Objectives Shift work may alter workers' leisure-time and occupational physical activity (PA) levels, which might be one of the potential underlying mechanisms of the negative health effects of shift ...work. Therefore, we compared objectively measured PA levels between hospital shift and non-shift workers. Methods Data were used from Klokwerk+, a cohort study examining the health effects of shift work among healthcare workers employed in hospitals. In total, 401 shift workers and 78 non-shift workers were included, all of whom wore Actigraph GT3X accelerometers for up to seven days. Time spent sedentary, standing, walking, running, stairclimbing, and cycling during leisure time and at work was estimated using Acti4 software. Linear regression was used to compare proportions of time spent in these activities between hospital shift and non-shift workers. Results Average accelerometer wear-time was 105.9 standard deviation (SD) 14.0 waking hours over an average of 6.9 (SD 0.6) days. No differences between hospital shift and non-shift workers were found in leisure-time PA (P＞0.05). At work, shift workers were less sedentary B=-10.6% (95% CI -14.3- -6.8) and spent larger proportions of time standing B=9.5% (95% CI 6.4-12.6) and walking B=1.2% (95% CI 0.1- 2.2) than non-shift workers. However, these differences in occupational PA became smaller when the number of night shifts during accelerometer wear-time increased. Conclusions Leisure-time PA levels of hospital shift workers were similar to those of non-shift workers, but shift workers were less sedentary and more physically active (ie, standing/walking) at work. Future research to the role of occupational activities in the health effects of shift work is recommended.
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.
Background:
Nightshift work introduces light at night and causes circadian rhythm among night workers, who are considered to be at increased risk of cancer. However, in the last 2 years, nine ...population-based studies reported insignificant associations between night-shift work and cancer risks. We aimed to conduct an updated systematic review and meta-analysis to ascertain the effect of night-shift work on the incidence of cancers.
Methods:
Our protocol was registered in PROSPERO and complied with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Embase, PubMed, and Web of Science databases were used to comprehensively search studies published up to May 31, 2019. The random-effect model (Der Simonian-Laird method) was carried out to combine the risk estimates of night-shift work for cancers. The dose-response meta-analysis was performed to verify whether the association was in a dose-dependent manner.
Results:
Our literature searching retrieved 1,660 publications. Included in the meta-analyses were 57 eligible studies with 8,477,849 participants (mean age 55 years; 2,560,886 men, 4,220,154 women, and 1,696,809 not mentioned). The pooled results showed that night-shift work was not associated with the risk of breast cancer (
OR
= 1.009, 95% CI = 0.984–1.033), prostate cancer (
OR
= 1.027, 95% CI = 0.982–1.071), ovarian cancer (
OR
= 1.027, 95% CI = 0.942–1.113), pancreatic cancer (
OR
= 1.007, 95% CI = 0.910–1.104), colorectal cancer (
OR
= 1.016, 95% CI = 0.964–1.068), non-Hodgkin's lymph (
OR
= 1.046, 95% CI = 0.994–1.098), and stomach cancer (
OR
= 1.064, 95% CI = 0.971–1.157), while night-shift work was associated with a reduction of lung cancer (
OR
= 0.949, 95% CI = 0.903–0.996), and skin cancer (
OR
= 0.916, 95% CI = 0.879–0.953). The dose-response meta-analysis found that cancer risk was not significantly elevated with the increased light exposure of night- shift work.
Conclusion:
This systematic review of 57 observational studies did not find an overall association between ever-exposure to night-shift work and the risk of breast, prostate ovarian, pancreatic, colorectal, non-Hodgkin's lymph, and stomach cancers.
Shift work is common worldwide and linked to deleterious cardiovascular effects that might be underlined by dyslipidemia. The aim of this systematic review and meta-analysis is to determine the ...impact of shiftwork on dyslipidemia.
Searching in PubMed, Cochrane Library, Science Direct and Embase databases without language restriction on 15 February 2020, included studies that describe blood lipids levels or a risk measure in shift workers compared with fixed-day workers (controls). Differences by study-level characteristics were estimated using stratified meta-analysis by type of shift work, and meta-regression to examine relations between dyslipidemia and demographic, lifestyle and work characteristics. Estimates were pooled using random-effect meta-analysis.
We included a total of 66 articles, representing 197,063 workers. Shift work globally increased the levels of triglycerides (overall SMD = 0.09; 95CI 0.05 to 0.13; p < 0.001), and globally decreased the levels of c-HDL (−0.08; 95CI −0.12 to −0.03; p = 0.001). Permanent night shift workers were an at-risk type of shift for dyslipidemia with significantly higher blood levels of total cholesterol (0.22; 95CI 0.01 to 0.42; p = 0.043) and triglycerides (0.18; 0.03 to 0.33; p = 0.017), and significantly lower blood levels of c-HDL (−0.16; 95CI −0.32 to 0.00; p = 0.05). Permanent night shift workers were more at-risk for total cholesterol than rotating 3 × 8 shift workers (Coefficient 0.22; 95CI 0.01 to 0.42; p = 0.038) and rotating 2 × 12 shift workers (0.24; 0.02 to 0.46; p = 0.037), and more at-risk for triglycerides than rotating day shift workers (0.21; 95CI 0.03 to 0.38; p = 0.023). Results were non-significant for c-LDL, nor depending on type of shifts.
Shift work, and particularly permanent night shift, is associated with dyslipidaemia via elevated total cholesterol and triglycerides, and reduced HDL-cholesterol. Our current study provides a practical and valuable strengthening of the evidence-base required for preventive health initiatives and workplace reform.
Display omitted
•Shift work, involving 20% of the work force, is associated with deleterious cardiovascular effects that might be underlined by dyslipidemia.•Considering that 20% of the work force is subjected to shift work, the question of the best shifting rotation is of particular interest.•Analyzing a total of 66 articles and 197,063 workers, we showed that shift workers are associated with dyslipidemia.•We showed that shift work, and particularly permanent night shift work, increases the risk of dyslipidemia.•Promoting rotating shifts instead of permanent night shifts could be an effective preventive strategy to reduce cardiovascular risk of shift workers.
Aims
To identify patterns of declining alertness at work among fixed night shift nurses using an objective measure and to determine the effect of sleep parameters on the decline in alertness at work.
...Design
A prospective observational study.
Methods
Data were collected from 65 fixed night shift nurses who provided direct nursing care for patients in Korean hospitals between September 2020 and March 2021. Participants wore an actigraph for 14 days on their non‐dominant hand to measure sleep parameters and predict their hourly alertness scores. They completed an online survey to provide their demographic information. Mixed‐effect models were employed to determine the association between sleep parameters and the decline in alertness.
Results
The alertness scores of fixed night shift nurses constantly dropped every working hour. Scores dropped below 20% after 4 h from the beginning of the shift and below 30% after 6 h. Increased minutes in bed, minutes asleep and sleep efficiency reduced the risk of decreased alertness scores below 70. Increased sleep latency was associated with an increased risk of alertness scores dropping below 70.
Conclusion
The alertness of fixed night shift nurses drops steeply during regular hours and remains low during overtime. Sleep parameters contribute to the decline in alertness at work among fixed night shift nurses.
Impact
This study identified patterns of decline in alertness among fixed night shift nurses and the contributing factors for this decline, using an objective measure. The findings have important implications for the development of future interventions to improve the sleep hygiene of fixed night shift nurses to enhance their alertness at work.
We investigated the relationship between maternal history of nightshift work before and shift work during pregnancy and offspring risk of depression and anxiety, among mothers participating in the ...Nurses Health Study II and in their offspring enrolled in the Growing Up Today Study 2 between 2004 and 2013. Case definitions were based on offspring self-reports of physician/clinician-diagnosed depression and/or anxiety, regular antidepressant use and depressive symptoms assessed using the Center for Epidemiologic Studies Depression Scale. Multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using generalized estimating equation models. We found no associations between maternal nightshift work before pregnancy or during pregnancy and offspring mental health disorders (e.g., nightshift work before pregnancy: depression (based on physician/clinician diagnosis): ORever nightwork = 1.14; 95% CI, 0.88–1.47; either depression or anxiety: ORever nightwork = 0.93; 95% CI, 0.81–1.08; nightshift work during pregnancy: depression: ORever nightwork = 1.14; 95% CI, 0.68–1.94; depression or anxiety: ORever nightwork = 1.17; 95% CI, 0.70–1.98) and no dose-response relationship with longer history of nightshift work (all PTrend >0.10). Stratifying by maternal chronotype revealed a higher risk of depression for offspring whose mothers worked nightshifts before pregnancy and reported being definite morning chronotypes (a proxy for circadian strain) (ORever nightwork = 1.95; 95% CI, 1.17, 3.24 vs. ORever nightwork = 0.93; 95 % CI, 0.68, 1.28 for any other chronotype; PInteraction = 0.03). Further studies replicating our findings and refined understanding regarding the interplay of nightshift work and chronotype and its potential influences on offspring mental health are needed.
Chronic disruption of circadian rhythms by night shift work is associated with an increased breast cancer risk. However, little is known about the impact of night shift on peripheral circadian genes ...(CGs) and circadian‐controlled genes (CCGs) associated with breast cancer. Hence, we assessed central clock markers (melatonin and cortisol) in plasma, and peripheral CGs (PER1, PER2, PER3, and BMAL1) and CCGs (ESR1 and ESR2) in peripheral blood mononuclear cells (PBMCs). In day shift nurses (n = 12), 24‐h rhythms of cortisol and melatonin were aligned with day shift‐oriented light/dark schedules. The mRNA expression of PER2, PER3, BMAL1, and ESR2 showed 24‐h rhythms with peak values in the morning. In contrast, night shift nurses (n = 10) lost 24‐h rhythmicity of cortisol with a suppressed morning surge but retained normal rhythmic patterns of melatonin, leading to misalignment between cortisol and melatonin. Moreover, night shift nurses showed disruption of rhythmic expressions of PER2, PER3, BMAL1, and ESR2 genes, resulting in an impaired inverse correlation between PER2 and BMAL1 compared to day shift nurses. The observed trends of disrupted circadian markers were recapitulated in additional day (n = 20) and night (n = 19) shift nurses by measurement at early night and midnight time points. Taken together, this study demonstrated the misalignment of cortisol and melatonin, associated disruption of PER2 and ESR2 circadian expressions, and internal misalignment in peripheral circadian network in night shift nurses. Morning plasma cortisol and PER2, BMAL1, and ESR2 expressions in PBMCs may therefore be useful biomarkers of circadian disruption in shift workers.
Day shift nurses presented circadian rhythmicity of plasma melatonin and cortisol, and cellular PER2, PER3, BMAL1, and ESR2 expressions. Night shift disrupted circadian rhythmicity of these markers except melatonin, showing misalignment of melatonin to cortisol and other clock markers. Disruptions of PER1 and ESR1 expressions were observed in night versus day shift, although none of them showed statistically significant rhythmicity in day shift. Yellow and blue areas represent average wake time and sleep time of day and night shift nurses, respectively.
•Cancer research has focused on sleep as an outcome or symptom.•Evidence suggests circadian disruption leads to increased breast cancer risk.•Effects of sleep disruption for mammary oncogenesis are ...relatively unknown.•Sleep and interrelated circadian disruption may combine to increase risk.•Nature and strength of combined or independent risk factors are unclear.
Opportunities for restorative sleep and optimal sleep-wake schedules are becoming luxuries in industrialized cultures, yet accumulating research has revealed multiple adverse health effects of disruptions in sleep and circadian rhythms, including increased risk of breast cancer. The literature on breast cancer risk has focused largely on adverse effects of night shift work and exposure to light at night (LAN), without considering potential effects of associated sleep disruptions. As it stands, studies on breast cancer risk have not considered the impact of both sleep and circadian disruption, and the possible interaction of the two through bidirectional pathways, on breast cancer risk in the population at large. We review and synthesize this literature, including: 1) studies of circadian disruption and incident breast cancer; 2) evidence for bidirectional interactions between sleep and circadian systems; 3) studies of sleep and incident breast cancer; and 4) potential mechanistic pathways by which interrelated sleep and circadian disruption may contribute to the etiology of breast cancer.
Night shift work has been associated with cardiovascular and metabolic disease, endocrine and immunological disorders. Published studies have reported that a reduced total sleep time with sleep-wake ...cycle alterations were associated with a reduced rate of humoral response following vaccination. Our study aimed to evaluate the association between night shift work and serological status for HBV among workers employed in a university hospital in Rome. We evaluated medical records of 986 HCWs working at Tor Vergata Policlinic of Rome. We screened all study subjects for anti-HBs IgG, anti-HBc IgG and HBsAg. Serological protection for HBV was evaluated in relation to sex, age group, job task, risk setting and night shift work status. Protective titer was found in 856 (86.8%) study participants and the mean titer was significantly high in females, in subjects aged less than 40 years, in night shift workers and in high-risk setting workers. After adjustment for study covariates, night shift work was no longer associated with an HBV-protective titer. This finding suggests that a vaccination strategy for dampening HBV transmission should be carefully addressed in health care workers (HCWs) doing night shift.
Sleep disruption and circadian disruption have been proposed to be risk factors of breast cancer. The present study examined the associations of sleep-related factors, referring to night shift work, ...sleep habits, and sleep disturbances, with the plasma levels of sex hormones in premenopausal Japanese women. Study participants were 432 women who had regular menstrual cycles less than 40 days long. Information on their history of night shift work and sleep disturbances was obtained using a self-administered questionnaire. Information on their sleep habits, such as usual wake-up times, bedtimes, and ambient light level while sleeping, was obtained in an interview. The participants’ height and weight were measured. Plasma concentrations of estradiol, testosterone, dehydroepiandrosterone sulfate, sex hormone-binding globulin (SHBG), FSH, and LH were also measured. After controlling for the phase of the menstrual cycle and other covariates, more years of night shift work ≥ once a week during the past 10 years was significantly associated with a lower SHBG and a higher free estradiol level. Shorter sleep duration was significantly associated with the higher total, bioavailable, and free testosterone levels. Sleep disturbance by awaking after sleep onset was significantly associated with a high free estradiol level. The data suggest that long-term night shift work, short sleep duration, and arousal during sleep are associated with higher estradiol or testosterone levels in premenopausal women.
PDF
