Sleep patterns among shift-working flight controllers of the International Space Station: an observational study on the JAXA Flight Control Team

Shift Work Sleep Disorder and Mental Health: An Integrative Review of Neurobiological, Sociological, and Psychological Perspectives With Public Policy Implications

Shift workers support critical 24-hr operations; their health can be impaired by disrupted circadian rhythms and dysfunctional sleep. Shift work sleep disorder (SWSD) is a prevalent condition with significant psychological consequences. Nurse leaders have not yet implemented effective policies to prevent SWSD and optimize shift workers' mental health. The purpose of this integrative review was to examine research about SWSD within the context of neurobiological, sociological, and psychological perspectives that can inform policy changes. The Centers for Disease Control and Prevention Policy Analytic Framework was used to determine the priority recommendations. A search of three databases provided 19 research articles about SWSD and mental health, which illustrated how SWSD is common around the world in many occupations. Backward-rotating schedules and quick returns were risk factors for SWSD. In addition, SWSD was associated with circadian languidity, sleep reactivity, depressive symptoms, and anxiety. Collectively, the studies lacked objective measures of sleep and circadian rhythms, which has hindered the ability to devise interventions that will target the neurobiological causes of SWSD. The research also lacked attention to important sociological factors, such as workers' pay and benefits. Using these findings, nurse leaders can contribute to public policy reforms that increase funding for more rigorous SWSD research. Lawmakers should be advised by nurse leaders to enforce new regulations that provide incentives for employers to create healthier workplaces, such as prohibiting the overuse of schedules that make employees vulnerable to SWSD and providing funds for interventions to prevent SWSD and support mental health.

Influence of Shift Work on The Health of Nursing Professionals

Shift work is increasingly common in health services, subjecting healthcare professionals to work schedules that can alter circadian rhythms and eating habits with consequent repercussions for the intestinal homeostasis. The objective of this study was to describe the relationship of rotating work shifts with the intestinal health, sleep quality, and emotional dimension of nursing professionals. In March and May 2019, an observational and comparative study was conducted among 380 nursing professionals from different Spanish cities and divided into fixed shift (n = 159) and rotating shift (n = 221). To carry out the present work, the variables measured were gastrointestinal symptoms, stool consistency and shape, anxiety, depression, sleep, as well as stress and work environment. Nurses with rotating shifts reported more abdominal pain and symptoms of depersonalization, as well as worse sleep efficiency and worse nursing practice environment. In addition, overall scores of the Gastrointestinal Symptom Rating Scale and Hospital Anxiety and Depression Scale were found to be significantly worse in nurses with these shifts. Rotating shift work by nursing staff may be associated with the occurrence of gastrointestinal and anxiety-related symptoms. These findings, together with the presence of negative and insensitive attitudes towards patients by nurses on rotating shifts, should be considered to maintain the quality of healthcare.

Sleep and Actigraphy Research Trends: A Bibliometric and Keyword Network Analysis From 2004 to 2020

Background and Objective As sleep is a predictor of quality of life, studying sleep health and measurement is important. Actigraphy as a physiologic measure based on monitoring an individual’s movement has also been increasing in use as it has several advantages over traditional self-reports. This study aimed to report the research trends of sleep and actigraphy using a bibliometric and keyword analysis.Methods Using topic search queries, this study collected data from 3955 publications published between 2004 and 2020 and listed in the Web of Science Core Collection. A text-mining unstructured data analysis was performed using author keywords and a bibliographic analysis.Results Studies on sleep and actigraphy have been actively conducted in the fields of neurosciences and neurology but not in other fields. A gradual increase in publication and the steep increase in citations related to this topic occurring during the period considered. By clustering the author keywords, the analysis revealed five clusters: 1) monitoring physical activity and blood pressure, 2) measuring sleep quality, 3) insomnia and cognitive behavioral therapy for adolescents and children, 4) disorders and circadian rhythms, and 5) shift work. The leading research cluster has changed over the time.Conclusions With the increase in the number of studies and citations on sleep and actigraphy over the past 16 years, the trend of sleep and actigraphy studies have shifted from a focus on sleeprelated psychiatric disorders to a focus on cognitive behavioral therapy for children and adolescents and, more recently, the measurement of sleep quality.

Fundamental Biological Features of Spaceflight: Advancing the Field to Enable Deep-Space Exploration

Research on astronaut health and model organisms have revealed six features of spaceflight biology that guide our current understanding of fundamental molecular changes that occur during space travel. The features include oxidative stress, DNA damage, mitochondrial dysregulation, epigenetic changes (including gene regulation), telomere length alterations, and microbiome shifts. Here we review the known hazards of human spaceflight, how spaceflight affects living systems through these six fundamental features, and the associated health risks of space exploration. We also discuss the essential issues related to the health and safety of astronauts involved in future missions, especially planned long-duration and Martian missions.

The circadian rhythm and core gene Period2 regulate the chemotherapy effect and multidrug resistance of ovarian cancer through the PI3K signaling pathway

Background: Ovarian cancer is the most lethal cancer in the female reproductive system. It has been shown that ‘time chemotherapy’ of ovarian cancer has an important impact on the chemotherapy effect and prognosis of patients, but the specific mechanism is not known. Methods: We designed a case–control study in strict accordance with epidemiological principles. We collected resection samples of ovarian cancer patients who worked night-shifts and those who did not, and analyzed the differences in protein expression. Through construction of a normal/circadian-rhythm disorder model of ovarian cancer in nude mice, we explored the molecular mechanism of a ‘biological clock’ rhythm on treatment of ovarian cancer. Results: Expression of interleukin (IL)-6, programmed cell death receptor-1 (PD-1) and programmed death ligand 1 (PD-L1) increased, and expression of tumor necrosis factor (TNF)-α, Period 1 (Per1) and Period 2 (Per2) decreased in the night-shift group. Methylation of CpG islands in the promoter of Per2 could result in its decreased expression in SKOV3/DDP (Cisplatin) cells. Dysrhythmia of the circadian clock: (i) had a negative effect on the chemotherapy effect against ovarian cancer; (ii) affected expression of immune factors and the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) signaling pathway. Conclusion: The Per2 gene can affect the drug resistance of ovarian cancer by inhibiting the PI3K/Akt signaling pathway and then acting on its downstream drug-resistance factors, thereby providing a new target for ovarian cancer treatment.

Prevalence of Shift Work Disorder: A Systematic Review and Meta-Analysis

Objectives: No systematic review or meta-analysis concerning the prevalence of shift work disorder (SWD) has been conducted so far. The aim was thus to review prevalence studies of SWD, to calculate an overall prevalence by a random effects meta-analysis approach and investigate correlates of SWD prevalence using a random-effects meta-regression.

Methods: Systematic searches were conducted in ISI Web of Science, PsycNET, PubMed, and Google Scholar using the search terms “shift work disorder” and “shift work sleep disorder.” No restrictions in terms of time frame were used. Included studies had to present original data on the prevalence of SWD in an occupational sample published in English. A total of 349 unique hits were made. In all, 29 studies were finally included from which two authors independently extracted data using predefined data fields. The meta-regression included four predictors (diagnostic criteria, study country, type of workers, and sample size).

Results: The overall prevalence of SWD was 26.5% (95% confidence interval = 21.0–32.8). Cochran Q was 1,845.4 (df = 28, p < 0.001), and the I² was 98.5%, indicating very high heterogeneity across the observed prevalence estimates. Diagnostic criteria (International Classification of Sleep Disorders-2 = 0, International Classification of Sleep Disorders-3 = 1) and sample size were inversely related to SWD prevalence.

Conclusions: The prevalence of SWD was high across the included studies. The between-study disparity was large and was partly explained by diagnostic criteria and sample size. In order to facilitate comparative research on SWD, there is a need for validation and standardization of assessment methodology as well as agreement in terms of sample restrictions.

Meta-analysis of differences in sleep quality based on actigraphs between day and night shift workers and the moderating effect of age

OBJECTIVES

This study was to conduct a meta-analysis of studies that used actigraphs to compare the influence of day and night shifts on the sleep quality of workers as well as examine the moderating effect of age.

METHODS

Databases including PubMed, CINAHL, the Cochrane Library, MEDLINE, and EBSCOhost were searched for relevant studies published in English between January 1st, 2000 and April 30st, 2021. Our main targets were studies that used actigraphs to assess the sleep quality of night shift workers. This meta-analysis included 12 papers and was performed using Comprehensive Meta-Analysis (CMA) Version 3.0. Effect sizes were displayed in a forest plot using standardized mean difference (SMD) and 95% confidence intervals (CI).

RESULTS

Among the sleep quality indices of the day and night shift workers, no significant difference existed in terms of sleep efficiency (SE) (SMD = 0.27, 95% CI: -0.03-0.57), whereas night shift workers presented longer sleep-onset latency (SOL) (SMD = 0.62, 95% CI: 0.15-1.08), greater wake after sleep onset (WASO) (SMD = 0.41, 95% CI: 0.12-0.70), and longer total sleep time (TST) (SMD = 0.85, 95% CI: 0.32-1.39) than did day shift workers. The differences between the day and night shift workers in SOL, WASO, and TST did not vary with age.

CONCLUSIONS

Among the sleep quality indices, night shift workers presented longer SOL and greater WASO than did day shift workers. However, night shift workers could regulate their rest time and had adequate TST; thus, their SE was not different from that of day shift workers.

Work and sleep quality in railway employees: an actigraphy study

This actigraphy study tests whether daily work stressors (time pressure, social stressors), work resources (control, social support) and mental detachment from work predict sleep quality, when controlling for demands and control after work. Fifty-two railway employees participated during five consecutive workdays by completing diary questionnaires and wearing an actigraphy device. The results confirmed that social stressors from supervisors predicted more frequent sleep fragmentation and lower sleep efficiency the following night. Higher levels of daily time control at work predicted shorter sleep-onset latency and better self-reported sleep quality. Leisure time control as a covariate turned out to be a private resource, followed by fewer awakenings the following night. Detachment after work related negatively to social stressors and time pressure at work but was unrelated to indicators of sleep quality; detachment after work neither mediated nor moderated the relationship between social stressors from supervisors and sleep quality. Work redesign to increase time control and reduce social stressors is recommended to preserve daily recovery in railway employees. Practitioner summary: Sleep is important to renew health- and safety-related resources in railway employees. This diary and actigraphy study shows that higher daily work stressors were antecedents of lower sleep quality the following night, while more time control was followed by better sleep quality. Work redesign could promote health and safety by improving sleep quality.