Few studies have analyzed on-shift naps with regard to shift workers' health. The aim of this study was to examine the association between exposure to night work (intensity and length of exposure to ...night work) and blood pressure (BP), considering the impact of on-shift naps. A cross-sectional study was carried out at a hospital based on a questionnaire and measurement of BP. The outcomes were systolic blood pressure (SBP), diastolic blood pressure (DBP), and casual hypertension (HTN), i.e., SBP > 140 mmHg, or DBP > 90 mmHg, or reporting a prescription of antihypertensive medication. The sample comprised 449 fixed 12 h night workers who were (unofficially) allowed to nap during the night shift for up to 3 h. Approximately 42% of the sample reported napping. Among non-nappers (but not among nappers), those exposed to more work nights (≥5/fortnight) showed a DBP that was 3.66 mmHg higher than that of the reference group. The likelihood of casual HTN was more than three-fold greater among non-nappers working more nights/fortnight than among those working fewer nights/fortnight. A similar tendency was observed in a subsample of workers who did not take antihypertensive medication. The results were less consistent regarding length of exposure to night work (in years). A possible explanation is that workers who usually take on-shift naps could experience suppression of the BP increase derived from the many nights worked, while the non-nappers did not experience this suppression. The results may be explained by the relationship between napping, melatonin secretion, and attenuation of circadian misalignment. Napping likely contributes to creating a "physiologically nocturnal environment" that tends to favor the circadian system and, therefore, health. Possible negative effects related to sleep inertia deserve attention. The findings encourage new studies on this topic to improve the management of night work at hospitals in regard to workers' health.
To examine night working conditions by shift work type and identify the effects of night working conditions on nurses' perceptions of shift work safety and health effects.
Night work is the main ...factor affecting nurses' health. However, the safety of night working conditions has not been sufficiently examined in previous studies.
This study used a cross-sectional research design and an online survey using a tool released by the Australian Manufacturing Workers' Union, and the responses of 348 shift work nurses in Korea were analyzed. Logistic regression analysis was used to examine the effects of shift work conditions on the perceived safety of night work and health effects. The STROBE reporting guidelines were utilized, and data were collected from December 1 to December 31, 2021.
The adjusted logistic regression analysis showed that perceived threat to safety and the health effects of shift work were not significant according to shift type. However, night-shift-work nurses who worked alone (P = 0.003), lacked an emergency recovery system (P = 0.026), and had difficulty commuting perceived a threat to their health (P = 0.007). Additionally, nurses who experienced loss of concentration (P = 0.006) and inadequate rest time (P < 0.001) perceived the health effects of shift work.
Urgent monitoring of night work conditions is necessary for the 2-shift work type. Nurses must work night shifts together and an emergency system should be established for their safety.
Night work conditions should be improved to prevent the hazards of night work and its negative health effects on nurses.
This study suggests the necessity of a policy to enhance night work safety, including emergency coping systems and sufficient inter-shift rest time.
There is conflicting evidence on the effect of night work on sickness absence. Most previous studies used self-reporting to identify shift patterns and measure levels of sickness absence. In ...contrast, this study used objective data from electronic rosters to explore the association of nurses' patterns of night work and sickness absence. This was a retrospective longitudinal study of nurse roster data from 32 general medical and surgical wards in a large acute hospital in England. We used data from 3 years and included both registered nurses and unregistered nursing assistants. We used generalized linear-mixed models to explore the association between night work and the subsequent occurrence of sickness absence. Of 601,282 shifts worked by 1944 nursing staff, 38,051 shifts were lost due to sickness absence. After controlling for potential confounders including proportion of long (≥12 h) shifts worked, proportion of overtime shifts, proportion of shifts worked in the past 7 days, and staff grade, we found that staff working more than 75% of their shifts in the past 7 days as night shifts were more likely to experience sickness absence (aOR = 1.12; 95% CI: 1.03-1.21), compared to staff working on day only schedules. Sub-group analysis found that an association between a high proportion of night shifts worked and long-term sickness (aOR = 1.31; 95% CI: 1.15-1.50), but not short-term sickness. Working high proportions of night shifts, likely representing permanent night work schedules, is associated with a higher risk of long-term sickness absence for nurses working in inpatient adult wards in acute hospitals. The higher sickness absence rates associated with permanent night shifts could result in additional costs or loss of productivity for hospitals. This study challenges the assumption that permanent night schedules maximize circadian adjustment and, therefore, reduce health problems.
Significance It is established that glucose tolerance decreases from the morning to the evening, and that shift work is a risk factor for diabetes. However, the relative importance of the endogenous ...circadian system, the behavioral cycle (including the sleep/wake and fasting/feeding cycles), and circadian misalignment on glucose tolerance is unclear. We show that the magnitude of the effect of the endogenous circadian system on glucose tolerance and on pancreatic β-cell function was much larger than that of the behavioral cycle in causing the decrease in glucose tolerance from morning to evening. Also, independent from circadian phase and the behavioral cycle, circadian misalignment resulting from simulated night work lowered glucose tolerance—without diminishing effects upon repeated exposure—with direct relevance for shift workers.
Glucose tolerance is lower in the evening and at night than in the morning. However, the relative contribution of the circadian system vs. the behavioral cycle (including the sleep/wake and fasting/feeding cycles) is unclear. Furthermore, although shift work is a diabetes risk factor, the separate impact on glucose tolerance of the behavioral cycle, circadian phase, and circadian disruption (i.e., misalignment between the central circadian pacemaker and the behavioral cycle) has not been systematically studied. Here we show—by using two 8-d laboratory protocols—in healthy adults that the circadian system and circadian misalignment have distinct influences on glucose tolerance, both separate from the behavioral cycle. First, postprandial glucose was 17% higher (i.e., lower glucose tolerance) in the biological evening (8:00 PM) than morning (8:00 AM; i.e., a circadian phase effect), independent of the behavioral cycle effect. Second, circadian misalignment itself (12-h behavioral cycle inversion) increased postprandial glucose by 6%. Third, these variations in glucose tolerance appeared to be explained, at least in part, by different mechanisms: during the biological evening by decreased pancreatic β-cell function (27% lower early-phase insulin) and during circadian misalignment presumably by decreased insulin sensitivity (elevated postprandial glucose despite 14% higher late-phase insulin) without change in early-phase insulin. We explored possible contributing factors, including changes in polysomnographic sleep and 24-h hormonal profiles. We demonstrate that the circadian system importantly contributes to the reduced glucose tolerance observed in the evening compared with the morning. Separately, circadian misalignment reduces glucose tolerance, providing a mechanism to help explain the increased diabetes risk in shift workers.
Exposure to Artificial Light At Night (ALAN) results in a disruption of the circadian system, which is deleterious to health. In industrialized countries, 75% of the total workforce is estimated to ...have been involved in shift work and night work. Epidemiologic studies, mainly of nurses, have revealed an association between sustained night work and a 50–100% higher incidence of breast cancer. The potential and multifactorial mechanisms of the effects include the suppression of melatonin secretion by ALAN, sleep deprivation, and circadian disruption.
Shift and/or night work generally decreases the time spent sleeping, and it disrupts the circadian time structure. In the long run, this desynchronization is detrimental to health, as underscored by a large number of epidemiological studies that have uncovered elevated rates of several diseases, including cancer, diabetes, cardiovascular risks, obesity, mood disorders and age-related macular degeneration. It amounts to a public health issue in the light of the very substantial number of individuals involved. The IARC has classified shift work in group 2A of “probable carcinogens to humans” since “they involve a circadian disorganization”. Countermeasures to the effects of ALAN, such as melatonin, bright light, or psychotropic drugs, have been proposed as a means to combat circadian clock disruption and improve adaptation to shift and night work. We review the evidence for the ALAN impacts on health. Furthermore, we highlight the importance of an in-depth mechanistic understanding to combat the detrimental properties of exposure to ALAN and develop strategies of prevention.
Shift work is a risk factor for hypertension, inflammation, and cardiovascular disease. This increased risk cannot be fully explained by classic risk factors. One of the key features of shift workers ...is that their behavioral and environmental cycles are typically misaligned relative to their endogenous circadian system. However, there is little information on the impact of acute circadian misalignment on cardiovascular disease risk in humans. Here we show—by using two 8-d laboratory protocols—that short-term circadian misalignment (12-h inverted behavioral and environmental cycles for three days) adversely affects cardiovascular risk factors in healthy adults. Circadian misalignment increased 24-h systolic blood pressure (SBP) and diastolic blood pressure (DBP) by 3.0 mmHg and 1.5 mmHg, respectively. These results were primarily explained by an increase in blood pressure during sleep opportunities (SBP, +5.6 mmHg; DBP, +1.9 mmHg) and, to a lesser extent, by raised blood pressure during wake periods (SBP, +1.6 mmHg; DBP, +1.4 mmHg). Circadian misalignment decreased wake cardiac vagal modulation by 8–15%, as determined by heart rate variability analysis, and decreased 24-h urinary epinephrine excretion rate by 7%, without a significant effect on 24-h urinary norepinephrine excretion rate. Circadian misalignment increased 24-h serum interleukin-6, C-reactive protein, resistin, and tumor necrosis factor-α levels by 3–29%. We demonstrate that circadian misalignment per se increases blood pressure and inflammatory markers. Our findings may help explain why shift work increases hypertension, inflammation, and cardiovascular disease risk.
Epidemiological studies on the relationship of shift work or night work with risk of total and cause-specific mortality have given conflicting results. We aimed at conducting a meta-analysis to ...summarize the evidence from cohort studies.
Embase, PubMed, Web of Science and Scopus databases were searched for eligible studies up to Mar 2021. Cohort studies evaluating the associations of shift work or night work with risk of all-cause, cardiovascular or cancer mortality were reviewed. Study-specific risk estimates were pooled by fixed-effect models when the heterogeneity was not detected; otherwise, random-effect models were employed.
We identified seventeen eligible articles (sixteen cohorts). A total of 958,674 cohort participants were included, with 38,413 total deaths, 24,713 cardiovascular deaths and 10,219 cancer deaths during follow-up. According to the Newcastle–Ottawa Scale, fifteen studies were considered as relatively high quality with low risk of bias. Compared with regular daytime workers, the pooled relative risks for all-cause, cardiovascular and cancer mortality were 1.02 (95% CI: 0.99, 1.06), 1.18 (95% CI: 0.94, 1.47) and 1.05 (95% CI: 0.83, 1.34) for those ever exposing to shift work, respectively. Compared with daytime workers or those never exposing to night work, the pooled relative risks for all-cause, cardiovascular and cancer mortality were 1.06 (95% CI: 1.03, 1.08), 1.15 (95% CI: 1.03, 1.29) and 1.04 (95% CI: 1.00, 1.08) for those ever exposing to night work, respectively. Moderate to high level of heterogeneity across the studies was detected. Publication bias was not detected.
Night work may be associated with higher risk of all-cause, cardiovascular and cancer mortality, suggesting that night workers compared with daytime workers may be at higher risk of death, especially due to cardiovascular disease.
•Night work was associated with higher risk of all-cause mortality.•Such higher risk of death may be driven by death from cardiovascular disease.•Night work might slightly increase the risk of death from cancer.•Moderate to high heterogeneity was detected in the meta-analysis.
A nighttime nap is expected to mitigate melatonin suppression during night work by blocking light input to the retina, but it is unclear. In the present study, we investigated the effects of a nap ...break on melatonin level, subjective sleepiness, and vigilance performance during simulated night work. Eleven healthy young males (mean ± SD age: 22.2 ± 4.1 years) participated in counterbalanced crossover design experiments with two conditions (nap vs. no nap). The subjects performed 12-hour simulated night work from 21:00 to 9:00 h (illuminance: ~500 lx). Subjects with a nap condition took a nap for 2 hours in a dark room from 3:00, while subjects with a no nap condition continued the simulated night work. The results showed that immediately after the 2-h nap break, the melatonin level at 5:00 h temporarily recovered from light-induced melatonin suppression during the simulated night work but significantly suppressed again at 7:00 and 9:00 h. Subjective alertness and vigilance performance were impaired immediately after the nap break but subsequently enhanced. The results suggest that a single nap break for 2 hours could be a strategy to enhance alertness during the last part of night shift but inadequate for mitigating melatonin suppression.
This study aims to quantitatively summarize the association between night shift work and the risk of metabolic syndrome (MetS), with special reference to the dose–response relationship with years of ...night shift work. We systematically searched all observational studies published in English on PubMed and Embase from 1971 to 2013. We extracted effect measures (relative risk, RR; or odd ratio, OR) with 95% confidence interval (CI) from individual studies to generate pooled results using meta‐analysis approach. Pooled RR was calculated using random‐ or fixed‐effect model. Downs and Black scale was applied to assess the methodological quality of included studies. A total of 13 studies were included. The pooled RR for the association between ‘ever exposed to night shift work’ and MetS risk was 1.57 (95% CI = 1.24–1.98, pₕₑₜₑᵣₒgₑₙₑᵢₜy = 0.001), while a higher risk was indicated in workers with longer exposure to night shifts (RR = 1.77, 95% CI = 1.32–2.36, pₕₑₜₑᵣₒgₑₙₑᵢₜy = 0.936). Further stratification analysis demonstrated a higher pooled effect of 1.84 (95% CI = 1.45–2.34) for studies using the NCEP‐ATPIII criteria, among female workers (RR = 1.61, 95% CI = 1.10–2.34) and the countries other than Asia (RR = 1.65, 95% CI = 1.39–1.95). Sensitivity analysis confirmed the robustness of the results. No evidence of publication bias was detected. The present meta‐analysis suggested that night shift work is significantly associated with the risk of MetS, and a positive dose–response relationship with duration of exposure was indicated.
The effect of shift work on eating habits Souza, Renata Vieira; Sarmento, Roberta Aguiar; de Almeida, Jussara Carnevale ...
Scandinavian journal of work, environment & health,
01/2019, Volume:
45, Issue:
1
Journal Article
Peer reviewed
Open access
Objective This systematic review aimed to evaluate the association between shift work and eating habits. Methods The protocol was registered in PROSPERO (number 42015024680). PubMed, EMBASE, Scopus, ...and Web of Science were searched for published reports. Of 2432 identified articles, 33 observational studies met the inclusion criteria. Their methodological approaches were assessed using the Newcastle-Ottawa Scale. Data were extracted using a standardized form. Studies were considered to have a low or a high risk of bias according to a percentage score of quality. Results The majority of the studies presented a quality score of <70% and a high risk of bias for comparability, sample selection and non-respondents. Shift workers show changes in meal patterns, skipping more meals and consuming more food at unconventional times. They also show higher consumption of unhealthy foods, such as saturated fats and soft drinks. Conclusions This review suggests that shift work can affect the quality of workers' diets, but new studies, especially longitudinal studies, which examine the time of exposure to shift work, the duration of the workday and sleep patterns, are necessary to confirm this association.
PDF
