Physical activity patterns, sleep quality, and stress levels among rotating-shift nurses during the COVID-19 pandemic.

AIM: To examine the associations between physical activity patterns, sleep quality, and stress levels among rotating-shift nurses during the COVID-19 pandemic. BACKGROUND: Stress adversely impacts hospital nurses, particularly those on rotating shifts. The effects of physical activity patterns and sleep quality on the stress levels of these nurses during the COVID-19 pandemic warrant investigation. METHODS: A multicenter cross-sectional study was conducted with 550 eligible registered hospital nurses, randomly selected from four hospitals during the COVID-19 pandemic in Taiwan. The work schedule type of these nurses was categorized into rotating shifts (working at least two shifts in a month, involving day, evening, and night shifts) or fixed-day shifts (working only the day shift). Data were collected on sociodemographic characteristics, physical activity patterns (sedentary or active), sleep quality (poor or adequate), and stress levels for analysis. RESULTS: Rotating-shift nurses with active physical activity patterns exhibited lower stress levels compared with those with sedentary patterns. Nurses who experienced adequate sleep quality had lower stress levels compared with those with poor sleep quality among rotating and fixed-day shift nurses. CONCLUSIONS: Active physical activity patterns and adequate sleep quality were associated with lower stress levels among rotating-shift nurses during the pandemic. Promoting active physical activity and enhancing sleep quality are essential strategies for reducing stress in these nurses. IMPLICATIONS FOR NURSING AND HEALTH POLICY: Strategies aimed at promoting physical activity and improving sleep quality should be integral components of health promotion programs and policymaking efforts directed at nursing leaders, to foster a healthy and supportive work environment and enhance the welfare of rotating-shift hospital nurses. REPORTING METHOD: The study is reported using the statement of Strengthening the Reporting of Observational Studies in Epidemiology (STROBE).

Independent and joint trajectories of depression and anxiety symptoms among Chinese male sailors throughout a prolonged non-24-h rotating shift schedule at sea: a parallel-process growth mixture modeling approach.

BACKGROUND: The predictive and protective effect of hardiness on mental health remains unclear among shift workers on non-24-h working schedules. The present study aimed to investigate the independent and joint trajectories of depression and anxiety symptoms and the role of hardiness during a prolonged period of non-24-h shift working schedule. METHODS: Four hundred nine Chinese male sailors (working on 18-h watchstanding schedule) were recruited and completed all 5-wave tests through online questionnaires (at Day 1, 14, 28, 42, 55, respectively) during a 55-day sailing. The questionnaires included sociodemographic variables, hardiness, depression and anxiety symptoms. Independent and joint trajectories of depression and anxiety symptoms were estimated by latent growth mixture models. The effect of hardiness on trajectories was examined by logistic regression models. RESULTS: 2 and 3 latent trajectories were identified for depression and anxiety symptoms, respectively. Based on initial levels and development trends, 3 distinct joint trajectories of depression and anxiety were identifed and named as: "Low-Inverted U" group (73.6%), "Moderate-Deterioration" group (6.9%), and "High-Stable" group (9.5%). Sailors with higher levels of hardiness were more likely to follow the "Low-Inverted U" trajectory of depression and anxiety symptoms (all p < 0.001). CONCLUSIONS: There existed individual differences in the trajectories of depression and anxiety. Hardiness may have a protective effect that can prevent and alleviate depression and anxiety symptoms. Therefore, hardiness-based intervention programs are encouraged among the shift workers on non-24-h working and rest schedules.

Association of breakfast skipping with habitual dietary intake and BMI in female rotating shift workers.

OBJECTIVE: Higher BMI, lower quality of diet and a higher percentage of breakfast-skippers have been reported among rotating shift (RS) workers compared with day shift (DS) workers. As such, this study examined the association between breakfast skipping, habitual food consumption and BMI in RS workers. DESIGN: Japanese nurses were studied using a self-administered questionnaire that assessed the height, weight, breakfast consumption habits, dietary consumption, physical activity, sleep habits, chronotype and demographic characteristics of the participants. SETTING: A cross-sectional study was conducted in a population of nurses in Japan. Dietary and health-related questionnaires were mailed to 5536 nurses aged 20-59 years, working at 346 institutions. PARTICIPANTS: A total of 3646 nurses at 274 institutions responded to the questionnaire. After removing those who met the exclusion criteria, 2450 participants were included in the statistical analysis. RESULTS: The RS breakfast-skippers had lower total energy intake, diet quality and higher BMI than DS workers, whereas the RS breakfast-consumers had a higher total energy intake and BMI than the DS workers. In the RS workers, breakfast skipping on the days of DS and the end days of evening/night shift was associated with a poorer diet quality. Additionally, breakfast skipping on the days of DS was positively associated with BMI, independent of the total energy intake and diet quality. CONCLUSIONS: Breakfast skipping on workdays may contribute to a difference in dietary intake and BMI between RS workers and DS workers and may increase BMI in RS workers, independent of dietary intake.

Influence of sleep fragmentation and fatigue on turnover of female nurses working rotating shifts.

AIMS AND OBJECTIVES: To investigate whether the sleep quality and fatigue of female nurses working rotating shifts could be used to predict future turnover status. BACKGROUND: Female nurses working rotating shifts often suffer from sleep problems and fatigue, and the turnover rates of nurses are generally higher than those of other hospital personnel. DESIGN: A prospective study. METHODS: We recruited a total of 198 female nurses working rotating shifts from December 2017 to March 2019. The nurses completed the Checklist Individual Strength (CIS) scale and wore an actigraph for seven consecutive days in order to collect their sleep parameters. Their turnover status was tracked until 31 May 2021 at which time 55 participants (27.8%) had resigned. The Cox proportional hazard model was used to analyse the factors influencing turnover. In addition, the study adhered to the STROBE checklist. RESULTS: The results revealed significant differences between the nurses in the still-working group and the resigned group in terms of the sleep quality parameters sleep efficiency (SE) and wake after sleep onset (WASO) as well as CIS scores. WASO was significantly correlated with intensity of fatigue, and fatigue was common among all of the nurses working rotating shifts. As time progressed, the sleep quality parameter WASO and CIS scores could be used to predict turnover status after 2.4 years. CONCLUSION: The results of this study indicated more sleep fragmentation and poor sleep efficiency in the resigned group. Sleep fragmentation was highly correlated with fatigue, and sleep fragmentation and fatigue could be used to predict turnover status. RELEVANCE TO CLINICAL PRACTICE: We suggest that relevant hospital management pay more attention to the sleep conditions and fatigue of female nurses working rotating shifts when arranging personnel and schedules and offer them more understanding.

The mediating role of lifestyle in the relationship between shift work, obesity and diabetes.

PURPOSE: Shift work has been related to obesity and diabetes, but the potential mediating role of lifestyle is yet unknown. Our aim was to investigate this mediating role of physical activity, diet, smoking, and sleep quality in the relationships between shift work, and obesity and diabetes. METHODS: In this cross-sectional study, 3188 shift workers and 6395 non-shift workers participated between 2013 and 2018 in periodical occupational health checks. Weight and height were objectively measured to calculate obesity (BMI ≥ 30 kg/m2). Diabetes status, physical activity, diet, smoking, and sleep quality were assessed using standardized questionnaires. Structural equation models adjusted for relevant confounders were used to analyze the mediating role of lifestyle in the relationships between shift work, and obesity and diabetes. RESULTS: Shift workers were more often obese (OR: 1.37, 95% CI 1.16-1.61) and reported more often to have diabetes (OR:1.35, 95% CI 1.003-1.11) than non-shift workers. Shift workers had lower physical activity levels, ate fruit and vegetables less often, smoked more often, and had poorer sleep quality (p < 0.05). Mediation analysis revealed that shift workers had a higher odds of obesity (OR: 1.07, 95% CI 1.01-1.15) and diabetes (OR: 1.13, 95% CI 1.02-1.27) mediated by poorer sleep quality. Lower physical activity levels (OR: 1.11, 95% CI 1.05-1.19) and lower intake of fruit and vegetables (OR: 1.04, 95% CI 1.01-1.15) were also mediators in the relationship between shift work and obesity, but not in the relationship between shift work and diabetes (p ≥ 0.05). CONCLUSION: These results imply that interventions targeting diet, physical activity and in particular sleep problems specifically developed for shift workers could potentially reduce the adverse health effects of shift work.

Relationship between the night shift work and thyroid disorders: A systematic review and meta-analysis.

OBJECTIVES: The night shift workers were reported to have health consequences, ranging from mild, as cluster headache, to severe, as heart attacks and hormonal irregularities. This study is aimed to perform a systematic review and meta-analyze of the association between the night shift work and the thyroid disorders. METHODS: We comprehensively searched eight databases, including PubMed and Google Scholar for the relevant articles. This systematic review and meta-analysis were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement. RESULTS: We finally included six papers involving 4074 participants. Four papers were eligible for meta-analysis involving 1864 night shift workers and 2017 day shift workers. We against found that thyroid stimulating hormone (TSH) is significantly higher in the night shift group compared to the day shift group. CONCLUSIONS: The higher TSH among the night shift workers is attributed to disruption of the circadian rhythm and sleep/wake cycle, with subsequent eating disorders. We proposed that more attention should be paid to the working pattern and the related health consequences.

The moderating role of lifestyle, age, and years working in shifts in the relationship between shift work and being overweight.

PURPOSE: This study aimed to investigate the relationship between the moderating role of lifestyle, age, and years working in shifts and, shift work and being overweight. METHODS: Cross-sectional data were used of 2569 shift and 4848 non-shift production workers who participated between 2013 and 2018 in an occupational health check. Overweight (BMI ≥ 25 kg/m2) was calculated using measured weight and height; lifestyle was assessed by questionnaires. Multiple-adjusted logistic regression with interaction terms between shift work and potential moderators assessed multiplicative interaction; the relative excess risk due to interaction assessed additive interaction (synergism). RESULTS: Shift work was significantly related to being overweight (OR 1.53, 95% CI 1.33 1.76). The strength of this association did not differ by level of sleep quality, fruit and vegetable intake, and physical activity (p ≥ 0.05). Additive and multiplicative interaction by smoking status was present (p < 0.01), with a stronger relationship between shift work and being overweight among non-smokers compared to smokers. Older age as well as more years of exposure to shift work were, independently from each other, related to a stronger relationship between shift work and being overweight (multiplicative interaction p < 0.05). CONCLUSION: Shift work was to a similar extent related to being overweight among those with a healthy and unhealthy lifestyle. This does, however, not imply that shift workers can behave unhealthy without any harm. Based on the evident health benefits of a healthy lifestyle, it is still recommended to get sufficient quality of sleep and to meet the recommended level of daily physical activity and, fruit and vegetable intake.

The longitudinal association between shift work and headache: results from the Danish PRISME cohort.

PURPOSE: We investigated the effect of shift work on headache. Furthermore, we investigated whether the association between shift work and headache was explained by potential mediators in terms of perceived stress, poor sleep and health behaviors. METHODS: In this longitudinal study, we used questionnaire data (collected in 2007 and 2009) from civil servants and hospital employees from the PRISME study. 2952 individuals were available for the analyses of shift work and headache and 2272 individuals were available for the analyses of shift work and migraine. Headache was operationalized as the participants' experience of "being bothered by headache during the past 4 weeks". Migraine was operationalized as "ever being diagnosed with migraine by a medical doctor". We used binary logistic regression to compare shift workers with permanent day workers and adjusted for socio-demographic factors. In a subsequent step, we adjusted for potential mediators. RESULTS: We found higher odds of unspecific headache (OR = 1.25; 95% CI 1.02-1.54) and migraine (OR = 1.72; 95% CI 1.04-2.86) among shift workers compared with day workers. Our results suggest that the effect of shift work on headache and migraine differ between men and women. Inclusion of potential mediators in the analyses did not attenuate the associations. CONCLUSION: Shift workers have higher risk of reporting being bothered by headache as well as reporting being diagnosed with migraine. Future research is needed to disentangle the underlying mechanisms with the aim of reducing headache related to occupational exposures.

Shift work, and burnout and distress among 7798 blue-collar workers.

OBJECTIVE: This study aimed to investigate the association between shift work, and burnout and distress, and differences by degree of satisfaction with shift schedule and its impact on private life. METHODS: Population 4275 non-shift factory workers and 3523 rotating 5-shift workers. Workers participated between 2009 and 2016 one to three times in the companies' periodical occupational health checks. Burnout was measured using the distance, exhaustion and competence subscales of the Dutch Maslach Burnout Inventory and distress by the subscale of the Four-Dimensional Symptom Questionnaire (scale: 0-100). Multiple-adjusted linear mixed models were used to assess between- and within-subject associations between shift work and outcomes, and differences by age, years of shift work, and satisfaction with and impact of shift schedule. RESULTS: Shift work was significantly associated with lower scores on burnout distance (B - 1.0, 95% - 1.8 to 0.3), and among those aged < 48 years with burnout exhaustion (range B - 1.3 to - 1.6). However, the effect sizes were small. Compared to non-shift workers, shift workers dissatisfied with their schedule and those experiencing a high impact on private life had significantly higher burnout (range B 1.7-6.3) and distress levels (range B 4.9-6.1). In contrast, satisfied shift workers and those experiencing a low impact of shift schedule had lower burnout (range B - 0.2 to - 2.2) and no difference in distress levels (P ≥ 0.05). No clear pattern by years of shift work was observed. CONCLUSIONS: Shift work was associated with burnout and distress in those who were dissatisfied with or who had perceived high impact on the private life of their shift schedule.

Excessive daytime sleepiness in general hospital nurses: prevalence, correlates, and its association with adverse events.

OBJECTIVE: To investigate the prevalence and correlates of excessive daytime sleepiness (EDS) in a population of hospital nurses in South China as well as the influence of EDS on the occurrence of adverse events. METHODS: A total of 1102 nurses working in a large medical center were invited to participate in this cross-sectional study (96.9% females, mean age 29.6 years). They all completed a self-reported questionnaire consisting of items on demographic variables, lifestyle factors, insomnia, anxiety, depression, and both work-related and sleep-related characteristics. RESULTS: A total of 1048 nurses gave a valid response (response rate 95.1%). Among them, 169 (16.1%) reported EDS as defined as an Epworth Sleepiness Scale ≥ 14. Depression (adjusted odds ratio = 2.24, 95% confidence interval 1.51-3.31), anxiety (1.65; 1.02-2.67), insomnia (2.29; 1.56-3.36), rotating shift work (1.98; 1.03-3.83), and low interest in work (1.74; 1.01-2.99) were all independent risk factors of the occurrence of EDS. EDS is associated with the occurrence of adverse events after controlling for confounding factors (adjusted OR 1.83, CI 1.26 to 2.67). CONCLUSIONS: EDS was common among this relatively young and healthy nurse population in south China. There were clear associations between EDS and depression, anxiety, insomnia, rotating shift work, and low work-related interest. Furthermore, EDS was an independent risk factor in the occurrence of adverse events (AEs) in our subjects.

The impact of shift and night work on health related quality of life of working women: findings from the Korea Health Panel.

BACKGROUND: Night and shift work status has been associated with health related quality of life (HRQoL) in economically active women. This study aimed to investigate the association between night or shift work status and HRQoL of economically active women and to further analyze how marital status interplays in the objected relationship. METHODS: Data were from the Korea Health Panel, 2011 to 2013. A total of 2238 working women were included for analysis. Work status was categorized into day work, night work, and rotating shift work and its association with HRQoL, measured using the EuroQol-5D (EQ-5D) index, was investigated using the generalized estimating equation (GEE) model. RESULTS: Compared to the day work reference group, the night work group (ß: -0.9757, P = 0.0202) and the rotating shift work group (ß: -0.7947, P = 0.0363) showed decreases in EQ-5D scores. This trend was maintained regardless of marital status, although decreases in health related quality of life were particularly pronounced among night shift workers with a spouse. CONCLUSION: Night and rotating shift work status was associated with HRQoL of economically active women as individuals working night and rotating shifts showed decreases in EQ-5D scores compared to individuals working day shifts. The findings of this study signify the importance of monitoring the HRQoL status of women working night and rotating shifts as these individuals may be comparatively vulnerable to reduced HRQoL.

Attitudes towards rotating shift work in clinical nurses: a Q-methodology study.

AIMS AND OBJECTIVES: To identify clinical nurses' attitudes towards rotating shift work. BACKGROUND: Many hospitals worldwide employ rotating shift work patterns to staff their facilities. Attitudes of clinical nurses towards rotating shift work vary. DESIGN: To understand clinical nurses' attitudes towards rotating shift work, Q-methodology, a method for the analysis of subjective viewpoints with the strengths of both qualitative and quantitative methods, was used. METHODS: Forty-six selected Q-statements from each of the 39 participants were classified into a normal distribution using an 11-point bipolar scale. The collected data were analysed using pc-QUANL program. RESULTS: Three discrete factors emerged as follows: factor I (rotating shift work is frustrating: objectionable perspective), factor II (rotating shift work is satisfactory: constructive perspective) and factor III (rotating shift work is problematic, but necessary: ambivalent perspective). CONCLUSIONS: The subjective viewpoints of the three identified factors can be applied in developing various roster designs for nurses engaging in rotating shift work. RELEVANCE TO CLINICAL PRACTICE: The findings provide the baseline for nurse leaders in helping nurses adjust and deal with rotating shift work.

The effects of shift work and time of day on fine motor control during handwriting.

Handwriting is an elaborate and highly automatised skill relying on fine motor control. In laboratory conditions handwriting kinematics are modulated by the time of day. This study investigated handwriting kinematics in a rotational shift system and assessed whether similar time of day fluctuations at the work place can be observed. Handwriting performance was measured in two tasks of different levels of complexity in 34 shift workers across morning (6:00-14:00), evening (14:00-22:00) and night shifts (22:00-6:00). Participants were tested during all three shifts in 2-h intervals with mobile testing devices. We calculated average velocity, script size and writing frequency to quantify handwriting kinematics and fluency. Average velocity and script size were significantly affected by the shift work schedule with the worst performance during morning shifts and the best performance during evening shifts. Our data are of high economic relevance as fine motor skills are indispensable for accurate and effective production at the work place. PRACTITIONER SUMMARY: Handwriting is one of the most complex fine motor skills in humans, which is frequently performed in daily life. In this study, we tested handwriting repeatedly at the work place in a rotational shift system. We found slower handwriting velocity and reduced script size during morning shifts.

Rotating shift and BMI increase among healthcare workers in a military hospital: pre- and post-pandemic analysis in Taiwan.

Background: The increasing prevalence of high body mass index (BMI) emphasizes the need for action. Understanding of BMI factors among military hospital healthcare workers remains limited. This study aims to address this gap by analyzing BMI risk factors and changes pre- and post-coronavirus 2019 pandemic among military hospital healthcare workers in central Taiwan from 2019 to 2021. Methods: Conducted at a military hospital in central Taiwan, this study analyzed anonymized health examination data from 2019 to 2021 for 483 healthcare workers. We performed generalized estimating equations to investigate trends in BMI and its association with various factors, including age, sex, job titles, military status, job tenure, work shifts, and lifestyle habits. Results: The risk of increased BMI was higher in 2021 compared to 2019 (risk ratio [RR]: 1.008, 95% confidence interval [CI]: 1.001-1.014). Individuals on rotating shifts had a higher risk of increased BMI compared to day shift workers (RR: 1.021; 95% CI: 1.008-1.035) and higher odds of obesity (odds ratio: 1.546; 95% CI: 1.099-2.175). Among obese individuals, BMI in soldiers was approximately 4.9% lower than in non-soldiers (RR: 0.951; 95% CI: 0.915-0.988). Conclusions: This study identified a significant post-pandemic increase in BMI among healthcare workers in a Taiwanese military hospital, with rotating shifts being a key risk factor for both increased BMI and obesity. Work-related factors influenced BMI changes among obese individuals, while non-work-related factors were significant for non-obese individuals. These findings highlight the broader effects of the pandemic and the specific impact of work-related factors on obese healthcare workers.

A latent profile analysis of shift work tolerance among Chinese male sailors during a prolonged non-24-h rotating shift schedule at sea.

Shift work tolerance (SWT) refers to the ability to adapt to shift work without significant adverse consequences. The present study aimed to examine the individual differences in SWT and their predictors and outcomes. Latent profile analyses were conducted using cross-sectional data collected form 448 Chinese male sailors who experienced a prolonged (>30 d) non-24-h rotating shift schedule at sea. Depression, anxiety, sleep disturbance, fatigue, domestic disruption, job satisfaction, work engagement, digestive and cardiovascular symptoms were included as indicators of SWT. The results showed that there existed 2 latent profiles of SWT named as High SWT group and Low SWT group. High SWT group was characterized by low levels on all negative bio-psycho-social outcomes but high levels of work engagement and job satisfaction, while Low SWT group exhibited completely opposite characteristics compared to High SWT group. The level of hardiness could predict profile membership that those with higher level of hardiness were more likely to belong to High SWT group. However, there were no significant differences observed in job performance between two groups. In conclusion, hardiness can serve as a predictor of personnel selection for shift work and hardiness-based intervention programs should be encouraged among the shift workers.

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.

Rotating night-shift work and lung cancer risk among female nurses in the United States.

The risk of lung cancer among night-shift workers is unknown. Over 20 years of follow-up (1988-2008), we documented 1,455 incident lung cancers among 78,612 women in the Nurses' Health Study. To examine the relationship between rotating night-shift work and lung cancer risk, we used multivariate Cox proportional hazard models adjusted for detailed smoking characteristics and other risk factors. We observed a 28% increased risk of lung cancer among women with 15 or more years spent working rotating night shifts (multivariate relative risk (RR) = 1.28, 95% confidence interval (CI): 1.07, 1.53; Ptrend = 0.03) compared with women who did not work any night shifts. This association was strongest for small-cell lung carcinomas (multivariate RR = 1.56, 95% CI: 0.99, 2.47; Ptrend = 0.03) and was not observed for adenocarcinomas of the lung (multivariate RR = 0.91, 95% CI: 0.67, 1.24; Ptrend = 0.40). Further, the increased risk associated with 15 or more years of rotating night-shift work was limited to current smokers (RR = 1.61, 95% CI: 1.21, 2.13; Ptrend < 0.001), with no association seen in nonsmokers (Pinteraction = 0.03). These results suggest that there are modestly increased risks of lung cancer associated with extended periods of night-shift work among smokers but not among nonsmokers. Though it is possible that this observation was residually confounded by smoking, our findings could also provide evidence of circadian disruption as a "second hit" in the etiology of smoking-related lung tumors.

Shift Work and Sleep Disturbance in the Oil Industry.

BACKGROUND: Rotating shift work is common in high-hazard industries, despite documented associations with sleep disturbance and impairment. In the oil industry, where rotating and extended shift schedules are used to staff safety-sensitive positions, work intensification and increasing overtime rates have been broadly documented over the last few decades. Research on the impacts of these work schedules on sleep and health has been limited for this workforce. METHODS: We examined sleep duration and quality among rotating shift workers in the oil industry and explored associations between schedule characteristics, sleep, and health outcomes. We recruited hourly refinery workers from the West and Gulf Coast oil sector members of the United Steelworkers union. FINDINGS: Impaired sleep quality and short sleep durations were common and associated with health and mental health outcomes common among shift workers. Shortest sleep durations followed shift rotations. Early rise and start times were associated with shorter sleep duration and poorer sleep quality. Drowsiness and fatigue-related incidents were common. CONCLUSION/APPLICATION TO PRACTICE: We observed lower sleep duration and quality and increased overtime in 12-hour rotating shift schedules. These long workdays with early start times may reduce available hours for quality sleep; here they were associated with reduced exercise and leisure activity which correlated with good sleep. This safety-sensitive population appears severely impacted by poor sleep quality, which has broader implications for process safety management. Later start times, slower rotation, and a reconsideration of two-shift schedules are interventions to consider for improving sleep quality among rotating shift workers.

The impact of shift-work light conditions on tissue-specific circadian rhythms of canonical clock genes: insights from a mouse model study.

Background: The natural day-night cycle synchronizes our circadian rhythms, but modern work practices like night shifts disrupt this pattern, leading to increased exposure to nighttime light. This exposure is linked to various health issues. While some studies have explored the effects of night shifts on human circadian rhythms, there is limited research on the consequences of long-term exposure to shift-work light conditions. Rodents can provide valuable insights into these effects. This study aimed to examine how short- or long-term exposure to rotating shifts and chronic jetlag affects the core circadian oscillators in the liver and skin of mammals. Methods: C57BL/6J male mice were subjected to simulated shift-work light conditions, including short-term or long-term rotating shifts and chronic jet-lag conditions. Liver and skin samples were collected every four hours over a 24-hour period on the second day of constant darkness. RNA was extracted and qRT-PCR analysis was conducted to measure the circadian gene expression in liver and skin tissues. Circadian rhythm analysis using CircaCompare compared the control group to mice exposed to shift-work light conditions. Results: The liver's circadian clock is significantly altered in mice under long-term rotating shift conditions, with a lesser but still noticeable impact in mice experiencing chronic jetlag. However, short-term rotating shift conditions do not significantly affect the liver's circadian clock. Conversely, all three simulated shift conditions affect the skin's circadian clock, indicating that the skin clock is more sensitive to shift-work light conditions than the liver clock. Compared to the liver, the skin's circadian clock is greatly affected by long-term rotating shift conditions. Conclusions: The study findings indicate more pronounced disturbances in the canonical clock genes of the skin compared to the liver under simulated shift-work light conditions. These results suggest that the skin clock is more vulnerable to the effects of shift-work.

The unfixed light pattern contributes to depressive-like behaviors in male mice.

Light pollution is now associated with an increased incidence of mental disorders in humans, and the unfixed light pattern (ULP) is a common light pollution that occurs in such as rotating shift work. However, how much contribution the ULP has to depression and its potential mechanism are yet unknown. Our study aimed to investigate the effect of the ULP on depressive-like behaviors in mice and to explore the links to the circadian-orexinergic system. Male C57BL/6 J mice were exposed to the ULP by subjecting them to an alternating light pattern every 6 days for 54 days. The tail suspension test (TST) and forced swimming test (FST) were conducted to assess depressive-like behaviors. The rhythm of locomotor activity and the circadian expression of cFOS in the suprachiasmatic nucleus (SCN), clock genes in the liver, and corticosterone (CORT) in serum were detected to observe changes in the circadian system. The circadian expression of orexin-A (OX-A) in the lateral hypothalamus area (LHA) and dorsal raphe nucleus (DRN) and serotonin (5-HT) in the DRN were measured to determine alterations in the orexinergic system. The results showed that mice exposed to the ULP exhibited increased immobility time in the TST and FST. The ULP significantly disrupted the circadian rhythm of locomotor activity, clock genes in the liver, and CORT in the serum. Importantly, when exposed to the ULP, cFOS expression in the SCN showed decreased amplitude. Its projection area, the LHA, had a lower mesor of OX-A expression. OX-A projection to the DRN and 5-HT expression in the DRN were reduced in mesor. Our research suggests that the ULP contributes to depressive-like behaviors in mice, which might be related to the reduced amplitude of circadian oscillation in the SCN and hypoactivity of the orexinergic system. These findings may provide novel insights into rotating shift work-related depression.