD gender or proportion of female residents, was associated with an increased likelihood of scheduling modifications. Twenty-five percent of PDs reported little knowledge of literature regarding night shift work and pregnancy. Qualitative themes supported quantitative findings.

Conclusions

Most EM residency programs do not have formal scheduling policies for pregnant residents, but most PDs support making adjustments and do so informally. More education and guidance for PDs are needed to promote the development of formal policies.

Stress and coping experience in Nurse Residency Programs for new graduate nurses: A qualitative meta-synthesis

Objectives

To determine the stress experience and coping styles of new nurses during Nurse Residency Programs (NRPs) by identifying, appraising, and synthesizing data from the qualitative studies.

Design

A systematic review and meta-synthesis of qualitative studies.

Review methods

Eleven databases were systematically searched for relevant publications in March 2022. All qualitative and mixed-method studies in English and Chinese that explored the stress and coping experience during NRPs of new graduate nurses were included. The qualitative meta-synthesis was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations. Two independent reviewers selected the studies and assessed the quality of each study. Meta-synthesis was performed to integrate the results.

Results

A total of 13 studies revealed 13 sub-themes and three descriptive themes: multi-dimensional stressors, somatic and emotional responses, coping resources and coping methods.

Conclusion

New nurses faced a lot of physical and emotional stress during NRPs, which had a negative impact on their physical and mental health. NRPs are a critical period for the career growth of new nurses. Effective management strategies must be implemented to improve nurse capacity, meet their needs, improve self-efficacy, and build organizational support, as this can improve the quality of clinical nursing and keep the enthusiasm and stability of the nursing team.

Concurrent trajectories of self-rated health and working hour patterns in health care shift workers: A longitudinal analysis with 8-year follow-up

Background

The association between health and working hours is hypothesized to be reciprocal, but few longitudinal studies have examined changes in both health and working hour patterns over time. We examined combined trajectories of self-related health and two working hour patterns (working <35 h/week and working night shifts) and the extent to which these trajectories were predicted by employees' lifestyle and mental health.

Methods

Participants of this cohort study with a 8-year follow-up were 5,947 health care shift workers. We linked self-reports of health from three repeated surveys with objective pay-roll based data on working hours. Using group-based multi-trajectory analysis we identified concurrent trajectories for self-rated health and working hour patterns. We examined their associations with baseline lifestyle-related factors (smoking, at-risk alcohol use, obesity, and physical inactivity) and mental health (sleep problems and psychological distress) using multinomial regression analysis.

Results

Three combined trajectories of self-rated health and working <35 h/week and four combined trajectories of self-rated health and night work were identified. Unhealthy lifestyle and poor mental health were associated with trajectories of moderate and declining health. Sleep problems were linked with working <35 h/week. Younger age and good mental health were associated with a combined trajectory of good health and continued night shift work.

Conclusion

Trajectories of suboptimal and declining health are associated with trajectories of reducing working hours and leaving night work, and are more common in employees with unhealthy lifestyle, sleep problems, and psychological distress.

Night Work and Sustainable Working Life-A Prospective Trajectory Analysis of Swedish Twins

The aim was to investigate the changes in sustainable working life over 10-13 years of follow-up and the effect of baseline night work. Data from the Swedish national registers were used to define sustainable working life. Survey data in the 1998-2003 "SALT" with 34,680 twins or in the 2004-2006 "STAGE" with 19,637 twins were utilized to assess night work at baseline. Group-based trajectory and multinomial regression models were applied. The results of the SALT cohort yielded five trajectory solutions: stable sustainable working life (40%), stable lack of sustainable working life (25%), later decreasingly sustainable working life (15%), increasingly sustainable working life (14%), and early decreasingly sustainable working life (7%). In the STAGE cohort, four trajectories were detected: stable sustainable working life (83%), decreasingly sustainable working life (7%), stable lack of sustainable working life (5%), and increasing sustainable working life (5%). Night work was associated with the decreasing or increasing sustainable working life in the trajectory groups. To conclude, the largest parts of both cohorts followed trajectories of stable sustainable working lives. Night work was associated with both the trajectories of decreasing and increasing sustainable working lives.

Effects of 90 Min Napping on Fatigue and Associated Environmental Factors among Nurses Working Long Night Shifts: A Longitudinal Observational Study

For nurses working long night shifts, it is imperative that they have the ability to take naps to reduce fatigue, and that an appropriate environment is prepared where such naps can be taken. We verified the effects of 90 min napping on fatigue and the associated factors among nurses working 16-h night shifts. We investigated 196-night shifts among 49 nurses for one month. Wearable devices, data logging devices, and questionnaires were used to assess nap parameters, fatigue, and environmental factors such as the napping environment, ways of spending breaks, and working environment. Nurses who nap at least 90 min on most night shifts had more nursing experience. Multivariable logistic regression analysis showed that the environmental factors significantly associated with total nap duration (TND) ≥ 90 min were noise, time spent on electronic devices such as cellphones and tablets during breaks, and nap break duration. The night shifts with TND ≥ 90 min showed lower drowsiness after nap breaks and less fatigue at the end of night shift compared to those with TND < 90 min. Nurses and nursing managers should recognize the importance of napping and make adjustments to nap for at least 90 min during long night shifts.

Ranking the effect of chronodisruption-based biomarkers in reproductive health

Chronodisruption alters circadian rhythms, which has negative consequences on different pathologies and mental disorders. This work studies whether factors related to chronodisruption of circadian rhythms motivated by shift works influence on reproductive health or not. In particular, this influence is studied on four particular aspects related to reproductive health: reproductive health disease, first pregnancy attempt, problems during pregnancy and gestation period. Some explainable machine learning models based on trees have been employed. These methods provided information about the importance of each predictor. The most important variables provided by each method were aggregated using a ranking aggregation function in order to reach a consensus ranking of variables that made possible to understand whether the chronodisruption factors had an effect on each of the aspects studied. The data have been obtained from 697 health professionals. Information about classical biomarkers, sleep quality indices and also other new variables related to eating jet lag, sleep hygiene and how the sleep is affected by shift works were considered as input data. Experiments have shown how some of these novel biomarkers are ranked in the top positions of the issues studied in relation to reproductive health. In particular, the light level and the use of electronic devices, which are features related to chronodisruption, are highlighted as biomarkers.

Environmental disruption of reproductive rhythms

Reproduction is a key biological function requiring a precise synchronization with annual and daily cues to cope with environmental fluctuations. Therefore, humans and animals have developed well-conserved photoneuroendocrine pathways to integrate and process daily and seasonal light signals within the hypothalamic-pituitary-gonadal axis. However, in the past century, industrialization and the modern 24/7 human lifestyle have imposed detrimental changes in natural habitats and rhythms of life. Indeed, exposure to an excessive amount of artificial light at inappropriate timing because of shift work and nocturnal urban lighting, as well as the ubiquitous environmental contamination by endocrine-disrupting chemicals, threaten the integrity of the daily and seasonal timing of biological functions. Here, we review recent epidemiological, field and experimental studies to discuss how light and chemical pollution of the environment can disrupt reproductive rhythms by interfering with the photoneuroendocrine timing system.

The relationship between night shift work and breast cancer incidence: A systematic review and meta-analysis of observational studies

The purpose of this study was to investigate the relationship between night shift work and breast cancer (BC) incidence. A search was performed in PubMed, EBSCO, Web of Science, and Cochrane Library databases before June 2021. The exposure factor of this study is night shift work, the primary outcome is the risk of BC. A total of 33 observational studies composed of 4,331,782 participants were included. Night shift work increases the risk of BC in the female population (hazard ratio [HR] = 1.20, 95% confidence interval [Cl] = 1.10–1.31, p < 0.001), especially receptor-positive BC, including estrogen receptor (ER)+ BC (HR = 1.35, p < 0.001), progesterone receptor (PR)+ BC (HR = 1.30, p = 0.003), and human epidermal growth factor receptor 2 (HER2)+ BC (HR = 1.42, p < 0.001), but has no effect on HER2− BC (HR = 1.10, p = 0.515) and ER−/PR− BC (HR = 0.98, p = 0.827). The risk of BC was positively correlated with night shift working duration, frequency, and cumulative times. For women who start night work before menopause, night work will increase the incidence of BC (HR = 1.17, p = 0.020), but for women who start night work after menopause, night work does not affect BC (HR = 1.04, p = 0.293). Night work can increase the incidence of BC in the female population. The effect of long working hours, frequency, and the cumulative number of night shifts on BC is influenced by menopausal status.

The association between shift work exposure and the variations in age at natural menopause among adult Canadian workers: results from the Canadian Longitudinal Study on Aging (CLSA)

OBJECTIVE

A wide range of negative health outcomes have been associated with shift work (SW) particularly night and rotating SW. However, little is known about effects of SW exposure on reproductive health outcomes. The objective of our study is to prospectively investigate the association between SW exposure and the variations in age at natural menopause among adult Canadian workers.

METHODS

Secondary data analyses were performed using the Canadian Longitudinal Study on Aging database. Premenopausal women (N = 3,688) at baseline were followed prospectively for 3 years. Three derived variables were used to measure SW primary exposure: 1) ever exposed to SW, 2) SW exposure in current job, and 3) SW exposure in the longest job. Cox proportional hazard regression models were used to evaluate risk of variations in age at natural menopause after adjusting for potential confounders.

RESULT

One out of five women (20%) reported to be ever exposed to SW during their jobs. Overall, women who were ever exposed to SW were significantly associated with a delayed onset of menopause compared with daytime workers (hazard ratios [HR] = 0.77, 95% CI, 0.61-0.98). Particularly, when compared with daytime workers, rotating shift worker in the current and longest job were significantly related to delayed onset of menopause (HR = 0.64, 95% CI, 0.46-0.89 and HR = 0.65, 95% CI, 0.49-0.86), respectively.

CONCLUSION

Our results suggest a relationship between rotating shift and delayed onset of menopause. We speculate that disruptive circadian stimuli may play a role in menopausal onset and this warrants further investigation.

VIDEO SUMMARY

http://links.lww.com/MENO/A940.

Sex and Gender Science: The World Writes on the Body

Sex and Gender Science seeks to better acknowledge that the body cannot be removed from the world it inhabits. We believe that to best answer any neuroscience question, the biological and the social need to be addressed through both objective means to learn, "how it is like" and subjective means to learn, "what it is like." We call bringing the biological and social together, "Situated Neuroscience" and the mixing of approaches to do so, Very Mixed Methods. Taken together, they constitute an approach to Sex and Gender Science. In this chapter, we describe neural phenomena for which considering sex and gender together produces a fuller knowledge base: sleep, pain, memory, and concussion. For these brain phenomena examples, studying only quantitative measures does not reveal the full impact of these lived experiences on the brain but studying only the qualitative would not reveal how the brain responds. We discuss how Sex and Gender Science allows us to begin to bring together biology and its social context and acknowledge where context can contribute to resolving ignorance to offer more expansive, complementary, and interrelating pictures of an intricate neuro-landscape.

Influence of Work on Andropause and Menopause: A Systematic Review

Aging is associated with gender-specific hormonal changes that progressively lead to gonadal insufficiency, a condition which characterizes a minority of men and all women. Work-related factors, such as stress and pollutant exposure, affect gonadal function and can interfere with reproduction in both genders. A systematic review of the PubMed, SCOPUS and EMBASE databases was conducted, according to the Preferred Reporting Items for Systemic Reviews and Meta-Analyses (PRISMA) statement to investigate the effect of occupational factors on andropause and menopause. A total of 26 studies met the inclusion and exclusion criteria: 9 studies evaluated the effects of work on andropause symptoms, 8 studies examined its effects on age at menopause onset, and 9 studies addressed its effects on menopausal symptoms. Work-related factors, such as psychological stress, physical effort, and sleep disorders, showed a significant correlation with andropause manifestations, whereas age at menopause and severity of menopausal symptoms were both influenced by factors such as pesticide exposure, high job strain, and repetitive work. Since work accompanies men and women for most of their lives, it is essential to identify and prevent the risk factors that may affect reproductive health.

Can time to menopause be predicted?

Menopause represents the definite end of a woman's reproductive life and the onset of a persistent hypoestrogenic state. This postmenopausal period will for most women last several decades. Although mean menopausal age seems to have increased somewhat during the last century, there is a significant individual variation in age at natural menopause. With efficient contraception, women of reproductive age can now, to some extent, choose when they want to have children. As a consequence of this and other sociodemographic changes, age at first birth has increased significantly over the last 50 years. It is well documented that long before a woman enters the menopausal transition and subsequent menopause, fertility declines and finally ceases. Being able to predict when a woman will enter menopause would therefore, from a reproductive perspective, be of major interest. Several sociodemographic, morphometric, and endocrine factors are associated with age at menopause or time to menopause. Unfortunately the sensitivity and specificity of these in predicting time to or age at menopause are low. Therefore, with the exception of anti-Müllerian hormone measurements, either alone or in combination with chronological age close to menopause, there are as of now no reliable ways of predicting when a woman will enter menopause.

Socioeconomic status and fertility treatment outcomes in high-income countries: a review of the current literature

The association between socioeconomic status and fertility is a subject that has received much attention. Yet, little is known as to whether the socioeconomic status has an impact on the outcomes of fertility treatment. This systematic review aims to assess any possible relationship between socioeconomic deprivation and treatment outcomes. A database search was conducted of all publications in this field up to March 2021. Eleven studies were identified and six of these specifically investigated the impact of socioeconomic status on fertility treatment outcomes. Children conceived following assisted conception are more likely to be born to mothers of a higher socioeconomic status than those conceived naturally. Of the few studies investigating the impact of socioeconomic status on fertility treatment outcomes and the results are conflicting, making it difficult to draw robust conclusions as to its effect. It is unknown which, if any, marker of socioeconomic status is the most significant for fertility patients: whether it is the characteristics of the individual or that of their surroundings. Further research is urgently needed.

Male and female gonadal ageing: its impact on health span and life span

Ageing is linked to changes in the hypothalamic-pituitary-gonadal axis and a progressive decline in gonadal function. While women become infertile when they enter menopause, fertility decline in ageing men does not necessarily involve a complete cessation of spermatogenesis. Gonadal dysfunction in elderly people is characterized by morphological, endocrine and metabolic alterations affecting the reproductive function and quality of life. With advancing age, sexuality turns into a critical emotional and physical factor actually defining the number of years that ageing people live a healthy life. Gonadal ageing correlates with comorbidities and an increased risk of age-related diseases including diabetes, kidney problems, cardiovascular failures and cancer. This article briefly summarizes the current state of knowledge on ovarian and testicular senescence, explores the experimental models used in the study of gonadal ageing, and describes the local pro-inflammatory, oxidative and apoptotic events and the associated signalling pathways that take place in the gonads while people get older. Overall, literature reports that ageing exacerbates a mutual crosstalk among oxidative stress, apoptosis and the inflammatory response in the gonads leading to detrimental effects on fertility. Data also highlight the clinical implications of novel therapeutic interventions using antioxidant, anti-apoptotic and anti-inflammatory drugs on health span and life span.

Associations of long-term exposure to environmental noise and outdoor light at night with age at natural menopause in a US women cohort

Previous studies have suggested noise, especially at night time, and light at night (LAN) could cause neuroendocrine disturbance and circadian disruption, which may lead to ovarian follicle atresia and earlier onset of menopause. However, no study to date has directly investigated the associations of exposure to these factors and menopausal age.

Methods

Premenopausal women from the Nurses' Health Study II (NHS II) were followed from age 40 through 2015. Median daytime and nighttime anthropogenic noise and outdoor LAN exposure were measured from a geospatial prediction model and satellite images, respectively, at residential addresses throughout the follow-up. Time-varying Cox proportional hazard models were used to calculate the hazard ratios and 95% confidence intervals, adjusting for individual lifestyle, reproductive history, and neighborhood socioeconomic factors. Possible effect modification by region, smoking status, body mass index, race/ethnicity, history of rotating shift work, and census tract population density and median income was examined.

Results

A total of 63,380 of 105,326 women self-reported natural menopause during 1,043,298 person-years of follow-up. No associations were found for noise (both daytime and nighttime) and outdoor LAN exposure with age at natural menopause (hazard ratios = 0.99-1.00) in the fully adjusted models. Sensitivity analyses showed similar null associations. No meaningful effect modification was found for region, smoking status, body mass index, race/ethnicity, history of rotating shift work, and census tract socioeconomic measures in stratified analyses.

Conclusion

No associations were found between environmental noise and outdoor LAN exposure in mid-adulthood and menopausal age in this cohort of US women.

Urban health advantage or urban health penalty? Urban-rural disparities in age trajectories of physiological health among Chinese middle-aged and older women and men

During the past decades, China has experienced rapid urbanization and aging. This study investigated sex-stratified urban-rural disparities in age trajectories of physiological health in China. We obtained data from 21686 individuals aged 45 years or above from 2011 baseline survey of the China Health and Retirement Longitudinal Study (CHARLS) and the 2015 follow-up. It examined 11 biomarkers of physiological health classified into four summary indices: cardiovascular index, metabolic index, inflammation index, and allostatic load. This study found that the "urban health penalty" approach dominates the "urban health advantage" approach in middle and early old age, but the dominance of the "urban health penalty" approach is offset or even reversed by the "urban health advantage" approach in older age.

The Role of Oxidative Stress and Natural Antioxidants in Ovarian Aging

The ovarian system comprises vital organs in females and is of great significance for the maintenance of reproductive potential and endocrine stability. Although complex pathogenesis undoubtedly contributes to ovarian aging, increasing attention is being paid to the extensive influence of oxidative stress. However, the role of oxidative stress in ovarian aging is yet to be fully elucidated. Exploring oxidative stress-related processes might be a promising strategy against ovarian aging. In this review, compelling evidence is shown that oxidative stress plays a role in the etiology of ovarian aging and promotes the development of other ovarian aging-related etiologies, including telomere shortening, mitochondrial dysfunction, apoptosis, and inflammation. In addition, some natural antioxidants such as quercetin, resveratrol, and curcumin have a protective role in the ovaries through multiple mechanisms. These findings raise the prospect of oxidative stress modulator-natural antioxidants as therapeutic interventions for delaying ovarian aging.

Shiftwork and Light at Night Negatively Impact Molecular and Endocrine Timekeeping in the Female Reproductive Axis in Humans and Rodents

Shiftwork, including work that takes place at night (nightshift) and/or rotates between day and nightshifts, plays an important role in our society, but is associated with decreased health, including reproductive dysfunction. One key factor in shiftwork, exposure to light at night, has been identified as a likely contributor to the underlying health risks associated with shiftwork. Light at night disrupts the behavioral and molecular circadian timekeeping system, which is important for coordinated timing of physiological processes, causing mistimed hormone release and impaired physiological functions. This review focuses on the impact of shiftwork on reproductive function and pregnancy in women and laboratory rodents and potential underlying molecular mechanisms. We summarize the negative impact of shiftwork on female fertility and compare these findings to studies in rodent models of light shifts. Light-shift rodent models recapitulate several aspects of reproductive dysfunction found in shift workers, and their comparison with human studies can enable a deeper understanding of physiological and hormonal responses to light shifts and the underlying molecular mechanisms that may lead to reproductive disruption in human shift workers. The contributions of human and rodent studies are essential to identify the origins of impaired fertility in women employed in shiftwork.

Role of Ovarian Hormones in the Modulation of Sleep in Females Across the Adult Lifespan

Ovarian hormones, including 17β-estradiol, are implicated in numerous physiological processes, including sleep. Beginning at puberty, girls report more sleep complaints than boys, which is maintained throughout the reproductive life stage. Sleep problems are exacerbated during the menopausal transition, evidenced by greater risk for sleep disorders. There is emerging evidence that menopause-associated hormone loss contributes to this elevated risk, but age is also an important factor. The extent to which menopause-associated sleep disturbance persists into postmenopause above and beyond the effects of age remains unknown. Untreated sleep disturbances have important implications for cognitive health, as they are emerging as risk factors for dementia. Given that sleep loss impairs memory, an important knowledge gap concerns the role played by menopause-associated hormone loss in exacerbating sleep disturbance and, ultimately, cognitive function in aging women. In this review, we take a translational approach to illustrate the contribution of ovarian hormones in maintaining the sleep-wake cycle in younger and middle-aged females, with evidence implicating 17β-estradiol in supporting the memory-promoting effects of sleep. Sleep physiology is briefly reviewed before turning to behavioral and neural evidence from young females linking 17β-estradiol to sleep-wake cycle maintenance. Implications of menopause-associated 17β-estradiol loss is also reviewed before discussing how ovarian hormones may support the memory-promoting effects of sleep, and why menopause may exacerbate pathological aging via effects on sleep. While still in its infancy, this research area offers a new sex-based perspective on aging research, with a focus on a modifiable risk factor for pathological aging.

Impact of Circadian Disruption on Female Mice Reproductive Function

In female mammals, cycles in reproductive function depend both on the biological clock synchronized to the light/dark cycle and on a balance between the negative and positive feedbacks of estradiol, whose concentration varies during oocyte maturation. In women, studies report that chronodisruptive environments such as shiftwork may impair fertility and gestational success. The objective of this study was to explore the effects of shifted light/dark cycles on both the robustness of the estrous cycles and the timing of the preovulatory luteinizing hormone (LH) surge in female mice. When mice were exposed to a single 10-hour phase advance or 10-hour phase delay, the occurrence and timing of the LH surge and estrous cyclicity were recovered at the third estrous cycle. By contrast, when mice were exposed to chronic shifts (successive rotations of 10-hoursour phase advances for 3 days followed by 10-hour phase delays for 4 days), they exhibited a severely impaired reproductive activity. Most mice had no preovulatory LH surge at the beginning of the chronic shifts. Furthermore, the gestational success of mice exposed to chronic shifts was reduced, because the number of pups was 2 times lower in shifted than in control mice. In conclusion, this study reports that exposure of female mice to a single phase shift has minor reproductive effects, whereas exposure to chronically disrupted light/dark cycles markedly impairs the occurrence of the preovulatory LH surge, leading to reduced fertility.

Clinical management of vaginal bleeding in postmenopausal women

Menopause is characterized by permanent cessation of menstrual periods and is clinically diagnosed after 12 months of complete amenorrhea. It occurs at a median age of 51 years alongside the physiological process of aging, although it can happen at an earlier age for other medical conditions or after surgery (surgical menopause). Due to reduced circulating estrogens and progesterone, the reproductive organs undergo progressive atrophy. This physiologic process of aging is also present at an endometrial level; without the cyclic hormonal actions of the menstrual cycle, the endometrium during menopause becomes atrophic. Postmenopausal bleeding (PMB) is a common gynecologic complaint encountered by the clinician. Endometrial cancer is present in about 10% of patients with PMB. Nevertheless, many other conditions, such as endometrial or cervical polyps, genital atrophy, or non-gynecologic conditions, may also be present. Historically, dilation and curettage (D&C) was the main diagnostic procedure in patients with PMB; however, newer methods of investigation have replaced D&C. The aim of this review is to present an up-to-date analysis of the current evidence for the clinical management of vaginal bleeding in postmenopausal women.

Role of core circadian clock genes in hormone release and target tissue sensitivity in the reproductive axis

Precise timing in hormone release from the hypothalamus, the pituitary and ovary is critical for fertility. Hormonal release patterns of the reproductive axis are regulated by a feedback loop within the hypothalamic-pituitary-gonadal (HPG) axis. The timing and rhythmicity of hormone release and tissue sensitivity in the HPG axis is regulated by circadian clocks located in the hypothalamus (suprachiasmatic nucleus, kisspeptin and GnRH neurons), the pituitary (gonadotrophs), the ovary (theca and granulosa cells), the testis (Leydig cells), as well as the uterus (endometrium and myometrium). The circadian clocks integrate environmental and physiological signals to produce cell endogenous rhythms generated by a transcriptional-translational feedback loop of transcription factors that are collectively called the "molecular clock". This review specifically focuses on the contribution of molecular clock transcription factors in regulating hormone release patterns in the reproductive axis, with an emphasis on the female reproductive system. Specifically, we discuss the contributions of circadian rhythms in distinct neuronal populations of the female hypothalamus, the molecular clock in the pituitary and its overall impact on female and male fertility.

Does night work affect age at which menopause occurs?

PURPOSE OF REVIEW

To delineate the current state of evidence on the impact of night shift work on age at natural menopause.

RECENT FINDINGS

The only direct evidence is from a single observational study, which indicates that women who work night shifts are at moderately higher risk for earlier menopause and that this risk is more pronounced among younger women. Underlying biological mechanisms have yet to be sufficiently substantiated. A long-held line of inquiry, most strongly propagated by the observed link between night shift work and female breast cancer, is the 'Light at Night' hypothesis, which suggests melatonin-mediated circadian disruption as a potential regulator of reproductive signaling in women. Supporting evidence is found from observations of changes in endogenous melatonin production among night working women or in response to light exposure, and corresponding changes in endogenous ovarian hormone levels and modulated menstrual patterns, among other indications of altered central ovulation-governing processes. Susceptibility to night shift work may be modified by chronotype.

SUMMARY

This review summarizes the literature related to night work and ovulatory regulation in humans, prioritizing population-based evidence to provide motivation for the study of circadian disruption and night shift work as a regulator of menopausal timing.