Shift Work Disorder

Healthily Nourished but Depleted? Is It Possible to Improve the Health of Shift Workers through Lifestyle Interventions?

The relationship between diet and health is well-researched, and there is also information regarding the effects of diet on mental health. This study aimed to investigate whether motivation to optimize lifestyles without regulations or restrictions could improve the health of rotating shift workers. In this pilot study, 18 male shift workers were randomly divided into two groups. All participants completed the Short Form Health Survey-36 questionnaire (SF-36) before the start and at the end of the study. Group I (n = 9, mean age 42 ± 6.6 y) received dietary and lifestyle information every other month for one year, and the other, Group II (n = 9 mean age 36 ± 7.3 y), one year later. All participants were motivated to follow the trained dietary recommendations and to engage in physical activity. Almost all scores had improved. Surprisingly, physical performance scores worsened, which was not expected. The impairment in mental health due to the change in ownership of the company could have been better explained. Nutritional advice over a longer period and the motivation to integrate more exercise into everyday life can potentially improve the health of rotating shift workers.

The influence of shift work: A bibliometric analysis of research progress and frontiers on health effects

Shift work has been found to disrupt the circadian system, leading to negative health effects. The objective of this study was to assess the progress and frontiers in research on the health-related influence of shift work. The study analyzed 3,696 data points from Web of Science, using the bibliometric software CiteSpace to visualize and analyze the field. The results showed a steady increase in annual publications, particularly in the last 5 years, with a rapid increase in publications from China. The United States contributed the most to the number of publications and worldwide collaborations. The most prolific institution and author were the Brigham and Women's Hospital and Professor Bjorn Bjorvatn, respectively. The Journal of Chronobiology International ranked at the top and focused primarily on shift worker research. In the first decade of study, the primary focus was on the associations between shift work and cardiovascular disease and metabolic disorders. Over time, research on the health effects of shift work has expanded to include cancer and mental health, with subsequent studies investigating molecular mechanisms. This study provides a comprehensive and intuitive analysis of the negative health impacts of shift work. It highlights existing research hotspots and provides a roadmap for future studies. Further research is needed to explore the adverse health consequences and related mechanisms of shift work exposure, as well as interventions to mitigate its health effects.

Sleep deprivation and medication administration errors in registered nurses-A scoping review

AIM

To explore whether sleep deprivation contributes to medication errors in registered nurses (RNs).

BACKGROUND

Sleep deprivation is a potential issue for RNs, particularly those who work shifts. Sleep deprivation has been found to have a negative impact on numerous cognitive processes. Nurses administer several medications to patients a day, potentially while sleep deprived-anecdotal reports suggest that this could result in an increased risk of error occurring.

DESIGN

A scoping review was conducted using the Prisma-ScR extension framework to explore what is known about the effect of RNs' sleep deprivation on medication administration errors.

METHODS

A search of databases generated 171 results. When inclusion and exclusion criteria were applied, 18 empirical studies were analysed. Studies included retrospective analysis of errors, surveys of perceptions of causes and observational studies.

RESULTS

Data indicated that RNs consider fatigue, which may be caused by sleep deprivation, to be a contributing factor to medication errors. The search only identified three observer studies, which provided conflicting results as to whether lack of sleep contributes to the error rate. Of the numerous tools used to measure sleep, the Pittsburgh Sleep Quality Index was the most frequently used.

CONCLUSION

Although RNs anecdotally consider a lack of sleep potentially contributes to medication errors, there is insufficient research to provide robust evidence to confirm this assumption.

NO PATIENT OR PUBLIC CONTRIBUTIONS

Patient or public contributions were not required for this scoping review.

RELEVANCE TO CLINICAL PRACTICE

Sleep deprivation is a potential issue for nurses, especially those who work shifts. Poor sleep impacts cognitive processes that potentially could increase errors. Nurses should be aware of the impact sleep may have on patient safety.

Alterations of functional brain activity and connectivity in female nurses working on long-term shift

AIM

To investigate the alterations of functional brain activity and connectivity in female nurses working on long-term shifts and explore their correlations with work-related psychological traits.

DESIGN

An exploratory cross-sectional study.

METHODS

Thirty-five female nurses working on long-term shifts (shift nurses) and 35 female nurses working on fixed days (fixed nurses) were enrolled. After assessing the work-related psychological traits, including burnout, perceived stress, anxiety, and depression of nurses, the fractional amplitude of low-frequency fluctuations (fALFF) and region of interest (ROI)-based functional connectivity (FC) analyses were performed to investigate the differences of brain spontaneous activity and functional connectivity between these two groups of nurses. Thereafter, correlations between the functional brain parameters (fALFF and FC) and clinical metrics were investigated among the shift nurses.

RESULTS

Compared to fixed nurses, shift nurses had higher burnout, perceived stress and depression scores, lower fALFF in the right dorsolateral prefrontal cortex (dlPFC), left and right superior parietal lobule (SPL), bilateral anterior cingulate cortex (ACC), and higher fALFF in the right superior/middle temporal gyrus, as well as decreased FC between the right dlPFC (the selected ROI) and bilateral ACC, left and right inferior frontal/orbitofrontal gyrus (IFG/IOFG), right SPL, and left middle occipital gyrus (voxel-level p < 0.001, cluster level p < 0.05, GRF correction). Correlation analyses demonstrated that the fALFF value of the right dlPFC was significantly correlated with the burnout and anxiety scores, the FC value of the right dlPFC-right SPL was correlated with the perceived stress and burnout scores, the FC value of the right dlPFC-right IFG/IOFG was correlated with the burnout score in shift nurses (p < 0.05).

CONCLUSION

Shift nurses had work-related altered functional activity and connectivity in the right frontoparietal network, which provided objective and visualised evidence to clarify the hazards of long-term shift work on female nurses.

PATIENT OR PUBLIC CONTRIBUTION

Seventy nurses participated deeply as subjects in this study. These findings are expected to draw managers' attention to the harmful influences of shift work on nurses.

The Effect of Sleep Quality on Coronary Lesion Severity and Prognosis in the Young Acute Coronary Syndrome Population

This study aimed to explore the effect of long-term (≥1 year) sleep quality on coronary lesion complexity and cardiovascular prognosis in young acute coronary syndrome (ACS) patients. We consecutively recruited young patients aged from 18 to 44 years old with first-episode ACS and significant epicardial stenosis on coronary angiography from January 2016 to January 2017. Coronary lesion complexity was evaluated based on SYNTAX scores. Long-term sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) (PSQI ≤ 5 and PSQI > 5 groups). The primary endpoints were major adverse cardiovascular events (MACEs). A total of 466 young ACS patients (93.13% male; median age, 41 years) were included. Poor sleepers (PSQI > 5) had higher SYNTAX scores. After adjusting for confounders, PSQI scores (continuous variables, OR: 1.264; 95%CI: 1.166-1.371; p < 0.001) and PSQI grade (binary variable, OR: 3.864; 95%CI: 2.313-6.394; p = 0.001) were significantly associated with an increased risk of complex coronary lesions. During a median follow-up of 74 months, long-term poor sleep quality (PSQI > 5) was significantly associated with an increased risk of MACEs (HR: 4.266; 95%CI: 2.274-8.001; p < 0.001). Long-term poor sleep quality was a risk factor for complex coronary lesions and has adverse effects on cardiovascular prognosis in the young ACS population.

Circadian misalignment alters resting-state functional connectivity of the salience network in rotating shift workers

STUDY OBJECTIVES

This study compared resting-state functional connectivity (rsFC) of the salience network (SN) between rotating shift workers (RSWs) and controls. Furthermore, we examined whether rsFC of the SN was correlated with sleep, emotion, cognition, and attention.

METHODS

The 60 RSWs and 57 controls enrolled in this study completed self-report questionnaires and sleep diaries to assess subjective sleep quality, and polysomnography and actigraphy to evaluate objective sleep and 24-hour rest-activity rhythm parameters. The participants also underwent resting-state functional magnetic resonance imaging and structural T1 scans. We performed a seed-based rsFC analysis of the SN using the anterior cingulate cortex (ACC) and anterior insula (AI) as seed regions. Furthermore, AI and ACC rsFC were compared in RSWs and controls, and we analyzed correlations between rsFC and variables of interest showing significant group differences.

RESULTS

Compared with controls, RSWs showed reduced rsFC between the ACC and right insula, and increased rsFC of the ACC with the left occipital lobe and right superior frontal gyrus extending to the supplementary motor area (SFG/SMA). Moreover, RSWs showed reduced rsFC between the right AI and right superior parietal lobule (SPL). Finally, rsFC between the ACC and right AI was correlated with 24-hour rest-activity rhythmicity.

CONCLUSIONS

Although RSWs did not show sleep disturbance, emotional distress, cognitive impairment, or attention deficits, alterations of right insula, left occipital lobe, right SFG/SMA, and right SPL rsFC in the SN indicate that impairments in salience detection and top-down attentional control may emerge in shift workers over time.

Gender and Nightshift Work: A Cross Sectional Study on Sleep Quality and Daytime Somnolence

A few studies suggested that female nightshift workers suffer more frequently from sleep deprivation and insomnia. We conducted a cross-sectional survey in two different occupational settings to address gender-related differences in nightshift work adaptation. We used the Epworth Sleepiness Scale and the Pittsburgh Sleep Quality Index questionnaires to quantify daytime sleepiness and sleep quality among 156 workers, 91 from a ceramic tile factory and 65 healthcare workers, including hospital doctors, nurses, and nurse assistants. Seventy-three percent of participants (40 women and 74 men) were engaged in nightshift work. We used logistic regression analysis to predict daytime sleepiness and poor sleep quality as a function of personal and lifestyle variables and nightshift work. The female gender showed a strong association with both daytime sleepiness and poor sleep quality. Results were also suggestive of an increase in the risk of daytime sleepiness associated with nightshift work and being married. Our results confirm that women are especially vulnerable to sleep disruption. Promoting adaptation to nightshift work requires special attention towards gender issues.

Shift work disorder, mental health and burnout among nurses: A cross-sectional study

AIM

The aim of the study was to examine the relationships among nurses' shift work disorder, mental health and burnout to inform efforts to alleviate shift work disorder.

DESIGN

This cross-sectional study was conducted in China using a web-based platform for questionnaire.

METHODS

The study was comprised of a convenience sample of 1,268 Registered Nurses from 21 public hospitals in mainland China from June 2019-July 2019. Participants completed a web-based survey designed to collect demographic and other self-reported data. An independent sample t test and Pearson correlation were performed to analyse the relationship between shift work disorder, mental health and burnout.

RESULTS

The vast majority (98.2%) of the participants were women between the ages of 20-59 years. The participants exhibited a higher incidence of mental health problems (58.1%) and burnout (65.5%) and those with shift work disorder exhibited a higher risk of mental health problems and burnout than those who did not have shift work disorder. Our research demonstrated that shift work disorder, combined with other variables, accounted for 40.5% of the variance in mental health (R²  = .405, adjusted R²  = .401, F = 107.214, p < .001) and 36.5% in burnout (R²  = .365, adjusted R²  = .361, F = 90.323, p < .001). Moreover, burnout negatively regulated the relationship between shift work disorder and mental health.

CONCLUSION

High-risk nurses with shift work disorder were at a much higher risk of mental health problems and burnout.

Daytime Sleep-Tracking Performance of Four Commercial Wearable Devices During Unrestricted Home Sleep

Purpose

Previous studies have found that many commercial wearable devices can accurately track sleep-wake patterns in laboratory or home settings. However, nearly all previous studies tested devices under conditions with fixed time in bed (TIB) and during nighttime sleep episodes only. Despite its relevance to shift workers and others with irregular sleep schedules, it is largely unknown how devices track daytime sleep. Therefore, we tested the sleep-tracking performance of four commercial wearable devices during unrestricted home daytime sleep.

Participants and Methods

Participants were 16 healthy young adults (6 men, 10 women; 26.6 ± 4.6 years, mean ± SD) with habitual daytime sleep schedules. Participants slept at home for 1 week under unrestricted conditions (ie, self-selecting TIB) using a set of four commercial wearable devices and completed reference sleep logs. Wearables included the Fatigue Science ReadiBand, Fitbit Inspire HR, Oura Ring, and Polar Vantage V Titan. Daytime sleep episode TIB biases and frequencies of missed and false-positive daytime sleep episodes were examined.

Results

TIB bias was low in general for all devices on most daytime sleep episodes, but some exhibited large biases (eg, >1 h). Total missed daytime sleep episodes were as follows: Fatigue Science: 3.6%; Fitbit: 4.8%; Oura: 6.0%; Polar: 37.3%. Missed episodes occurred most often when TIB was short (eg, naps <4 h).

Conclusion

When daytime sleep episodes were recorded, the devices generally exhibited similar performance for tracking TIB (ie, most episodes had low bias). However, the devices failed to detect some daytime episodes, which occurred most often when TIB was short, but varied across devices (especially Polar, which missed over one-third of episodes). Findings suggest that accurate daytime sleep tracking is largely achievable with commercial wearable devices. However, performance differences for missed recordings suggest that some devices vary in reliability (especially for naps), but improvements could likely be made with changes to algorithm sensitivities.

Neural activation underlying emotional interference of cognitive control in rotating shift workers: moderating effects of the prefrontal cortex response on the association between sleep disturbance and depressive symptoms

Study Objectives

This study investigated the altered neural function involved in emotional interference and its role in linking sleep disturbance and depressive/anxiety symptoms in rotating shift workers.

Methods

Sixty rotating shift workers and 61 controls performed the emotional Stroop task in three blocks (emotional-related, sleep-related, and neutral words) during functional magnetic resonance imaging (fMRI) assessments. Sleep disturbance and depressive/anxiety symptoms were assessed using self-report measures and sleep diaries. Actigraphy was used to assess the sleep and circadian variables. fMRI scans were performed to compare brain activation during the emotional Stroop task. The proposed moderating models were tested using the PROCESS macro in SPSS software.

Results

A significant condition effect on reaction time was detected. Regardless of the group, reaction times were longer in the negative emotional word and sleep-related conditions than in the neutral word condition. Whole-brain analysis revealed that rotating shift workers show greater neural activation in the left dorsolateral prefrontal cortex (DLPFC) compared with controls while performing the emotional Stroop task with negative emotional words. Sleep disturbance was more strongly associated with depressive symptoms when activation of the left DLPFC was higher during the emotional Stroop task with negative words.

Conclusions

The left DLPFC may play important roles in increased sensitivity to emotional information, possibly due to circadian misalignment, and has moderating effects on the association between sleep disturbance and depressive symptoms in rotating shift workers. These findings will help to identify possible brain regions where interventions can be performed to correct sleep and mood problems in rotating shift workers.

Effects of Lighting Interventions to Improve Sleepiness in Night-Shift Workers: A Systematic Review and Meta-Analysis

Shift work disrupts an otherwise normal circadian rhythm, which may result in sleepiness among night-shift workers. Artificial light has been shown to alter the light–dark cycle of shift workers and reset or phase shift the biological clock, improving nighttime alertness in workers. However, the effect of light therapy on improving sleepiness in nighttime workers has not been effectively confirmed in nursing clinical studies, and it is worth using relevant studies to provide the best evidence in any clinical setting. Systematic review and meta-analysis were used. The study was performed using PRISMA. Academic Search Complete, Embase, MEDLINE, the Cochrane Library, and CINAHL were searched, from the inception of each database to 27 December 2021. The Cochrane risk of bias tool was used to assess the methodological quality of each study. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were synthesized using a random-effects model to assess the efficacy of lighting intervention to improve sleepiness in night-shift workers. Sensitivity analysis followed by subgroup analysis was employed to examine heterogeneity. The meta-analysis was performed using Review Manager 5.4.1 software. A total of 14 studies from 7 countries were included. The overall result shows that lighting interventions significantly improved sleepiness. Further, the blue-enriched white light with a color temperature greater than 5000 Kelvin was effective in improving sleepiness of night-shift workers. This study unveils the emergent knowledge that light interventions with blue-enriched white were effective in improving sleepiness for night-shift workers, including nurses. This finding can be applied to ensure patient safety, reduce accidents, and improve work efficiency and job satisfaction. Nurses constitute the largest health professional workforce. We suggest that hospitals can insert blue-enriched white light equipment for night-shift healthcare providers. Several evidence-based suggestions are made for further consideration.

Shift-work sleep disorder among health care workers at public hospitals, the case of Sidama national regional state, Ethiopia: A multicenter cross-sectional study

Introduction

Shift-work disrupts circadian rhythm, resulting in disturbed sleep time and excessive sleepiness during the work shift. Little is known about shift-work sleep disorder among health care workers in Ethiopia. This study examined the magnitude and associated factors of shift-work sleep disorder among health care workers in Public Hospitals in Sidama National Regional State, Southern Ethiopia.

Methods

An institution-based cross-sectional study was carried out on 398 health care workers selected using a systematic random sampling technique. A self-administered structured questionnaire consisting of insomnia, sleepiness scales and international classification of sleep disorder criteria items was employed. Epi data version 4.6 and Stata 14 were used for data entry and statistical analysis respectively. Binary logistic regression was fitted to determine associated factors and decision for the statistical significance was made at p<0.05 in the multivariable binary logistic regression.

Results

Three hundred and ninety-eight health care workers (female = 53%) were included in the analysis with a response rate of 94.8%. The prevalence of shift-work sleep disorder was 33.67% (95% CI: 29.17%-38.45%). Being married (AOR = 1.88 (1.01–3.28)), three-shift (AOR = 1.078 (1.00–3.16)), ≥11 night shifts per month (AOR = 2.44 (1.36–4.38)), missing nap (AOR = 1.85 (1.04–3.30)), daily sleep time < 7hours (AOR = 1.88 (1.05–3.38)), khat chewing (AOR = 2.98 (1.27–8.09)), alcohol drinking (AOR = 2.6(1.45–4.92)), and cigarette smoking (AOR = 3.32 (1.35–8.14)) were significantly associated with shift-work sleep disorder.

Conclusion

This study showed a high prevalence of shift-work sleep disorder. Two shift schedule, napping, and reduction of substance use might reduce shift-work sleep disorder.

Technical, Regulatory, Economic, and Trust Issues Preventing Successful Integration of Sensors into the Mainstream Consumer Wearables Market

Sensors that track physiological biomarkers of health must be successfully incorporated into a fieldable, wearable device if they are to revolutionize the management of remote patient care and preventative medicine. This perspective article discusses logistical considerations that may impede the process of adapting a body-worn laboratory sensor into a commercial-integrated health monitoring system with a focus on examples from sleep tracking technology.

Shift work disorder and the prevalence of help seeking behaviors for sleep concerns in Australia: A descriptive study

Shift work disorder (SWD) is a circadian rhythm sleep-wake disorder, defined by symptoms of insomnia and excessive levels of sleepiness resulting from work that occurs during non-standard hours. Sleep problems are common in shift workers, yet our understanding of help seeking behaviours for sleep in shift workers is limited. The primary aim of this study was to examine the help seeking behaviours of Australian workers who meet criteria for SWD. Of the 448 (46% of sample, n = 964 total) Australian workers reporting non-standard work hours, 10.5% (n = 41) met the criteria for probable shift work disorder (pSWD). Non-standard workers with pSWD did not seek help for sleep problems at higher rates than workers without SWD. Of the small proportion of workers with pSWD who sought help, general practitioners were the most common healthcare professionals for sleep problems. Self-management was common in workers with pSWD, with a high self-reported prevalence of alcohol use (31.7%) as a sleep management strategy, and caffeine consumption (76.9%) as a sleepiness management strategy. The majority of individuals with pSWD reported the mentality of 'accept it and keep going' as a sleepiness management strategy, highlighting a potential barrier to help seeking behaviour in workers with pSWD. These findings provide novel insight into the help seeking behaviours of those with pSWD. There is a need for further research to understand why individuals at risk for SWD are not actively seeking help, and to develop health promotion and intervention strategies to improve help seeking when needed.

Turnover Time Between Elective Operative Cases: Does the Witching Hour Exist for the Operating Room?

BACKGROUND

Efficient resource management in the operating room (OR) contributes significantly to healthcare expenditure and revenue generation for health systems. We aim to assess the influence that surgeon, anesthesiology, and nursing team assignments and time of day have on turnover time (TOT) in the OR.

METHODS

We performed a retrospective review of elective cases at a single academic hospital that were completed between Monday and Friday between the hours of 0700 and 2359 from July 1, 2017, through March 31, 2018. Emergent cases and unplanned, add-on cases were excluded. Data regarding patient characteristics, OR teams, TOT, and procedure start and end times were collected and analyzed.

RESULTS

A total of 2174 total cases across 13 different specialties were included in our study. A multivariate regression of relevant variables affecting TOT was performed. Consecutive specialty (p < 0.0001), consecutive surgeon (p < 0.0001), anesthesiologist (p < 0.0001), and prior case ending before 1400 (p < 0.0001) were independent predictors of lower TOT. A receiver operating characteristic analysis demonstrated an area under the curve of 0.848 and a cutoff of 1400 having the highest sensitivity and specificity for TOT difference.

CONCLUSIONS

TOT can be significantly affected by the time of the day the procedure is performed. Staffing availability during late procedures and the differences in how OR team staff are scheduled may affect OR efficiency. Additional studies may be needed to determine the long-term implications of changes implemented to decrease organizational operational costs related to the OR.

Predictors of Shift Work Sleep Disorder Among Nurses During the COVID-19 Pandemic: A Multicenter Cross-Sectional Study

Background: Nurses have a high incidence of shift work sleep disorder, which places their health and patient safety in danger. Thus, exploring the factors associated with shift work sleep disorder in nurses is of great significance in improving their sleep health, nursing personnel staffing, and scheduling during the COVID-19 pandemic.

Objectives: The purpose of this study was to investigate the incidence of shift work sleep disorder during the COVID-19 pandemic and explore the factors associated with shift work sleep disorder in Chinese nurses.

Methods: This was a multicenter cross-sectional study using an online survey. Stratified cluster sampling was used to include 4,275 nurses from 14 hospitals in Shandong, China from December 2020 to June 2021. Stepwise multivariate logistic regression analysis and random forest were used to identify the factors associated with shift work sleep disorder.

Results: The prevalence of shift work sleep disorder in the sampled shift nurses was 48.5% during the COVID-19 pandemic. Physical fatigue, psychological stress, shift work more than 6 months per year, busyness during night shift, working more than 40 h per week, working more than four night shifts per month, sleeping more than 8 h before night shift, using sleep medication, irregular meals, and high-intensity physical activity were associated with increased odds of shift work sleep disorder. Good social support, good work-family balance, napping two or three times per week, resting more than one day after shifts, intervals of 8 days or more between shifts, and taking turns to rest during the night shift were associated with decreased odds of shift work sleep disorder.

Conclusions: Shift work sleep disorder may be associated with scheduling strategies and personal behavior during the COVID-19 pandemic. To reduce the incidence of shift work sleep disorders in nurses, nursing managers should increase night shift staffing, extend rest days after shift, increase night shift spacing, and reduce overtime, and nurses need to seek more family and social support and control their sleep schedules and diet.

Shift work tolerance

BACKGROUND

Shift work is widespread due to 24-h work in many occupations. Understanding differences in individual shift work tolerance (SWT) can help develop coping strategies for shift workers.

AIMS

This in-depth qualitative review elucidates the architecture of SWT, providing an overview of the research advances in the last decade (2011-2021).

METHODS

We searched Google Scholar, PubMed and Medline for different word combinations concerning SWT. Genome-wide association studies (GWAS) for the potential genetic basis of SWT were additionally searched in GWAS Central and GWAS Catalogue.

RESULTS

Eleven new studies were published since 2011, with the proportion of longitudinal studies on SWT having more than doubled in the past decade. They consolidate prior findings (e.g. hardiness most consistently associated with SWT) and discovered additional aspects of SWT like resistance to change and job stress. The 15 large-scale GWAS identified, most of which using UK Biobank (UKB) and 23andMe data, involved mapped genes showing overlap especially within analysis of the same phenotype (e.g. PER2/3 for morningness, PAX8 for sleep duration and LINGO1 for neuroticism). Individual GWAS for additional traits such as resilience have also been published though assessments of gene overlap are not yet possible.

CONCLUSIONS

Progress regarding longitudinal studies on SWT has been made though a more consistent definition of SWT remains crucial for future research. Non-genetic studies on SWT suggest several important traits and factors; many of which have now also been explored using GWAS. Such evidence could serve as basis for individualized risk prediction and disease prevention approaches for night-shift workers.

Shift rotation scheme, sleepiness and sleep quality in night-shift workers

BACKGROUND

Shift rotation schemes can influence workers' tolerance of night-shift work and its impact on health.

AIMS

This study was aimed to assess the influence of shift work rotation schemes on sleepiness and sleep quality.

METHODS

We conducted a cross-sectional study of 145 male workers, 77 from a ceramic tile factory on a fixed, forward-rotating shift work scheme, and 68 from a dockyard company, working on-call night shifts. Participants self-administered the Epworth Sleepiness Scale (ESS) and the Pittsburgh Sleep Quality Index (PSQI) questionnaires and provided data on demographic and lifestyle variables. We set two logistic regression models to predict the risk of daytime sleepiness and poor sleep quality as a function of night-shift work and on-call night shifts, adjusting for personal and lifestyle covariates.

RESULTS

Marital status, body mass index, smoking and alcohol intake did not affect ESS and PSQI scores, nor did they differ between the two cohorts. Night-shift workers from both cohorts were more likely to have a PSQI score ≥6, suggestive of poor sleep quality, with no variation between the two cohorts. ESS scores suggestive of daytime sleepiness were strongly associated with on-call night shifts among dockyard workers for (odds ratio = 13.4; 95% confidence interval 2.9-63.9), in respect the regular, forward-rotating night-shift work among ceramic tile factory workers.

DISCUSSION

Daytime sleepiness occurred more frequently among dockyard workers working on-call night shifts. Poor sleep quality occurred more frequently among night-shift workers, but it did not differ between the two companies.

Should We Re-think Regulations and Standards for Lighting at Workplaces? A Practice Review on Existing Lighting Recommendations

Nowadays lighting projects often include temporal variations of the light, both spectrally and in terms of intensity to consider non-visual effects of light on people. However, as of today there are no specific regulations. Compliance with common lighting standards that address visual aspects of light, often means that only little non-visually effective light reaches the eye. In this practice review we confront existing regulations and standards on visual lighting aspects with new recommendations on non-visual aspects and highlight conflicts among them. We conclude with lighting recommendations that address both aspects.

Association of Sleep Duration and Working Hours with Suicidal Ideation in Shift Workers: The Korean National Health and Nutrition Examination Survey 2007-2018

OBJECTIVE

This study investigated whether sleep duration and working hours were associated with the risk of suicidal ideation.

METHODS

Data from 13,628 shift workers (age ≥19) were obtained from the nationwide cross-sectional Korea National Health and Nutrition Examination Surveys conducted in 2007-2018. We included healthy shift workers without depressive disorders and chronic medical illnesses. Sleep duration, working hours, and suicidal ideation were assessed using a self-reported questionnaire. Logistic regressions were used to examine the association of sleep duration and working hours with the risk of suicidal ideation. We examined interactions between sleep duration and working hours in association with suicidal ideation. In addition, interactions of sex or age were also analyzed.

RESULTS

Shift workers sleeping for <6 and ≥10 hours/day were associated with suicidal ideation compared with those sleeping for 7 to <9 hours/day. Individuals working >52 hours/week had a higher risk of suicidal ideation compared with those working ≤40 hours/week. In terms of interaction by sex or age groups in the association between working hours and the risk of suicidal ideation, the relationship was stronger for men than for women and for those aged <45 years than for those aged ≥45 years.

CONCLUSION

Shorter or longer sleep durations, and long working hours were associated with a higher risk of suicidal ideation. Under long working hours, male shift workers or those aged <45 years were more vulnerable to suicidal ideation.

The prevalence of male rotating shift work correlates with reduced total fertility rate: an ecological study of 54,734 reproductive-aged males in 35 European countries between 2000 and 2015

Europe has the lowest fertility rate in the world, and 19 European countries are already experiencing negative population growth. Previous studies have shown that light-dark cycle misalignment induces damages to semen quality in animals, but whether shift work impairs male human fertility remains controversial. The diverse types of shift work, which may have distinct health impacts, have not been differentiated in the few previous studies. The present study aims to assess the impact of different male shift work types, i.e., rotating shift work (RSW), permanent shift work (PSW), and daily split shifts (DSS), on male fertility in European countries, based on the European Working Conditions Survey of 54,734 men and 52,457 women of reproductive (15-49 years) age from 35 countries conducted between 2000 and 2015. Year-specific total fertility rate (TFR) for each country was obtained from the World Bank. Mixed linear model was used to analyze the association between the prevalence of shift work types and TFR among the countries during the 15 years span, with adjustment for latitude, per capita GDP, working duration, working frequency, median age of men or women engaged in shift work, education level of men or women, and female shift-work condition in reproductive aged participants. The results showed that the average prevalence of RSW declined from 15.6% in 2000 to 9.8% in 2010, and then rose to 11.1% by 2015, while TFR went up from 1.45 in 2000 to 1.60 in 2010, and then decreased to 1.56 in 2015. A 10% increase of RSW prevalence was associated with a 0.114 decrease of TFR (95% CI: -0.167, -0.061, P < .001), indicating 11.4 fewer births per 100 women throughout lifetime. The association remained significant (β = -0.088, 95% CI: -0.160, -0.015, P = .020) after adjusting for confounding factors. However, no association was observed between TFR and the prevalence of male PSW (β = -0.011, 95% CI: -0.094, 0.073, P = .801) or DSS (β = 0.357, 95% CI: -0.171, 0.884, P = .189). In conclusion, male RSW, rather than PSW and DSS, may reduce TFR. Further studies are needed to validate our findings.

Circadian clocks in the digestive system

Many molecular, physiological and behavioural processes display distinct 24-hour rhythms that are directed by the circadian system. The master clock, located in the suprachiasmatic nucleus region of the hypothalamus, is synchronized or entrained by the light-dark cycle and, in turn, synchronizes clocks present in peripheral tissues and organs. Other environmental cues, most importantly feeding time, also synchronize peripheral clocks. In this way, the circadian system can prepare the body for predictable environmental changes such as the availability of nutrients during the normal feeding period. This Review summarizes existing knowledge about the diurnal regulation of gastrointestinal processes by circadian clocks present in the digestive tract and its accessory organs. The circadian control of gastrointestinal digestion, motility, hormones and barrier function as well as of the gut microbiota are discussed. An overview is given of the interplay between different circadian clocks in the digestive system that regulate glucose homeostasis and lipid and bile acid metabolism. Additionally, the bidirectional interaction between the master clock and peripheral clocks in the digestive system, encompassing different entraining factors, is described. Finally, the possible behavioural adjustments or pharmacological strategies for the prevention and treatment of the adverse effects of chronodisruption are outlined.

Changes in work schedule affect the prevalence of shift work disorder among Norwegian nurses - a two year follow-up study

This study aimed to explore how changes in the work schedule would affect the prevalence of Shift Work Disorder (SWD) over time. Two-year follow-up data from 1076 nurses participating in the longitudinal SUrvey of Shift work, Sleep and Health among Norwegian nurses (SUSSH) were included in the study. The questionnaires included measures of work-related factors, i.e., work schedule and numbers of night shifts and quick returns (QRs) worked the last year, as well as questions related to SWD according to the ICSD-3 diagnostic criteria at both baseline and at 2-year follow-up. Data were analyzed with paired samples t-tests, chi-square tests, and logistic regression analyses adjusting for sex and age. Terminating night work was the strongest predictor for recovering from SWD from baseline to follow-up (OR 10.91, 95% CI 6.11-19.46). Additionally, changing the work schedule from day work to night work from baseline to follow-up was the strongest predictor for developing SWD in the same period (OR 4.75, 95% CI 2.39-9.47). Reductions in number of nights (more than 10) and QRs (more than 10) worked the last year were associated with recovering from SWD between baseline and follow-up. Nurses who recovered from SWD had significantly reduced the mean number of night shifts worked the last year from 32.3 at baseline to 20.4 at follow-up (p = .001). Furthermore, an increase of more than 10 nights or more than 10 QRs worked the last year between baseline and follow-up predicted developing SWD. Nurses developing SWD between baseline and follow-up had significantly increased the mean number of nights worked the last year from 25.8 at baseline to 31.0 at follow-up (p =-.043). Changes in night work exposure were the strongest predictors for both recovering from or developing SWD from baseline to follow-up. Reducing exposure to night work and QRs were associated with recovering from SWD and increasing exposure to night work and QRs were associated with developing SWD. The results imply that unfavorable work schedules play a role in the development of sleep problems among nurses. These results may be useful when designing healthy working schedules.

Blue light insertion at night is involved in sleep and arousal-promoting response delays and depressive-like emotion in mice

Light plays a direct crucial role in the switch between sleep and arousal and the regulation of physiology and behaviour, such as circadian rhythms and emotional change. Artificial lights, which are different from natural light sources with a continuous light spectrum, are composed of three single-colour lights and are increasingly applied in modern society. However, in vivo research on the mechanisms of blue light-regulated sleep and arousal is still insufficient. In this work, we detected the effects of inserting white or blue light for 1 h during the dark period on the wheel-running activity and sucrose preference of C57 mice. The results showed that blue light could induce delays in sleep and arousal-promoting responses. Furthermore, this lighting pattern, including blue light alone, induced depressive-like emotions. The c-fos expression in the blue light group was significantly higher in the arcuate hypothalamic nucleus (Arc) and significantly lower in the cingulate cortex (Cg) and anterior part of the paraventricular thalamic nucleus (PVA) than in the white light group. Compared with the white light group, the phospho-ERK expression in the paraventricular hypothalamic nucleus (PVN) and PVA was lower in the blue light group. These molecular changes indicated that certain brain regions are involved in blue light-induced response processes. This study may provide useful information to explore the specific mechanism of special light-regulated physiological function.

Predicting circadian misalignment with wearable technology: validation of wrist-worn actigraphy and photometry in night shift workers

STUDY OBJECTIVES

A critical barrier to successful treatment of circadian misalignment in shift workers is determining circadian phase in a clinical or field setting. Light and movement data collected passively from wrist actigraphy can generate predictions of circadian phase via mathematical models; however, these models have largely been tested in non-shift working adults. This study tested the feasibility and accuracy of actigraphy in predicting dim light melatonin onset (DLMO) in fixed night shift workers.

METHODS

A sample of 45 night shift workers wore wrist actigraphs before completing DLMO in the laboratory (17.0 days ± 10.3 SD). DLMO was assessed via 24 hourly saliva samples in dim light (<10 lux). Data from actigraphy were provided as input to a mathematical model to generate predictions of circadian phase. Agreement was assessed and compared to average sleep timing on non-workdays as a proxy of DLMO. Model code and an open-source prototype assessment tool are available (www.predictDLMO.com).

RESULTS

Model predictions of DLMO showed good concordance with in-lab DLMO, with Lin's concordance coefficient of 0.70, which was twice as high as agreement using average sleep timing as a proxy of DLMO. The absolute mean error of the predictions was 2.88 h, with 76% and 91% of the predictions falling with 2 and 4 h, respectively.

CONCLUSION

This study is the first to demonstrate the use of wrist actigraphy-based estimates of circadian phase as a clinically useful and valid alternative to in-lab measurement of DLMO in fixed night shift workers. Future research should explore how additional predictors may impact accuracy.

Clocks, cancer, and chronochemotherapy

The circadian clock coordinates daily rhythmicity of biochemical, physiologic, and behavioral functions in humans. Gene expression, cell division, and DNA repair are modulated by the clock, which gives rise to the hypothesis that clock dysfunction may predispose individuals to cancer. Although the results of many epidemiologic and animal studies are consistent with there being a role for the clock in the genesis and progression of tumors, available data are insufficient to conclude that clock disruption is generally carcinogenic. Similarly, studies have suggested a circadian time-dependent efficacy of chemotherapy, but clinical trials of chronochemotherapy have not demonstrated improved outcomes compared with conventional regimens. Future hypothesis-driven and discovery-oriented research should focus on specific interactions between clock components and carcinogenic mechanisms to realize the full clinical potential of the relationship between clocks and cancer.

Study for the Design of a Protocol to Assess the Impact of Stress in the Quality of Life of Workers

(1) Background: Work stress is one of the most relevant issues in public health. It has a significant impact on health, especially the development of mental disorders, causing occupational imbalance. There is a growing interest in the development of tools with a positive effect on workers. To this end, wearable technology is becoming increasingly popular, as it measures biometric variables like heartbeat, activity, and sleep. This information may be used to assess the stress a person is suffering, which could allow the development of stress coping strategies, both at a professional and personal level. (2) Methods: This paper describes an observational, analytical, and longitudinal study which will be set at a research center in A Coruña, Spain. Various scales and questionnaires will be filled in by the participants throughout the study. For the statistical analysis, specific methods will be used to evaluate the association between numerical and categorical variables. (3) Discussion: This study will lay the foundation for a bigger, more complete study to assess occupational stress in different work environments. This will allow us to begin to understand how occupational stress influences daily life activity and occupational balance, which could directly enhance the quality of life of workers if the necessary measures are taken.

Work-Fitness Evaluation for Shift Work Disorder

Shift work disorder (SWD), which is characterized by insomnia and excessive sleepiness related with shift work, is one of the most common health problems in shift workers. Shift work disorder causes insomnia, fatigue, worse work performance, an increased likelihood of accidents, and a poor quality of life. In addition, SWD is associated with decreased productivity and increased economic costs. The correct management of SWD is important to prevent sleep disturbances and maintain work performance in shift workers. To diagnose and evaluate SWD, it is necessary to take detailed medical histories, assess the severity of sleep disturbances, and evaluate shift workers’ sleep using a sleep diary and actigraphy. The work-fitness evaluation should include recommendations on how shift workers can reduce their sleep disturbances and increase work performance, as well as the assessment of work performance. This paper reviews previous research on the evaluation, diagnosis, and management of SWD and summarizes the work-fitness evaluation of SWD.

A systematic review and meta-analysis of the association between shift work and metabolic syndrome: The roles of sleep, gender, and type of shift work

This study was conducted to investigate the association between shift work and metabolic syndrome (MetS) and quantify the roles of sleep, gender, and type of shift work. We searched online databases, including PubMed, Scopus, and Web of Science on November 17, 2019. Of the 821 articles identified, 38 observational studies (27 cross-sectional, 10 cohorts, and one nested case-control), conducted on 128,416 participants, met our eligibility criteria. The pooled Odds ratio (OR) and 95% Confidence interval (CI) of MetS in shift-versus day-workers were estimated as 1.14 (1.07, 1.21) and 1.11 (1.06, 1.17) for the unadjusted and adjusted models. This association remained significant only for the studies with a cross-sectional design. There was a significantly higher odds of MetS in the studies conducted only on females (1.13 [1.06, 1.20]) or males (1.12 [1.02, 1.21]). The pooled adjusted OR (95% CI) for the studies without and with sleep adjustment was calculated as 1.14 (1.08, 1.21) and 1.29 (1.06, 1.52). We observed that rotating shift workers had stronger odds of MetS than the other shift workers. In conclusion, our findings revealed the significant odds of an association between shift work and MetS and different effects for sleep, gender, and type of shift work.

Circadian Deregulation as Possible New Player in Pollution-Induced Tissue Damage

Circadian rhythms are 24-h oscillations driven by a hypothalamic master oscillator that entrains peripheral clocks in almost all cells, tissues and organs. Circadian misalignment, triggered by industrialization and modern lifestyles, has been linked to several pathological conditions, with possible impairment of the quality or even the very existence of life. Living organisms are continuously exposed to air pollutants, and among them, ozone or particulate matters (PMs) are considered to be among the most toxic to human health. In particular, exposure to environmental stressors may result not only in pulmonary and cardiovascular diseases, but, as it has been demonstrated in the last two decades, the skin can also be affected by pollution. In this context, we hypothesize that chronodistruption can exacerbate cell vulnerability to exogenous damaging agents, and we suggest a possible common mechanism of action in deregulation of the homeostasis of the pulmonary, cardiovascular and cutaneous tissues and in its involvement in the development of pathological conditions.

Attention Performance Correlated With White Matter Structural Brain Networks in Shift Work Disorder

Neuroimaging studies have revealed that shift work disorder (SWD) affected the functional connectivity in specific brain regions and networks. However, topological disruptions in the structural connectivity of the white matter (WM) networks associated with attention function remain poorly understood. In the current study, we recruited 33 patients with SWD and 29 matched healthy subjects. The attention network test (ANT) was employed to investigate the efficiency of alerting, orienting, and executive control networks. The diffusion tensor imaging (DTI) tractography was used to construct the WM structural networks. The graph theory analysis was applied to detect the alterations of topological properties of structural networks. Our results showed lower alerting effect and higher executive effect for patients with SWD. Using the link-based analysis, 15 altered connectivity matrices (lower fiber numbers) were found between the two groups. Meanwhile, the graph theoretical analysis showed that the global efficiency and characteristic path length within SWD patients declined in contrast with the healthy controls. Furthermore, a significantly negative correlation was found between the executive effect and global network efficiency. Our findings provide the new insights into the fundamental architecture of interregional structural connectivity underlying attention deficits in SWD, which may be a potential biomarker for SWD.

The fMRI study for acupuncture on shift work sleep disorder: Study protocol for a randomized controlled neuroimaging trial

INTRODUCTION

Nearly 20% of night shift nurses will cause shift work disorder (SWD) due to the disruption of sleep-wake cycle, which not only affects the daily work efficiency, but also brings a huge burden on physical and mental health. Acupuncture is a safe and effective intervention on SWD. This trial will combine with functional magnetic resonance imaging (fMRI) to study the clinical effects and potential mechanism of acupuncture in the treatment of SWD.

METHODS AND ANALYSIS

This is a randomized controlled neuroimaging trial, with enrolled participants, outcome assessors, and data statisticians blinded. 60 patients with SWD and 30 healthy controls who sleep regularly will be recruited and divided into divided into a control group, a true acupoints treatment group (TATG) and a sham acupoints treatment group (SATG) by the ratio of 1:1:1. The TATG and SATG will receive 8 sessions of acupuncture treatment in 4 weeks. Cognitive function scales and MRI scanning will be performed before and after 4-week acupuncture treatment. The control group will receive no intervention. Functional connectivity of intra-network and inter-network will be the primary outcome and effect indicator. The secondary outcomes included Repeatable Battery for the Assessment of Neuropsychological Status, Attentional Network Test, Pittsburgh Sleep Quality Index scale and needle sensation assessment scale. Neuroimage indicators will be correlated with clinical data and scores of cognitive function assessment to explore the possible mechanisms underlying the changes of brain activity caused by acupuncture treatment.

DISCUSSION

The results of this study will enable us to verify the therapeutic effect of acupuncture on SWD and explore the potential central mechanism of acupuncture on SWD from the change of brain activity.

Assessing Cognitive Abilities of Patients With Shift Work Disorder: Insights From RBANS and Granger Causality Connections Among Resting-State Networks

BACKGROUND

Numerous studies have confirmed that long-term shift work is not only associated with increased health problems and acute impact on safety but also with impaired cognitive abilities. However, very little is known about effects of shift work on cognition-related brain resting-state networks. The aim of this study was to explore the effects of shift work disorder (SWD) on granger causality connection among resting-state brain networks.

METHODS

Thirty patients with SWD and 25 matched healthy subjects were recruited to undergo the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and resting-state fMRI scanning. We employed independent component analysis (ICA) to extract resting-state brain networks and granger causality analysis (GCA) to characterize the difference of granger causality connection among cognition-related resting-state brain networks.

RESULTS

Compared with healthy subjects, patients with SWD showed impairments on the attention and immediate memory. Seven resting-state brain networks were identified, and patients with SWD showed more numerous granger causality connections in comparison with healthy subjects. Two-sample t test results showed that there were significantly increased inflows from the anterior default mode network (aDMN) to sensorimotor network (SMN) and left frontoparietal network (LFPN) to salience network (SN). Correlation analyses showed that the increased inflows from aDMN to SMN were negatively associated with the score of attention, while LFPN to SN were negatively associated with the score of visuospatial/constructional ability.

CONCLUSIONS

This study indicates that SWD impairs cognitive performance, and the specific intrinsic brain granger causality connectivity among resting-state networks in SWD patients is affected after long-term shift works.